WorldWideScience

Sample records for free-space optical communications

  1. Free space optical communication

    CERN Document Server

    Kaushal, Hemani; Kar, Subrat

    2017-01-01

    This book provides an in-depth understanding of free space optical (FSO) communication with a particular emphasis on optical beam propagation through atmospheric turbulence. The book is structured in such a way that it provides a basic framework for the beginners and also gives a concise description from a designer’s perspective. The book provides an exposure to FSO technology, fundamental limitations, design methodologies, system trade-offs, acquisition, tracking and pointing (ATP) techniques and link-feasibility analysis. The contents of this book will be of interest to professionals and researchers alike. The book may also be used as a textbook for engineering coursework and professional training.

  2. Exotic Optical Beam Classes for Free-Space Communication

    Science.gov (United States)

    2016-03-24

    AFRL-AFOSR-VA-TR-2016-0131 Exotic optical beam classes for free- space communication Greg Gbur UNIVERSITY OF NOTH CAROLINA AT CHARLOTTE Final Report...12-2015 4. TITLE AND SUBTITLE Exotic optical beam classes for free- space communication 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1-0009 5c...free- space communication and sensing applications Final Performance Report Greg Gbur University of North Carolina at Charlotte Department of

  3. Systems and methods for free space optical communication

    Science.gov (United States)

    Harper, Warren W [Benton City, WA; Aker, Pamela M [Richland, WA; Pratt, Richard M [Richland, WA

    2011-05-10

    Free space optical communication methods and systems, according to various aspects are described. The methods and systems are characterized by transmission of data through free space with a digitized optical signal acquired using wavelength modulation, and by discrimination between bit states in the digitized optical signal using a spectroscopic absorption feature of a chemical substance.

  4. Optical multiaccess free-space laser communication system

    Science.gov (United States)

    Jiang, Lun; Zhang, Li-Zhong; Wang, Chao; An, Yan; Hu, Yuan

    2016-08-01

    With urgent demand for an integrated information network and development of free-space laser communication technology, research on high-rate laser communication networking technology is vital. This study analyzed the technical difficulties related to space laser communication networking and proposed a laser communication networking solution. A wide-angle beam expander and dual-rotating prism group were incorporated into a multiaccess optical laser communication antenna. The wide-angle beam expander collects signal light from different directions; the dual-rotating prism group tracks different targets simultaneously. This paper presents an overall scheme allowing multiaccess free-space laser communications based on the optical antenna described and the associated relay optics and transceiver subsystems.

  5. Free Space Optical Communication for Tactical Operations

    Science.gov (United States)

    2016-09-01

    Approved by: John H. Gibson Thesis Advisor Gurminder Singh, Ph.D. Co-Advisor Peter Denning, Ph.D. Chair , Department of...experiments pertaining to a laser communications system and to provide a fair analysis of the FSO product’s network performance. C. SCOPE This thesis...process is required to disable sighting scopes before laser is turned on. 18. IR cameras may be able to detect scintillation effects at the terminal

  6. Spectrum Scarcity and Free Space Optical Communications

    KAUST Repository

    Alouini, Mohamed-Slim

    2014-01-06

    Exact and asymptotic studies of the average error probability of wireless communication systems over generalized fading channels have been extensively pursued over the last two decades. In contrast, studies and results dealing with the channel capacity in these environments have been more scarce. In the first part of this talk, we present a generic moment generating function-based approach for the exact computation of the channel capacity in such kind of environments. The resulting formulas are applicable to systems having channel state information (CSI) at the receiver and employing maximal-ratio combining or equal-gain combining multichannel reception. The analysis covers the case where the combined paths are not necessarily independent or identically distributed. In all cases, the proposed approach leads to an expression of the ergodic capacity involving a single finite-range integral, which can be easily computed numerically. In the second part of the talk, we focus on the asymptotic analysis of the capacity in the high and low signal-to-noise ratio (SNR) regimes. More specifically, we offer new simple closed-form formulas that give an intuitive understanding of the capacity behavior at these two extreme regimes. Our characterization covers not only the case where the CSI is available only at the receiver but also the case where the CSI is available at both the transmitter and receiver.

  7. Development of the free-space optical communications analysis software

    Science.gov (United States)

    Jeganathan, Muthu; Mecherle, G. Stephen; Lesh, James R.

    1998-05-01

    The Free-space Optical Communication Analysis Software (FOCAS) was developed at the Jet Propulsion Laboratory (JPL) to provide mission planners, systems engineers and communications engineers with an easy to use tool to analyze direct-detection optical communication links. The FOCAS program, implemented in Microsoft Excel, gives it all the power and flexibility built into the spreadsheet. An easy-to-use interface, developed using Visual Basic for Applications (VBA), to the spreadsheet allows easy input of data and parameters. A host of pre- defined components allow an analyst to configure a link without having to know the details of the components. FOCAS replaces the over-a-decade-old FORTRAN program called OPTI widely used previously at JPL. This paper describes the features and capabilities of the Excel-spreadsheet-based FOCAS program.

  8. Free space optical communication links in a marine environment

    Science.gov (United States)

    Gadwal, Veena; Hammel, Stephen

    2006-08-01

    We present an analysis of Free Space Optical (FSO) signal attenuation experienced in a marine environment. This work is in support of the Communication Link Assessment in Marine Environments program (CLAIME), for the Navy's investment in a network infrastructure for high altitude tactical layer connectivity to the Global Information Grid. The expanded bandwidth requirement can be realized using FSO networking capabilities. The performance of the link needs to be evaluated for different platforms such as ship-to-ship, airborne-to-ship, as well as airborne-to-airborne links. Near surface horizontal links required for ship-to-ship communications will be described in detail. The challenges faced in this environment include determining the attenuation due to aerosol scattering as well as optical turbulence. Determining the attenuation due to fog, haze, rain and snow will be addressed as well.

  9. Free-Space Optical communication using visible light

    Institute of Scientific and Technical Information of China (English)

    HU Guo-yong; CHEN Chang-ying; CHEN Zhen-qiang

    2007-01-01

    The possibility of visible red light laser being used as signal light source for Free-Space Optical (FSO) communication is proposed. Based on analysis of transmission in atmospheric channel concerning 650 nm laser beam, performance of wireless laser communication link utilizing a low power red laser diode was evaluated. The proposed system can achieve a maximum range of 300 m at data rate 100 Mb/s theoretically. An experimental short-range link at data rate 10 Mb/s covering 300 m has been implemented in our university. It is feasible to enhance the system performance such as link range and data rate by increasing transmitting power and decreasing laser beam divergence angle or through other approaches.

  10. Semiconductor optoelectronic devices for free-space optical communications

    Science.gov (United States)

    Katz, J.

    1983-01-01

    The properties of individual injection lasers are reviewed, and devices of greater complexity are described. These either include or are relevant to monolithic integration configurations of the lasers with their electronic driving circuitry, power combining methods of semiconductor lasers, and electronic methods of steering the radiation patterns of semiconductor lasers and laser arrays. The potential of AlGaAs laser technology for free-space optical communications systems is demonstrated. These solid-state components, which can generate and modulate light, combine the power of a number of sources and perform at least part of the beam pointing functions. Methods are proposed for overcoming the main drawback of semiconductor lasers, that is, their inability to emit the needed amount of optical power in a single-mode operation.

  11. Fading testbed for free-space optical communications

    Science.gov (United States)

    Shrestha, Amita; Giggenbach, Dirk; Mustafa, Ahmad; Pacheco-Labrador, Jorge; Ramirez, Julio; Rein, Fabian

    2016-10-01

    Free-space optical (FSO) communication is a very attractive technology offering very high throughput without spectral regulation constraints, yet allowing small antennas (telescopes) and tap-proof communication. However, the transmitted signal has to travel through the atmosphere where it gets influenced by atmospheric turbulence, causing scintillation of the received signal. In addition, climatic effects like fogs, clouds and rain also affect the signal significantly. Moreover, FSO being a line of sight communication requires precise pointing and tracking of the telescopes, which otherwise also causes fading. To achieve error-free transmission, various mitigation techniques like aperture averaging, adaptive optics, transmitter diversity, sophisticated coding and modulation schemes are being investigated and implemented. Evaluating the performance of such systems under controlled conditions is very difficult in field trials since the atmospheric situation constantly changes, and the target scenario (e.g. on aircraft or satellites) is not easily accessible for test purposes. Therefore, with the motivation to be able to test and verify a system under laboratory conditions, DLR has developed a fading testbed that can emulate most realistic channel conditions. The main principle of the fading testbed is to control the input current of a variable optical attenuator such that it attenuates the incoming signal according to the loaded power vector. The sampling frequency and mean power of the vector can be optionally changed according to requirements. This paper provides a brief introduction to software and hardware development of the fading testbed and measurement results showing its accuracy and application scenarios.

  12. Transceiving protocol design for a free space optical communication system

    Science.gov (United States)

    Wang, Hualong; Su, Wanxin; Xing, Zhongbao

    2008-12-01

    A new transceiving protocol is demonstrated for a Free Space Optical (FSO) communication system, and it's discussed in two parts: the transmitting protocol and the receiving protocol. During the discussion of these two parts, the cooperation of them is also discussed. Different from wired communication, an FSO system modulates the data on a narrow beam of laser transmitting through the free space or the atmosphere, and the protocol presented in this paper is mainly optimized for terrestrial Free Space Optical links, in which the signal channel of the system is mainly the atmosphere. Due to the complex composition and activity of the atmosphere, this signal channel brings in great influence on the transmitting laser in it, for example, the absorption and scattering of the atmosphere molecules and aerosols, the scintillation of received laser power caused by the turbulence of the atmosphere, all of which results in a much higher Bit Error Rate (BER) of the communication system. Thus in designing a protocol for an FSO system, more effort should be taken in the encoding of the data stream, the synchronization of the data stream, error checking and exception handling. The main function of the transmitting protocol includes interfacing the outer input data with a parallel port, buffering the input data, encoding the input data stream, serializing the parallel data and output the serialized data. It also has an output management unit to manage the activity of each part of the transmitting protocol. The main function of the receiving protocol includes filtering and synchronizing the input serial data stream, paralleling the serial data stream, decoding the input data, error checking, exception handling and interfacing the outer receiver with a parallel port. The entire transceiving protocol could be programmed into a single FPGA chip to improve system integrity and reduce the system cost. The presented protocol could be taken as "protocol transparent" for outer interfaces

  13. Development of the Free-space Optical Communications Analysis Software (FOCAS)

    Science.gov (United States)

    Jeganathan, M.; Mecherle, G.; Lesh, J.

    1998-01-01

    The Free-space Optical Communications Analysis Software (FOCAS) was developed at the Jet Propulsion Laboratory (JPL) to provide mission planners, systems engineers and communications engineers with an easy to use tool to analyze optical communications link.

  14. Fast QC-LDPC code for free space optical communication

    Science.gov (United States)

    Wang, Jin; Zhang, Qi; Udeh, Chinonso Paschal; Wu, Rangzhong

    2017-02-01

    Free Space Optical (FSO) Communication systems use the atmosphere as a propagation medium. Hence the atmospheric turbulence effects lead to multiplicative noise related with signal intensity. In order to suppress the signal fading induced by multiplicative noise, we propose a fast Quasi-Cyclic (QC) Low-Density Parity-Check (LDPC) code for FSO Communication systems. As a linear block code based on sparse matrix, the performances of QC-LDPC is extremely near to the Shannon limit. Currently, the studies on LDPC code in FSO Communications is mainly focused on Gauss-channel and Rayleigh-channel, respectively. In this study, the LDPC code design over atmospheric turbulence channel which is nether Gauss-channel nor Rayleigh-channel is closer to the practical situation. Based on the characteristics of atmospheric channel, which is modeled as logarithmic-normal distribution and K-distribution, we designed a special QC-LDPC code, and deduced the log-likelihood ratio (LLR). An irregular QC-LDPC code for fast coding, of which the rates are variable, is proposed in this paper. The proposed code achieves excellent performance of LDPC codes and can present the characteristics of high efficiency in low rate, stable in high rate and less number of iteration. The result of belief propagation (BP) decoding shows that the bit error rate (BER) obviously reduced as the Signal-to-Noise Ratio (SNR) increased. Therefore, the LDPC channel coding technology can effectively improve the performance of FSO. At the same time, the BER, after decoding reduces with the increase of SNR arbitrarily, and not having error limitation platform phenomenon with error rate slowing down.

  15. Performance analysis of fiber-based free-space optical communications with coherent detection spatial diversity.

    Science.gov (United States)

    Li, Kangning; Ma, Jing; Tan, Liying; Yu, Siyuan; Zhai, Chao

    2016-06-10

    The performances of fiber-based free-space optical (FSO) communications over gamma-gamma distributed turbulence are studied for multiple aperture receiver systems. The equal gain combining (EGC) technique is considered as a practical scheme to mitigate the atmospheric turbulence. Bit error rate (BER) performances for binary-phase-shift-keying-modulated coherent detection fiber-based free-space optical communications are derived and analyzed for EGC diversity receptions through an approximation method. To show the net diversity gain of a multiple aperture receiver system, BER performances of EGC are compared with a single monolithic aperture receiver system with the same total aperture area (same average total incident optical power on the aperture surface) for fiber-based free-space optical communications. The analytical results are verified by Monte Carlo simulations. System performances are also compared for EGC diversity coherent FSO communications with or without considering fiber-coupling efficiencies.

  16. Laser guide stars for optical free-space communications

    Science.gov (United States)

    Mata-Calvo, Ramon; Bonaccini Calia, Domenico; Barrios, Ricardo; Centrone, Mauro; Giggenbach, Dirk; Lombardi, Gianluca; Becker, Peter; Zayer, Igor

    2017-02-01

    The German Aerospace Center (DLR) and the European Southern Observatory (ESO) performed a measurement campaign together in April and July 2016 at Teide-Observatory (Tenerife), with the support of the European Space Agency (ESA), to investigate the use of laser guide stars (LGS) in ground to space optical communications. Atmospheric turbulence causes strong signal fluctuations in the uplink, due to scintillation and beam wander. In space communications, the use of the downlink channel as reference for pointing and for pre-distortion adaptive optics is limited by the size of the isokinetic and isoplanatic angle in relation to the required point-ahead angle. Pointing and phase errors due to the decorrelation between downward and upward beam due to the point-ahead angle may have a severe impact on the required transmit power and the stability of the communications link. LGSs provide a self-tailored reference to any optical ground-to-space link, independently of turbulence conditions and required point-ahead angle. In photon-starved links, typically in deep-space scenarios, LGSs allow dedicating all downlink received signal to communications purposes, increasing the available link margin. The scope of the joint DLR-ESO measurement campaign was, first, to measure the absolute value of the beam wander (uplink-tilt) using a LGS, taking a natural star as a reference, and, second, to characterize the decrease of correlation between uplink-tilt and downlink-tilt with respect to the angular separation between both sources. This paper describes the experiments performed during the measurement campaigns, providing an overview of the measured data and the first outcomes of the data post-processing.

  17. Integrated Approach to Free Space Optical Communications in Strong Turbulence

    Science.gov (United States)

    2011-09-01

    24 EDFA erbium-doped fiber amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 APD...either optically or electrically. An erbium-doped fiber amplifier ( EDFA ), which optically enhances the signal but is susceptible to increased noise due to

  18. Experimental demonstration of the full-wave iterative compensation in free space optical communications.

    Science.gov (United States)

    Biérent, Rudolph; Velluet, Marie-Thérèse; Védrenne, Nicolas; Michau, Vincent

    2013-07-01

    Long-range free space optical communications suffer from atmospheric turbulence effects. To mitigate them, a bidirectional full-wave compensation technique seems promising. We present an experimental implementation and characterization of this concept on a laboratory breadboard. Experimental results confirm former numerical results for similar propagation conditions. The effects of measurement and control errors are analyzed by numerical modeling.

  19. New challenges in wireless and free space optical communications

    Science.gov (United States)

    Mansour, A.; Mesleh, R.; Abaza, M.

    2017-02-01

    This manuscript presents a survey on new challenges in wireless communication systems and discusses recent approaches to address some recently raised problems by the wireless community. At first a historical background is briefly introduced. Challenges based on modern and real life applications are then described. Up to date research fields to solve limitations of existing systems and emerging new technologies are discussed. Theoretical and experimental results based on several research projects or studies are briefly provided. Essential, basic and many self references are cited. Future researcher axes are briefly introduced.

  20. Free space optical communication based on pulsed lasers

    Science.gov (United States)

    Drozd, Tadeusz; Mierczyk, Zygmunt; Zygmunt, Marek; Wojtanowski, Jacek

    2016-12-01

    Most of the current optical data transmission systems are based on continuous wave (cw) lasers. It results from the tendency to increase data transmission speed, and from the simplicity in implementation (straightforward modulation). Pulsed lasers, which find many applications in a variety of industrial, medical and military systems, in this field are not common. Depending on the type, pulsed lasers can generate instantaneous power which is many times greater when compared with cw lasers. As such, they seem to be very attractive to be used in data transmission technology, especially due to the potentially larger ranges of transmission, or in adverse atmospheric conditions where low power cw-lasersbased transmission is no longer feasible. It is also a very practical idea to implement data transmission capability in the pulsed laser devices that have been around and already used, increasing the functionality of this type of equipment. At the Institute of Optoelectronics at Military University of Technology, a unique method of data transmission based on pulsed laser radiation has been developed. This method is discussed in the paper in terms of both data transmission speed and transmission range. Additionally, in order to verify the theoretical assumptions, modules for voice and data transmission were developed and practically tested which is also reported, including the measurements of Bit Error Rate (BER) and performance vs. range analysis.

  1. Data transmission with twisted light through a free-space to fiber optical communication link

    Science.gov (United States)

    Brüning, Robert; Ndagano, Bienvenu; McLaren, Melanie; Schröter, Siegmund; Kobelke, Jens; Duparré, Michael; Forbes, Andrew

    2016-03-01

    Mode division multiplexing (MDM), where information is transmitted in the spatial modes of light, is mooted as a future technology with which to transmit large bits of information. However, one of the key issues in optical communication lies in connecting free-space to optical fiber networks, otherwise known as the ‘last mile’ problem. This is particularly problematic for MDM as the eigenmodes of free-space and fibers are in general not the same. Here we demonstrate a data transmission scheme across a free-space and fiber link using twisted light in the form of Laguerre-Gaussian (LG) azimuthal modes. As a proof-of-principle we design and implement a custom fiber where the supported LG modes can be grouped into five non-degenerate sets, and successfully transmit a gray-scale image across the composite link using one mode from each group, thereby ensuring minimal crosstalk.

  2. Fiber coupling and field mixing of coherent free-space optical beams in satellite communications

    Science.gov (United States)

    Poliak, J.; Giggenbach, D.; Mata Calvo, R.; Bok, D.

    2016-03-01

    Effective coupling of the optical field from free-space to optical fiber is an essential prerequisite for modern free-space optical communications systems. It allows for easier system integration with active and passive optical fiber-coupled components as well as for efficient optical field mixing for coherent communications. While coupling into single-mode fiber provides the advantage of using low-noise erbium-doped fiber preamplifiers, its relatively small mode field diameter limits achievable fiber coupling efficiency. Coupling into multimode fiber (MMF) increases the fiber coupling efficiency while introducing other spurious effects the authors have set out to analyze. The study of free-space optical beam coupling in the context of satellite communications will be presented. Here, we assume satellite link scenarios with different elevations, which correspond to different index-of-refraction turbulence (IRT) conditions. IRT gives rise to both intensity and phase aberration of the received optical field, which then causes extended speckle patterns in the focus of the receiver telescope. The speckle field at the fiber input is calculated by means of Fourier transform of the received field. Using dedicated modelling software, study of the fiber coupling efficiency, polarization preservation and high-order mode coupling in different multi-mode fibers is carried out.

  3. Retro-detective control structures for free-space optical communication links.

    Science.gov (United States)

    Jin, Xian; Barg, Jason E; Holzman, Jonathan F

    2009-12-21

    A corner-cube-based retro-detection photocell is introduced. The structure consists of three independent and mutually perpendicular photodiodes (PDs), whose differential photocurrents can be used to probe the alignment state of incident beams. These differential photocurrents are used in an actively-controlled triangulation procedure to optimize the communication channel alignment in a free-space optical (FSO) system. The active downlink and passive uplink communication capabilities of this system are demonstrated.

  4. Atmospheric transmission at ~1.55 μm for free-space optical communication

    Science.gov (United States)

    Zeller, John; Manzur, Tariq

    2010-04-01

    Free-space optics (FSO) holds the potential for high bandwidth communication, but atmospheric conditions can significantly affect the capability of a communication system to transfer information successfully. The effects of atmosphere on FSO communication and consequent optimal wavelength range for transmission are investigated through MODTRAN-based modeling of 1.55 μm transmission for multiple elevation angles in atmospheric conditions including clear maritime, desert extinction, and various levels of rain and fog. Beam transmission was also simulated for different relevant elevations for surface-to-surface and surface-to-air free-space optical communication networks. The atmospheric, free-space, and scintillation losses are investigated for optical path lengths of 2 km to determine transmit power required for successful data reception. In addition, FSO transmitter and receiver circuits were designed to optically relay an analog video signal and tested at path distances of up to 130 m. Using advanced tunable laser sources to provide illumination across wavelength ranges, particularly around the eye-safe 1.55 μm wavelength, it should be possible to overcome transmission limitations associated with adverse weather and atmospheric conditions.

  5. Active disturbance rejection controller of fine tracking system for free space optical communication

    Science.gov (United States)

    Cui, Ning; Liu, Yang; Chen, Xinglin; Wang, Yan

    2013-08-01

    Free space optical communication is one of the best approaches in future communications. Laser beam's acquisition, pointing and tracking are crucial technologies of free space optical communication. Fine tracking system is important component of APT (acquisition, pointing and tracking) system. It cooperates with the coarse pointing system in executing the APT mission. Satellite platform vibration and disturbance, which reduce received optical power, increase bit error rate and affect seriously the natural performance of laser communication. For the characteristic of satellite platform, an active disturbance rejection controller was designed to reduce the vibration and disturbance. There are three major contributions in the paper. Firstly, the effects of vibration on the inter satellite optical communications were analyzed, and the reasons and characters of vibration of the satellite platform were summarized. The amplitude-frequency response of a filter was designed according to the power spectral density of platform vibration of SILEX (Semiconductor Inter-satellite Laser Experiment), and then the signals of platform vibration were generated by filtering white Gaussian noise using the filter. Secondly, the fast steering mirror is a key component of the fine tracking system for optical communication. The mechanical design and model analysis was made to the tip/tilt mirror driven by the piezoelectric actuator and transmitted by the flexure hinge. The transfer function of the fast steering mirror, camera, D/A data acquisition card was established, and the theory model of transfer function of this system was further obtained. Finally, an active disturbance rejection control method is developed, multiple parallel extended state observers were designed for estimation of unknown dynamics and external disturbance, and the estimated states were used for nonlinear feedback control and compensation to improve system performance. The simulation results show that the designed

  6. Reflection-Style Optical Antenna Deformations in Free-Space Laser Communications

    Directory of Open Access Journals (Sweden)

    Wanqing Xie

    2011-01-01

    Full Text Available Diversified deformations on reflection-style optical antennas caused by processing technique and complex outer-space environment in free-space laser communications are modeled by wavelet analysis. Influence due to the deformations on received power is studied by distortion attenuation factor based on the model. Theoretical and numerical analysis shows that distortion attenuation factor increases with shift factor of the model, decreases with dilation factor of the model, and decreases with irregular fluctuations with wavelet coefficient of the model. To the special case that the deformation can be well approximated to a constant, distortion attenuation factor varies periodically with the linear increase of the deformation coefficient. A reference for the requirement on the precision of optical antenna is proposed, and a method to reduce the effect of deformation is recommended. It is hoped that the study can be used in the design of free space laser communication systems.

  7. Swarm intelligence for atmospheric compensation in free space optical communication-Modified shuffled frog leaping algorithm

    Science.gov (United States)

    Li, Zhaokun; Cao, Jingtai; Zhao, Xiaohui; Liu, Wei

    2015-03-01

    A conventional adaptive optics (AO) system is widely used to compensate atmospheric turbulence in free space optical (FSO) communication systems, but wavefront measurements based on phase-conjugation principle are not desired under strong scintillation circumstances. In this study we propose a novel swarm intelligence optimization algorithm, which is called modified shuffled frog leaping algorithm (MSFL), to compensate the wavefront aberration. Simulation and experiments results show that MSFL algorithm performs well in the atmospheric compensation and it can increase the coupling efficiency in receiver terminal and significantly improve the performance of the FSO communication systems.

  8. Free-space optical communication link using perfect vortex beams carrying orbital angular momentum (OAM)

    Science.gov (United States)

    Zhu, Fuquan; Huang, Sujuan; Shao, Wei; Zhang, Jie; Chen, Musheng; Zhang, Weibing; Zeng, Junzhang

    2017-08-01

    We experimentally demonstrate a free-space optical communication link using perfect vortex beams. Perfect vortex beams with different topological charges are generated using a phase-modulation-type spatial light modulator (SLM) loaded with novel phase holograms based on the Bessel function. With the help of a microscope objective and simple lens, perfect vortex beams are transmitted effectively for a certain distance. After completing the demodulation of perfect vortex beams carrying OFDM 16-QAM signals and a series of offline processing on the Gaussian bright spot demodulated from the perfect vortex beams, we also achieve a communication link. The constellations and mean bit error rates (BER) of subcarriers are shown.

  9. Research on free-space optical communication based on time-division multiplexing

    Science.gov (United States)

    Wang, Dan; Zhou, Wenchao; Li, Zhen; Chen, Zhenqiang; Yin, Hao; Zhu, Siqi; Li, Anming

    2016-10-01

    This paper aims at designing and demonstrating a video and audio signals synchronous wireless transmission of free-space optical communication (FSO) system. Video and audio signals were modulated by the acousto-optical modulator (AOM). With the help of a designed circuit and programmable microcontroller, the system based on time division multiplexing (TDM) achieves the functions of signal de-multiplexing and wireless transmitting. Proved by experiments, the system meets the actual requirements with advantages of flexibility, practicality and low cost. And it provides an efficient scheme of synchronous wireless transmission of video and audio signals for monitoring system and TV access network.

  10. Multi-Hop Free Space Optical Communications Using Serial Decode-and-Forward Relay Transmissions

    Institute of Scientific and Technical Information of China (English)

    Wang Junbo; Jiao Yuan; Chen Ming; Wang Jinyuan; Cao Zhe

    2011-01-01

    This paper investigates the performance of multi-hop Free Space Optical (FSO) communications using serial Decode-and-Forward (DF) relay transmissions.A statistical model for the optical intensity fluctuation at the receiver due to the combined effects of atmospheric turbulence-induced fading,misalignment fading and pass-loss is presented.Under given weather and misalignment conditions,a closed-form analytical expression for the end-to-end outage probability of serial Decode-and-Forward (DF) multi-hop FSO communications is derived.Numerical results show that the serial DF multi-hop transmission is a promising technology to enhance the performance of FSO communications.Moreover,the derived analytical expression can provide close approximations to the simulation results.

  11. Mobile free-space optical communications: a feasibility study of various battlefield scenarios

    Science.gov (United States)

    Harris, Alan; Al-Akkoumi, Mouhammad K.; Sluss, James J., Jr.

    2012-06-01

    Free Space Optics (FSO) technology was originally envisioned to be a viable solution for the provision of high bandwidth optical connectivity in the last mile of today's telecommunications infrastructure. Due to atmospheric limitations inherent to FSO technology, FSO is now widely envisioned as a solution for the provision of high bandwidth, temporary mobile communications links. The need for FSO communications links will increase as mobility is introduced to this technology. In this paper, a theoretical solution for adding mobility to FSO communication links is introduced. Three-dimensional power estimation studies are presented to represent mobile FSO transmission under various weather conditions. Three wavelengths, 0.85, 1.55 and 10 um, are tested and compared to illustrate the pros and cons of each source wavelength used for transmission, depending on prevalent weather conditions and atmospheric turbulence conditions. A simulation analysis of the transmission properties of the source wavelengths used in the study is shown.

  12. On the performance of free-space optical communication systems with multiuser diversity

    KAUST Repository

    Yang, Liang

    2014-09-01

    Free space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over weak atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, and coverage are analyzed.

  13. 850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes

    DEFF Research Database (Denmark)

    Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng;

    2015-01-01

    Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO...... modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by M turbulence is coupled...

  14. A new generation of IC based beam steering devices for free-space optical communication

    Science.gov (United States)

    Bedi, Vijit

    Free Space Optical (FSO) communication has tremendously advanced within the last decade to meet the ever increasing demand for higher communication bandwidth. Advancement in laser technology since its invention in the 1960's [1] attracted them to be the dominant source in FSO communication modules. The future of FSO systems lay in implementing semiconductor lasers due to their small size, power efficiency and mass fabrication abilities. In the near future, these systems are very likely to be used in space and ground based applications and revolutionary beam steering technologies will be required for distant communications in free-space. The highly directional characteristic inherent to a laser beam challenges and calls for new beam pointing and steering technologies for such type of communication. In this dissertation, research is done on a novel FSO communication device based on semiconductor lasers for high bandwidth communication. The "Fly eye transceiver" is an extremely wide steering bandwidth, completely non-mechanical FSO laser communication device primarily designed to replace traditional mechanical beam steering optical systems. This non-mechanical FSO device possesses a full spherical steering range and a very high tracking bandwidth. Inspired by the evolutionary model of a fly's eye, the full spherical steering range is assured by electronically controlled switching of its sub-eyes. Non mechanical technologies used in the past for beam steering such as acousto-optic Bragg cells, liquid crystal arrays or piezoelectric elements offer the wide steering bandwidth and fast response time, but are limited in their angular steering range. Mechanical gimbals offer a much greater steering range but face a much slower response time or steering bandwidth problem and often require intelligent adaptive controls with bulky driver amplifiers to feed their actuators. As a solution to feed both the fast and full spherical steering, the Fly-eye transceiver is studied as

  15. The architecture of blind equalizer for MIMO free space optical communication system

    Science.gov (United States)

    Li, Hongwei; Huang, Yongmei

    2016-10-01

    The free space optical (FSO) communication system has attracted many researchers from different countries, owning to its advantages such as high security, high speed and anti-interference. Among all kinds of the channels of the FSO communication system, the atmosphere channel is very difficult to deal with for two typical disadvantages at least. The one is the scintillation of the optical carrier intensity caused by the atmosphere turbulence and the other is the multipath effect by the optical scattering. A lot of studies have shown that the MIMO (Multiple Input Multiple Output) technology can overcome the scintillation of the optical carrier through the atmosphere effectively. So the background of this paper is a MIMO system which includes multiple optical transmitting antennas and multiple optical receiving antennas. A number of particles such as hazes, water droplets and aerosols exit in the atmosphere widely. When optical carrier meets these particles, the scattering phenomenon is inevitable, which leads to the multipath effect. As a result, a optical pulse transmitted by the optical transmitter becomes wider, to some extent, when it gets to the optical receiver due to the multipath effect. If the information transmission rate is quite low, there is less relationship between the multipath effect and the bit error rate (BER) of the communication system. Once the information transmission rate increases to a high level, the multipath effect will produce the problem called inter symbol inference (ISI) seriously and the bit error rate will increase severely. In order to take the advantage of the FSO communication system, the inter symbol inference problem must be solved. So it is necessary to use the channel equalization technology. This paper aims at deciding a equalizer and designing suitable equalization algorithm for a MIMO free space optical communication system to overcome the serious problem of bit error rate. The reliability and the efficiency of

  16. Fade-resistant forward error correction method for free-space optical communications systems

    Science.gov (United States)

    Johnson, Gary W.; Dowla, Farid U.; Ruggiero, Anthony J.

    2007-10-02

    Free-space optical (FSO) laser communication systems offer exceptionally wide-bandwidth, secure connections between platforms that cannot other wise be connected via physical means such as optical fiber or cable. However, FSO links are subject to strong channel fading due to atmospheric turbulence and beam pointing errors, limiting practical performance and reliability. We have developed a fade-tolerant architecture based on forward error correcting codes (FECs) combined with delayed, redundant, sub-channels. This redundancy is made feasible though dense wavelength division multiplexing (WDM) and/or high-order M-ary modulation. Experiments and simulations show that error-free communications is feasible even when faced with fades that are tens of milliseconds long. We describe plans for practical implementation of a complete system operating at 2.5 Gbps.

  17. Design of a stabilized, compact gimbal for space-based free space optical communications (FSOC)

    Science.gov (United States)

    Cline, A.; Shubert, P.; McNally, J.; Jacka, N.; Pierson, R.

    2017-02-01

    Data transmits via optical communications through fibers at 10's of Terabits per second. Given the recent rapid explosion for bandwidth and competing demand for radio frequency (RF) spectrum allocations among differing interests, the need for space-based free space optical communications (FSOC) systems is ever increasing. FSOC systems offer advantages of higher data rates, smaller size and weight, narrower beam divergence, and lower power than RF systems. Lightweight, small form factor, and high performance two-axis gimbals are of strong interest for satellite FSOC applications. Small gimbal and optical terminal designs are important for widespread implementation of optical communications systems; in particular, for satellite-to-satellite crosslinks where the advantages of more secure communications links (Lower Probability of Intercept (LPI)/Lower Probability of Detect (LPD)) are very important. We developed design concepts for a small gimbal focusing on the use of commercial off-the-shelf (COTS) subsystems to establish their feasible implementation against the pointing stabilization, size, weight and power (SWaP), and performance challenges. The design drivers for the gimbal were weight, the elevation and azimuth field of regards, the form factor envelope (1U CubeSats), 100 μrad pointing accuracy, and 10 degrees per second slew capability. Innovations required in this development included a continuous fiber passed through an Azimuth Fiber Wrap and Elevation Fiber Wrap, overcoming typical mechanical and stress related limitations encountered with fiber optic cable wraps. In this presentation, we describe the configuration trades and design of such a gimbal.

  18. Effect of atmosphere on free-space optical communication networks for border patrol

    Science.gov (United States)

    Zeller, John; Manzur, Tariq

    2010-04-01

    Free-space optics (FSO) communication links for relaying video from cameras are investigated in relation to atmospheric attenuation. Through MODTRAN-based modeling of transmission bands across the NIR to MWIR (1.5-4.2 μm) portion of the infrared spectrum in atmospheric conditions including clear maritime, desert extinction, and various levels of rain and fog, we seek to identify which wavelength ranges are the most practical for minimizing transmission losses in both ideal and unfavorable conditions. Atmospheric, free-space, and scintillation losses are investigated for various FSO configurations and atmospheric conditions to determine incident beam power required for successful data transmission in view of a 2 km FSO link at various path elevation angles from the horizon. In addition, FSO transmitter and receiver circuits were designed to optically relay an analog video signal at IR wavelengths. Using advanced tunable laser sources to provide illumination across wavelength ranges from visible to mid-wave infrared, it should be possible to overcome transmission limitations associated with adverse weather and atmospheric conditions for communication networks to benefit border protection.

  19. Prototyping FM data demodulation in free-space optical communication systems using discrete wavelet transformation

    Science.gov (United States)

    Tran, Lan; El-Araby, Esam; Namazi, Nader

    2013-09-01

    Free-Space Optical (FSO) communications is a vital area of research due to its important advantages of providing a very large bandwidth and relatively low cost of implementation. One of the inherent limitations on the quality of an FSO communication link is the degradation of the received beam due to atmospheric turbulence. This paper is concerned with prototyping a wavelet-based algorithm to remove or reduce the effect of the scintillation noise and other unwanted signal on an FSO link that uses analog frequency modulation. The applicability of these concepts will be demonstrated by providing a real-time prototype using reconfigurable hardware, namely Field Programmable Gate Arrays (FPGA), and high-level design tools such as System Generator for DSP from Xilinx. Our proposed prototype was realized on the Virtex-6 FPGA ML605 board using the XC6VLX240T-1FFG1156 device.

  20. Performance analysis of multihop coherent OFDM free-space optical communication systems

    Science.gov (United States)

    Wang, Yi; Wang, Deli; Ma, Jing

    2016-10-01

    This paper proposes a multihop coherent orthogonal frequency division multiplexing free space optical (OFDM-FSO) communication system model based on a relay transmission mode of decode and forward (DF) with the Gamma-Gamma channel. In the study of atmospheric statistical model, mainly considering the combined action by the following three aspects, they are the light intensity scintillation caused by the atmospheric turbulence, the pointing error caused the transmitter and the receiver without aiming at each other and the path loss. We derived closed-form expressions of outage probability and symbol error rate of the multihop coherent OFDM-FSO system with serial DF relay transmission. We simulated and analyzed the influence of the atmospheric turbulence, the modulation order, the beam width and the jitter factor on the communication interruption performance and bit error performance of the multihop coherent OFDM-FSO system with different number of hops.

  1. BP artificial neural network based wave front correction for sensor-less free space optics communication

    Science.gov (United States)

    Li, Zhaokun; Zhao, Xiaohui

    2017-02-01

    The sensor-less adaptive optics (AO) is one of the most promising methods to compensate strong wave front disturbance in free space optics communication (FSO). The back propagation (BP) artificial neural network is applied for the sensor-less AO system to design a distortion correction scheme in this study. This method only needs one or a few online measurements to correct the wave front distortion compared with other model-based approaches, by which the real-time capacity of the system is enhanced and the Strehl Ratio (SR) is largely improved. Necessary comparisons in numerical simulation with other model-based and model-free correction methods proposed in Refs. [6,8,9,10] are given to show the validity and advantage of the proposed method.

  2. Experiment study of ATP system for free-space optical communications

    Institute of Scientific and Technical Information of China (English)

    XIAO Yong-jun; LIU Yan-fei; DONG Ran; XIONG Zhun

    2011-01-01

    To meet the requirement of high tracking angular accuracy for the acquisition,tracking,and pointing (ATP) subsystem of the free-space optical communication,and provide the basis for the further optical communication between maritime mobile platforms,the experimental system,which executing part for the fine tracking is voice coil motor with high frequency and good performance for error compensation,is established,and the whole system can be controlled by personal computer.A series of experiments has been done for the simulation target of different uniform speed,and the data of tracking error for fine tracking and coarse tracking are collected,analyzed and evaluateds separately,and the real-time optical power of communication laser is also collected.The result shows that standard deviation for ATP system tracking error increases with the increase of target speed,while the range of tracking error appears to be no order.Furthermore,communication link can be hold for a long time.

  3. Free Space Optical (FSO) Communications, Towards the Speeds of Wireline Networks

    KAUST Repository

    Alouini, Mohamed-Slim

    2015-01-07

    Rapid increase in the use of wireless services over the last two decades has lead the problem of the radio-frequency (RF) spectrum exhaustion. More specifically, due to this RF spectrum scarcity, additional RF bandwidth allocation, as utilized in the recent past, is not anymore a viable solution to fulfill the demand for more wireless applications and higher data rates. Among the many proposed solutions, optical wireless communication or free-space optical (FSO) systems have gained an increasing interest due to their advantages including higher bandwidth and higher capacity compared to the traditional RF communication systems. This promising technology offers full-duplex Gigabit throughput in certain applications and environment while benefiting from a huge license-free spectrum, immunity to interference, and high security. These features of FSO communication systems potentially enable solving the issues that the RF communication systems face due to the expensive and scarce RF spectrum. The first part of the talk will give an overview of FSO communication systems by offering examples of advantages and application areas of this emerging technology. In the second part of talk, we will focus on some recent results and on-going research directions in the accurate characterization of the performance of FSO systems in the presence of inevitable impairments due to atmospheric turbulence and misalignment between transmitter and receiver.

  4. 850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes.

    Science.gov (United States)

    Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng; Olmos, Juan José Vegas; Garrido-Balsells, José María; Monroy, Idelfonso Tafur

    2015-12-28

    Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO communications are considered as an alternative and promising mean complementing the traditional optical communications in many applications where the use of fiber cable is not justified. This next generation FSO communication systems have attracted much interest recently, and the inclusion of beams carrying OAM modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by ℳ turbulence is coupled to the multimode fiber link. In addition, we report a better and more robust behavior of higher order OAM modes when the intermodal dispersion is dominant in the fiber after exceeding its maximum range of operation.

  5. MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels

    Science.gov (United States)

    Ghassemlooy, Zabih; Popoola, Wasiu O.; Ahmadi, Vahid; Leitgeb, Erich

    In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects.

  6. Simple and Universal Current Modulator Circuit for Indoor Mobile Free-Space-Optical Communications Testing

    Directory of Open Access Journals (Sweden)

    Stanislav Hejduk

    2014-01-01

    Full Text Available The use of LED for illumination and communication together is more and more interesting with the increasing deployment of LEDs to our homes and industrial buildings. Modulation of this kind of light sources is difficult because of high voltage and current demands. Since the LED configurations and values of current and voltage are different, our universal modulator has to be able to operate even under these circumstances. This paper proposes simple and universal current modulator for LED lighting modulation for frequencies around 1MHz. Main objective is to allow initial testing of different types of High Power LEDs and different photodetector configurations and circuits in diffusive based Free-Space-Optical networks. In the experimental part we also compare results for some different types of LED light sources.

  7. Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

    KAUST Repository

    Yang, Liang

    2014-04-01

    Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over both weak and strong atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, average capacity, diversity order, and coverage are analyzed. Results show that the diversity order for the gamma-gamma fading is N min{α, β}/2, where N is the number of users, and α and β are the channel fading parameters related to the effective atmospheric conditions of the link.

  8. Free-space-coupled superconducting nanowire single-photon detectors for infrared optical communications.

    Science.gov (United States)

    Bellei, Francesco; Cartwright, Alyssa P; McCaughan, Adam N; Dane, Andrew E; Najafi, Faraz; Zhao, Qingyuan; Berggren, Karl K

    2016-02-22

    This paper describes the construction of a cryostat and an optical system with a free-space coupling efficiency of 56.5% ± 3.4% to a superconducting nanowire single-photon detector (SNSPD) for infrared quantum communication and spectrum analysis. A 1K pot decreases the base temperature to T = 1.7 K from the 2.9 K reached by the cold head cooled by a pulse-tube cryocooler. The minimum spot size coupled to the detector chip was 6.6 ± 0.11 µm starting from a fiber source at wavelength, λ = 1.55 µm. We demonstrated photon counting on a detector with an 8 × 7.3 µm2 area. We measured a dark count rate of 95 ± 3.35 kcps and a system detection efficiency of 1.64% ± 0.13%. We explain the key steps that are required to improve further the coupling efficiency.

  9. Impulse Radio Ultra-Wideband Communication Over Free-Space Optical Links

    CERN Document Server

    Davaslioglu, Kemal

    2013-01-01

    A composite impulse radio ultra-wideband (IR-UWB) communication system is presented. The proposed system model aims to transmit UWB pulses over several kilometers through free-space optical (FSO) links and depending on the link design, the electrical estimates of the FSO system can be directly used or distributed to end-user through radio-frequency (RF) links over short ranges. However, inhomogeneities on the FSO transmission path cause random fluctuations in the received signal intensity and these effects induced by atmospheric turbulence closely effect the system performance. Several distinct probability distributions based on experimental measurements are used to characterize FSO channels and using these probabilistic models, detection error probability analysis of the proposed system for different link designs are carried out under weak, moderate and strong turbulence conditions. The results of the analysis show that depending on the atmospheric conditions, system performance of the composite link can hav...

  10. PDM-DPSK-MPPM hybrid modulation for multi-hop free-space optical communication

    Science.gov (United States)

    Wang, Zhuo; Shi, Wen-xiao; Wu, Peng-xia

    2016-11-01

    A hybrid polarization division multiplexed-differential phase shift keying-multipulse pulse position modulation (PDM-DPSK-MPPM) scheme for multi-hop free-space optical (FSO) communication is investigated. The analytical bit error rate ( BER) of the proposed system in Gamma-Gamma turbulence channels is derived and verified using computer simulation. The results show that both multi-hop and hybrid modulation schemes are efficient techniques to improve the performance of FSO links. Compared with the traditional binary phase shift keying (BPSK) and MPPM, the hybrid scheme can improve the bandwidth-utilization efficiency and reliability of the system. Compared with the coherent demodulation of PDM-QPSK-MPPM, the system complexity is reduced at the cost of the degradation of BER performance, which can improve the practicality of hybrid modulation technology in FSO system.

  11. MIMO free space optical communication based on orthogonal space time block code

    Institute of Scientific and Technical Information of China (English)

    WANG HuiQin; KE XiZheng; ZHAO Li

    2009-01-01

    School of Automation & Information Engineering, Xi'an University of Technology, Xi'an 710048, China An appropriate coding method that can reduce the error rate of communication system is especially Important to the free space optical communication. STBC (space-time block code) is an orthogonal encoding method Integrating space domain and time domain. The technology can combat fading effectlvely and improve error rate performance. In this paper, first, an STBC fit for optical communication with Intensity modulation and direct detection (IM/DD) is proposed by combining the orthogonality of the Alamouti space-time code and the QPPM modulation. Then, the error rate performance of the system Is analyzed under four cases: with or without channel fading, with or without background radiation. At last, this scheme is confirmed by Monte Carlo approach. It is shown that this method not only realizes the full speed rate transmission, and can improve the error rate performance of the system effectively, but also overcomes the scintillation effect exerted by atmosphere turbulence. When the symbol error probability (SEP) is 2×103, according to the 1×1 system, the sending power of the 2×1 system is nearly reduced by 3.5 dBJ, and the 2×2 system Is nearly reduced by 9 dBJ.

  12. Data Relay Board with Protocol for High-Speed, Free-Space Optical Communications

    Science.gov (United States)

    Wright, Malcolm; Clare, Loren; Gould, Gary; Pedyash, Maxim

    2004-01-01

    In a free-space optical communication system, the mitigation of transient outages through the incorporation of error-control methods is of particular concern, the outages being caused by scintillation fades and obscurants. The focus of this innovative technology is the development of a data relay system for a reliable high-data-rate free-spacebased optical-transport network. The data relay boards will establish the link, maintain synchronous connection, group the data into frames, and provide for automatic retransmission (ARQ) of lost or erred frames. A certain Quality of Service (QoS) can then be ensured, compatible with the required data rate. The protocol to be used by the data relay system is based on the draft CCSDS standard data-link protocol Proximity-1, selected by orbiters to multiple lander assets in the Mars network, for example. In addition to providing data-link protocol capabilities for the free-space optical link and buffering the data, the data relay system will interface directly with user applications over Gigabit Ethernet and/or with highspeed storage resources via Fibre Channel. The hardware implementation is built on a network-processor-based architecture. This technology combines the power of a hardware switch capable of data switching and packet routing at Gbps rates, with the flexibility of a software- driven processor that can host highly adaptive and reconfigurable protocols used, for example, in wireless local-area networks (LANs). The system will be implemented in a modular multi-board fashion. The main hardware elements of the data relay system are the new data relay board developed by Rockwell Scientific, a COTS Gigabit Ethernet board for user interface, and a COTS Fibre Channel board that connects to local storage. The boards reside in a cPCI back plane, and can be housed in a VME-type enclosure.

  13. Influence of wind speed on free space optical communication performance for Gaussian beam propagation through non Kolmogorov strong turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Deng Peng; Yuan Xiuhua; Zeng Yanan; Zhao Ming; Luo Hanjun, E-mail: yuanxh@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei (China)

    2011-02-01

    In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, affecting link performance. Most theoretical treatments have been described by Kolmogorov's power spectral density model through weak turbulence with constant wind speed. However, several experiments showed that Kolmogorov theory is sometimes incomplete to describe atmospheric turbulence properly, especially through the strong turbulence with variable wind speed, which is known to contribute significantly to the turbulence in the atmosphere. We present an optical turbulence model that incorporates into variable wind speed instead of constant value, a non-Kolmogorov power spectrum that uses a generalized exponent instead of constant standard exponent value 11/3, and a generalized amplitude factor instead of constant value 0.033. The free space optical communication performance for a Gaussian beam wave of scintillation index, mean signal-to-noise ratio, and mean bit error rate , have been derived by extended Rytov theory in non-Kolmogorov strong turbulence. And then the influence of wind speed variations on free space optical communication performance has been analyzed under different atmospheric turbulence intensities. The results suggest that the effects of wind speed variation through non-Kolmogorov turbulence on communication performance are more severe in many situations and need to be taken into account in free space optical communication. It is anticipated that this work is helpful to the investigations of free space optical communication performance considering wind speed under severe weather condition in the strong atmospheric turbulence.

  14. Atmospheric channel transfer function estimation from experimental free-space optical communications data

    Science.gov (United States)

    Reinhardt, Colin N.; Tsintikidis, Dimitris; Hammel, Stephen; Kuga, Yasuo; Ritcey, James A.; Ishimaru, Akira

    2012-03-01

    Using an 850-nanometer-wavelength free-space optical (FSO)communications system of our own design, we acquired field data for the transmitted and received signals in fog at Point Loma, CA for a range of optical depths within the multiple-scattering regime. Statistical estimators for the atmospheric channel transfer function and the related coherency function were computed directly from the experimental data. We interpret the resulting channel transfer function estimates in terms of the physics of the atmospheric propagation channel and fog aerosol particle distributions. We investigate the behavior of the estimators using both real field-test data and simulated propagation data. We compare the field-data channel transfer function estimates against the outputs from a computationally-intensive radiative-transfer theory model-based approach, which we also developed previously for the FSO multiple-scattering atmospheric channel. Our results show that the data-driven channel transfer function estimates are in close agreement with the radiative transfer modeling, and provide comparable receiver signal detection performance improvements while being significantly less time and computationally-intensive.

  15. Fading probability density function of free-space optical communication channels with pointing error

    Science.gov (United States)

    Zhao, Zhijun; Liao, Rui

    2011-06-01

    The turbulent atmosphere causes wavefront distortion, beam wander, and beam broadening of a laser beam. These effects result in average power loss and instantaneous power fading at the receiver aperture and thus degrade performance of a free-space optical (FSO) communication system. In addition to the atmospheric turbulence, a FSO communication system may also suffer from laser beam pointing error. The pointing error causes excessive power loss and power fading. This paper proposes and studies an analytical method for calculating the FSO channel fading probability density function (pdf) induced by both atmospheric turbulence and pointing error. This method is based on the fast-tracked laser beam fading profile and the joint effects of beam wander and pointing error. In order to evaluate the proposed analytical method, large-scale numerical wave-optics simulations are conducted. Three types of pointing errors are studied , namely, the Gaussian random pointing error, the residual tracking error, and the sinusoidal sway pointing error. The FSO system employs a collimated Gaussian laser beam propagating along a horizontal path. The propagation distances range from 0.25 miles to 2.5 miles. The refractive index structure parameter is chosen to be Cn2 = 5×10-15m-2/3 and Cn2 = 5×10-13m-2/3. The studied cases cover from weak to strong fluctuations. The fading pdf curves of channels with pointing error calculated using the analytical method match accurately the corresponding pdf curves obtained directly from large-scale wave-optics simulations. They also give accurate average bit-error-rate (BER) curves and outage probabilities. Both the lognormal and the best-fit gamma-gamma fading pdf curves deviate from those of corresponding simulation curves, and they produce overoptimistic average BER curves and outage probabilities.

  16. Impact-ionization-engineered avalanche photodiode arrays for free-space optical communication

    Science.gov (United States)

    Ferraro, Mike S.; Rabinovich, William S.; Clark, William R.; Waters, William D.; Campbell, Joe C.; Mahon, Rita; Vaccaro, Kenneth; Krejca, Brian D.; D'Ambrosio, Philip

    2016-11-01

    High-sensitivity photodetectors serve two purposes in free-space optical communication: data reception and position sensing for pointing, tracking, and stabilization. Two separate detectors are traditionally utilized to perform these tasks, but recent advances in the fabrication and development of large area, low-noise avalanche photodiode (APD) arrays have enabled these devices to be used both as position-sensitive detectors and communications receivers because of the conflicting performance criteria. Combining these functionalities allows for more flexibility and simplicity in optical assembly design without sacrificing the sensitivity and bandwidth performance of smaller, single-element data receivers. Beyond eliminating the need to separate the return beam into two separate paths, these devices enable implementation of adaptive approaches to compensate for focal plane beam wander and breakup, which is often seen in highly scintillated terrestrial and maritime optical links. While the Naval Research Laboratory and Optogration, Inc. have recently demonstrated the performance of single period, InAlAs/InGaAs APD arrays as combined data reception and tracking sensors, an impact-ionization-engineered epilayer design achieves even lower carrier ionization ratios by incorporating multiple multiplication periods engineered to suppress lower ionization rate carriers while enhancing the higher ionization rate carriers of interest. This work presents a three-period I2E concentric, five-element APD array rated for bandwidths beyond 1 GHz with measured carrier ionization ratios of 0.05 to 0.1 at moderate APD gains. The epilayer design of the device will be discussed along with initial device characterization and high-speed performance measurements.

  17. Simultaneous data communication and position sensing with an impact ionization engineered avalanche photodiode array for free space optical communication

    Science.gov (United States)

    Ferraro, Mike S.; Mahon, Rita; Rabinovich, William S.; Murphy, James L.; Dexter, James L.; Clark, William R.; Waters, William D.; Vaccaro, Kenneth; Krejca, Brian D.

    2017-02-01

    Photodetectors in free space optical communication systems perform two functions: reception of data communication signals and position sensing for pointing, tracking, and stabilization. Traditionally, the optical receive path in an FSO system is split into separate paths for data detection and position sensing. The need for separate paths is a consequence of conflicting performance criteria between position sensitive detectors (PSD) and data detectors. Combining the functionality of both detector types requires that the combinational sensor not only have the bandwidth to support high data rate communication but the active area and spatial discrimination to accommodate position sensing. In this paper we present a large area, concentric five element impact ionization engineered avalanche photodiode array rated for bandwidths beyond 1GHz with a measured carrier ionization ratio of less than 0.1 at moderate APD gains. The integration of this array as a combinational sensor in an FSO system is discussed along with the development of a pointing and stabilization algorithm.

  18. Average Secrecy Capacity of Free-Space Optical Communication Systems with On-Off Keying Modulation and Threshold Detection

    OpenAIRE

    Zhu, Jinxiao; Chen, Yin; Sasaki, Masahide

    2016-01-01

    This paper considers secure communication over free-space optical (FSO) links suffering from turbulence-induced fading. In particular, we study the average secrecy capacity of applying physical layer security to achieve security in an FSO communication system with binary-level on-off keying intensity modulation and threshold detection, a widely used system in FSO communication. We first define the instantaneous secrecy capacity for our system and then provide a lower bound of it, which is ach...

  19. Analysis of fog effects on terrestrial Free Space optical communication links

    KAUST Repository

    Esmail, Maged Abdullah

    2016-07-26

    In this paper, we consider and examine fog measurement data, coming from several locations in Europe and USA, and attempt to derive a unified model for fog attenuation in free space optics (FSO) communication links. We evaluate and compare the performance of our proposed model to that of many well-known alternative models. We found that our proposed model, achieves an average RMSE that outperforms them by more than 9 dB. Furthermore, we have studied the performance of the FSO system using different performance metrics such as signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. Our results show that FSO is a short range technology. Therefore, FSO is expected to find its place in future networks that will have small cell size, i.e., <1 km diameter. Moreover, our investigation shows that under dense fog, it is difficult to maintain a communications link because of the high signal attenuation, which requires switching the communications to RF backup. Our results show that increasing the transmitted power will improve the system performance under light fog. However, under heavy fog, the effect is minor. To enhance the system performance under low visibility range, multi-hop link is used which can enhance the power budget by using short segments links. Using 22 dBm transmitted power, we obtained BER=10-3 over 1 km link length with 600 m visibility range which corresponds to light fog. However, under lower visibility range equals 40 m that corresponds to dense fog, we obtained the same BER but over 200 m link length. © 2016 IEEE.

  20. Free space-coupled superconducting nanowire single photon detectors for infrared optical communications

    CERN Document Server

    Bellei, Francesco; McCaughan, Adam N; Dane, Andrew E; Najafi, Faraz; Zhao, Quinyuan; Berggren, Karl K

    2015-01-01

    This paper describes the construction of a cryostat and an optical system with a free-space coupling efficiency of 56.5% +/- 3.4% to a superconducting nanowire single-photon detector (SNSPD) for infrared quantum communication and spectrum analysis. A 1K pot decreases the base temperature to T = 1.7 K from the 2.9 K reached by the cold head cooled by a pulse-tube cryocooler. The minimum spot size coupled to the detector chip was 6.6 +/- 0.11 {\\mu}m starting from a fiber source at wavelength, {\\lambda} = 1.55 {\\mu}m. We demonstrated efficient photon counting on a detector with an 8 x 7.3 {\\mu}m^2 area. We measured a dark count rate of 95 +/- 3.35 kcps and a system detection efficiency of 1.64% +/- 0.13%. We explain the key steps that are required to further improve the coupling efficiency.

  1. BICM-ID with Physical Layer Network Coding in TWR Free Space Optical Communication Links

    Directory of Open Access Journals (Sweden)

    Alaa A. Saeed Al-Rubaie

    2017-07-01

    Full Text Available Physical layer network coding (PNC is a promising technique to improve the network throughput in a two-way relay (TWR channel for two users to exchange messages across a wireless network. The PNC technique incorporating a TWR channel is embraced by a free space optical (FSO communication link for full utilization of network resources, namely TWR-FSO PNC. In this paper, bit interleaved coded modulation with iterative decoding (BICM-ID is adopted to combat the deleterious effect of the turbulence channel by saving the message being transmitted to increase the reliability of the system. Moreover, based on this technique, comparative studies between end-to-end BICM-ID code, non-iterative convolutional coded and uncoded systems are carried out. Furthermore, this paper presents the extrinsic information transfer (ExIT charts to evaluate the performance of BICM-ID code combined with the TWR-FSO PNC system. The simulation results show that the proposed scheme can achieve a significant bit error rate (BER performance improvement through the introduction of an iterative process between a soft demapper and decoder. Similarly, Monte Carlo simulation results are provided to support the findings. Subsequently, the ExIT functions of the two receiver components are thoroughly analysed for a variety of parameters under the influence of a turbulence-induced channel fading, demonstrating the convergence behaviour of BICM-ID to enable the TWR-FSO PNC system, effectively mitigating the impact of the fading turbulence channel.

  2. INVESTIGATION ON HYBRID WDM (DWDM+CWDM FREE SPACE OPTICAL COMMUNICATION SYSTEM

    Directory of Open Access Journals (Sweden)

    S. Robinson

    2015-12-01

    Full Text Available Free Space Optical (FSO communication is being realized as an effective solution for future accessing networks, offering light passed through air. The performance of FSO can be primarily degraded by various atmospheric attenuation namely, rain, fog, haze and snow. At present, hybridization of Dense Wavelength Division Multiplexing (DWDM with Coarse Wavelength Division Multiplexing (CWDM becomes necessary to scale the speed and high bandwidth of the services. In this paper, hybrid WDM system is proposed, designed and the network parameters such as Bit Error Rate (BER, Quality Factor and receiver sensitivity are analyzed with respect to link distance for various weather conditions. For investigation, 4 CWDM and 8 DWDM channels are considered whose corresponding channel spacing is 20nm and 0.8nm, respectively. From the simulation, it is investigated that the average link distance of proposed hybrid WDM-FSO system for DWDM and CWDM system at very clear condition are around 810km and 780km. The proposed hybrid WDM based FSO system is designed to handle the quality of transmission for 12 users, each at a data rate of 2.5Gbps.

  3. Impacts of environmental factors to bi-directional 2×40 Gb/s WDM free-space optical communication

    Science.gov (United States)

    Liaw, Shien-Kuei; Hsu, Kuang-Yu; Yeh, Jai-Ger; Lin, Yu-Ming; Yu, Yi-Lin

    2017-08-01

    Bi-directional short-range free-space optical (FSO) communication with bi-directional 2×4×10 Gb/s wavelength division multiplexing (WDM) channel signals is demonstrated by using a transmission distance of 25 m. The single-mode-fiber components are used in the optical terminals for both optical transmitting and receiving functions. The measured power penalties for the 25-m bi-directional four-channel FSO communication compared with the back-to-back link and uni-directional transmission system are less than 0.8 dB and 0.2 dB, respectively. The environmental factor effects, including the oblique incidence through the building window glasses, thermally induced non-uniform air index as well as rainfall on the FSO performance are investigated and analyzed. The experimental results show that rainfall is influential for free space optical transmission.

  4. Studies of pointing, acquisition, and tracking of agile optical wireless transceivers for free-space optical communication networks

    Science.gov (United States)

    Ho, Tzung-Hsien; Trisno, Sugianto; Smolyaninov, Igor I.; Milner, Stuart D.; Davis, Christopher C.

    2004-02-01

    Free space, dynamic, optical wireless communications will require topology control for optimization of network performance. Such networks may need to be configured for bi- or multiple-connectedness, reliability and quality-of-service. Topology control involves the introduction of new links and/or nodes into the network to achieve such performance objectives through autonomous reconfiguration as well as precise pointing, acquisition, tracking, and steering of laser beams. Reconfiguration may be required because of link degradation resulting from obscuration or node loss. As a result, the optical transceivers may need to be re-directed to new or existing nodes within the network and tracked on moving nodes. The redirection of transceivers may require operation over a whole sphere, so that small-angle beam steering techniques cannot be applied. In this context, we are studying the performance of optical wireless links using lightweight, bi-static transceivers mounted on high-performance stepping motor driven stages. These motors provide an angular resolution of 0.00072 degree at up to 80,000 steps per second. This paper focuses on the performance characteristics of these agile transceivers for pointing, acquisition, and tracking (PAT), including the influence of acceleration/deceleration time, motor angular speed, and angular re-adjustment, on latency and packet loss in small free space optical (FSO) wireless test networks.

  5. Demonstration of 2.5 Gbit/sec free space optical communication by using Y-00 cipher: toward secure aviation systems

    Science.gov (United States)

    Futami, Fumio; Hirota, Osamu

    2014-09-01

    Wireless communication of aviation contains high capacity confidential information and therefore such communication requires secure high speed data communication scheme by using reliable cipher. In this report, the authors propose free space optical communication by utilizing optical intensity-modulated Y-00 cipher for applications of secure aviation systems including unmanned aircraft systems. Y-00 cipher transmitter and receiver with intensity levels of 4096 at data rate of 2.5 Gbit/s are fabricated for secure free space optical communication and a free space Y-00 cipher transmission is experimentally demonstrated.

  6. High-dimensional structured light coding/decoding for free-space optical communications free of obstructions.

    Science.gov (United States)

    Du, Jing; Wang, Jian

    2015-11-01

    Bessel beams carrying orbital angular momentum (OAM) with helical phase fronts exp(ilφ)(l=0;±1;±2;…), where φ is the azimuthal angle and l corresponds to the topological number, are orthogonal with each other. This feature of Bessel beams provides a new dimension to code/decode data information on the OAM state of light, and the theoretical infinity of topological number enables possible high-dimensional structured light coding/decoding for free-space optical communications. Moreover, Bessel beams are nondiffracting beams having the ability to recover by themselves in the face of obstructions, which is important for free-space optical communications relying on line-of-sight operation. By utilizing the OAM and nondiffracting characteristics of Bessel beams, we experimentally demonstrate 12 m distance obstruction-free optical m-ary coding/decoding using visible Bessel beams in a free-space optical communication system. We also study the bit error rate (BER) performance of hexadecimal and 32-ary coding/decoding based on Bessel beams with different topological numbers. After receiving 500 symbols at the receiver side, a zero BER of hexadecimal coding/decoding is observed when the obstruction is placed along the propagation path of light.

  7. Wave optics simulation of spatially partially coherent beams: Applications to free space laser communications

    Science.gov (United States)

    Xiao, Xifeng

    One of the main drawbacks that prevent the extensive application of free space laser communications is the atmospheric turbulence through which the beam must propagate. For the past four decades, much attention has been devoted to finding different methods to overcome this difficulty. A partially coherent beam (PCB) has been recognized as an effective approach to improve the performance of an atmospheric link. It has been examined carefully with most analyses considering the Gaussian Schell-model (GSM) beam. However, practical PCBs may not follow GSM theory and are better examined through some numerical simulation approach such as a wave optics simulation. Consequently, an approach for modeling the spatially PCB in wave optics simulation is presented here. The approach involves the application of a sequence of random phase screens to an initial beam field and the summation of the intensity results after propagation. The relationship between the screen parameters and the spatial coherence function for the beam is developed and the approach is verified by comparing results with analytic formulations for a Gaussian Schell-model (GSM) beam. A variety of simulation studies were performed for this dissertation. The propagation through turbulence of a coherent beam and a particular version of a PCB, a pseudo-partially coherent beam (PPCB), is analyzed. The beam is created with a sequence of several Gaussian random phase screens for each atmospheric realization. The average intensity profiles, the scintillation index and aperture averaging factor for a horizontal propagation scenario are examined. Comparisons between these results and their corresponding analytic results for the well-known GSM beam are also made. Cumulative probability density functions for the received irradiance are initially investigated. Following the general simulation investigations, a performance metric is proposed as a general measure for optimizing the transverse coherence length of a partial

  8. Integrating free-space optical communication links with existing WiFi (WiFO) network

    Science.gov (United States)

    Liverman, S.; Wang, Q.; Chu, Y.; Duong, T.; Nguyen-Huu, D.; Wang, S.; Nguyen, T.; Wang, A. X.

    2016-02-01

    Recently, free-space optical (FSO) systems have generated great interest due to their large bandwidth potential and a line-of-sight physical layer of protection. In this paper, we propose WiFO, a novel hybrid system, FSO downlink and WiFi uplink, which will integrate currently available WiFi infrastructure with inexpensive infrared light emitting diodes. This system takes full advantage of the mobility inherent in WiFi networks while increasing the downlink bandwidth available to each end user. We report the results of our preliminary investigation that show the capabilities of our prototype design in terms of bandwidth, bit error rates, delays and transmission distances.

  9. Omnidirectional free-space optical receiver architecture

    Science.gov (United States)

    Murshid, Syed H.; Lovell, Gregory L.; Finch, Michael F.

    2013-05-01

    Free Space Optical (FSO) communication is the fusion of wireless technology and optical fiber communications systems. It has the potential of providing fiber optic data rates without the physical restraints of optical fiber cables. This endeavor presents a novel receiver structure with potential for omnidirectional free space optical communications. Interesting approaches for accomplishing omnidirectional free space lasercomm such as direct detection and solar blind non-line of sight UV scattering have been reported over the last few years. However, these technologies have resulted in limited distances of the order of 10 to 100 meters and data rates often limited to less than 1 Mb/s. This endeavor reports the architecture of an omnidirectional receiver setup by integrating an off the shelf detector and a fiber bundle, where the fiber bundle couples omnidirectional photons within its field of view and delivers these photons to the detector. The coupling of light from all directions into a detector is regulated by the cone of the acceptance angle of the fiber. Multiple fibers with overlapping acceptance angles provide the necessary coverage that may be needed to extract the optical signal from the free space optical channel. Simulated results showing the normalized power pattern of the system is presented to demonstrate omnidirectional potential of the structure. Theoretical power level versus distance plot for an FSO System employing On-O Keying (OOK) is also presented.

  10. Introduction of a terrestrial free-space optical communications network facility: IN-orbit and Networked Optical ground stations experimental Verification Advanced testbed (INNOVA)

    Science.gov (United States)

    Toyoshima, Morio; Munemasa, Yasushi; Takenaka, Hideki; Takayama, Yoshihisa; Koyama, Yoshisada; Kunimori, Hiroo; Kubooka, Toshihiro; Suzuki, Kenji; Yamamoto, Shinichi; Taira, Shinichi; Tsuji, Hiroyuki; Nakazawa, Isao; Akioka, Maki

    2014-03-01

    A terrestrial free-space optical communications network facility, named IN-orbit and Networked Optical ground stations experimental Verification Advanced testbed (INNOVA) is introduced. Many demonstrations have been conducted to verify the usability of sophisticated optical communications equipment in orbit. However, the influence of terrestrial weather conditions remains as an issue to be solved. One potential solution is site diversity, where several ground stations are used. In such systems, implementing direct high-speed optical communications links for transmission of data from satellites to terrestrial sites requires that links can be established even in the presence of clouds and rain. NICT is developing a terrestrial free-space optical communications network called INNOVA for future airborne and satellitebased optical communications projects. Several ground stations and environmental monitoring stations around Japan are being used to explore the site diversity concept. This paper describes the terrestrial free-space optical communications network facility, the monitoring stations around Japan for free-space laser communications, and potential research at NICT.

  11. 850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes

    DEFF Research Database (Denmark)

    Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng;

    2015-01-01

    communications are considered as an alternative and promising mean complementing the traditional optical communications in many applications where the use of fiber cable is not justified. This next generation FSO communication systems have attracted much interest recently, and the inclusion of beams carrying OAM...

  12. Low-Impact Air-to-Ground Free-Space Optical Communication System Design and First Results

    CERN Document Server

    Carrasco-Casado, Alberto; Vergaz, Ricardo; Geday, Morten A; Sanchez-Pena, Jose M; Oton, Jose M

    2015-01-01

    An air-to-ground free-space optical communication system has been designed and partially developed. The design covers both the communications between the airborne and the ground station, and the acquisition, tracking and pointing. A strong effort has been made in order to achieve the minimum payload power, size and weight, for which a MEMS modulating retroreflector has been chosen. In the ground station, a new technique for fine pointing, based on a liquid crystal device, is proposed and will be demonstrated, as well as other improvements with the aim of optimizing the ground station performance.

  13. Infrared Free Space Communication - The Autonomous Testing of Free Space Infrared Communication

    Science.gov (United States)

    Heldman, Christopher

    2017-01-01

    Fiber optics has been a winning player in the game of high-speed communication and data transfer in cable connections. Yet, in free space RF has been the repeated choice of communication medium of the space industry. Investigating the benefits of free space optical communication over radio frequency is worthwhile. An increase in science data rate return capabilities could occur if optical communication is implemented. Optical communication systems also provide efficiencies in power, mass, and volume over RF systems1. Optical communication systems have been demonstrated from a satellite in orbit with the moon to earth, and resulted in the highest data rates ever seen through space (622Mbps)2. Because of these benefits, optical communication is far superior to RF. The HiDRA (High Data Rate Architecture) project is researching Passive Misalignment Mitigation of Dynamic Free Apace Optical Communication Links. The goal of this effort is to enable gigabit per second transmission of data in short range dynamic links (less than 100 meters). In practice this would enhance data rates between sites on the International Space Station with minimal size, weight, and power requirements. This paper will focus on an autonomous code and a hardware setup that will be used to fulfill the next step in the research being conducted. The free space optical communications pointing downfalls will be investigated. This was achieved by creating 5 python programs and a top-level code to automate this test.

  14. Free-space optical communications with peak and average constraints: High SNR capacity approximation

    KAUST Repository

    Chaaban, Anas

    2015-09-07

    The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel with both average and peak intensity constraints is studied. A new capacity lower bound is derived by using a truncated-Gaussian input distribution. Numerical evaluation shows that this capacity lower bound is nearly tight at high signal-to-noise ratio (SNR), while it is shown analytically that the gap to capacity upper bounds is a small constant at high SNR. In particular, the gap to the high-SNR asymptotic capacity of the channel under either a peak or an average constraint is small. This leads to a simple approximation of the high SNR capacity. Additionally, a new capacity upper bound is derived using sphere-packing arguments. This bound is tight at high SNR for a channel with a dominant peak constraint.

  15. Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective

    KAUST Repository

    Chaaban, Anas

    2016-02-03

    The capacity of the free-space optical channel is studied. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed. This approach leads to new capacity upper bounds for a channel with a peak intensity constraint or an average intensity constraint. Under an average constraint only, the derived bound is tighter than an existing sphere-packing bound derived earlier by Farid and Hranilovic. The achievable rate of a truncated-Gaussian input distribution is also derived. It is shown that under both average and peak constraints, this achievable rate and the sphere-packing bounds are within a small gap at high SNR, leading to a simple high-SNR capacity approximation. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions.

  16. Feasibility of utilizing Cherenkov Telescope Array gamma-ray telescopes as free-space optical communication ground stations

    CERN Document Server

    Carrasco-Casado, Alberto; Vergaz, Ricardo; Cabrero, Juan Francisco

    2013-01-01

    The signals that will be received on Earth from deep-space probes in future implementations of free-space optical communication will be extremely weak, and new ground stations will have to be developed in order to support these links. This paper addresses the feasibility of using the technology developed in the gamma-ray telescopes that will make up the Cherenkov Telescope Array (CTA) observatory in the implementation of a new kind of ground station. Among the main advantages that these telescopes provide are the much larger apertures needed to overcome the power limitation that ground-based gamma-ray astronomy and optical communication both have. Also, the large number of big telescopes that will be built for CTA will make it possible to reduce costs by economy-scale production, enabling optical communications in the large telescopes that will be needed for future deep-space links.

  17. Optical Spatial Filter to Suppress Beam Wander and Spatial Noise Induced by Atmospheric Turbulence in Free-Space Optical Communications

    Directory of Open Access Journals (Sweden)

    Ucuk Darusalam

    2015-01-01

    Full Text Available We propose an optical spatial filter (OSF method to suppress beam wander and spatial noise effects. Signal from random displacements of the focus spot around the optical axis within the constricted area is collected. This method advantageously suppresses fluctuations in signal intensity. The OSF consists of a pinhole and cone reflector. The pinhole produces Fresnel diffraction on the focus spot. The cone reflector provides directed reflectance onto the pinhole for random focus spot displacements due to beam wander. The calculations of signal power are based on fluctuations of signal intensity that are minimized by the circular aperture function of the pinhole and the cosine of the reflectance angle from the cone reflector. The method is applied to free-space optical communications at a wavelength of 1.55 μm with an atmospheric chamber to provide optical propagation media. Based on calculations, the beam wander angles that can be received by the OSF are from 14.0° to 28.0°. Moreover, based on experiment, the OSF with a pinhole diameter of 20.0 μm and cone reflector diameter of 1.5 mm produces signal power of −15.3 dBm. Both calculations and experiment show that the OSF enhances the received signal power in the presence of turbulence.

  18. Free space optical networks for ultra-broad band services

    CERN Document Server

    Kartalopoulos, Stamatios V

    2011-01-01

    "Free Space Optical Network is a next generation communication network which uses optical waves instead of microwaves, potentially offering faster communication with ultra band width, meaning more complex communication services can be simultaneously offered. This book describes the network concepts in simple language starting with point-to-point free space optics basics and discusses networking, interoperability with existing communication network, and security. An ideal resource for communication professionals just entering the free space optical communication field and graduate students majoring in optical communications"--Provided by publisher.

  19. Coding techniques to mitigate fading on free-space optical communication links

    Science.gov (United States)

    Henniger, Hennes; Epple, Bernhard; Milner, Stuart D.; Davis, Christopher C.

    2008-08-01

    Free-space directional communication links (FSO) experience short-term link outages or fades because of atmospheric turbulence, and longer term link outages because of obscuration resulting from either atmospheric conditions, beam pointing errors, or temporary line-of-sight obstructions for links from mobile or static nodes. Various approaches can be used to mitigate these effects. Physical-layer techniques, such as dynamic thresholding, time delayed diversity, and data encoding can significantly reduce the effects of short term (millisecond scale) outages caused by deep turbulenceinduced fades. Outages on a longer term (second scale) producing large data loss can be mitigated by packet-layer largeblock, error protection techniques. In this paper, we will first introduce physical-layer mitigation techniques. Second we present experimental data comparing the latencies and throughput of different means of packet-based error protection techniques. We will discuss the influence of error protection techniques to quality of service issues like error probability and delay and further compare this with service requirements given by the application.

  20. On the Performance of Free-Space Optical Communication Systems over Double Generalized Gamma Channel

    KAUST Repository

    Al-Quwaiee, Hessa

    2015-05-13

    Starting with the double generalized Gamma (GG) model to describe turbulence-induced fading in free-space optical (FSO) systems, we propose a new unified model that accounts for the impact of pointing errors and type of receiver detector. More specifically, we present unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function, and the moments of the end-toend signal-to-noise ratio (SNR) of a single link FSO transmission system in terms of the Meijer’s G-function. We then use these unified expressions to evaluate performance measures such as the bit error rate, the outage probability, and the ergodic capacity of (i) a single FSO link operating over double GG fading model (ii) asymmetric RF-FSO dual-hop relay transmission system with fixed gain relay. Using an asymptotic expansion of the Meijer’s G-function at high SNR, we express all the expressions, derived earlier, in terms of elementary functions. All our analytical results are verified using computer based Monte-Carlo simulations.

  1. Free-space optical communication links and evaporation layer study near sea surface at 1.55 μm

    Science.gov (United States)

    Zeller, John; Manzur, Tariq

    2011-06-01

    In many situations where it is necessary to set up a communication link such as emergencies or in remote locations, running fiber between two sites is not practical. Free-space optics (FSO) holds the potential for high bandwidth communication in such situations with relatively low cost, low maintenance, quick installation times, and average 70- 80% connectivity. Since atmospheric conditions can significantly affect the capability of this type of communication system to transfer information consistently and operate effectively, the effects of atmosphere on FSO communication and consequent optimal wavelength range for transmission are investigated through MODTRAN-based modeling of 1.55 μm transmission. Simulations were performed for multiple elevation angles in atmospheric weather conditions including clear maritime, desert extinction, and various levels of rain and fog to simulate surface-to-surface and surfaceto- air FSO communication networks. Atmospheric, free-space, and scintillation losses are analyzed for optical path lengths of up to 2 km or greater to determine minimum transmit power required for successful data reception. In addition, the effects of atmospheric turbulence on beam propagation in the evaporation layer are investigated, where wavefront sensing with adaptive optics as well as a software Kalman filter are seen as a means to compensate for wavefront distortion. Using advanced laser sources to provide illumination at infrared wavelengths, particularly around the eye-safe 1.55 μm wavelength, it should be possible to overcome many transmission limitations associated with atmospheric conditions such as adverse weather and turbulence to enable high data rate communication links where the use of fiber is not practical or prohibited.

  2. Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective

    KAUST Repository

    Chaaban, Anas

    2015-04-01

    The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel is studied. It is shown that for an IM-DD channel with generally input-dependent noise, the worst noise at high SNR is input-independent Gaussian with variance dependent on the input cost. Based on this result, a Gaussian IM-DD channel model is proposed where the noise variance depends on the optical intensity constraints only. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed, which leads to a tighter bound than an existing sphere-packing bound for the channel with only an average intensity constraint. Under both average and peak constraints, it yields bounds that characterize the high SNR capacity within a negligible gap, where the achievability is proved by using a truncated Gaussian input distribution. This completes the high SNR capacity characterization of the channel, by closing the gap in the existing characterization for a small average-to-peak ratio. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of significant practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions. Finally, the capacity/SNR loss between heterodyne detection (HD) systems and IM-DD systems is bounded at high SNR, where it is shown that the loss grows as SNR increases for a complex-valued HD system, while it is bounded by 1.245 bits or 3.76 dB at most for a real-valued one.

  3. Detecting binary non-return-to-zero data in free-space optical communication systems using FPGAs

    Science.gov (United States)

    Bui, Vy; Tran, Lan; El-Araby, Esam; Namazi, Nader M.

    2014-06-01

    High bandwidth, fast deployment with relatively low cost implementation are some of the important advantages of free space optical (FSO) communications. However, the atmospheric turbulence has a substantial impact on the quality of a laser beam propagating through the atmosphere. A new method was presented in [1] and [2] to perform bit synchronization and detection of binary Non-Return-to-Zero (NRZ) data from a free-space optical (FSO) communication link. It was shown that, when the data is binary NRZ with no modulation, the Haar wavelet transformation can effectively reduce the scintillation noise. In this paper, we leverage and modify the work presented in [1] in order to provide a real-time streaming hardware prototype. The applicability of these concepts will be demonstrated through providing the hardware prototype using one of the state-of-the-art reconfigurable hardware, namely Field Programmable Gate Arrays, and highly productive high-level design tools such as System Generator for DSP from Xilinx.

  4. Spatial correlation and irradiance statistics in a multiple-beam terrestrial free-space optical communication link.

    Science.gov (United States)

    Anguita, Jaime A; Neifeld, Mark A; Vasic, Bane V

    2007-09-10

    By means of numerical simulations we analyze the statistical properties of the power fluctuations induced by the incoherent superposition of multiple transmitted laser beams in a terrestrial free-space optical communication link. The measured signals arising from different transmitted optical beams are found to be statistically correlated. This channel correlation increases with receiver aperture and propagation distance. We find a simple scaling rule for the spatial correlation coefficient in terms of the propagation distance and we are able to predict the scintillation reduction in previously reported experiments with good accuracy. We propose an approximation to the probability density function of the received power of a spatially correlated multiple-beam system in terms of the parameters of the single-channel gamma-gamma function. A bit-error-rate evaluation is also presented to demonstrate the improvement of a multibeam system over its single-beam counterpart.

  5. Single-source bidirectional free-space optical communications using reflective SOA-based amplified modulating retro-reflection

    Science.gov (United States)

    Wang, Xiaoyan; Feng, Xianglian; Zhang, Peng; Wang, Tianshu; Gao, Shiming

    2017-03-01

    A novel amplified modulating retro-reflector (AMRR) based on a reflective semiconductor optical amplifier (RSOA) is proposed and a bidirectional free-space optical communication (FSO) system including both downstream and upstream links is experimentally demonstrated with only a single light source using this AMRR. The RSOA-based AMRR can provide a net gain more than 4 dB and support the modulation bit rate up to 1.25 Gbit/s. The bidirectional FSO transmission performance is evaluated by observing eye diagrams and measuring bit error rate (BER) results of both 10-Gbit/s DPSK downstream and 1.25-Gbit/s OOK upstream signals. The factors that limit the modulation bit rate and transmission quality are analyzed. The power penalties of both links are less than 0.69 dB in the bidirectional FSO system at the BER of 1×10-3.

  6. Recent advances in high-capacity free-space optical and radio-frequency communications using orbital angular momentum multiplexing

    Science.gov (United States)

    Willner, Alan E.; Ren, Yongxiong; Xie, Guodong; Yan, Yan; Li, Long; Zhao, Zhe; Wang, Jian; Tur, Moshe; Molisch, Andreas F.; Ashrafi, Solyman

    2017-02-01

    There is a continuing growth in the demand for data bandwidth, and the multiplexing of multiple independent data streams has the potential to provide the needed data capacity. One technique uses the spatial domain of an electromagnetic (EM) wave, and space division multiplexing (SDM) has become increasingly important for increased transmission capacity and spectral efficiency of a communication system. A subset of SDM is mode division multiplexing (MDM), in which multiple orthogonal beams each on a different mode can be multiplexed. A potential modal basis set to achieve MDM is to use orbital angular momentum (OAM) of EM waves. In such a system, multiple OAM beams each carrying an independent data stream are multiplexed at the transmitter, propagate through a common medium and are demultiplexed at the receiver. As a result, the total capacity and spectral efficiency of the communication system can be multiplied by a factor equal to the number of transmitted OAM modes. Over the past few years, progress has been made in understanding the advantages and limitations of using multiplexed OAM beams for communication systems. In this review paper, we highlight recent advances in the use of OAM multiplexing for high-capacity free-space optical and millimetre-wave communications. We discuss different technical challenges (e.g. atmospheric turbulence and crosstalk) as well as potential techniques to mitigate such degrading effects. This article is part of the themed issue 'Optical orbital angular momentum'.

  7. Recent advances in high-capacity free-space optical and radio-frequency communications using orbital angular momentum multiplexing.

    Science.gov (United States)

    Willner, Alan E; Ren, Yongxiong; Xie, Guodong; Yan, Yan; Li, Long; Zhao, Zhe; Wang, Jian; Tur, Moshe; Molisch, Andreas F; Ashrafi, Solyman

    2017-02-28

    There is a continuing growth in the demand for data bandwidth, and the multiplexing of multiple independent data streams has the potential to provide the needed data capacity. One technique uses the spatial domain of an electromagnetic (EM) wave, and space division multiplexing (SDM) has become increasingly important for increased transmission capacity and spectral efficiency of a communication system. A subset of SDM is mode division multiplexing (MDM), in which multiple orthogonal beams each on a different mode can be multiplexed. A potential modal basis set to achieve MDM is to use orbital angular momentum (OAM) of EM waves. In such a system, multiple OAM beams each carrying an independent data stream are multiplexed at the transmitter, propagate through a common medium and are demultiplexed at the receiver. As a result, the total capacity and spectral efficiency of the communication system can be multiplied by a factor equal to the number of transmitted OAM modes. Over the past few years, progress has been made in understanding the advantages and limitations of using multiplexed OAM beams for communication systems. In this review paper, we highlight recent advances in the use of OAM multiplexing for high-capacity free-space optical and millimetre-wave communications. We discuss different technical challenges (e.g. atmospheric turbulence and crosstalk) as well as potential techniques to mitigate such degrading effects.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Author(s).

  8. Transportable optical ground station for high-speed free-space laser communication

    Science.gov (United States)

    Shrestha, Amita; Brechtelsbauer, Martin

    2012-10-01

    Near real-time data downlinks from aircrafts, satellites and high altitude platforms via high-speed laser commu- nication links is an important research topic at the Institute of Communications and Navigation of the German Aerospace Center (DLR). Ground stations for such scenarios are usually fixed at a certain location. With a mo- tivation to provide a ground station that is quickly and easily deployed anywhere in the world, a transportable optical ground station (TOGS) has been developed. TOGS features a pneumatically deployable Cassegrain-type telescope with main mirror diameter of 60 cm, including optical tracking and receiving system. For calibration of position and attitude, multiple sensors like dual-antenna GPS and inclination sensors have been installed. In order to realize these systems, robust software that operates and controls them is essential. The software is platform independent and is aimed to be used on both mobile and ground terminals. It includes implementa- tion of accurate pointing, acquisition and tracking algorithms, hardware drivers, and user interfaces. Important modules of the software are GPS tracking, optical tracking, star- and satellite tracking, and calibration of the TOGS itself. Recently, a first successful data-downlink from an aircraft to TOGS using GPS tracking has been performed. To streamline the software development and testing process, some simulation environments like mount simulator, aircraft path simulator, tracking camera simulator and tracking error analysis tool have also been developed. This paper presents the overall hardware/software structure of the TOGS, and gives results of the tracking accuracy improvement techniques like GPS extrapolation and optical tracking.

  9. Multi-aperture digital coherent combining for free-space optical communication receivers.

    Science.gov (United States)

    Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

    2016-06-13

    Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

  10. Adaptive free-space optical communications through turbulence using self-healing Bessel beams.

    Science.gov (United States)

    Li, Shuhui; Wang, Jian

    2017-02-23

    We present a scheme to realize obstruction- and turbulence-tolerant free-space orbital angular momentum (OAM) multiplexing link by using self-healing Bessel beams accompanied by adaptive compensation techniques. Compensation of multiple 16-ary quadrature amplitude modulation (16-QAM) data carrying Bessel beams through emulated atmospheric turbulence and obstructions is demonstrated. The obtained experimental results indicate that the compensation scheme can effectively reduce the inter-channel crosstalk, improve the bit-error rate (BER) performance, and recuperate the nondiffracting property of Bessel beams. The proposed scheme might be used in future high-capacity OAM links which are affected by atmospheric turbulence and obstructions.

  11. Adaptive free-space optical communications through turbulence using self-healing Bessel beams

    Science.gov (United States)

    Li, Shuhui; Wang, Jian

    2017-02-01

    We present a scheme to realize obstruction- and turbulence-tolerant free-space orbital angular momentum (OAM) multiplexing link by using self-healing Bessel beams accompanied by adaptive compensation techniques. Compensation of multiple 16-ary quadrature amplitude modulation (16-QAM) data carrying Bessel beams through emulated atmospheric turbulence and obstructions is demonstrated. The obtained experimental results indicate that the compensation scheme can effectively reduce the inter-channel crosstalk, improve the bit-error rate (BER) performance, and recuperate the nondiffracting property of Bessel beams. The proposed scheme might be used in future high-capacity OAM links which are affected by atmospheric turbulence and obstructions.

  12. Free-space optical communications using orbital-angular-momentum multiplexing combined with MIMO-based spatial multiplexing.

    Science.gov (United States)

    Ren, Yongxiong; Wang, Zhe; Xie, Guodong; Li, Long; Cao, Yinwen; Liu, Cong; Liao, Peicheng; Yan, Yan; Ahmed, Nisar; Zhao, Zhe; Willner, Asher; Ashrafi, Nima; Ashrafi, Solyman; Linquist, Roger D; Bock, Robert; Tur, Moshe; Molisch, Andreas F; Willner, Alan E

    2015-09-15

    We explore the potential of combining the advantages of multiple-input multiple-output (MIMO)-based spatial multiplexing with those of orbital angular momentum (OAM) multiplexing to increase the capacity of free-space optical (FSO) communications. We experimentally demonstrate an 80 Gbit/s FSO system with a 2×2 aperture architecture, in which each transmitter aperture contains two multiplexed data-carrying OAM modes. Inter-channel crosstalk effects are minimized by the OAM beams' inherent orthogonality and by the use of 4×4 MIMO signal processing. Our experimental results show that the bit-error rates can reach below the forward error correction limit of 3.8×10(-3) and the power penalties are less than 3.6 dB for all channels after MIMO processing. This indicates that OAM and MIMO-based spatial multiplexing could be simultaneously utilized, thereby providing the potential to enhance system performance.

  13. On fading probability density functions of fast-tracked and untracked free-space optical communication channels

    Science.gov (United States)

    Zhao, Zhijun; Liao, Rui

    2011-03-01

    Free-space optical (FSO) communication systems suffer from average power loss and instantaneous power fading due to the atmospheric turbulence. The channel fading probability density function (pdf) is of critical importance for FSO communication system design and evaluation. The performance and reliability of FSO communication systems can be greatly enhanced if fast-tacking devices are employed at the transmitter in order to compensate laser beam wander at the receiver aperture. The fast-tracking method is especially effective when communication distance is long. This paper studies the fading probability density functions of both fast-tracked and untracked FSO communication channels. Large-scale wave-optics simulations are conducted for both tracked and untracked lasers. In the simulations, the Kolmogorov spectrum is adopted, and it is assumed that the outer scale is infinitely large and the inner scale is negligibly small. The fading pdfs of both fast-tracked and untracked FSO channels are obtained from the simulations. Results show that the fast-tracked channel fading can be accurately modeled as gamma-distributed if receiver aperture size is smaller than the coherence radius. An analytical method is given for calculating the untracked fading pdfs of both point-like and finite-size receiver apertures from the fast-tracked fading pdf. For point-like apertures, the analytical method gives pdfs close to the well-known gamma-gamma pdfs if off-axis effects are omitted in the formulation. When off-axis effects are taken into consideration, the untracked pdfs obtained using the analytical method fit the simulation pdfs better than gamma-gamma distributions for point-like apertures, and closely fit the simulation pdfs for finite-size apertures where gamma-gamma pdfs deviate from those of the simulations significantly.

  14. Shipboard Radio Frequency and Free Space Optics Communications System using an Airborne Relay

    Science.gov (United States)

    2005-09-01

    gain for FSO systems has the potential to be several orders of magnitude greater than RF gain by virtue of the 21λ factor. An optical antenna with... optical antenna , in this case, has a 40 dB advantage, ten-thousand times the gain, despite its smaller dimensions. 1. Transmit Gain A parabolic...3rd Edition. 2001. [19] Klein, B. J., and Degnan, J. J. “ Optical Antenna Gain. 1: Transmitting Antennas.” Applied Optics, Vol. 13, No. 9

  15. Coherent free space optics communications over the maritime atmosphere with use of adaptive optics for beam wavefront correction.

    Science.gov (United States)

    Li, Ming; Cvijetic, Milorad

    2015-02-20

    We evaluate the performance of the coherent free space optics (FSO) employing quadrature array phase-shift keying (QPSK) modulation over the maritime atmosphere with atmospheric turbulence compensated by use of adaptive optics (AO). We have established a comprehensive FSO channel model for maritime conditions and also made a comprehensive comparison of performance between the maritime and terrestrial atmospheric links. The FSO links are modeled based on the intensity attenuation resulting from scattering and absorption effects, the log-amplitude fluctuations, and the phase distortions induced by turbulence. The obtained results show that the FSO system performance measured by the bit-error-rate (BER) can be significantly improved when the optimization of the AO system is achieved. Also, we find that the higher BER is observed in the maritime FSO channel with atmospheric turbulence, as compared to the terrestrial FSO systems if they experience the same turbulence strength.

  16. Employing circle polarization shift keying in free space optical communication with gamma-gamma atmospheric turbulence channel

    Science.gov (United States)

    Wang, Yi; Du, Fan; Ma, Jing; Tan, Liying

    2014-12-01

    A novel theoretical model of a circular polarization shift keying (CPolSK) system for free space optical links through an atmospheric turbulence channel, is proposed. Intensity scintillation and phase fluctuation induced in atmospheric turbulence, from weak to strong levels, are specifically researched with respect to circular polarization control error caused by the system design. We derive closed form expressions of the bit error rate (BER) and outage probability for evaluating the BER performance and communication interruption in the Gamma-Gamma distributed channel model. Simulation results show that atmospheric turbulence and circular polarization control error have significant effects on the BER performance and interruption of communication in the CPolSK system. The deterioration in BER performance, caused by intensity scintillation and phase fluctuation, is augmented by the power penalty conditioned by the circular polarization control error. This consequently adds to the demand for emissive power from the CPolSK system. Furthermore, we demonstrate that controlling the circular polarization control error below 8° as well as the normalized threshold within 8 dB, 9 dB and 10 dB in turbulent scenarios from weak to strong levels can significantly reduce the probability of communication interruption occurring. This study provides reference material for further design of the CPolSK system.

  17. MEMS-based beam-steerable free-space optical communication link for reconfigurable wireless data center

    Science.gov (United States)

    Deng, Peng; Kavehrad, Mohsen; Lou, Yan

    2017-01-01

    Flexible wireless datacenter networks based on free space optical communication (FSO) links are being considered as promising solutions to meet the future datacenter demands of high throughput, robustness to dynamic traffic patterns, cabling complexity and energy efficiency. Robust and precise steerable FSO links over dynamic traffic play a key role in the reconfigurable optical wireless datacenter inter-rack network. In this work, we propose and demonstrate a reconfigurable 10Gbps FSO system incorporated with smart beam acquisition and tracking mechanism based on gimballess two-axis MEMS micro-mirror and retro-reflective film marked aperture. The fast MEMS-based beam acquisition switches laser beam of FSO terminal from one rack to the next for reconfigurable networks, and the precise beam tracking makes FSO device auto-correct the misalignment in real-time. We evaluate the optical power loss and bit error rate performance of steerable FSO links at various directions. Experimental results suggest that the MEMS based beam steerable FSO links hold considerable promise for the future reconfigurable wireless datacenter networks.

  18. Performance of Cat’s Eye Modulating Retro-Reflectors for Free-Space Optical Communications

    Science.gov (United States)

    2004-01-01

    attenuation is higher and in addition they fall off as 1/R 4 instead of 1/R 2 . The MRR parameters that affect the link are the MRR’s optical antenna gain...its modulation efficiency, and it modulation bandwidth. To overcome, its large propagation losses the MRR must exhibit a high optical antenna gain...light as its retro-reflects it. Thus its optical antenna gain is the product of the classical formulas for receiver gain and transmitter gain. The

  19. Asynchronous Free-Space Optical CDMA Communications System for Last-mile Access Network

    DEFF Research Database (Denmark)

    Jurado-Navas, Antonio; Raddo, Thiago R.; Sanches, Anderson L.

    2016-01-01

    We propose a new hybrid asynchronous OCDMA-FSO communications system for access network solutions. New ABER expressions are derived under gamma-gamma scintillation channels, where all users can surprisingly achieve error-free transmissions when FEC is employed....

  20. Synchronization and Detection of Binary Data in Free-Space Optical Communication Systems using Haar Wavelet Transformation

    Science.gov (United States)

    2006-01-01

    atory in Washington, D.C. since 1998. His current research inter- sts are free-space laser communications, satellite laser ranging, nd Geiger mode ... avalanche photodiode detectors. harles Conner received his PhD in electrical engineering from the atholic University of America in 1998. His specialties

  1. General scale-dependent anisotropic turbulence and its impact on free space optical communication system performance.

    Science.gov (United States)

    Toselli, Italo; Korotkova, Olga

    2015-06-01

    We generalize a recently introduced model for nonclassic turbulent spatial power spectrum involving anisotropy along two mutually orthogonal axes transverse to the direction of beam propagation by including two scale-dependent weighting factors for these directions. Such a turbulent model may be pertinent to atmospheric fluctuations in the refractive index in stratified regions well above the boundary layer and employed for air-air communication channels. When restricting ourselves to an unpolarized, coherent Gaussian beam and a weak turbulence regime, we examine the effects of such a turbulence type on the OOK FSO link performance by including the results on scintillation flux, probability of fade, SNR, and BERs.

  2. Contributions to free-space optical communications: feasibility of utilizing Cherenkov telescopes as receivers and beam-wander correction in quantum communications

    CERN Document Server

    Carrasco-Casado, Alberto

    2015-01-01

    This thesis focuses on the two main applications where free-space optical communication (FSOC) can bring the most significant impact: interplanetary communications and quantum communications. Consequently, the dissertation is structured in two sections. In the first one, a novel proposal is suggested regarding to using Cherenkov telescopes as ground-station receivers. A feasibility study addresses the posibility of using the technology developed for the gamma-ray telescopes that will make up the Cherenkov Telescope Array (CTA) in the implementation of a new kind of ground station. Among the main advantages that these telescopes provide are the much larger apertures needed to overcome the power limitation that ground-based gamma-ray astronomy and deep-space optical communication both have. Also, the large number of big telescopes that will be built for CTA will make it possible to reduce unitary costs by economy-scale production. The second section of the thesis is framed in the field of free-space Quantum Key...

  3. On the performance of free-space optical wireless communication systems over double generalized gamma fading channels

    KAUST Repository

    Al-Quwaiee, Hessa

    2014-03-01

    Starting with the double generalized Gamma (GG) model that was proposed in [1] to describe turbulence-induced fading in free-space optical (FSO) systems, we propose a new unified model which accounts for the impact of pointing errors and type of receiver detector. Based on this new unified model, we study the performance of FSO links operating over these kind of channels. All our analytical results are verified using computer based Monte-Carlo simulations. © 2014 IEEE.

  4. Demonstration of free-space optical communication for long-range data links between balloons on Project Loon

    Science.gov (United States)

    Moision, Bruce; Erkmen, Baris; Keyes, Edward; Belt, Todd; Bowen, Oliver; Brinkley, Devin; Csonka, Paul; Eglington, Michael; Kazmierski, Andrei; Kim, Nam-hyong; Moody, John; Tu, Thanh; Vermeer, William

    2017-02-01

    Internet connectivity is limited and in some cases non-existent for a significant part of the world's population. Project Loon aims to address this with a network of high-altitude balloons traveling in the stratosphere, at an altitude of approximately 20 km. The balloons navigate by using the stratified wind layers at different altitudes, adjusting the balloon's altitude to catch winds in a desired direction. Data transfer is achieved by 1) uplinking a signal from an Internet-connected ground station to a balloon terminal, 2) crosslinking the signal through the balloon network to reach the geographic area of the users, and 3) downlinking the signal directly to the end-users' phones or other LTE-enabled devices. We describe Loon's progress on utilizing free-space optical communications (FSOC) for the inter-balloon crosslinks. FSOC, offering high data rates and long communication ranges, is well-suited for communication between high-altitude platforms. A stratospheric link is sufficiently high to be above weather events (clouds, fog, rain, etc.), and the impact of atmospheric turbulence is significantly weaker than at ground level. In addition, being in the stratosphere as opposed to space helps avoid the typical challenges faced by space-based systems, namely operation in a vacuum environment with significant radiation. Finally, the angular pointing disturbances introduced by a floating balloon-based platform are notably less than any propelled platform, which simplifies the disturbance rejection requirements on the FSOC system. We summarize results from Project Loon's early-phase experimental inter-balloon links at 20 km altitude, demonstrating full duplex 130 Mbps throughput at distances in excess of 100 km over the course of several-day flights. The terminals utilize a monostatic design, with dual wavelengths for communication and a dedicated wide-angle beacon for pointing, acquisition, and tracking. We summarize the constraints on the terminal design, and the

  5. Study of Lateral Misalignment Tolerance of a Symmetric Free-Space Optical Link for Intra International Space Station Communication

    Science.gov (United States)

    Tedder, Sarah A.; Schoenholz, Bryan; Suddath, Shannon N.

    2016-01-01

    This paper describes the study of lateral misalignment tolerance of a symmetric high-rate free-space optical link (FSOL) for use between International Space Station (ISS) payload sites and the main cabin. The link will enable gigabit per second (Gbps) transmission of data, which is up to three orders of magnitude greater than the current capabilities. This application includes 10-20 meter links and requires minimum size, weight, and power (SWaP). The optical power must not present an eye hazard and must be easily integrated into the existing ISS infrastructure. On the ISS, rapid thermal changes and astronaut movement will cause flexure of the structure which will potentially misalign the free space transmit and receive optics 9 cm laterally and 0.2 degrees angularly. If this misalignment is not accounted for, a loss of the link or degradation of link performance will occur. Power measurements were collected to better understand the effect of various system design parameters on lateral misalignment. Parameters that were varied include: the type of small form pluggable (SFP) transceivers, type of fiber, and transmitted power level. A potential solution was identified that can reach the lateral misalignment tolerance (decenter span) required to create an FSOL on the ISS by using 105 m core fibers, a duplex SFP, two channels of light, and two fiber amplifiers.

  6. Performance analysis of multihop heterodyne free-space optical communication over general Malaga turbulence channels with pointing error

    KAUST Repository

    Alheadary, Wael Ghazy

    2017-09-21

    This work investigates the end-to-end performance of a free space optical amplify-and-forward (AF) channel-state-information (CSI)-assisted relaying system using heterodyne detection over Malaga turbulence channels at the presence of pointing error employing rectangular quadrature amplitude modulation (R-QAM). More specifically, we present exact closed-form expressions for average bit-error rate for adaptive/non-adaptive modulation, achievable spectral efficiency, and ergodic capacity by utilizing generalized power series of Meijer\\'s G-function. Moreover, asymptotic closed form expressions are provided to validate our work at high power regime. In addition, all the presented analytical results are illustrated using a selected set of numerical results. Moreover, we applied the bisection method to find the optimum beam width for the proposed FSO system.

  7. Free-space communication with over 100 spatial modes

    CSIR Research Space (South Africa)

    Rosales-Guzmán, C

    2016-10-01

    Full Text Available Congress 2016: Advanced Solid State Lasers (ASSL); Applications of Lasers for Sensing and Free Space Communications (LS&C), 30 October - 3 November 2016, Boston, Massachusetts, United States Free-space communication with over 100 spatial modes...

  8. A 400 Gbps/100 m free-space optical link

    Science.gov (United States)

    Lin, Chun-Yu; Lu, Hai-Han; Ho, Chun-Ming; Cheng, Ming-Te; Huang, Sheng-Jhe; Wang, Yun-Chieh; Chi, Jing-Kai

    2017-02-01

    A 400 Gbps/100 m free-space optical (FSO) link with dense-wavelength-division-multiplexing (DWDM)/space-division-multiplexing (SDM) techniques and a doublet lens scheme is proposed. To the best of our knowledge, this is the first time that a link adopting DWDM and SDM techniques and a doublet lens scheme has demonstrated a 400 Gbps/100 m FSO link. The experimental results show that the free-space transmission rate is significantly enhanced by the DWDM and SDM techniques, and the free-space transmission distance is greatly increased by the doublet lens scheme. A 16-channel FSO link with a total transmission rate of 400 Gbps (25 Gbps/λ  ×  16 λ  =  400 Gbps) over a 100 m free-space link is successfully demonstrated. Such a 400 Gbps/100 m DWDM/SDM FSO link provides the advantages of optical wireless communications for high transmission rates and long transmission distances, which is very useful for high-speed and long-haul light-based WiFi (LiFi) applications.

  9. Free-space communication based on quantum cascade laser

    Science.gov (United States)

    Chuanwei, Liu; Shenqiang, Zhai; Jinchuan, Zhang; Yuhong, Zhou; Zhiwei, Jia; Fengqi, Liu; Zhanguo, Wang

    2015-09-01

    A free-space communication based on a mid-infrared quantum cascade laser (QCL) is presented. A room-temperature continuous-wave distributed-feedback (DFB) QCL combined with a mid-infrared detector comprise the basic unit of the communication system. Sinusoidal signals at a highest frequency of 40 MHz and modulated video signals with a carrier frequency of 30 MHz were successfully transmitted with this experimental setup. Our research has provided a proof-of-concept demonstration of space optical communication application with QCL. The highest operation frequency of our setup was determined by the circuit-limited modulation bandwidth. A high performance communication system can be obtained with improved modulation circuit system. Project supported by the State Key Development Program for Basic Research of China (Nos. 2013CB632801, 2013CB632803) and the National Natural Science Foundation of China (Nos. 61435014, 61306058, 61274094).

  10. CO2 laser as a possible candidate for optical transmitter in free-space satellite-ground-satellite laser communication: a case study

    Science.gov (United States)

    Kumar, M. A.; Naik, Govind; Shenoy, N. V.; Rao, Mandavilli M.

    1999-04-01

    Terrestrial fiber optic communication systems handle most of the inter-continental communication systems today. However recent studies indicate that these links, in spite of their huge bandwidth will be saturated in the near future. Hence attempts are being made is augment and may be even replace these by inter satellite links (ISLs). Though high power laser diodes have been found to be suitable for ISLs, they are unfortunately inadequate for satellite-ground links (SGL and GSL) as they are not powerful enough. So we have to look for more powerful lasers for SGLs & GSLs. One possible candidate is the CO2 laser. It is a gas laser. It provides a number of advantages over other sources. They include high life time, high efficiency and stability. Besides it can generate a high power continuous wave and requires only radiative cooling. CO2 can provide a high bit rate and long range transmission with low bit error rate. Also CO2 laser is in near infra-red and hence the turbulence effects due to clouds is minimum. All these make CO2 laser a very economical choice. The use of optical communication in GSLs provides many advantages over radio links. Laser being a high energy source provides the advantage of greater bandwidth, smaller beam divergence angles, smaller antennae, greater security and a new spectrum. Lesser power consumption and smaller size make it more suitable for use in a satellite. The present paper deals with a case study of a CO2 laser based free space optical communication link by making the link budget analysis.

  11. Free Space Optics: Current Applications and Future Challenges

    Directory of Open Access Journals (Sweden)

    Aditi Malik

    2015-01-01

    Full Text Available FSO is a communication system where free space acts as medium between transceivers and they should be in LOS for successful transmission of optical signal. Medium can be air, outer space, or vacuum. This system can be used for communication purpose in hours and in lesser economy. There are many advantages of FSO like high bandwidth and no spectrum license. The transmission in FSO is dependent on the medium because the presence of foreign elements like rain, fog, and haze, physical obstruction, scattering, and atmospheric turbulence are some of these factors. Different studies on weather conditions and techniques employed to mitigate their effect are discussed in this paper.

  12. Free-Space Optical Communications Link at 1550-nm using Multiple-Quantum-Well Modulating Retroreflectors in a Marine Environment

    Science.gov (United States)

    2005-05-01

    is D rec . We define a retroreflector transmit/receive optical antenna gain G retro for use in the link budget. This parameter is simply the product... Optical antenna gain. 1: Transmitting antennas,’’ Appl. Opt. 13~9!, 2134–2140 ~1974!. 21. L. C. Andrews and R. L. Phillips, Laser Beam Propagation through

  13. Experimental realization of quantum cryptography communication in free space

    Institute of Scientific and Technical Information of China (English)

    WANG; Chuan; ZHANG; Jingfu; WANG; Pingxiao; DENG; Fuguo; A

    2005-01-01

    Utilizing linear optical devices, the principle of B92 quantum key distribution (QKD) protocol is demonstrated in free space with a distance of transmission of 2.2 meters. The faint laser pulses with 650 nm wavelength are used as the single photon sources. The experimental results show that the eavesdropping behavior in the signal transmission can be detected. We also discuss the problems and solutions in using the quantum cryptography communication practically. It is pointed out that one of the approaches to increasing the distance of the quantum communication is to overcome the attenuation of the single photon in transmission. This could not be solved by the use of single photon source, and new quantum communication protocols are needed to solve these problems.

  14. Quantum cryptography for secure free-space communications

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.J.; Buttler, W.T.; Kwiat, P.G.; Lamoreaux, S.K.; Luther, G.G.; Morgan, G.L.; Nordholt, J.E.; Peterson, C.G.

    1999-03-01

    The secure distribution of the secret random bit sequences known as key material, is an essential precursor to their use for the encryption and decryption of confidential communications. Quantum cryptography is a new technique for secure key distribution with single-photon transmissions: Heisenberg`s uncertainty principle ensures that an adversary can neither successfully tap the key transmissions, nor evade detection (eavesdropping raises the key error rate above a threshold value). The authors have developed experimental quantum cryptography systems based on the transmission of non-orthogonal photon polarization states to generate shared key material over line-of-sight optical links. Key material is built up using the transmission of a single-photon per bit of an initial secret random sequence. A quantum-mechanically random subset of this sequence is identified, becoming the key material after a data reconciliation stage with the sender. The authors have developed and tested a free-space quantum key distribution (QKD) system over an outdoor optical path of {approximately}1 km at Los Alamos National Laboratory under nighttime conditions. Results show that free-space QKD can provide secure real-time key distribution between parties who have a need to communicate secretly. Finally, they examine the feasibility of surface to satellite QKD.

  15. Bit error rate analysis of free-space optical communication over general Malaga turbulence channels with pointing error

    KAUST Repository

    Alheadary, Wael G.

    2016-12-24

    In this work, we present a bit error rate (BER) and achievable spectral efficiency (ASE) performance of a freespace optical (FSO) link with pointing errors based on intensity modulation/direct detection (IM/DD) and heterodyne detection over general Malaga turbulence channel. More specifically, we present exact closed-form expressions for adaptive and non-adaptive transmission. The closed form expressions are presented in terms of generalized power series of the Meijer\\'s G-function. Moreover, asymptotic closed form expressions are provided to validate our work. In addition, all the presented analytical results are illustrated using a selected set of numerical results.

  16. Memory assisted free space quantum communication

    Science.gov (United States)

    Jordaan, Bertus; Namazi, Mehdi; Goham, Connor; Shahrokhshahi, Reihaneh; Vallone, Giuseppe; Villoresi, Paolo; Figueroa, Eden

    2016-05-01

    A quantum memory assisted node between different quantum channels has the capability to modify and synchronize its output, allowing for easy connectivity, and advanced cryptography protocols. We present the experimental progress towards the storage of single photon level pulses carrying random polarization qubits into a dual rail room temperature quantum memory (RTQM) after ~ 20m of free space propagation. The RTQM coherently stores the input pulses through electromagnetically induced transparency (EIT) of a warm 87 Rb vapor and filters the output by polarization elements and temperature-controlled etalon resonators. This allows the characterization of error rates for each polarization basis and the testing of the synchronization ability of the quantum memory. This work presents a steppingstone towards quantum key distribution and quantum repeater networks. The work was supported by the US-Navy Office of Naval Research, Grant Number N00141410801 and the Simons Foundation, Grant Number SBF241180.B. J. acknowledges financial assistance of the National Research Foundation (NRF) of South Africa.

  17. On the Maximum and Minimum of Double Generalized Gamma Variates with Applications to the Performance of Free-space Optical Communication Systems

    KAUST Repository

    Al-Quwaiee, Hessa

    2016-01-07

    In this work, we derive the exact statistical characteristics of the maximum and the minimum of two modified1 double generalized gamma variates in closed-form in terms of Meijer’s G-function, Fox’s H-function, the extended generalized bivariate Meijer’s G-function and H-function in addition to simple closed-form asymptotic results in terms of elementary functions. Then, we rely on these new results to present the performance analysis of (i) a dual-branch free-space optical selection combining diversity and of (ii) a dual-hop free-space optical relay transmission system over double generalized gamma fading channels with the impact of pointing errors. In addition, we provide asymptotic results of the bit error rate of the two systems at high SNR regime. Computer-based Monte-Carlo simulations verify our new analytical results.

  18. Multi-Element Free Space Optical (FSO) Modules for Mobile Opportunistic Networking

    Science.gov (United States)

    2016-11-14

    Workshops (ICC). 23-MAY-16, Kuala Lumpur, Malaysia . : , . Autonomous Alignment of Free-Space-Optical Links Between UAVs, ACM MobiCom Workshop on...achieved a 3.5 GPA to 4.0 (4.0 max scale): Number of graduating undergraduates funded by a DoD funded Center of Excellence grant for Education , Research...Free-Space-Optical Links: A Prototype, Proceedings of IEEE ICC Workshop on Optical Wireless Communication (OWC), Pages 157-162, Kuala Lumpur, Malaysia

  19. Optical free-space wavelength-division-multiplexing transport system.

    Science.gov (United States)

    Lin, Chun-Yu; Lin, Ying-Pyng; Lu, Hai-Han; Chen, Chia-Yi; Jhang, Tai-Wei; Chen, Min-Chou

    2014-01-15

    An optical free-space wavelength-division-multiplexing (WDM) transport system employing vertical cavity surface emitting lasers and spatial light modulators with 16-quadrature amplitude modulation orthogonal frequency-division multiplexing modulating signals over a 17.5 m free-space link is proposed and demonstrated. With the help of a low-noise amplifier and data comparator, good bit error rate performance is obtained for each optical channel. Such an optical free-space WDM transport system would be attractive for providing services including data and telecommunication services.

  20. Advanced free space optics (FSO) a systems approach

    CERN Document Server

    Majumdar, Arun K

    2015-01-01

    This book provides a comprehensive, unified tutorial covering the most recent advances in the technology of free-space optics (FSO). It is an all-inclusive source of information on the fundamentals of FSO as well as up-to-date information on the state-of-the-art in technologies available today. This text is intended for graduate students, and will also be useful for research scientists and engineers with an interest in the field. FSO communication is a practical solution for creating a three dimensional global broadband communications grid, offering bandwidths far beyond what is possible in the Radio Frequency (RF) range. However, the attributes of atmospheric turbulence and scattering impose perennial limitations on availability and reliability of FSO links. From a systems point-of-view, this groundbreaking book provides a thorough understanding of channel behavior, which can be used to design and evaluate optimum transmission techniques that operate under realistic atmospheric conditions. Topics addressed...

  1. Protocols for Relay-Assisted Free-Space Optical Systems

    CERN Document Server

    Chatzidiamantis, Nestor D; Kriezis, Emmanouil E; Karagiannidis, George K; Schober, Robert

    2011-01-01

    We investigate transmission protocols for relay-assisted free-space optical (FSO) systems, when multiple parallel relays are employed and there is no direct link between the source and the destination. As alternatives to all-active FSO relaying, where all the available relays transmit concurrently, we propose schemes that select only a single relay to participate in the communication between the source and the destination in each transmission slot. This selection is based on the channel state information (CSI) obtained either from all or from some of the FSO links. Thus, the need for synchronizing the relays' transmissions is avoided and the slowly varying nature of the atmospheric channel is exploited. For both relay selection and all-active relaying, novel closed-form expressions for their outage performance are derived, assuming the versatile Gamma-Gamma channel model. Furthermore, based on the derived analytical results, the problem of allocating the optical power resources to the FSO links is addressed, ...

  2. Free-space optics: broadband wireless supplement to fiber networks

    Science.gov (United States)

    Leitgeb, Erich; Bregenzer, Josef; Gebhart, M.; Fasser, Peter; Merdonig, A.

    2003-07-01

    Free Space Optics (FSO) is an excellent supplement to conventional radio links and fiber optics. It is the broadband wireless solution for closing the "Last Mile" connectivity gap throughout metropolitan networks. FSO is useful in dense urban and urban applications. The realiabilty and availability of the FSO-link is mainly determined by the local atmospheric condition. In this paper the results of the investigations of the research group "OptiKon" on different installed common network-architectures (ring, mesh and star) are presented. An "Optical Repeater" was used, if there was no line of sight between transmitter and receiver. The usage of optical free space propagation wthi Light Emitting Diodes are source instead of conventionally broadband transmission systems like optical fibers or radio links was also investigated at the Department of Communications and Wave Propagation. Using extended light sources like LEDs and/or multiple transmitter optics due to new laser safety regulations allows multiple output power within the same laser class, increasing the power link budget especially for short range FSO systems. In a first step two families of cost-effective systems were developed and realized. One is based on a modular concept using available standard components, allowing demonstrates at 2×10 Mbps data rae. Another is used for the larger distnaces of about 300 m at a specific power margin of 25 dB/km. Systems for higher data rate are under development. Additionally some ideas and their possible realization for point-to-multipoint configuration are considered. In the last chapter a short overivew about the main results of the work of "OptiKom" is discussed.

  3. Free space optical sensor network for fixed infrastructure sensing

    Science.gov (United States)

    Agrawal, Navik; Milner, Stuart D.; Davis, Christopher C.

    2009-08-01

    Free space optical (FSO) links for indoor sensor networks can provide data rates that can range from bits/s to hundreds of Mb/s. In addition, they offer physical security, and in contrast with omnidirectional RF networks, they avoid interference with other electronic systems. These features are advantageous for communication over short distances in fixed infrastructure sensor networks. In this paper the system architecture for a fixed infrastructure FSO sensor network is presented. The system includes a network of small, low power (mW), sensor systems, or "motes," that transmit data optically to a central "cluster head," which controls the network traffic of all the motes and can aggregate the sensor information. The cluster head is designed with multiple vertical cavity surface emitting lasers oriented in different directions and controlled to diverge at 12º in order to provide signal coverage over a wide field of view. Both the cluster head and motes form a local area network. Our system design focuses on low-power wireless motes that can maintain successful communication over distances up to a few meters without having to use stringent optical alignment techniques, and our network design focuses on controlling mote sleep cycles for energy efficiency. This paper presents the design as well as the experimental link and optical communications performance of a prototype FSO-based sensor network.

  4. Novel Photon-Counting Detectors for Free-Space Communication

    Science.gov (United States)

    Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Lu, Wei; Merritt, Scott; Beck, Jeff

    2016-01-01

    We present performance data for novel photon counting detectors for free space optical communication. NASA GSFC is testing the performance of three novel photon counting detectors 1) a 2x8 mercury cadmium telluride avalanche array made by DRS Inc. 2) a commercial 2880 silicon avalanche photodiode array and 3) a prototype resonant cavity silicon avalanche photodiode array. We will present and compare dark count, photon detection efficiency, wavelength response and communication performance data for these detectors. We discuss system wavelength trades and architectures for optimizing overall communication link sensitivity, data rate and cost performance. The HgCdTe APD array has photon detection efficiencies of greater than 50 were routinely demonstrated across 5 arrays, with one array reaching a maximum PDE of 70. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 m to 25 m resulting in a 2x increase in e-APD gain from 470 on the 2010 array to 1100 on the array delivered to NASA GSFC. Mean single photon SNRs of over 12 were demonstrated at excess noise factors of 1.2-1.3.The commercial silicon APD array has a fast output with rise times of 300ps and pulse widths of 600ps. Received and filtered signals from the entire array are multiplexed onto this single fast output. The prototype resonant cavity silicon APD array is being developed for use at 1 micron wavelength.

  5. Free-space optical channel estimation for physical layer security.

    Science.gov (United States)

    Endo, Hiroyuki; Fujiwara, Mikio; Kitamura, Mitsuo; Ito, Toshiyuki; Toyoshima, Morio; Takayama, Yoshihisa; Takenaka, Hideki; Shimizu, Ryosuke; Laurenti, Nicola; Vallone, Giuseppe; Villoresi, Paolo; Aoki, Takao; Sasaki, Masahide

    2016-04-18

    We present experimental data on message transmission in a free-space optical (FSO) link at an eye-safe wavelength, using a testbed consisting of one sender and two receiver terminals, where the latter two are a legitimate receiver and an eavesdropper. The testbed allows us to emulate a typical scenario of physical-layer (PHY) security such as satellite-to-ground laser communications. We estimate information-theoretic metrics including secrecy rate, secrecy outage probability, and expected code lengths for given secrecy criteria based on observed channel statistics. We then discuss operation principles of secure message transmission under realistic fading conditions, and provide a guideline on a multi-layer security architecture by combining PHY security and upper-layer (algorithmic) security.

  6. Free-space optical channel estimation for physical layer security

    Science.gov (United States)

    Endo, Hiroyuki; Fujiwara, Mikio; Kitamura, Mitsuo; Ito, Toshiyuki; Toyoshima, Morio; Takayama, Yoshihisa; Takenaka, Hideki; Shimizu, Ryosuke; Laurenti, Nicola; Vallone, Giuseppe; Villoresi, Paolo; Aoki, Takao; Sasaki, Masahide

    2016-04-01

    We present experimental data on message transmission in a free-space optical (FSO) link at an eye-safe wavelength, using a testbed consisting of one sender and two receiver terminals, where the latter two are a legitimate receiver and an eavesdropper. The testbed allows us to emulate a typical scenario of physical-layer (PHY) security such as satellite-to-ground laser communications. We estimate information-theoretic metrics including secrecy rate, secrecy outage probability, and expected code lengths for given secrecy criteria based on observed channel statistics. We then discuss operation principles of secure message transmission under realistic fading conditions, and provide a guideline on a multi-layer security architecture by combining PHY security and upper-layer (algorithmic) security.

  7. Visible laser and superluminescent diode based free space and underwater communications

    KAUST Repository

    Ooi, Boon S.

    2017-01-30

    We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

  8. Information Theoretical Limits of Free-Space Optical Links

    KAUST Repository

    Ansari, Imran Shafique

    2016-08-25

    Generalized fading has been an imminent part and parcel of wireless communications. It not only characterizes the wireless channel appropriately but also allows its utilization for further performance analysis of various types of wireless communication systems. Under the umbrella of generalized fading channels, a unified ergodic capacity analysis of a free-space optical (FSO) link under both types of detection techniques (i.e., intensity modulation/direct detection (IM/DD) as well as heterodyne detection) over generalized atmospheric turbulence channels that account for generalized pointing errors is presented. Specifically, unified exact closed-form expressions for the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system are presented. Subsequently, capitalizing on these unified statistics, unified exact closed-form expressions for ergodic capacity performance metric of FSO link transmission systems is offered. Additionally, for scenarios wherein the exact closed-form solution is not possible to obtain, some asymptotic results are derived in the high SNR regime. All the presented results are verified via computer-based Monte-Carlo simulations.

  9. Free Space Optics – Monitoring Setup for Experimental Link

    Directory of Open Access Journals (Sweden)

    Ján Tóth

    2015-12-01

    Full Text Available This paper deals with advanced Free Space Optics communication technology. Two FSO nodes are needed in order to make a connection. Laser diodes are used as light sources. Simple OOK modulation is involved in this technology. FSO system offers multiple advantages indeed. However, a direct visibility is required in order to set up a communication link. This fact yields perhaps the most significant weakness of this technology. Obviously, there is no a chance to fight the weather phenomena like fog, heavy rain, dust and many other particles which are naturally present in the atmosphere. That’s why there is a key task to find a suitable solution to keep FSO link working with high reliability and availability. It turns out that it’s necessary to have knowledge about weather situation when FSO link operates (liquid water content - LWC, geographical location, particle size distribution, average particle diameter, temperature, humidity, wind conditions, pressure and many other variable weather parameters. It’s obvious that having most of mentioned parameter’s values stored in database (implicitly in charts would be really beneficial. This paper presents some of mentioned indicators continuously gathered from several sensors located close to one of FSO nodes.

  10. DLR's free space experimental laser terminal for optical aircraft downlinks

    Science.gov (United States)

    Fuchs, Christian; Schmidt, Christopher; Rödiger, Benjamin; Shrestha, Amita; Brechtelsbauer, Martin; Ramirez Molina, Julio; Pacheco, Jorge; Gstaiger, Veronika

    2017-02-01

    The German Aerospace Center's Institute of Communications and Navigation developed the Free Space Experimental Laser Terminal II and has been using it for optical downlink experiments since 2008. It has been developed for DLR's Dornier 228 aircraft and is capable of performing optical downlink as well as inter-platform experiments. After more than 5 years of successful operation, it has been refurbished with up-to-date hardware and is now available for further aircraft-experiments. The system is a valuable resource for carrying out measurements of the atmospheric channel, for testing new developments, and of course to transmit data from the aircraft to a ground station with a very high data rate. This paper will give an overview about the system and describe the capabilities of the flexible platform. The current status of the system will be described and measurement results of a recent flight campaign will be presented. Finally, an outlook to future use of the system will be given.

  11. Atmospheric effects on Quaternary polarization encoding for free space communication

    Science.gov (United States)

    Soorat, Ram; Vudayagiri, Ashok

    2016-10-01

    We have simulated atmospheric effects such as fog and smoke in laboratory environment to simulate depolarisation due to atmospheric effects during a free space optical communi- cation. This has been used to study noise in two components of quaternary encoding for polarization shift keying. Individual components of a Quaternary encoding, such as vertical and horizontal as well as 45$^\\circ$ and 135$^\\circ$ , are tested separately and indicates that the depo- larization effects are different for these two situation. However, due to a differential method used to extract information bits, the protocol shows extremely low bit error rates. The information obtained is useful during deployment of a fully functional Quaternary encoded PolSK scheme in free space.

  12. Free-space laser communication system with rapid acquisition based on astronomical telescopes.

    Science.gov (United States)

    Wang, Jianmin; Lv, Junyi; Zhao, Guang; Wang, Gang

    2015-08-10

    The general structure of a free-space optical (FSO) communication system based on astronomical telescopes is proposed. The light path for astronomical observation and for communication can be easily switched. A separate camera is used as a star sensor to determine the pointing direction of the optical terminal's antenna. The new system exhibits rapid acquisition and is widely applicable in various astronomical telescope systems and wavelengths. We present a detailed analysis of the acquisition time, which can be decreased by one order of magnitude compared with traditional optical communication systems. Furthermore, we verify software algorithms and tracking accuracy.

  13. Free-space wavelength-multiplexed optical scanner.

    Science.gov (United States)

    Yaqoob, Z; Rizvi, A A; Riza, N A

    2001-12-10

    A wavelength-multiplexed optical scanning scheme is proposed for deflecting a free-space optical beam by selection of the wavelength of the light incident on a wavelength-dispersive optical element. With fast tunable lasers or optical filters, this scanner features microsecond domain scan setting speeds and large- diameter apertures of several centimeters or more for subdegree angular scans. Analysis performed indicates an optimum scan range for a given diffraction order and grating period. Limitations include beam-spreading effects based on the varying scanner aperture sizes and the instantaneous information bandwidth of the data-carrying laser beam.

  14. Optical sensing in high voltage transmission lines using power over fiber and free space optics

    Science.gov (United States)

    Rosolem, João Batista; Bassan, Fabio Renato; Penze, Rivael Strobel; Leonardi, Ariovaldo Antonio; Fracarolli, João Paulo Vicentini; Floridia, Claudio

    2015-12-01

    In this work we propose the use of power over fiber (PoF) and free space optics (FSO) techniques to powering and receive signals from an electrical current sensor placed at high voltage potential using a pair of optical collimators. The technique evaluation was performed in a laboratorial prototype using 62.5/125 μm multimode fiber to study the sensitivity of the optical alignment and the influence of the collimation process in the sensing system wavelengths: data communication (1310 nm) and powering (830 nm). The collimators were installed in a rigid electric insulator in order to maintain the stability of transmission.

  15. Numerical simulation of linear and nonlinear quantum optics as a design tool for free-space quantum communications and quantum imaging

    Science.gov (United States)

    Meyers, Ronald E.; Deacon, Keith S.; Rosen, D.

    2002-12-01

    A new quantum optics tool for simulating quantum probability density functions resulting from the linear and nonlinear interaction of photons with atoms and with other photons is developed and presented. It can be used to design and simulate quantum optics experiments used in quantum communications, quantum computing, and quantum imaging. Examples of a photon interacting with linears systems of mirrors and beamsplitters are simulated. Nonlinear simulations of the interaction of three photons resulting in photon momentum entanglement is presented. The wavefunction is expanded in Fock states. Fock states cannot be represented by classical modeling and therefore, the results of our modeling can in general represent phenomena in both the linear and nonlinear cases which cannot be modeled by classical linear optics. The modeling presented here is more general than the classical linear optics. Models of atmospheric turbulence and their simulations are presented and demonstrate the potential for first principles physics quantum optics simulations through turbulence in realistic environments.

  16. A Review on Free Space Optics with Atmospheric and Geometrical Attenuation

    Science.gov (United States)

    Lath, Suruchi; Goyal, Rakesh; Kaler, Rajinder Singh

    2016-12-01

    Free space optics (FSO) communication is a short-distance wireless communication system. It can be used where optical fiber cables cannot be implemented. In FSO, the energy beam is accumulated and transmitted through space instead of guiding through an optical cable. FSO communication provides data at a rate of Gbps; it is highly secure because it uses narrow beam to transmit data from transmitter to receiver, uses license-free operation, has no electromagnetic interference and has quick installation. This paper gives an overview of performance of FSO communication with environmental attenuation.

  17. Free Space Optical Polarization De-multiplexing and Multiplexing by means of Conical Refraction

    OpenAIRE

    Turpin Avilés, Alejandro; Loiko, Yurii; Kalkandjiev, Todor Kirilov; Mompart Penina, Jordi

    2013-01-01

    Polarization demultiplexing and multiplexing by means of conical refraction is proposed to increase the channel capacity for free-space optical communication applications. The proposed technique is based on the forward-backward optical transform occurring when a light beam propagates consecutively along the optic axes of two identical biaxial crystals with opposite orientations of their conical refraction characteristic vectors. We present an experimental proof of usefulness of the conical re...

  18. Outage analysis for parallel relay free-space optical communication in strong turbulence%强湍流下并行中继自由空间光通信的中断分析

    Institute of Scientific and Technical Information of China (English)

    王俊波; 盛明; 谢秀秀; 焦媛

    2012-01-01

    在大气强湍流条件下,对并行中继自由空间光通信系统的中断概率进行了研究.考虑大气衰减、大气湍流和指向误差对自由空间光通信系统传输性能的影响,建立了自由空间光通信系统的复合信道模型.基于此信道模型,推导了并行中继自由空间光通信系统端到端中断概率的解析表达式.最后,通过计算机仿真分析了发送功率、指向误差及通信距离对通信系统中断概率的影响.仿真结果表明,并行中继传输技术可以有效提高自由空间光通信系统的中断性能.此外,所推导中断概率的解析表达式可准确地评估并行中继自由空间光通信系统的传输性能,为未来自由空间光通信系统的设计提供理论依据.%This paper studies the outage probability for parallel relay Free-space Optical(FSO) communication systems under a condition of strong turbulence. By considering the influences of atmospheric attenuation, atmospheric turbulence and pointing errors on the transmission performance of FSO communication systems, this paper establishes a composite channel model. Based on the model, an analytical expression is further derived for the end-to-end outage probability of parallel relay FSO communication systems. Finally, the effects of transmitted powers, pointing errors and communication distances on outage probability are analyzed through computer simulation. Simulation results show that parallel relay transmission is a promising technology to increase the outage performance and the de-rived analytical expression can provide sufficient precision for evaluating the outage performance of parallel relay free-space optical communication systems, which is helpful to the design of future free space optical communication systems.

  19. Towards Quantum Communication in Free-Space Seawater

    CERN Document Server

    Ji, Ling; Yang, Ai-Lin; Feng, Zhen; Zhang, Chen; Jiang, Xiao; Lin, Xiao-Feng; Li, Hong-Gen; Jin, Xian-Min

    2016-01-01

    Long-distance quantum channels capable of transferring quantum states faithfully for unconditionally secure quantum communication have been so far confirmed feasible in both fiber and free-space air. However, it remains unclear whether seawater, which covers more than 70% of the earth, can also be utilized, leaving global quantum communication incomplete. Here we experimentally demonstrate that polarization quantum states including general qubits and entangled states can well survive after travelling through seawater. We performed experiments in a 3.3-meter-long tube filled with seawater samples collected in a range of 36 kilometers in Yellow sea, which conforms to Jerlov water type I. For single photons at 405 nm in blue-green window, we obtained average process fidelity above 98%. For entangled photons at 810 nm, even with high loss, we observe violation of Bell inequality with 33 standard deviations. This work confirms feasibility of seawater quantum channel, representing the first step towards underwater ...

  20. Light beams with orbital angular momentum for free space optics

    Institute of Scientific and Technical Information of China (English)

    Wu Jing-Zhi; Li Yang-Jun

    2007-01-01

    The light's orbital angular momentum (OAM) is a consequence of the spiral flow of the electromagnetic energy. In this paper, an analysis of light beams with OAM used for free space optics (FSO) is conducted. The basic description and conception of light's OAM are reviewed. Both encoding information into OAM states of single light beam and encoding information into spatial structure of the mixed optical vortex with OAM are discussed, and feasibility to improve the FSO's performance of security and obstruction of line of sight is examined.

  1. Free Space Optics for Next Generation Cellular Backhaul

    KAUST Repository

    Zedini, Emna

    2016-11-01

    The exponential increase in the number of mobile users, coupled with the strong demand for high-speed data services results in a significant growth in the required cellular backhaul capacity. Optimizing the cost efficiency while increasing the capacity is becoming a key challenge to the cellular backhaul. It refers to connections between base stations and mobile switching nodes over a variety of transport technologies such as copper, optical fibers, and radio links. These traditional transmission technologies are either expensive, or cannot provide high data rates. This work is focused on the opportunities of free-space-optical (FSO) technology in next generation cellular back- haul. FSO is a cost effective and wide bandwidth solution as compared with the traditional radio-frequency (RF) transmission. Moreover, due to its ease of deployment, license-free operation, high transmission security, and insensitivity to interference, FSO links are becoming an attractive solution for next generation cellular networks. However, the widespread deployment of FSO links is hampered by the atmospheric turbulence-induced fading, weather conditions, and pointing errors. Increasing the reliability of FSO systems, while still exploiting their high data rate communications, is a key requirement in the deployment of an FSO-based backhaul. Therefore, the aim of this work is to provide different approaches to address these technical challenges. In this context, investigation of hybrid automatic repeat request (HARQ) protocols from an information-theoretic perspective is undertaken. Moreover, performance analysis of asymmetric RF/FSO dual-hop systems is studied. In such system models, multiple RF users can be multiplexed and sent over the FSO link. More specifically, the end-to-end performance metrics are presented in closed-form. This also has increased the interest to study the performance of dual-hop mixed FSO/RF systems, where the FSO link is used as a multicast channel that serves

  2. Link Margin Optimization of Free Space Optical Link under the Impact of Varying Meteorological Conditions

    Directory of Open Access Journals (Sweden)

    Amandeep Kaur Virk

    2012-03-01

    Full Text Available FSO is a free space optical technology synonymous to optical wireless communication and often called as openair photonics or infrared broadband. In free space optical communication, data is transmitted from point-to-point and multipoint using low-powered infrared lasers. FSO allows transmitting and receiving of voice, video, and data information. High speed and license free installation are the key features of this technology. The performance of FSO link is significantly affected by meteorological conditions viz. rain, scintillation, geometric attenuation and snow etc. In this paper we have formulated the link margin equation for the performanceevaluation of FSO link under varying meteorological conditions. Performance of the considered FSO link has been optimized on the basis of signal wavelength, link length and launched power level.

  3. Spontaneous emergence of free-space optical and atomic patterns

    CERN Document Server

    Schmittberger, Bonnie L

    2016-01-01

    The spontaneous formation of patterns in dynamical systems is a rich non-equilibrium phenomenon that is studied in fields ranging from atomic physics to cosmology. Here, we report our observation of coupled optical-atomic pattern formation, which results in the creation of self-organized, multimode structures in free-space laser-driven cold atoms. We show that this process gives rise to spontaneous three-dimensional Sisyphus cooling even at very low light intensities and the emergence of self-organized atomic structures on multiple spatial scales.

  4. Free-space laser communication performance in the atmospheric channel

    Science.gov (United States)

    Majumdar, Arun K.

    In spite of the tremendous technical advancement of available components, the major limitation of free-space laser communication (lasercom) performance is due to the atmosphere, because a portion of the atmospheric path always includes turbulence and multiple scattering effects. Starting from a fundamental understanding of the laser communications system under diverse weather conditions, this chapter provides a comprehensive treatment of the evaluation of parameters needed for analyzing system performance. The significance of higher-order statistics of probability density functions of irradiance fluctuations due to turbulence to performance analysis is explained. Starting from link analysis, the necessary expressions relating link margin, bit-error-rate, signal-to-noise-ratio, and probability of fade statistics are presented. Results for laboratory-simulated atmospheric turbulence and multiple scattering are presented. Example numerical results for simulations of lasercom systems operating under various at mospheric conditions are presented for various scenarios such as uplink-downlink (e.g., between ground and satellite, aircraft or UAV) and horizontal (terrestrial) link. Both turbulence and multiple scattering effects have been included in the analysis with both on-off keying and pulse-position modulation schemes. Statistical estimation and computation of communication parameters presented in this chapter will be useful in designing and optimizing lasercom systems that are reliable under all weather conditions.

  5. Free-space coherent optical communication with orbital angular, momentum multiplexing/demultiplexing using a hybrid 3D photonic integrated circuit.

    Science.gov (United States)

    Guan, Binbin; Scott, Ryan P; Qin, Chuan; Fontaine, Nicolas K; Su, Tiehui; Ferrari, Carlo; Cappuzzo, Mark; Klemens, Fred; Keller, Bob; Earnshaw, Mark; Yoo, S J B

    2014-01-13

    We demonstrate free-space space-division-multiplexing (SDM) with 15 orbital angular momentum (OAM) states using a three-dimensional (3D) photonic integrated circuit (PIC). The hybrid device consists of a silica planar lightwave circuit (PLC) coupled to a 3D waveguide circuit to multiplex/demultiplex OAM states. The low excess loss hybrid device is used in individual and two simultaneous OAM states multiplexing and demultiplexing link experiments with a 20 Gb/s, 1.67 b/s/Hz quadrature phase shift keyed (QPSK) signal, which shows error-free performance for 379,960 tested bits for all OAM states.

  6. Physical layer simulator for undersea free-space laser communications

    Science.gov (United States)

    Dalgleish, Fraser R.; Shirron, Joseph J.; Rashkin, David; Giddings, Thomas E.; Vuorenkoski Dalgleish, Anni K.; Cardei, Ionut; Ouyang, Bing; Caimi, Frank M.; Cardei, Mihaela

    2014-05-01

    High bandwidth (10 to 100 Mbps), real-time data networking in the subsea environment using free-space lasers has a potentially high impact as an enabling technology for a variety of future subsea operations in the areas of distributed sensing, real-time wireless data transfer, control of unmanned undersea vehicles, and other submerged assets. However, the development and testing of laser networking equipment in the undersea environment are expensive and time consuming, and there is a clear need for a network simulation framework that will allow researchers to evaluate the performance of alternate optical and electronic configurations under realistic operational and environmental constraints. The overall objective of the work reported in this paper was to develop and validate such a simulation framework, which consists of (1) a time-dependent radiative transfer model to accurately predict the channel impulse characteristics for alternate system designs over a range of geometries and optical properties and (2) digital modulation and demodulation blocks which accurately simulate both laser source and receiver noise characteristics in order to generate time domain bit stream samples that can be digitally demodulated to predict the resulting bit error rate of the simulated link.

  7. Free-space optical polarization demultiplexing and multiplexing by means of conical refraction.

    Science.gov (United States)

    Turpin, Alex; Loiko, Yurii; Kalkandjiev, Todor K; Mompart, Jordi

    2012-10-15

    Polarization demultiplexing and multiplexing by means of conical refraction is proposed to increase the channel capacity for free-space optical communication applications. The proposed technique is based on the forward-backward optical transform occurring when a light beam propagates consecutively along the optic axes of two identical biaxial crystals with opposite orientations of their conical refraction characteristic vectors. We present an experimental proof of usefulness of the conical refraction demultiplexing and multiplexing technique by increasing in one order of magnitude the channel capacity at optical frequencies in a propagation distance of 4 m.

  8. Mode-Division-Multiplexing of Multiple Bessel-Gaussian Beams Carrying Orbital-Angular-Momentum for Obstruction-Tolerant Free-Space Optical and Millimetre-Wave Communication Links.

    Science.gov (United States)

    Ahmed, Nisar; Zhao, Zhe; Li, Long; Huang, Hao; Lavery, Martin P J; Liao, Peicheng; Yan, Yan; Wang, Zhe; Xie, Guodong; Ren, Yongxiong; Almaiman, Ahmed; Willner, Asher J; Ashrafi, Solyman; Molisch, Andreas F; Tur, Moshe; Willner, Alan E

    2016-03-01

    We experimentally investigate the potential of using 'self-healing' Bessel-Gaussian beams carrying orbital-angular-momentum to overcome limitations in obstructed free-space optical and 28-GHz millimetre-wave communication links. We multiplex and transmit two beams (l = +1 and +3) over 1.4 metres in both the optical and millimetre-wave domains. Each optical beam carried 50-Gbaud quadrature-phase-shift-keyed data, and each millimetre-wave beam carried 1-Gbaud 16-quadrature-amplitude-modulated data. In both types of links, opaque disks of different sizes are used to obstruct the beams at different transverse positions. We observe self-healing after the obstructions, and assess crosstalk and power penalty when data is transmitted. Moreover, we show that Bessel-Gaussian orbital-angular-momentum beams are more tolerant to obstructions than non-Bessel orbital-angular-momentum beams. For example, when obstructions that are 1 and 0.44 the size of the l = +1 beam, are placed at beam centre, optical and millimetre-wave Bessel-Gaussian beams show ~6 dB and ~8 dB reduction in crosstalk, respectively.

  9. Outage Probability of the Gaussian MIMO Free-Space Optical Channel with PPM

    CERN Document Server

    Letzepis, Nick

    2008-01-01

    The free-space optical channel has the potential to facilitate inexpensive, wireless communication with fiber-like bandwidth under short deployment timelines. However, atmospheric effects can significantly degrade the reliability of a free-space optical link. In particular, atmospheric turbulence causes random fluctuations in the irradiance of the received laser beam, commonly referred to as scintillation. The scintillation process is slow compared to the large data rates typical of optical transmission. As such, we adopt a quasi-static block fading model and study the outage probability of the channel under the assumption of orthogonal pulse-position modulation. We investigate the mitigation of scintillation through the use of multiple lasers and multiple apertures, thereby creating a multiple-input multiple output (MIMO) channel. Non-ideal photodetection is also assumed such that the combined shot noise and thermal noise are considered as signal-independent Additive Gaussian white noise. Assuming perfect re...

  10. Orbital angular momentum (OAM) multiplexing in free-space optical data transfer

    Science.gov (United States)

    Lin, Jiao; Yuan, Xiao-Cong; Tao, Shaohua

    2006-08-01

    In the optical wireless communication systems proposed by Gibson, et al, the information is encoded as states of orbital angular momentum (OAM) of light and the transmitter unit can produce laser beam with single OAM-state in a time-slot. Recently we have proved that it is possible to generate multiple OAM-states simultaneously by single spatial light modulator. This method is adopted in our free-space optical wireless communication system and these OAM-states can be detected in the receiving unit by a computer-generated hologram. Hence, the transmission capacity is enhanced significantly without increasing the complexity of system.

  11. Free-space wavelength-multiplexed optical scanner demonstration.

    Science.gov (United States)

    Yaqoob, Zahid; Riza, Nabeel A

    2002-09-10

    Experimental demonstration of a no-moving-parts free-space wavelength-multiplexed optical scanner (W-MOS) is presented. With fast tunable lasers or optical filters and planar wavelength dispersive elements such as diffraction gratings, this microsecond-speed scanner enables large several-centimeter apertures for subdegree angular scans. The proposed W-MOS design incorporates a unique optical amplifier and variable optical attenuator combination that enables the calibration and modulation of the scanner response, leading to any desired scanned laser beam power shaping. The experimental setup uses a tunable laser centered at 1560 nm and a 600-grooves/mm blazed reflection grating to accomplish an angular scan of 12.92 degrees as the source is tuned over an 80-nm bandwidth. The values for calculated maximum optical beam divergance, required wavelength resolution, beam-pointing accuracy, and measured scanner insertion loss are 1.076 mrad, 0.172 nm, 0.06 mrad, and 4.88 dB, respectively.

  12. 市内建筑间无线光通信GPS辅助单向捕获研究%Research on unidirectional acquisition in free-space optical communication between buildings in cities based on GPS

    Institute of Scientific and Technical Information of China (English)

    肖永军; 董冉; 熊准; 杨智

    2012-01-01

    为减小无线光通信链路建立时间及增加系统捕获可靠性,提出将GPS技术应用于光通信实验系统中.以TMS320F2812为控制核心,搭建了无线光通信定点单向捕获实验系统.系统采用用户界面统一控制,双方GPS坐标手工输入至用户界面,解算出需调整的方位及俯仰角后送于F2812,驱动二维转台完成初始捕获,据此选择多点进行了多次单向初始捕获实验.结果表明,采用GPS导航定位技术,可快速实现信标光的初始捕获,且具有较高的捕获成功概率.%To reduce of setup time of communication link and increase of acquisition reliability for free-space optical communication, the GPS technology is applied in the optical communication, and the unidirectional acquisition experiment system, controlled through user interface, is established with the control core of TMS320F2812. the coordinate from GPS is input to user interface by manual, formed into the horizontal- and vertical- Angle to adjust based on the GPS coordinate and sent to F2812 for driving of two-dimension platform to finish initial acquisition. The acquisition experiment is done many times and the result show that the quick and high probability acquisition could be achieved based on GPS technology.

  13. Effects of atmosphere on free-space optical transmission at 1.55 μm

    Science.gov (United States)

    Zeller, John; Manzur, Tariq

    2010-10-01

    Free-space optics (FSO) holds the potential for high bandwidth communication, but atmospheric conditions can significantly affect the capability of this type of communication system to transfer information consistently and operate effectively. The effects of atmosphere on FSO communication and consequent optimal wavelength range for transmission are investigated through MODTRAN-based modeling of 1.55 μm transmission for multiple elevation angles in atmospheric weather conditions including clear maritime, desert extinction, and various levels of rain and fog, to simulate surface-to-surface and surface-to-air FSO communication networks. Furthermore, atmospheric, free-space, and scintillation losses are analyzed for optical path lengths of 2 km to determine minimum transmit power required for successful data reception. In addition, FSO transmitter and receiver circuits were designed to optically relay analog video signals and their operation verified at path distances of up to 130 m. Using advanced laser sources to provide illumination at infrared wavelengths, particularly around the eye-safe 1.55 μm wavelength, it should be possible to overcome many transmission limitations associated with atmospheric conditions such as adverse weather and turbulence.

  14. Simulating atmospheric free-space optical propagation: rainfall attenuation

    Science.gov (United States)

    Achour, Maha

    2002-04-01

    With recent advances and interest in Free-Space Optics (FSO) for commercial deployments, more attention has been placed on FSO weather effects and the availability of global weather databases. The Meteorological Visual Range (Visibility) is considered one of the main weather parameters necessary to estimate FSO attenuation due to haze, fog and low clouds. Proper understanding of visibility measurements conducted throughout the years is essential. Unfortunately, such information is missing from most of the databases, leaving FSO players no choice but to use the standard visibility equation based on 2% contrast and other assumptions on the source luminance and its background. Another challenge is that visibility is measured using the visual wavelength of 550 nm. Extrapolating the measured attenuations to longer infrared wavelengths is not trivial and involves extensive experimentations. Scattering of electromagnetic waves by spherical droplets of different sizes is considered to simulate FSO scattering effects. This paper serves as an introduction to a series of publications regarding simulation of FSO atmospheric propagation. This first part focuses on attenuation due to rainfall. Additional weather parameters, such as rainfall rate, temperature and relative humidity are considered to effectively build the rain model. Comparison with already published experimental measurement is performed to validate the model. The scattering cross section due to rain is derived from the density of different raindrop sizes and the raindrops fall velocity is derived from the overall rainfall rate. Absorption due the presence of water vapor is computed using the temperature and relative humidity measurements.

  15. 空间光通信中分布式天线的信号检测研究%Signal detection algorithm in free-space optical communication systems with distributed transmit antennas

    Institute of Scientific and Technical Information of China (English)

    黎明; 李书明; 杨绍文

    2013-01-01

    The distributed multiple-input multiple-output (MIMO) technique is one of the effective ways to mitigate the effect of atmospheric turbulence and reduce the packet error rate in free-space optical communications. Because the time of laser propagation is different and random among atmospheric turbulence links, signals arrive at the receiving antennas randomly and asynchronously, which causes the problem of inter-symbol interference. But linear detection algorithms are more complicated to solve it for the free-space optical (FSO) system with distributed transmit antennas. The valuable information obtained from signs of distributed receiving antennas depends on combining mode, and the performance of anti-interference is determined by the detection algorithm. Focusing on the problem above, this paper proposes the algorithm based on maximum likelihood detection and Neyman-Pearson (NP) fusion criterion for distributed receiving antennas system. Simulation results show that when receiving signal is synchronous, NP algorithm has better robustness,it is comparable to optimal combining (OC) algorithm, and it is better than the equal gain combining (EGO algorithm. When receiving signal is asynchronous, NP algorithm is better than EGC and OC algorithms, which improves spatial diversity performance in the distributed antennas system,suppressing inter-symbol interference.%针对空间光通信中随机信道传播时延导致接收信号符号间干扰的特殊性使分布式发射天线多入多出(MIMO)信号的线性检测算法更加复杂这一问题,提出了一种基于Neyman-Pearson(NP)融合准则的分布式天线信号检测算法.仿真结果表明,当接收信号同步时,NP算法具有较好的健壮性,其性能优于等增益合并(EGC)算法,与最佳合并(OC)算法相当;当接收信号异步时,NP算法要明显优于EGC和OC算法,抑制接收符号间干扰,能体现出分布式天线系统的空间分集性能.

  16. Error Probability Analysis of Free-Space Optical Links with Different Channel Model under Turbulent Condition

    CERN Document Server

    Barua, Bobby; Islam, Md Rezwan

    2012-01-01

    Free space optics (FSO) is a promising solution for the need to very high data rate point-to point communication. FSO communication technology became popular due to its large bandwidth potential, unlicensed spectrum, excellent security and quick and inexpensive setup. Unfortunately, atmospheric turbulence-induced fading is one of the main impairments affecting FSO communications. To design a high performance communication link for the atmospheric FSO channel, it is of great importance to characterize the channel with proper model. In this paper, the modulation format is Q-ary PPM across lasers, with intensity modulation and ideal photodetectors are assumed to investigate the most efficient PDF models for FSO communication under turbulent condition. The performance results are evaluated in terms of symbol error probability (SEP) for different type of channel model and the simulation results confirm the analytical findings.

  17. Analysis of Rain Effects on Terrestrial Free Space Optics based on Data Measured in Tropical Climate

    Directory of Open Access Journals (Sweden)

    Suriza Ahmad Zabidi

    2012-01-01

    Full Text Available Free Space Optics (FSO shows a great alternative as the solution for last mile problem where fiber optics is unavailable due to deployment time and cost constraint.  However, the feasibility of using FSO system as communication link very much depends on local weather.  Since tropical region experiences heavy rainfall, rain with high intensity is expected to affect the FSO link severely. Few prediction models have been proposed by ITU-R based on France and Japan’s measurement. This paper has compared  rain attenuation predicted by  models and  data measured in Malaysia over Free Space Optical links for one year period. Prediction models are clearly unable to predict attenuation measured in tropical climate. ABSTRAK: Wayarles optik menjadi alternatif sebagai satu penyelesaian kepada masalah kesesakan terutama diakhir sesuatu talian dimana ianya tidak dapat diselesaikan dengan menggunakan gentian fiber akibat daripada kekangan masa pemasangan dan masalah kewangan.  Walaubagaimanapun, kejayaan untuk menggunakan wayarless optic ini amat bergantung kepada keadaan cuaca di sesuatu tempat.  Di rantau tropika  hujan lebat sentiasa dialami, oleh itu hujan dengan kepadatan tinggi adalah dijangkakan lebih memberi kesan kepada talian wayarles optic ini. Beberapa model yang telah dicadangkan oleh ITU-R berlandaskan kepada pengumpulan data yang dibuat di Perancis dan Jepun.  Kertas kajian ini akan membandingkan antara model-model yang telah digunapakai dengan data yang dikumpulkan di Malaysia selama setahun.  Jelasnya model yang telah digunapakai tidak dapat digunakan secara berkesan di rantau tropika.KEYWORDS: free space optics; rainfall rate; rain attenuation

  18. On the Performance Analysis of Free-Space Optical Links under Generalized Turbulence and Misalignment Models

    KAUST Repository

    AlQuwaiee, Hessa

    2016-11-01

    One of the potential solutions to the radio frequency (RF) spectrum scarcity problem is optical wireless communications (OWC), which utilizes the unlicensed optical spectrum. Long-range outdoor OWC are usually referred to in the literature as free-space optical (FSO) communications. Unlike RF systems, FSO is immune to interference and multi-path fading. Also, the deployment of FSO systems is flexible and much faster than optical fibers. These attractive features make FSO applicable for broadband wireless transmission such as optical fiber backup, metropolitan area network, and last mile access. Although FSO communication is a promising technology, it is negatively affected by two physical phenomenon, namely, scintillation due to atmospheric turbulence and pointing errors. These two critical issues have prompted intensive research in the last decade. To quantify the effect of these two factors on FSO system performance, we need effective mathematical models. In this work, we propose and study a generalized pointing error model based on the Beckmann distribution. Then, we aim to generalize the FSO channel model to span all turbulence conditions from weak to strong while taking pointing errors into consideration. Since scintillation in FSO is analogous to the fading phenomena in RF, diversity has been proposed too to overcome the effect of irradiance fluctuations. Thus, several combining techniques of not necessarily independent dual-branch free-space optical links were investigated over both weak and strong turbulence channels in the presence of pointing errors. On another front, improving the performance, enhancing the capacity and reducing the delay of the communication link has been the motivation of any newly developed schemes, especially for backhauling. Recently, there has been a growing interest in practical systems to integrate RF and FSO technologies to solve the last mile bottleneck. As such, we also study in this thesis asymmetric an RF-FSO dual-hop relay

  19. Characterization of dual-polarization LTE radio over a free-space optical turbulence channel.

    Science.gov (United States)

    Bohata, J; Zvanovec, S; Korinek, T; Mansour Abadi, M; Ghassemlooy, Z

    2015-08-10

    A dual polarization (DP) radio over a free-space optical (FSO) communication link using a long-term evolution (LTE) radio signal is proposed and analyzed under different turbulence channel conditions. Radio signal transmission over the DP FSO channel is experimentally verified by means of error vector magnitude (EVM) statistics. We demonstrate that such a system, employing a 64 quadrature amplitude modulation at the frequency bands of 800 MHz and 2.6 GHz, evinces reliability with LTE signal over the FSO channel is a potential solution for last-mile access or backbone networks, when using multiple-input multiple-output based DP signals.

  20. Adaptive Bit Rate Video Streaming Through an RF/Free Space Optical Laser Link

    Directory of Open Access Journals (Sweden)

    A. Akbulut

    2010-06-01

    Full Text Available This paper presents a channel-adaptive video streaming scheme which adjusts video bit rate according to channel conditions and transmits video through a hybrid RF/free space optical (FSO laser communication system. The design criteria of the FSO link for video transmission to 2.9 km distance have been given and adaptive bit rate video streaming according to the varying channel state over this link has been studied. It has been shown that the proposed structure is suitable for uninterrupted transmission of videos over the hybrid wireless network with reduced packet delays and losses even when the received power is decreased due to weather conditions.

  1. Free Space Optical Channel Characterization and Modeling with Focus on Algeria Weather Conditions

    Directory of Open Access Journals (Sweden)

    Mehdi ROUISSAT

    2012-04-01

    Full Text Available Free-Space Optics (FSO is a wireless optical technology that enables optical transmission of data, voice and video communications through the air, up to 10 Gbps of data, based on the use of the free space (the atmosphere as transmission medium and low power lasers as light sources.Quality and performance of FSO links are generally affected by link distance and weather conditions like environmental temperature and light, sun, fog, snow, smoke, haze and rain. In this paper we study the effects of weather conditions on the performance of FSO links, taking the climate of Algeria as an example, and since there is no known analysis on the effects of weather conditions in this country, this paper offers an attempt to analyze and identify the challenges related to the deployment of FSO links under Algeria’s weather. We also present a Graphic User Interface “GUI” to provide an approximate availability estimate of an atmospheric optical link in term of probability of connection.

  2. Practical Quantum Cryptography for Secure Free-Space Communications

    Energy Technology Data Exchange (ETDEWEB)

    Buttler, W.T.; Hughes, R.J.; Kwiat, P.G.; Lamoreaux, S.K.; Morgan, G.L.; Nordholt, J.E.; Peterson, C.G.

    1999-02-01

    Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. The security of these transmissions is based on the inviolability of the laws of quantum mechanics and information-theoretically secure post-processing methods. An adversary can neither successfully tap the quantum transmissions, nor evade detection, owing to Heisenberg's uncertainty principle. In this paper we describe the theory of quantum cryptography, and the most recent results from our experimental free-space system with which we have demonstrated for the first time the feasibility of quantum key generation over a point-to-point outdoor atmospheric path in daylight. We achieved a transmission distance of 0.5 km, which was limited only by the length of the test range. Our results provide strong evidence that cryptographic key material could be generated on demand between a ground station and a satellite (or between two satellites), allowing a satellite to be securely re-keyed on orbit. We present a feasibility analysis of surface-to-satellite quantum key generation.

  3. 空间光通信系统发射光束的准直特性研究%Research on collimating characteristics of the emitted laser beam in free space optical communication system

    Institute of Scientific and Technical Information of China (English)

    王怡; 杜凡; 马晶; 谭立英

    2015-01-01

    A polymer straight tapered fiber collimation system with a fiber plano- convex lens coupled directly into the front- end was developed. We demonstrate that the cone angle and taper length of polymer straight tapered fiber have remarkable effects on the collimation performance based on the theory of rays propagation and geometrical optics. We show that the collimation accuracy improves obviously with small cone angle of long straight tapered fiber. In addition, the cone angle and taper length are further optimally designed so that both the coupling efficiency and collimation accuracy are well balanced and maximized in the collimating process. This study can benefit the collimation of the emitted laser beam in free space optical communication systems.%提出一种前端直接耦合光纤平凸透镜的聚合物直光锥光束准直系统。通过具体地对直光锥的端体结构参数进行优化设计以得到高耦合效率高准直精度的直接耦合式聚合物直光锥准直系统。并利用光线传输理论和仿真实验,论证了直光锥的锥角和锥长对准直效能的较大影响。结果表明,选择合适的锥角和锥长能达到十微弧度级的准直精度,能较好地满足空间光通信系统远距离发射和接收对于光束质量的要求。此外,理论数值和仿真实验同样验证了该直接耦合式直光锥准直系统对于较大发散角的发散光束具有较好的准直效果。

  4. 湍流大气光通信系统误码率分析与实验研究%Analysis and Experimental Research on Bit Error Rate for Free-Space Optical Communication Systems through Turbulent Atmosphere

    Institute of Scientific and Technical Information of China (English)

    李菲; 吴毅; 侯再红

    2012-01-01

    自由空间光通信(FSO)系统的性能由于受大气湍流影响会产生剧烈波动.根据系统和大气参数评估系统差错性能的研究具有现实意义.以大气湍流信道和光电探测两个模型为基础,建立了FSO系统差错性能的数学仿真模型,提出了湍流条件下系统误码率计算公式.对仿真结果与弱湍流条件下获得的实验数据进行了比较,并依据此模型对光强起伏和背景噪声等因素的影响进行仿真.仿真结果表明,基于该模型的仿真结果与实验数据一致,光强起伏是引起系统性能波动的主要因素,最优判决阈值需根据实际大气条件进行调整.该模型可有效评估湍流条件下FSO系统性能,并为相关理论研究提供参考.%Performance of free-space optical communication (FSO) system fluctuates greatly due to influence by atmospheric turbulence. Research about evaluating system error performance according to parameters of system and atmosphere is a subject of current interest. Based on both optical turbulence channel and photoelectric detection model, a ma thematic simulation model of error performance for FSO system is established, and an expression of bit error rate for FSO system through turbulent atmosphere is proposed. Results of simulation are compared with experimental data obtained under weak turbulence condition and the model is used to characterize factors in turbulence, such as intensity fluctuation and background noise, etc. Simulation results are shown to be consistent with experimental data, intensity fluctuation is a chief factor of system performance fluctuation, and optimized threshold should be adjusted according to pratical atmosphere. The presented model can lead to an efficient performance evaluation and provide reference to correlative theoretical researches.

  5. Unified performance analysis of hybrid-ARQ with incremental redundancy over free-space optical channels

    KAUST Repository

    Zedini, Emna

    2014-09-01

    In this paper, we carry out a unified performance analysis of hybrid automatic repeat request (HARQ) with incremental redundancy (IR) from an information theoretic perspective over a point-to-point free-space optical (FSO) system. First, we introduce a novel unified expression for the distribution of a single FSO link modeled by the Gamma fading that accounts for pointing errors subject to both types of detection techniques at the receiver side (i.e. heterodyne detection and intensity modulation with direct detection (IM/DD)). Then, we provide analytical expressions for the outage probability, the average number of transmissions, and the average transmission rate for HARQ with IR, assuming a maximum number of rounds for the HARQ protocol. In our study, the communication rate per HARQ round is constant. Our analysis demonstrates the importance of HARQ in improving the performance and reliability of FSO communication systems. All the given results are verified via computer-based Monte-Carlo simulations.

  6. Proposed parameters of specific rain attenuation prediction for Free Space Optics link operating in tropical region

    Science.gov (United States)

    Suriza, A. Z.; Md Rafiqul, Islam; Wajdi, A. K.; Naji, A. W.

    2013-03-01

    As the demand for higher and unlimited bandwidth for communication channel is increased, Free Space Optics (FSO) is a good alternative solution. As it is protocol transparent, easy to install, cost effective and have capabilities like fiber optics, its demand rises very fast. Weather condition, however is the limiting factor for FSO link. In the temperate region the major blockage for FSO link feasibility is fog. In the tropical region high rainfall rate is expected to be the major drawback of FSO link availability. Rain attenuation is the most significant to influence FSO link availability in tropical region. As for now the available k and α values are developed using data from temperate regions. Therefore, the objective of this paper is to propose new parameters for specific rain attenuation prediction model that represents tropical weather condition. The proposed values are derived from data measured in Malaysia and using methods recommended by ITU-R.

  7. Free-space propagation of guided optical vortices excited in an annular core fiber.

    Science.gov (United States)

    Yan, Hongwei; Zhang, Entao; Zhao, Baoyin; Duan, Kailiang

    2012-07-30

    The analytical expression for the propagation of guided optical vortices through free space is derived and used to study the dynamic evolution of guided optical vortices after passing through the free space, and the dependence of guided optical vortices on the control parameters where the effect of propagation distance is stressed. It is shown that the motion, pair creation and annihilation of guided optical vortices may take place. In particular, the creation and annihilation of a pair of guided optical vortices do not take place by varying fiber length.

  8. Modeled and experimental results of an omnidirectional free-space optical receiver architecture

    Science.gov (United States)

    Murshid, Syed H.; Lovell, Gregory L.; Finch, Michael F.

    2017-03-01

    Free-space optical (FSO) communications provide point-to-point connectivity while offering many advantages in size, weight, and power as compared to radio frequency. It has the potential to provide fiber-optic data rates without the need for lengthy fiber cables. Omnidirectional FSO, also known as O-FSO systems, provide a non-line-of-sight option for data communications. They are gaining popularity in short-distance networks. Most existing O-FSO links range from 1 to 100 m and present experimental/simulated data rates ranging between 5 kb/s and 1 Mb/s. A 2.5-Gb/s O-FSO system was recently reported with a range of 25 cm. This paper employs a fiber bundle as an O-FSO receiver. The energy collected by the receiver is related to the acceptance cone of each fiber. The fiber bundle integrates the optical power gathered by the individual fibers and couples it to the photodetector. Experimental data rates approaching 100 kb/s over a meter long system are presented, whereas simulated results support a data rate up to 52 Mb/s for distances approaching a kilometer. Theoretical and experimental optical power versus range is also presented for the proposed O-FSO architecture, using on-off keying.

  9. The performance of coherent receiver controlled by the phase lock loop in dual rate free-space laser communication

    Science.gov (United States)

    Ma, Xiaoping; Sun, Jianfeng; Hou, Peipei; Lu, Wei; Xu, Qian; Liu, Liren

    2015-09-01

    The technique of differential phase shift keying(DPSK) modulation is applied into demodulating phase information in the coherent optical receiver. The dual rate free-space receiving structure on the base of Mach-Zehnder delay interferometer with the lens is used suitably for differential delay which is equal to the one bit corresponding to a certain data rate. Delay distance at the interference receiver is varied with transmission rata from satellite to ground. Differential information is obtained by the subtraction of the two successive wave-front phases when made to interfere. The phase demodulation is extremely sensitive to phase fluctuation. Because of the incident light through atmospheric turbulence, the wave-front of optical signal became jittered in the temporal and spatial domain rapidly. In the paper, the dual rate free-space laser communication receiver for phase lock to stable signal light phase is proposed, increasing the homodyne efficiency and decreasing the bit error rate.

  10. A Novel Statistical Channel Model for Turbulence-Induced Fading in Free-Space Optical Systems

    CERN Document Server

    Aminikashani, Mohammadreza; Kavehrad, Mohsen

    2015-01-01

    In this paper, we propose a new probability distribution function which accurately describes turbulence-induced fading under a wide range of turbulence conditions. The proposed model, termed Double Generalized Gamma (Double GG), is based on a doubly stochastic theory of scintillation and developed via the product of two Generalized Gamma (GG) distributions. The proposed Double GG distribution generalizes many existing turbulence channel models and provides an excellent fit to the published plane and spherical waves simulation data. Using this new statistical channel model, we derive closed form expressions for the outage probability and the average bit error as well as corresponding asymptotic expressions of free-space optical communication systems over turbulence channels. We demonstrate that our derived expressions cover many existing results in the literature earlier reported for Gamma-Gamma, Double-Weibull and K channels as special cases.

  11. Performance Analysis of a Free Space Optics Link with Multiple Transmitters/Receivers

    Directory of Open Access Journals (Sweden)

    Nur Haedzerin Md Noor

    2012-04-01

    Full Text Available ABSTRACT:  Multiple transmitters/receivers (TX/RX are used to improve the quality of Free Space Optics (FSO communication systems. With the current needs of this technology for longer distance communication, the qualitative analysis of the system has become essential. In this work, the received power level (PR and bit error rate (BER are considered to influence the FSO link performance. The relationship between the two parameters are investigated and analysed. Furthermore, the received power for various numbers of TXs and RXs are experimentally measured and compared with the values obtained from theoretical calculations. The first part of the work deals with the theoretical calculation and simulation designs of multiple laser beams based on the commercial FSO used in actual sites. The second part describes the practical work and analysis of the system’s performance.ABSTRAK: Pemancar/penerima berganda (TX/RX digunakan bagi meningkatkan kualiti sistem komunikasi Ruang Optik Bebas (FSO. Analisis kualitatif ke atas sistemnya adalah penting bagi keperluan semasa teknologi ini untuk jarak jauh. Di dalam kajian ini, aras kuasa penerima (PR dan kadar ralat bit (BER telah diambilkira bagi menentukan prestasi rangkaian FSO. Hubungan di antara kedua-dua parameter telah dikaji dan dianalisis. Seterusnya, kuasa penerima untuk pelbagai nombor TXs dan RXs diukur secara eksperimen dan dibandingkan dengan nilai teori yang dikira. Bahagian pertama skop kajian berkaitan dengan pengiraan teori dan rekabentuk simulasi sinaran laser berdasarkan FSO komersial di lapangan. Bahagian kedua kajian adalah kerja lapangan dan analisis prestasi sistem.KEY WORDS:  Free Space Optics (FSO link; Multiple TX/RX FSO; bit error rate (BER; eye diagram.

  12. Free-space optical data link to a small robot using modulating retroreflectors

    Science.gov (United States)

    Rabinovich, William S.; Murphy, James L.; Suite, Michele; Ferraro, Mike; Mahon, Rita; Goetz, Peter; Hacker, Kurt; Freeman, Wade; Saint Georges, Eric; Uecke, Stan; Sender, John

    2009-08-01

    Small robots are finding increasing use for operations in areas that may be dangerous to humans. These robots often have needs for high bandwidth communications to return video and other data. While radio frequency (RF) links can be used in may cases, in some circumstances they may be impractical due to frequency congestion, reflections off surfaces, jamming or other RF noise. In these cases an optical link may be advantageous, particularly when a clear line of sight exists. However, a conventional optical link has limitations for this application. For example, a conventional optical link operating at rates of megabits per second at ranges of 1 Km requires about a 1 degree pointing accuracy. This implies a need for active pointing and tracking, which maybe be unacceptable for a small platform. We explored an optical modulating retroreflector (MRR) link for these cases. An array of 6 MRRs and photodetectors with a field of view of 180 degrees (azimuth)x 30 degrees (elevation) was constructed and mounted a small robot, the iRobot PackbotTM. An Ethernet modem designed to work with MRR links was also part of the system. Using a tracking laser interrogator at the other end of the link, a 1.5 Mbps free space optical Ethernet link was established that completely replaced the normal RF Ethernet link. The link was demonstrated out to ranges of 1 Km down a road, exceeding the range of the RF link. Design issues and measurements of performance will be described.

  13. Ethernet access network based on free-space optic deployment technology

    Science.gov (United States)

    Gebhart, Michael; Leitgeb, Erich; Birnbacher, Ulla; Schrotter, Peter

    2004-06-01

    The satisfaction of all communication needs from single households and business companies over a single access infrastructure is probably the most challenging topic in communications technology today. But even though the so-called "Last Mile Access Bottleneck" is well known since more than ten years and many distribution technologies have been tried out, the optimal solution has not yet been found and paying commercial access networks offering all service classes are still rare today. Conventional services like telephone, radio and TV, as well as new and emerging services like email, web browsing, online-gaming, video conferences, business data transfer or external data storage can all be transmitted over the well known and cost effective Ethernet networking protocol standard. Key requirements for the deployment technology driven by the different services are high data rates to the single customer, security, moderate deployment costs and good scalability to number and density of users, quick and flexible deployment without legal impediments and high availability, referring to the properties of optical and wireless communication. We demonstrate all elements of an Ethernet Access Network based on Free Space Optic distribution technology. Main physical parts are Central Office, Distribution Network and Customer Equipment. Transmission of different services, as well as configuration, service upgrades and remote control of the network are handled by networking features over one FSO connection. All parts of the network are proven, the latest commercially available technology. The set up is flexible and can be adapted to any more specific need if required.

  14. Test of mode-division multiplexing and demultiplexing in free-space with diffractive transformation optics

    OpenAIRE

    Ruffato, Gianluca; Massari, Michele; Parisi, Giuseppe; Romanato, Filippo

    2016-01-01

    In recent years, mode-division multiplexing (MDM) has been proposed as a promising solution in order to increase the information capacity of optical networks both in free-space and in optical fiber transmission. Here we present the design, fabrication and test of diffractive optical elements for mode-division multiplexing based on optical transformations in the visible range. Diffractive optics have been fabricated by means of 3D high-resolution electron beam lithography on polymethylmethacry...

  15. Seamless Transmission between Single-Mode Optical Fibers Using Free Space Optics System

    Science.gov (United States)

    Yoshida, Koichi; Tsujimura, Takeshi

    This paper presents a free space optics system installed between two single-mode optical fibers (SMFs). The result looks as if the two SMFs were seamlessly connected without the need for any photoelectric devices. Misalignments between the two SMFs caused by disturbances are actively compensated for by introducing a laser beam controller that incorporates an opto-mechatronic mechanism with four degrees of freedom. Experiments using a prototype are conducted to verify the effectiveness of the proposed FSO system for initial beam acquisition and beam tracking when there is a vibration disturbance.

  16. Free-Space Optical Interconnect Employing VCSEL Diodes

    Science.gov (United States)

    Simons, Rainee N.; Savich, Gregory R.; Torres, Heidi

    2009-01-01

    Sensor signal processing is widely used on aircraft and spacecraft. The scheme employs multiple input/output nodes for data acquisition and CPU (central processing unit) nodes for data processing. To connect 110 nodes and CPU nodes, scalable interconnections such as backplanes are desired because the number of nodes depends on requirements of each mission. An optical backplane consisting of vertical-cavity surface-emitting lasers (VCSELs), VCSEL drivers, photodetectors, and transimpedance amplifiers is the preferred approach since it can handle several hundred megabits per second data throughput.The next generation of satellite-borne systems will require transceivers and processors that can handle several Gb/s of data. Optical interconnects have been praised for both their speed and functionality with hopes that light can relieve the electrical bottleneck predicted for the near future. Optoelectronic interconnects provide a factor of ten improvement over electrical interconnects.

  17. Effects of phase conjugation on electromagnetic optical fields propagating in free space

    Science.gov (United States)

    Kanseri, Bhaskar

    2017-03-01

    By using the property of phase conjugation, we demonstrate that the inverse of van Cittert–Zernike theorem holds for electromagnetic (EM) fields propagating in free space. This essentially implies that spatially incoherent partially polarized field distributions can be generated from spatially coherent partially polarized optical fields. We further utilize phase conjugation with a polarization rotator to swap the spatial coherence properties of orthogonal polarization components of EM fields on propagation, at least in free space. This study suggests that the method of phase conjugation could be potentially useful in arbitrarily manipulating spatial coherence properties of vector optical fields in the field plane.

  18. Role of transverse-momentum currents in the optical Magnus effect in free space

    OpenAIRE

    Luo, Hailu; Wen, Shuangchun; Shu, Weixing; Fan, Dianyuan

    2010-01-01

    We establish a general vector field model to describe the role of transverse-momentum currents in the optical Magnus effect in free space. As an analogy of the mechanical Magnus effect, the circularly polarized wave packet in our model acts as the rotating ball, and its rotation direction depends on the polarization state. Based on this model, we demonstrate the existence of an optical polarization-dependent Magnus effect which is significantly different from the conventional optical Magnus e...

  19. Enhancement of security for free space optics based on reconfigurable chaotic technique

    Science.gov (United States)

    Abdulameer, Lwaa F.; Jignesh, Jokhakar D.; Sripati, U.; Kulkarni, Murlidhar

    2013-01-01

    Free Space Optical (FSO) technology offers highly directional, high bandwidth communication channels. This technology can provide fiber-like data rate over short distances. In order to improve security associated with data transmission in FSO networks, a secure communication method based on chaotic technique is presented. In this paper, we have turned our focus on a specific class of piece wise linear one-dimensional chaotic maps. Simulation results indicate that this approach has the advantage of possessing excellent correlation property. In this paper we examine the security vulnerabilities of single FSO links and propose a solution to this problem by implementing the chaotic signal generator "reconfigurable tent map". As synchronization between transmitter and receiver is essential for the correct operation of such schemes, we have also attempted to determine parameters such as auto- and cross-correlation that determine the ease with which synchronization between transmitter and receiver can be achieved. It is demonstrated that cross correlation is very close to zero and auto-correlation is 􀟜-like. The overall system is implemented in the MATLAB Simulink DSP Builder.

  20. The role of transverse momentum currents in optical Magnus effect in a free-space

    CERN Document Server

    Luo, Hailu; Shu, Weixing; Fan, Dianyuan

    2010-01-01

    We establish a general vector field model to describe the role of transverse momentum currents in optical Magnus effect in a free-space. As an analogous of mechanical Magnus effect, the circularly polarized wavepacket in our model plays the role of the rotating ball. For a certain circularly polarized wavepacket, whether the rotation is clockwise or anticlockwise depends on the polarization state. We demonstrate the existence of a novel optical polarization-dependent rotation effect which is signally different from conventional optical Magnus effect in that light-matter interaction is not required. Further, we reveal the relation between transverse momentum currents and optical Magnus effect. Such a polarization-dependent rotation is unavoidable when the wavepacket possesses transverse momentum currents. The intriguing effect should be able to be observed experimentally even in the propagation direction. These findings provide direct evidence for the optical Magnus effect in the free-space. The physics underl...

  1. Atmospheric effects on Quaternary polarization encoding for free space communication, laboratory simulation

    CERN Document Server

    Soorat, Ram

    2015-01-01

    We have simulated atmospheric effects such as fog and smoke in laboratory environment to simulate depolarisation due to atmospheric effects during a free space optical communi- cation. This has been used to study noise in two components of quaternary encoding for polarization shift keying. Individual components of a Quaternary encoding, such as vertical and horizontal as well as 45$^\\circ$ and 135$^\\circ$ , are tested separately and indicates that the depo- larization effects are different for these two situation. However, due to a differential method used to extract information bits, the protocol shows extremely low bit error rates. The information obtained is useful during deployment of a fully functional Quaternary encoded PolSK scheme in free space.

  2. Method for simulating free space optical data links for personnel applications

    Science.gov (United States)

    Mateti, Kiron; Clarke, Brandon R.; Seals, Ean J.; Petty, Gregory J.; Tran, Hoang Q.; Boykin, Courtney L.; Nicholson, Gail M.; Borneman, Joshua D.

    2013-05-01

    Free Space Optical (FSO) wireless data links are attractive alternatives to RF communications. This technology could enable vision around corners or barriers, and allow covert, secure, and wireless distribution of scope images to other squad helmet mounted displays (HMDs), with minimal additional hardware to the current equipment. A major design challenge for FSO links in personnel applications is ensuring line of sight (LoS) between transmitter and receiver. This work captures warfighter helmet and gun movement using video motion tracking in a typical application for FSO data links. A method to simulate transmitter and receiver on the warfighter helmet and gun scope and analyze LoS and FOV is presented. This method allows optimization of FSO data link placement and provides requirements for future FSO technology. The initial results suggest that to meet 100% of the threshold requirements, the vertical FOV of a receiver must be 80° and the horizontal FOV must be 60° and oriented 10° in pitch and -7.5° in yaw. Simulating a FSO link with horizontal and vertical FOV of 60° shows expected performance using a visual method from a helmet mounted camera. Additionally, the FOV of the transmitter and receiver can be visualized with arbitrary FOV, position, and orientation.

  3. Debunking the recurring myth of a magic wavelength for free-space optics

    Science.gov (United States)

    Korevaar, Eric J.; Kim, Isaac I.; McArthur, Bruce

    2002-12-01

    Free-Space Optics (FSO) is a proven, reliable technology for last mile telecommunications applications, used worldwide for both enterprise network building-to-building connections and for wireless access to more traditional land line communications networks. In most mid-latitude coastal cities, link availability at distances above a few hundred meters is primarily affected by fog and low clouds. At longer distances, heavy rain and snow can also affect the link. The most mature technology used in FSO equipment relies on low cost semiconductor lasers or LED"s operating in the near infrared at wavelengths of 785 nm or 850 nm. In the past few years, systems operating at 1550 nm have also been developed. At first the vendors of these systems claimed that the 1550 nm wavelength had better propagation characteristics in severe weather than the 785 nm wavelength. With further analysis and research, those claims were withdrawn. Now there are claims that even longer wavelengths near 10 microns will solve the FSO link availability issues associated with severe weather. Hype about such magic wavelengths for FSO is both a disservice to the investors who will lose the money they are investing based on exaggerated claims, and to the rest of the FSO industry which should be creating realistic expectations for the capability of its equipment. In the weather conditions which normally cause the highest attenuation for FSO systems, namely coastal fog and low clouds, 10 microns offers no propagation advantage over shorter wavelengths.

  4. Intra-Chip Free-Space Optical Interconnect: System, Device, Integration and Prototyping

    Science.gov (United States)

    Ciftcioglu, Berkehan

    Currently, on-chip optical interconnect schemes already proposed utilize circuit switching using wavelength division multiplexing (WDM) or all-optical packet switching, all based on planar optical waveguides and related photonic devices such as microrings. These proposed approaches pose significant challenges in latency, energy efficiency, integration, and scalability. This thesis presents a new alternative approach by utilizing free-space optics. This 3-D integrated intra-chip free-space optical interconnect (FSOI) leverages mature photonic devices such as integrated lasers, photodiodes, microlenses and mirrors. It takes full advantages of the latest developments in 3-D integration technologies. This interconnect system provides point-to-point free-space optical links between any two communication nodes to construct an all-to-all intra-chip communication network with little or no arbitration. Therefore, it has significant networking advantages over conventional electrical and waveguide-based optical interconnects. An FSOI system is evaluated based on the real device parameters, predictive technology models and International Roadmap of Semiconductor's predictions. A single FSOI link achieves 10-Gbps data rate with 0.5-pJ/bit energy efficiency and less than 10--12 bit-error-rate (BER). A system using this individual link can provide scalability up to 36 nodes, providing 10-Tbps aggregate bandwidth. A comparison analysis performed between a WDM-based waveguide interconnect system and the proposed FSOI system shows that FSOI achieves better energy efficiency than the WDM one as the technology scales. Similarly, network simulation on a 16-core microprocessor using the proposed FSOI system instead of mesh networks has been shown to speed up the system by 12% and reduce the energy consumption by 33%. As a part of the development of a 3-D integrated FSOI system, operating at 850 nm with a 10-Gbps data rate per optical link, the photonics devices and optical components are

  5. Feasibility Analysis Of Free Space Earth To Satellite Optical Link In Tropical Region

    Directory of Open Access Journals (Sweden)

    Norhanis Aida M. Nor

    2012-01-01

    Full Text Available Free Space Optics (FSO becomes a great attention because of the chances in transmitting data up to 2.5Gbps. There are a lot of advantages offered by FSO such as easily deployment with saving time and cost and no electromagnetic interference. In spite of the advantages, FSO has an uncontrolled drawback which is highly sensitive to atmospheric phenomena because uses air as tranmission medium. Current studies and researches are only focusing on FSO terrestrial link with short path length and based on data from temperate region. Therefore, this paper is aiming to provide feasibility analysis of FSO link from earth to satellite especially Low Earth Orbit (LEO based on atmospheric data in tropical region. The analysis will include the losses from geometrical attenuation, absorption, scintillation, haze attenuation, and rain attenuation. ABSTRAK: Ruang Bebas Optik (Free Space Optics (FSO mendapat perhatian kerana kebolehannya memancarkan data pada kelajuan tinggi. Di sebalik kelebihannya, FSO amat sensitif terhadap fenomena atmosfera kerana ia menggunakan udara sebagai perantara transmisi. Penyelidikan dan kajian terkini hanya memfokus kepada jalinan darat FSO dengan kepanjangan jarak pendek dan bergantung kepada kawasan tenang.  Oleh itu, kertas ini menyasarkan untuk memberikan analisis kebolehlaksanaan  jalinan FSO dari bumi ke satelit terutamanya Orbit Rendah Bumi (Low Earth Orbit (LEO bergantung kepada data atmosfera di kawasan tropika. Analisa termasuklah kehilangannya akibat pengecilan geometri, penyerapan, kelipan, pelemahan jerebu dan pelemahan hujan.KEYWORDS:  feasibility; Free Space Optics; availability; atmospheric attenuation; beam divergence angle; elevation angle

  6. Superresolution far-field diffraction spot in the free-space laser communication system due to radially polarized beam

    Science.gov (United States)

    Wang, Chao; Jiang, Lun; Hu, Yuan; Liu, Zhuang; Li, Ying-chao; Wang, Le

    2016-10-01

    In the free-space laser communication, there is a strong need for a technology that can decrease the size of the diffraction spot in the receiver port, because a smaller diffraction spot in the receive port makes the transmit data more secure. In this paper, instead of the usage of the larger size aperture lens in the free-space laser communication system, we introduce a diffractive superresolution technology that changing the received information laser beam into radially polarized beam which is focused on the detector array. In the paper, firstly, the conversion method of the information natural light which the optical antenna received to the radially polarized beam is discussed in detail. Then, in the focal plane, the transverse intensity distribution expression near the focal point for the radially polarized laser beam are presented, and the numerical simulation results of the intensity distributions around the focal point on different numerical apertures (NA) are given. The full width at half-maximum (FWHM) values of the main lobe are considered for the standard of the spot size. Through a comparison of the focal point FWHM values with the natural light and radially polarized beam, we judge the superresolution performance of the receiver optical system with radially polarized beam on different NA of 0.4, 0.6 and 0.75. We find that the method of focusing with radially polarized beam generates a smaller spot size than the Airy spot size when the NA is no less than 0.6; when the NA reach to 0.75, the resolution is 1.5 times than the diffraction limit. But it will decrease the light power in the process of natural light converted to radially polarized beam. When the communication laser is polarized laser, the energy loss can be reduced to around 20%. This technology can be applied when the laser energy is not the main concern in the communication.

  7. Free-space quantum key distribution

    CERN Document Server

    Buttler, W T; Kwiat, P G; Luther, G G; Morgan, G L; Nordholt, J E; Peterson, C G; Simmons, C M

    1998-01-01

    A working free-space quantum key distribution (QKD) system has been developed and tested over a 205-m indoor optical path at Los Alamos National Laboratory under fluorescent lighting conditions. Results show that free-space QKD can provide secure real-time key distribution between parties who have a need to communicate secretly.

  8. Optical communication theory.

    Science.gov (United States)

    Hoversten, E. V.

    1972-01-01

    An introduction is provided to the important ideas involved in the design and the evaluation of optical communication systems which transmit digital or analog data. Field representations are discussed together with background noise, a detector statistical model, quantum receivers, and turbulent and scatter channels. Free-space channels are considered, taking into account heterodyne systems, preamplifier and homodyne systems, direct-detection systems, and optimum quantum systems.

  9. Experimental demonstration of free-space optical vortex transmutation with polygonal lenses.

    Science.gov (United States)

    Gao, Nan; Xie, Changqing

    2012-08-01

    Vortex transmutation was predicted to take place when vortices interact with systems possessing discrete rotational symmetries of finite order [Phys. Rev. Lett.95, 123901 (2005)]. Here we report what is believed to be the first experimental demonstration of vortex transmutation. We show that in free space, by simply inserting polygonal lenses into the optical path, the central vorticity of a coaxially incident optical vortex can be changed following the modular transmutation rule. We generate the wavefront at the exit face of the lenses with computer generated holograms and measure the output vorticity using the interference patterns at the focal plane. The results agree well with theoretical predictions.

  10. Time-Resolved Terahertz Spectroscopy with Free-Space Electro-Optic Sampling

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liang-Liang; ZHAO Guo-Zhong; ZHONG Hua; HU Ying; ZHANG Cun-Lin

    2004-01-01

    @@ We present a time-resolved ultrafast measurement in terahertz (THz) frequency region by means of the free-space electro-optic sampling. The fast delay scan technique is used to suppress the noise with low frequency and to improve the signal-to-noise ratio of the system. The transmission spectra of different materials are obtained.The optical properties of these materials in a THz region are shown. The broadening of spectrum and chirping phenomena are illustrated. We find that polystyrene is an excellent material for the THz application.

  11. Chromatic effects in beam wander correction for free-space quantum communications

    CERN Document Server

    Carrasco-Casado, Alberto; Fernandez, Veronica

    2016-01-01

    Beam wander caused by atmospheric turbulence can significantly degrade the performance of horizontal free-space quantum communication links. Classical beam wander correction techniques cannot be applied due to the stronger requirements of transmitting single photons. One strategy to overcome this limitation consists in using a separate wavelength from that of the quantum signal to analyze the beam wander and use this information for its correction. For this strategy to work adequately, both wavelengths should be affected equally by atmospheric turbulence, i.e. no chromatic effects should be originated from beam wander. In this letter, a series of experiments are performed to prove that this is the case for {\\lambda} ~ 850 nm as the quantum signal and {\\lambda} ~ 1550 nm as the tracking signal of a quantum communication system.

  12. Ergodic channel capacity of spatial correlated multiple-input multiple-output free space optical links using multipulse pulse-position modulation

    Science.gov (United States)

    Wang, Huiqin; Wang, Xue; Cao, Minghua

    2017-02-01

    The spatial correlation extensively exists in the multiple-input multiple-output (MIMO) free space optical (FSO) communication systems due to the channel fading and the antenna space limitation. Wilkinson's method was utilized to investigate the impact of spatial correlation on the MIMO FSO communication system employing multipulse pulse-position modulation. Simulation results show that the existence of spatial correlation reduces the ergodic channel capacity, and the reception diversity is more competent to resist this kind of performance degradation.

  13. Design of a multi-channel free space optical interconnec-tion component

    Institute of Scientific and Technical Information of China (English)

    JIA Da-gong; ZHANG Pei-song; JING Wen-cai; TAN Jun; ZHANG Hong-xia; ZHANG Yi-mo

    2008-01-01

    A multi-channel free space optical interconnection component, fiber optic rotary joint, was designed using a Dove prism.When the Dove prism is rotated an angle of α around the longitudinal axis, the image rotates an angle of 2α. The opticalinterconnection component consists of the signal transmission system, Dove prim and driving mechanism. The planetarygears are used to achieve the speed ratio of 2:1 between the total optical interconnection component and the Dove prism.The C-lenses are employed to couple different optical signals in the signal transmission system. The coupling loss betweenthe receiving fiber of stationary part and the transmitting fiber of rotary part is measured.

  14. Performance analysis of free space optical system with spatial modulation and diversity combiners over the Gamma Gamma atmospheric turbulence

    Science.gov (United States)

    Odeyemi, Kehinde O.; Owolawi, Pius A.; Srivastava, Viranjay M.

    2017-01-01

    Atmospheric turbulence is a major impairment that degrades the performance of free space optical (FSO) communication systems. Spatial modulation (SM) with receive spatial diversity is considered as a powerful technique to mitigate the fading effect induced by atmospheric turbulence. In this paper, the performance of free space optical spatial modulation (FSO-SM) system under Gamma-Gamma atmospheric turbulence is presented. We studied the Average Bit Error Rate (ABER) for the system by employing spatial diversity combiners such Maximum Ratio Combining (MRC) and Equal Gain Combining (EGC) at the receiving end. In particular, we provide a theoretical framework for the system error by deriving Average Pairwise Error Probability (APEP) expression using a generalized infinite power series expansion approach and union bounding technique is applied to obtain the ABER for each combiner. Based on this study, it was found that spatial diversity combiner significantly improved the system error rate where MRC outperforms the EGC. The performance of this system is also compared with other well established diversity combiner systems. The proposed system performance is further improved by convolutional coding technique and our analysis confirmed that the system performance of MRC coded system is enhanced by approximately 20 dB while EGC falls within 17 dB.

  15. Performance optimization of a free space optical interconnect system with a metal-semiconductor-metal detector

    Science.gov (United States)

    Al-Ababneh, Nedal; Khader, Ateka

    2011-08-01

    In this paper we study the possibility and the potentiality of using metal semiconductor-metal photodetector (MSM-PD) in three-dimensional parallel free space optical interconnect (FSOI) systems. The signal-to-noise ratio (SNR) and time response are used as performance measures to optimize the geometry of MSM-PD used in FSOI systems. Both SNR and time response are evaluated, analyzed, and their dependence on feature parameters of the MSM-PD, including finger size, spacing, and number of fingers, are considered. Based on the results obtained, we show that the use of MSM-PD in FSOI improves the interconnect speed at a given acceptable SNR.

  16. Visibility effect on the availability of a terrestrial free space optics link under a tropical climate

    Science.gov (United States)

    Basahel, Ahmed; Rafiqul, Islam Md.; Habaebi, Mohamad Hadi; Suriza, A. Z.

    2016-06-01

    Haze, fog and rain limit the visibilities and acts as dominant parameter for free space optics availability estimation. Low visibilities increase atmospheric attenuation and reduce the availability of optical signals from free space optics (FSO) links. Thus, this study determines the effect of visibility on FSO link availability in a tropical climate. Visibility data were measured in Malaysia for three years and used to estimate availability of FSO links. Rain and haze are two phenomena which reduces the visibility in tropical climate like Malaysia. Hence three cases were considered for measured data analysis: rain with dense haze, dense haze, and normal haze cases. In Malaysia, seasonal dense haze is mainly attributed to forest fires in Indonesia and in parts of Malaysia. The atmospheric attenuations predicted based on measured visibility (km) were compared across the three cases. The attenuations in the first two cases are found severe (almost 155 dB/km); while in the third case it is very low (almost 6 dB/km). The worst case (dense haze) is equivalent to a thick fog in temperate regions and must be examined carefully with respect to FSO deployment in a tropical environment.

  17. Estimation of Outage Capacity for Free Space Optical Links Over I-K and K Turbulent Channels

    Directory of Open Access Journals (Sweden)

    D. Marinos

    2011-06-01

    Full Text Available The free space optical communication systems are attracting great research and commercial interest due to their capability of transferring data, over short distances, with high rate and security, low cost demands and without licensing fees. However, their performance depends strongly on the atmospheric conditions in the link’s area. In this work, we investigate the influence of the turbulence on the outage capacity of such a system for weak to strong turbulence channels modeled by the I-K and the K-distribution and we derive closed-form expressions for its estimation. Finally, using these expressions we present numerical results for various link cases with different turbulence conditions.

  18. High power free space optical link for rapid energy and data transmission

    Science.gov (United States)

    Dhadwal, Harbans S.; Rastegar, Jahangir; Feng, Dake; Kwok, Philip

    2016-05-01

    Design and experimental data for a high power laser diode based free space point-to-point optical power/data link is presented. In time critical power up applications, such as providing power and guidance information to a munition shell just prior to deployment, energy of the order of 100 J needs to be transferred in under 10 s. Current inductive technology is slow and broadcasts a radio-frequency signal which is undesirable for stealth operation. Rapid energy transfer times require high irradiance levels at the surface of the photovoltaic cells, typically, exceeding 1000X suns. Through efficient thermal design of heat sinks, high optical to electrical power conversion efficiencies of 50%, which are usually attainable at low power levels of 1 W, are achievable at higher power levels.

  19. Phase-Stable Free-Space Optical Lattices for Trapped Ions.

    Science.gov (United States)

    Schmiegelow, C T; Kaufmann, H; Ruster, T; Schulz, J; Kaushal, V; Hettrich, M; Schmidt-Kaler, F; Poschinger, U G

    2016-01-22

    We demonstrate control of the absolute phase of an optical lattice with respect to a single trapped ion. The lattice is generated by off-resonant free-space laser beams, and we actively stabilize its phase by measuring its ac-Stark shift on a trapped ion. The ion is localized within the standing wave to better than 2% of its period. The locked lattice allows us to apply displacement operations via resonant optical forces with a controlled direction in phase space. Moreover, we observe the lattice-induced phase evolution of spin superposition states in order to analyze the relevant decoherence mechanisms. Finally, we employ lattice-induced phase shifts for inferring the variation of the ion position over the 157  μm range along the trap axis at accuracies of better than 6 nm.

  20. Phase-stable free-space optical lattices for trapped ions

    CERN Document Server

    Schmiegelow, Christian Tomas; Ruster, Thomas; Schulz, Jonas; Kaushal, Vidyut; Hettrich, Max; Schmidt-Kaler, Ferdinand; Poschinger, Ulrich G

    2016-01-01

    We demonstrate control of the absolute phase of an optical lattice with respect to a single trapped ion. The lattice is generated by off-resonant free-space laser beams, we actively stabilize its phase by measuring its ac-Stark shift on a trapped ion. The ion is localized within the standing wave to better than 2\\% of its period. The locked lattice allows us to apply displacement operations via resonant optical forces with a controlled direction in phase space. Moreover, we observe the lattice-induced phase evolution of spin superposition states in order to analyze the relevant decoherence mechanisms. Finally, we employ lattice-induced phase shifts for inferring the variation of the ion position over 157~$\\mu$m range along the trap axis at accuracies of better than 6~nm.

  1. Modified optical fiber daylighting system with sunlight transportation in free space.

    Science.gov (United States)

    Vu, Ngoc-Hai; Pham, Thanh-Tuan; Shin, Seoyong

    2016-12-26

    We present the design, optical simulation, and experiment of a modified optical fiber daylighting system (M-OFDS) for indoor lighting. The M-OFDS is comprised of three sub-systems: concentration, collimation, and distribution. The concentration part is formed by coupling a Fresnel lens with a large-core plastic optical fiber. The sunlight collected by the concentration sub-system is propagated in a plastic optical fiber and then collimated by the collimator, which is a combination of a parabolic mirror and a convex lens. The collimated beam of sunlight travels in free space and is guided to the interior by directing flat mirrors, where it is diffused uniformly by a distributor. All parameters of the system are calculated theoretically. Based on the designed system, our simulation results demonstrated a maximum optical efficiency of 71%. The simulation results also showed that sunlight could be delivered to the illumination destination at distance of 30 m. A prototype of the M-OFDS was fabricated, and preliminary experiments were performed outdoors. The simulation results and experimental results confirmed that the M-OFDS was designed effectively. A large-scale system constructed by several M-OFDSs is also proposed. The results showed that the presented optical fiber daylighting system is a strong candidate for an inexpensive and highly efficient application of solar energy in buildings.

  2. Ergodic Capacity Analysis of Free-Space Optical Links with Nonzero Boresight Pointing Errors

    KAUST Repository

    Ansari, Imran Shafique

    2015-04-01

    A unified capacity analysis of a free-space optical (FSO) link that accounts for nonzero boresight pointing errors and both types of detection techniques (i.e. intensity modulation/ direct detection as well as heterodyne detection) is addressed in this work. More specifically, an exact closed-form expression for the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system is presented in terms of well-known elementary functions. Capitalizing on these new moments expressions, we present approximate and simple closedform results for the ergodic capacity at high and low SNR regimes. All the presented results are verified via computer-based Monte-Carlo simulations.

  3. Composite optical vortices in noncollinear Laguerre-Gaussian beams and their propagation in free space

    Institute of Scientific and Technical Information of China (English)

    Cheng Ke; Liu Pu-Sheng; Lü Bai-Da

    2008-01-01

    Taking two Laguerre-Gauasian beams with topological charge l=±1 as an example,this paper studies the composite optical vortices formed by two noncollinear Laguerre-Gaussian beams with different phases,amplitudes,waist widths,off-axis distances,and their propagation in flee space. It is shown by detailed numerical illustrative examples that the number and location of composite vortices at the waist plane are variable by varying the relative phase β,amplitude ratio η,waist width ratio ξ,or off-axis distance ratio μ.The net topological charge lnet is not always equal to the sum lsum of charges of the two component beams.The motion,creation and annihilation of composite vortices take place in the free-space propagation,and the net charge during the propagation remains unchanged and equals to the net charge at the waist plane.

  4. Probabilistic Model for Free-Space Optical Links Under Continental Fog Conditions

    Directory of Open Access Journals (Sweden)

    Marzuki

    2010-09-01

    Full Text Available The error characteristics of a free-space optical (FSO channel are significantly different from the fiber based optical links and thus require a deep physical understanding of the propagation channel. In particular different fog conditions greatly influence the optical transmissions and thus a channel model is required to estimate the detrimental fog effects. In this paper we shall present the probabilistic model for radiation fog from the measured data over a 80 m FSO link installed at Graz, Austria. The fog events are classified into thick fog, moderate fog, light fog and general fog based on the international code of visibility range. We applied some probability distribution functions (PDFs such as Kumaraswamy, Johnson SB and Logistic distribution, to the actual measured optical attenuations. The performance of each distribution is evaluated by Q-Q and P-P plots. It is found that Kumaraswamy distribution is the best fit for general fog, while Logistic distribution is the optimum choice for thick fog. On the other hand, Johnson SB distribution best fits the moderate and light fog related measured attenuation data. The difference in these probabilistic models and the resultant variation in the received signal strength under different fog types needs to be considered in designing an efficient FSO system.

  5. Simulating Atmospheric Free-Space Optical Propagation; Part II: Haze, Fog, and Low Clouds Attenuations

    Science.gov (United States)

    Achour, Maha

    2002-12-01

    One of the biggest challenges facing Free-Space Optics deployment is proper understanding of optical signal propagation in different atmospheric conditions. In an earlier study by the author (30), attenuation by rain was analyzed and successfully modeled for infrared signal transmission. In this paper, we focus on attenuation due to scattering by haze, fog and low clouds droplets using the original Mie Scattering theory. Relying on published experimental results on infrared propagation, electromagnetic waves scattering by spherical droplet, atmospheric physics and thermodynamics, UlmTech developed a computer-based platform, Simulight, which simulates infrared signal (750 nm-12 μm) propagation in haze, fog, low clouds, rain and clear weather. Optical signals are scattered by fog droplets during transmission in the forward direction preventing the receiver from detecting the minimum required power. Weather databases describe foggy conditions by measuring the visibility parameter, which is, in general, defined as the maximum distance that the visible 550 nm signal can travel while distinguishing between the target object and its background at 2% contrast. Extrapolating optical signal attenuations beyond 550 nm using only visibility is not as straightforward as stated by the Kruse equation which is unfortunately widely used. We conclude that it is essential to understand atmospheric droplet sizes and their distributions based on measured attenuations to effectively estimate infrared attenuation. We focus on three types of popular fogs: Evolving, Stable and Selective.

  6. Characterization of a Reconfigurable Free-Space Optical Channel for Embedded Computer Applications with Experimental Validation Using Rapid Prototyping Technology

    Directory of Open Access Journals (Sweden)

    Rafael Gil-Otero

    2007-02-01

    Full Text Available Free-space optical interconnects (FSOIs are widely seen as a potential solution to current and future bandwidth bottlenecks for parallel processors. In this paper, an FSOI system called optical highway (OH is proposed. The OH uses polarizing beam splitter-liquid crystal plate (PBS/LC assemblies to perform reconfigurable beam combination functions. The properties of the OH make it suitable for embedding complex network topologies such as completed connected mesh or hypercube. This paper proposes the use of rapid prototyping technology for implementing an optomechanical system suitable for studying the reconfigurable characteristics of a free-space optical channel. Additionally, it reports how the limited contrast ratio of the optical components can affect the attenuation of the optical signal and the crosstalk caused by misdirected signals. Different techniques are also proposed in order to increase the optical modulation amplitude (OMA of the system.

  7. Characterization of a Reconfigurable Free-Space Optical Channel for Embedded Computer Applications with Experimental Validation Using Rapid Prototyping Technology

    Directory of Open Access Journals (Sweden)

    Lim Theodore

    2007-01-01

    Full Text Available Free-space optical interconnects (FSOIs are widely seen as a potential solution to current and future bandwidth bottlenecks for parallel processors. In this paper, an FSOI system called optical highway (OH is proposed. The OH uses polarizing beam splitter-liquid crystal plate (PBS/LC assemblies to perform reconfigurable beam combination functions. The properties of the OH make it suitable for embedding complex network topologies such as completed connected mesh or hypercube. This paper proposes the use of rapid prototyping technology for implementing an optomechanical system suitable for studying the reconfigurable characteristics of a free-space optical channel. Additionally, it reports how the limited contrast ratio of the optical components can affect the attenuation of the optical signal and the crosstalk caused by misdirected signals. Different techniques are also proposed in order to increase the optical modulation amplitude (OMA of the system.

  8. Resilient backhaul network design using hybrid radio/free-space optical technology

    KAUST Repository

    Douik, Ahmed

    2016-07-26

    The radio-frequency (RF) technology is a scalable solution for the backhaul planning. However, its performance is limited in terms of data rate and latency. Free Space Optical (FSO) backhaul, on the other hand, offers a higher data rate but is sensitive to weather conditions. To combine the advantages of RF and FSO backhauls, this paper proposes a cost-efficient backhaul network using the hybrid RF/FSO technology. To ensure a resilient backhaul, the paper imposes a given degree of redundancy by connecting each node through K link-disjoint paths so as to cope with potential link failures. Hence, the network planning problem considered in this paper is the one of minimizing the total deployment cost by choosing the appropriate link type, i.e., either hybrid RF/FSO or optical fiber (OF), between each couple of base-stations while guaranteeing K link-disjoint connections, a data rate target, and a reliability threshold. The paper solves the problem using graph theory techniques. It reformulates the problem as a maximum weight clique problem in the planning graph, under a specified realistic assumption about the cost of OF and hybrid RF/FSO links. Simulation results show the cost of the different planning and suggest that the proposed heuristic solution has a close-to-optimal performance for a significant gain in computation complexity. © 2016 IEEE.

  9. Hybrid Radio/Free-Space Optical Design for Next Generation Backhaul Systems

    KAUST Repository

    Douik, Ahmed

    2016-04-22

    The deluge of date rate in today\\'s networks imposes a cost burden on the backhaul network design. Developing cost-efficient backhaul solutions becomes an exciting, yet challenging, problem. Traditional technologies for backhaul networks, including either radio-frequency (RF) backhauls or optical fibers (OF). While RF is a cost-effective solution as compared with OF, it supports the lower data rate requirements. Another promising backhaul solution is the free-space optics (FSO) as it offers both a high data rate and a relatively low cost. The FSO, however, is sensitive to nature conditions, e.g., rain, fog, and line-of-sight. This paper combines both the RF and FSO advantages and proposes a hybrid RF/FSO backhaul solution. It considers the problem of minimizing the cost of the backhaul network by choosing either OF or hybrid RF/FSO backhaul links between the base stations, so as to satisfy data rate, connectivity, and reliability constraints. It shows that under a specified realistic assumption about the cost of OF and hybrid RF/FSO links, the problem is equivalent to a maximum weight clique problem, which can be solved with moderate complexity. Simulation results show that the proposed solution shows a close-to-optimal performance, especially for reasonable prices of the hybrid RF/FSO links. They further reveal that the hybrid RF/FSO is a cost-efficient solution and a good candidate for upgrading the existing backhaul networks. © 2016 IEEE.

  10. Simulation of turbulences and fog effects on the free space optical link inside of experimental box

    Science.gov (United States)

    Latal, Jan; Vitasek, Jan; Hajek, Lukas; Vanderka, Ales; Koudelka, Petr; Kepak, Stanislav; Vasinek, Vladimir

    2016-12-01

    This paper deals with problematic of Free Space Optical (FSO) Links. The theoretical part describes the effects of atmospheric transmission environment on these FSO connections. The practical part is focused on the creation of an appropriate experimental workplace for turbulences simulation (mechanical and thermal turbulences), fog effects and subsequent measurement of these effects. For definition how big impact these effects on the FSO system have is used the statistical analysis and simulation software Optiwave. Overall there were tested three optical light sources operating at wavelengths of 632.8 nm, 850 nm and 1550 nm respectively. Influences of simulated atmospheric effects on the signal attenuation were observed. Within the frame of simulation in Optiwave software there were studied influences of attenuation on given wavelengths in form of FSO link transmission parameters degradation. Also for the purposes of real measurements it was necessary to fabricate an experimental box. This box was constructed with sizes of 2.5 and 5 meters and was used for simulation of atmospheric environment.

  11. Channel Characterization for Free-Space Optical Communications

    Science.gov (United States)

    2012-07-01

    users. Susceptibility to fog has slowed the commercial deployment of near-ground FSOC systems. It turns out that fog (and perhaps rain and snow ...Airplane video data at a 30 fps rate. The following atmospheric conditions were also measured at a height of 1-2 meters above the surface of the... Avalanche photo diode voltage signal collected with LabView utilizing National Instruments 9234 24-Bit digitizer. Irradiance voltage signal was

  12. Free Space Optical Communication in the Military Environment

    Science.gov (United States)

    2014-09-01

    placement on the platform given proper aerodynamic consideration [28]. 5. Scintillation Atmospheric scintillation is defined as the changing of light...exposed for signal transmission and reception. This is almost always achievable with highflying fixed-wing aircraft and high-altitude airships ...tethered aerostats, or between an aircraft and a high altitude airship (HAA). The AFRL demonstrated this capability with the FALCON system [83

  13. Improving Performance of Free Space Optics Link Using Array of Receivers in Terrible Weather Conditions of Plain and Hilly Areas

    Directory of Open Access Journals (Sweden)

    Amit Gupta

    2016-03-01

    Full Text Available Free-space optical (FSO communication is a cost effective and high data rate access technique, which has been proving itself a best alternative to radio frequency technology. FSO link provides high bandwidth solution to the last mile access bottleneck. However, for terrestrial communication systems, the performance of these links is severely degraded from atmospheric loss mainly due to fog, rain and snow. So, a continuous availability of the link is always a concern. This paper investigates the dreadful weather effects such as rain, fog, snow, and other losses on the transmission performance of FSO systems. The technique of using an array of receivers for improving the performance of FSO links is explored in this paper. It involves the deployment of multiple photo detectors at the receiver end to mitigate effects of various weather conditions. The performance of the proposed system is evaluated in terms of bit error rate, received signal power, Q- factor and height of eye diagram. The influence of various weather conditions of plain and hilly areas are taken into consideration and results are compared with conventional FSO links.

  14. Performance Analysis on 16-Channels Wavelength Division Multiplexing in Free Space Optical Transmission under Tropical Regions Environment

    Directory of Open Access Journals (Sweden)

    Ratna K.Z. Sahbudin

    2012-01-01

    Full Text Available Problem statement: Wavelength-Division-Multiplexing (WDM is a promising technique for meeting the growing demand for increased bandwidth and various types of services in the optical access network. For wide area or metropolitan networks, fibers are deployed to provide huge bandwidth. In access networks, the fiber-to-the-home will partially solve the last mile problem. However, some environmentally sensitive area such as housing areas, tower buildings and national parks are not allowed to deploy fibers. Therefore, Radio Frequency (RF is normally used to overcome this problem. The incompatibility of RF and optical channels is now widely believed to be the limiting factor in efforts to further increase transport capabilities. Free Space Optical (FSO communication is the technology that can address any connectivity needed in optical networks, such as core, edge, or access networks. Approach: In this project, the simulation software namely Optical System version 7 is used to simulate the design of WDM in FSO transmission. The total losses that have been considered in this design are geometric loss, transmitter and receiver loss and atmospheric attenuation which focus on nonselective scattering during heavy rainfall condition in Malaysian environment. Malaysian weather data are used to reflect the conditions particularly in tropical regions. Results: We have presented the results of 16-channels WDM at 100-GHz channel spacing. The simulated results show that this system can support a higher bit rate up to 2.5 Gbps over 2.4 km distance. Conclusion: Simulation results showed that WDM FSO system may be a good candidate to solve the last mile problem and also it has capability to accommodate the channels more than 16. By introducing the error correction code or balance detection, the transmission distance might be increased further.

  15. High Precision Ranging and Range-Rate Measurements over Free-Space-Laser Communication Link

    Science.gov (United States)

    Yang, Guangning; Lu, Wei; Krainak, Michael; Sun, Xiaoli

    2016-01-01

    We present a high-precision ranging and range-rate measurement system via an optical-ranging or combined ranging-communication link. A complete bench-top optical communication system was built. It included a ground terminal and a space terminal. Ranging and range rate tests were conducted in two configurations. In the communication configuration with 622 data rate, we achieved a two-way range-rate error of 2 microns/s, or a modified Allan deviation of 9 x 10 (exp -15) with 10 second averaging time. Ranging and range-rate as a function of Bit Error Rate of the communication link is reported. They are not sensitive to the link error rate. In the single-frequency amplitude modulation mode, we report a two-way range rate error of 0.8 microns/s, or a modified Allan deviation of 2.6 x 10 (exp -15) with 10 second averaging time. We identified the major noise sources in the current system as the transmitter modulation injected noise and receiver electronics generated noise. A new improved system will be constructed to further improve the system performance for both operating modes.

  16. Microphysical characterization of free space optical link due to hydrometeor and fog effects.

    Science.gov (United States)

    Mori, Saverio; Marzano, Frank S

    2015-08-01

    Free space optics (FSO) channel availability is affected by atmospheric water particles, which may introduce severe path attenuation. A unified microphysically oriented atmospheric particle scattering (MAPS) model is proposed and described to simulate particle scattering effects on FSO links. Atmospheric particles, such as raindrops, graupel particles, and snowflakes, together with fog droplets, are considered. Input data to characterize liquid and frozen water particle size distribution, density, and refractivity are derived from available literature data and measurements. Scattering, absorption, and extinction coefficients as well as the asymmetry factor are numerically simulated for each particle class and then parametrized with respect to particle water content, fall rate, and visibility, spanning from visible to infrared wavelengths. Both single- and multiple-scattering effects are discussed and quantified by using a radiative transfer model for small-angle approximation. MAPS simulations confirm that fog layers are those causing the largest power extinction on FSO links, but also several decibels of attenuation can be attributed to snow and rain conditions. Multiple-scattering effects, especially due to fog droplets, heavy rain, and dry snowflakes, typically tend to reduce the total attenuation by increasing the received power. An estimate of these effects, parameterized to single-scattering extinction, is proposed for near-infrared FSO link design.

  17. Cost-effective backhaul design using hybrid radio/free-space optical technology

    KAUST Repository

    Douik, Ahmed S.

    2015-06-08

    The deluge of date rate in today\\'s networks poses a cost burden on the backhaul network design. Developing cost efficient backhaul solutions becomes an interesting, yet challenging, problem. Traditional technologies for backhaul networks include either radio-frequency backhauls (RF) or optical fibres (OF). While RF is a cost-effective solution as compared to OF, it supports lower data rate requirements. Another promising backhaul solution that may combine both a high data rate and a relatively low cost is the free-space optics (FSO). FSO, however, is sensitive to nature conditions (e.g., rain, fog, line-ofsight, etc.). A more reliable alternative is, therefore, to combine RF and FSO solutions through a hybrid structure called hybrid RF/FSO. Consider a backhaul network, where the base-stations (BS) can be connected to each other either via OF or hybrid RF/FSO backhaul links. The paper addresses the problem of minimizing the cost of backhaul planning under connectivity and data rates constraints, so as to choose the appropriate costeffective backhaul type between BSs (i.e., either OF or hybrid RF/FSO). The paper solves the problem using graph theory techniques by introducing the corresponding planning graph. It shows that under a specified realistic assumption about the cost of OF and hybrid RF/FSO links, the problem is equivalent to a maximum weight clique problem, which can be solved with moderate complexity. Simulation results show that our proposed solution shows a close-to-optimal performance, especially for practical prices of the hybrid RF/FSO.

  18. Free-Space Quantum Key Distribution

    CERN Document Server

    Carrasco-Casado, Alberto; Denisenko, Natalia

    2016-01-01

    Based on the firm laws of physics rather than unproven foundations of mathematical complexity, quantum cryptography provides a radically different solution for encryption and promises unconditional security. Quantum cryptography systems are typically built between two nodes connected to each other through fiber optic. This chapter focuses on quantum cryptography systems operating over free-space optical channels as a cost-effective and license-free alternative to fiber optic counterparts. It provides an overview of the different parts of an experimental free-space quantum communication link developed in the Spanish National Research Council (Madrid, Spain).

  19. Performance Analysis of Free-Space Optical Links Over Malaga (M) Turbulence Channels with Pointing Errors

    KAUST Repository

    Ansari, Imran Shafique

    2015-08-12

    In this work, we present a unified performance analysis of a free-space optical (FSO) link that accounts for pointing errors and both types of detection techniques (i.e. intensity modulation/direct detection (IM/DD) as well as heterodyne detection). More specifically, we present unified exact closedform expressions for the cumulative distribution function, the probability density function, the moment generating function, and the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system, all in terms of the Meijer’s G function except for the moments that is in terms of simple elementary functions. We then capitalize on these unified results to offer unified exact closed-form expressions for various performance metrics of FSO link transmission systems, such as, the outage probability, the scintillation index (SI), the average error rate for binary and M-ary modulation schemes, and the ergodic capacity (except for IM/DD technique, where we present closed-form lower bound results), all in terms of Meijer’s G functions except for the SI that is in terms of simple elementary functions. Additionally, we derive the asymptotic results for all the expressions derived earlier in terms of Meijer’s G function in the high SNR regime in terms of simple elementary functions via an asymptotic expansion of the Meijer’s G function. We also derive new asymptotic expressions for the ergodic capacity in the low as well as high SNR regimes in terms of simple elementary functions via utilizing moments. All the presented results are verified via computer-based Monte-Carlo simulations.

  20. Effect of Rain Attenuations on Free Space Optic Transmission in Kuala Lumpur

    Directory of Open Access Journals (Sweden)

    Fatin Hamimi Mustafa

    2011-01-01

    Full Text Available This research paper describes the effects of rain attenuation on the free space optical (FSO transmission system. The entire research was conducted in the heart of Kuala Lumpur city- year 2001, as the city was using such systems (LAN-to-LAN & WLAN-to-WLAN widely to connect the metropolitan areas for data transmission. The preliminary experiments were done using PAVLight product modeled PL-1G/1Tx/GigE which leaded to maximum reach of 700m distance with 810nm wavelength and also laser power of 14dBm. The data for rain intensities were obtained from measuring unit at UTM Jalan Semarak, Kuala Lumpur following the ITU protocols such as ITU-R P.1814 and ITU-R P.1817. The transmission and reception were achieved by using Continuous Wave (CW Laser signals as transmitting signals and APD photo detector to receive it on the other end. The experiments were fully carried out for two conditions (heavy-rain and lighter rain or drizzle with multiple repetitions. At last, the collected data were compiled and compared with other researcher's results. It was found to be the same as how the other researchers have obtained before for various cities worldwide. The results were found to be very satisfactory. It obeyed the theoretical aspects as higher the rain, higher the attenuations then. These results the degradation on the received signals. As a guide for future implementation of FSO systems for various atmospheric conditions in the metropolitan areas of Kuala Lumpur; we believed that this preliminary works may help.

  1. Optics. Spatially structured photons that travel in free space slower than the speed of light.

    Science.gov (United States)

    Giovannini, Daniel; Romero, Jacquiline; Potoček, Václav; Ferenczi, Gergely; Speirits, Fiona; Barnett, Stephen M; Faccio, Daniele; Padgett, Miles J

    2015-02-20

    That the speed of light in free space is constant is a cornerstone of modern physics. However, light beams have finite transverse size, which leads to a modification of their wave vectors resulting in a change to their phase and group velocities. We study the group velocity of single photons by measuring a change in their arrival time that results from changing the beam's transverse spatial structure. Using time-correlated photon pairs, we show a reduction in the group velocity of photons in both a Bessel beam and photons in a focused Gaussian beam. In both cases, the delay is several micrometers over a propagation distance of ~1 meter. Our work highlights that, even in free space, the invariance of the speed of light only applies to plane waves. Copyright © 2015, American Association for the Advancement of Science.

  2. Use of satellite natural vibrations to improve performance of free-space satellite laser communication.

    Science.gov (United States)

    Arnon, S

    1998-07-20

    In some of the future laser communication satellites, it is plausible to assume that tracking and communication receivers will use the same detector array. The reason for dual use of the detector is to design simpler and less expensive satellites. Satellites vibrate continually because of their subsystems and environmental sources. The vibrations cause nonuniform spreading of the received energy on the detector array. In view of this, the information from the tracking system is used to adapt individually the communication signal gain of each of the detectors in the array. This adaptation of the gains improves communication system performance. It is important to emphasize that the communication performance improvement is achieved only by gain adaptation. Any additional vibrations decrease the tracking and laser pointing system performances, which decrease the return communication performances (two-way communication). A comparison of practical communication systems is presented. The novelty of this research is the utilization of natural satellite vibrations to improve the communication system performance.

  3. Advanced techniques for free-space optical quantum cryptography over water

    Science.gov (United States)

    Hill, Alexander D.; Christensen, Bradley; Kwiat, Paul G.

    2016-03-01

    Free-space quantum key distribution (QKD) over water (e.g., ship to ship) may be limited by ship motion and atmospheric effects, such as mode distortion and beam wander due to turbulence. We report on a technique which reduces noise by excluding spatial modes which are less likely to contain QKD signal photons and experimentally demonstrate an improvement in QKD key generation rates in various noise and turbulence regimes.

  4. Free-space optical crossbar network integrated in a single block of LiNbO3 crystal.

    Science.gov (United States)

    Song, Zhe; Hou, Peipei; Fu, Lili; Fan, Liuyan; Gao, Yan; Ding, Yi; Wang, Yuxin; Feng, Qiuju

    2012-03-20

    A free-space optical crossbar network integrated in a single block of LiNbO(3) crystal is proposed, which consists of stages of 2×2 switches making use of the electro-optic effect of crystal and in-between routing devices for permutation based on double refraction and internal double reflection on interfaces. Two basic configurations are suggested. A control algorithm for the crossbar network is discussed, which may control a nonblocking interconnection between any input and output. The integrated crossbar network is low energy loss, nonblocking, easy to assemble, and insensitive to environment. A 3×3 crossbar network is designed and the experiment is demonstrated.

  5. Polarization preservation of partially coherent Hermite-Gaussian beams for multiple-degrees-of-freedom free-space communication

    CERN Document Server

    Ji, Ling; Lin, Xiao-Feng; Jin, Xian-Min

    2016-01-01

    Multiple-degrees-of-freedom free-space communication combining polarization and high-order spatial modes promises high-capacity communication channel. While high-order spatial modes have been widely exploited for dense coding and high-dimensional quantum information processing, the properties of polarization preservation of high-order spatial beams propagating in turbulent atmosphere have not been comprehensively investigated yet. Here we focus on the properties of polarization preservation of partially coherent Hermite-Gaussian beams propagating along different atmospheric turbulence paths. The analytical expressions for the polarization of partially coherent Hermite-Gaussian beams propagating through atmospheric turbulence along different paths have been derived. It is shown that the larger the coherence length is, and the larger the beam order m, n are, the less the polarization is changed. We find that the evolution properties of the polarization in slant-down paths through turbulent atmosphere are simila...

  6. Stable, Free-space Optical Trapping and Manipulation of Sub-micron Particles in an Integrated Microfluidic Chip

    Science.gov (United States)

    Kim, Jisu; Shin, Jung H.

    2016-01-01

    We demonstrate stable, free-space optical trapping and manipulation in an integrated microfluidic chip using counter-propagating beams. An inverted ridge-type waveguide made of SU8 is cut across by an open trench. The design of the waveguide provides low propagation losses and small divergence of the trapping beam upon emergence from the facet, and the trench designed to be deeper and wider than the optical mode enables full utilization of the optical power with an automatic alignment for counter-propagating beams in a trap volume away from all surfaces. After integration with polydimethylsiloxane (PDMS) microfluidic channel for particle delivery, 0.65 μm and 1 μm diameter polystyrene beads were trapped in free space in the trench, and manipulated to an arbitrary position between the waveguides with a resolution of < 100 nm. Comparison with numerical simulations confirm stable trapping of sub-micron particles, with a 10 kBT threshold power of less than 1 mW and a stiffness that can be 1 order of magnitude larger than that of comparable fiber-based trapping methods. PMID:27653191

  7. Experimental free-space distribution of entangled photon pairs over 13 km: towards satellite-based global quantum communication.

    Science.gov (United States)

    Peng, Cheng-Zhi; Yang, Tao; Bao, Xiao-Hui; Zhang, Jun; Jin, Xian-Min; Feng, Fa-Yong; Yang, Bin; Yang, Jian; Yin, Juan; Zhang, Qiang; Li, Nan; Tian, Bao-Li; Pan, Jian-Wei

    2005-04-22

    We report free-space distribution of entangled photon pairs over a noisy ground atmosphere of 13 km. It is shown that the desired entanglement can still survive after both entangled photons have passed through the noisy ground atmosphere with a distance beyond the effective thickness of the aerosphere. This is confirmed by observing a spacelike separated violation of Bell inequality of 2.45+/-0.09. On this basis, we exploit the distributed entangled photon source to demonstrate the Bennett-Brassard 1984 quantum cryptography scheme. The distribution distance of entangled photon pairs achieved in the experiment is for the first time well beyond the effective thickness of the aerosphere, hence presenting a significant step towards satellite-based global quantum communication.

  8. Encoding information using Laguerre Gaussian modes over free space turbulence media

    CSIR Research Space (South Africa)

    Trichili, A

    2016-07-01

    Full Text Available of the atmospheric turbulence on the proposed communication system. We believe that the proposed technique is promising for high-bit-rate spatial division multiplexing in optical fiber and free space communication systems....

  9. Information on a Photon: Free-Space Quantum Communication (InPho: FSQC)

    Science.gov (United States)

    2015-10-06

    photonic states, EPL ( Europhysics Letters ), (11 2013): 30003. doi: 10.1209/0295-5075/104/30003 Daniel J. Gauthier, Yu-Po Wong, Hannah E. Guilbert...Miles J. Padgett, Marco W. Beijersbergen. Measuring orbital angular momentum superpositions of light by mode transformation, Optics Letters , (05...Characterization of High- Dimensional Entangled Systems via Mutually Unbiased Measurements, Physical Review Letters , (04 2013): 143601. doi: 10.1103

  10. Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Zellar, Ronald S.; Fong, Wai H; Krainak, Michael A.; Neumann, Gregory A.; Smith, David E.

    2013-01-01

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  11. Free space laser communication experiments from Earth to the Lunar Reconnaissance Orbiter in lunar orbit.

    Science.gov (United States)

    Sun, Xiaoli; Skillman, David R; Hoffman, Evan D; Mao, Dandan; McGarry, Jan F; McIntire, Leva; Zellar, Ronald S; Davidson, Frederic M; Fong, Wai H; Krainak, Michael A; Neumann, Gregory A; Zuber, Maria T; Smith, David E

    2013-01-28

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

  12. Bit error rate analysis of free-space optical system with spatial diversity over strong atmospheric turbulence channel with pointing errors

    Science.gov (United States)

    Krishnan, Prabu; Sriram Kumar, D.

    2014-12-01

    Free-space optical communication (FSO) is emerging as a captivating alternative to work out the hindrances in the connectivity problems. It can be used for transmitting signals over common lands and properties that the sender or receiver may not own. The performance of an FSO system depends on the random environmental conditions. The bit error rate (BER) performance of differential phase shift keying FSO system is investigated. A distributed strong atmospheric turbulence channel with pointing error is considered for the BER analysis. Here, the system models are developed for single-input, single-output-FSO (SISO-FSO) and single-input, multiple-output-FSO (SIMO-FSO) systems. The closed-form mathematical expressions are derived for the average BER with various combining schemes in terms of the Meijer's G function.

  13. Hybrid pulse position modulation and binary phase shift keying subcarrier intensity modulation for free space optics in a weak and saturated turbulence channel.

    Science.gov (United States)

    Faridzadeh, Monire; Gholami, Asghar; Ghassemlooy, Zabih; Rajbhandari, Sujan

    2012-08-01

    In this paper a hybrid modulation scheme based on pulse position modulation (PPM) and binary phase shift keying subcarrier intensity modulation (BPSK-SIM) schemes for free-space optical communications is proposed. The analytical bit error rate (BER) performance is investigated in weak and saturated turbulence channels and results are verified with the simulation data. Results show that performance of PPM-BPSK-SIM is superior to BPSK-SIM in all turbulence regimes; however, it outperforms 2-PPM for the turbulence variance σ(1)(2)>0.2. PPM-BPSK-SIM offers a signal-to-noise ratio (SNR) gain of 50 dB in the saturation regime compared to BPSK at a BER of 10(-6). The SNR gain in comparison to PPM improves as the strength of the turbulence level increases.

  14. Noise adaptive fading Kalman filter for free-space laser communication beacon tracking.

    Science.gov (United States)

    Li, Lixing; Huang, Yongmei; Wang, Qiang; Yang, Fasheng

    2016-10-20

    We proposed a prediction algorithm for laser communication pointing, acquisition, and tracking (PAT) subsystems in order to further improve PAT accuracy and reduce the effect of processing delay. In terms of this prediction algorithm, a fading Kalman filter is employed, with the observation noise obtained by the gray value distribution of the laser images. Moreover, to better fit the dynamics of a laser target, the two-stage dynamic model has been chosen as the state transition model for Kalman filtering. In addition, the two-stage dynamic model has been modified by accommodating its form to a change of time lag, thereby compensating the effect of time delay. A series of horizontal path (17 km) experiments under different atmospheric conditions were conducted in the fields. According to the experimental results, the algorithm we proposed could effectively reduce the tracking error and improve pointing accuracy.

  15. Optimal Performance Monitoring of Hybrid Mid-Infrared Wavelength MIMO Free Space Optical and RF Wireless Networks in Fading Channels

    Science.gov (United States)

    Schmidt, Barnet Michael

    An optimal performance monitoring metric for a hybrid free space optical and radio-frequency (RF) wireless network, the Outage Capacity Objective Function, is analytically developed and studied. Current and traditional methods of performance monitoring of both optical and RF wireless networks are centered on measurement of physical layer parameters, the most common being signal-to-noise ratio, error rate, Q factor, and eye diagrams, occasionally combined with link-layer measurements such as data throughput, retransmission rate, and/or lost packet rate. Network management systems frequently attempt to predict or forestall network failures by observing degradations of these parameters and to attempt mitigation (such as offloading traffic, increasing transmitter power, reducing the data rate, or combinations thereof) prior to the failure. These methods are limited by the frequent low sensitivity of the physical layer parameters to the atmospheric optical conditions (measured by optical signal-to-noise ratio) and the radio frequency fading channel conditions (measured by signal-to-interference ratio). As a result of low sensitivity, measurements of this type frequently are unable to predict impending failures sufficiently in advance for the network management system to take corrective action prior to the failure. We derive and apply an optimal measure of hybrid network performance based on the outage capacity of the hybrid optical and RF channel, the outage capacity objective function. The objective function provides high sensitivity and reliable failure prediction, and considers both the effects of atmospheric optical impairments on the performance of the free space optical segment as well as the effect of RF channel impairments on the radio frequency segment. The radio frequency segment analysis considers the three most common RF channel fading statistics: Rayleigh, Ricean, and Nakagami-m. The novel application of information theory to the underlying physics of the

  16. Preparation of an Exponentially Rising Optical Pulse for Efficient Excitation of Single Atoms in Free Space

    CERN Document Server

    Dao, Hoang Lan; Maslennikov, Gleb; Kurtsiefer, Christian

    2012-01-01

    We report on a simple method to prepare optical pulses with exponentially rising envelope on the time scale of a few ns. The scheme is based on the exponential transfer function of a fast transistor, which generates an exponentially rising envelope that is transferred first on a radio frequency carrier, and then on a coherent cw laser beam with an electro-optical phase modulator (EOM). The temporally shaped sideband is then extracted with an optical resonator and can be used to efficiently excite a single Rb-87 atom.

  17. Experimental characterization of a 400 Gbit/s orbital angular momentum multiplexed free-space optical link over 120 m.

    Science.gov (United States)

    Ren, Yongxiong; Wang, Zhe; Liao, Peicheng; Li, Long; Xie, Guodong; Huang, Hao; Zhao, Zhe; Yan, Yan; Ahmed, Nisar; Willner, Asher; Lavery, Martin P J; Ashrafi, Nima; Ashrafi, Solyman; Bock, Robert; Tur, Moshe; Djordjevic, Ivan B; Neifeld, Mark A; Willner, Alan E

    2016-02-01

    We experimentally demonstrate and characterize the performance of a 400-Gbit/s orbital angular momentum (OAM) multiplexed free-space optical link over 120 m on the roof of a building. Four OAM beams, each carrying a 100-Gbit/s quadrature-phase-shift-keyed channel are multiplexed and transmitted. We investigate the influence of channel impairments on the received power, intermodal crosstalk among channels, and system power penalties. Without laser tracking and compensation systems, the measured received power and crosstalk among OAM channels fluctuate by 4.5 dB and 5 dB, respectively, over 180 s. For a beam displacement of 2 mm that corresponds to a pointing error less than 16.7 μrad, the link bit error rates are below the forward error correction threshold of 3.8×10(-3) for all channels. Both experimental and simulation results show that power penalties increase rapidly when the displacement increases.

  18. 19-core MCF transmission system using EDFA with shared core pumping coupled via free-space optics.

    Science.gov (United States)

    Sakaguchi, Jun; Klaus, Werner; Puttnam, Benjamin J; Mendinueta, José Manuel Delgado; Awaji, Yoshinari; Wada, Naoya; Tsuchida, Yukihiro; Maeda, Koichi; Tadakuma, Masateru; Imamura, Katsunori; Sugizaki, Ryuichi; Kobayashi, Tetsuya; Tottori, Yusaku; Watanabe, Masayuki; Jensen, R V

    2014-01-13

    We report the development of a space division multiplexed (SDM) transmission system consisting of a 19-core fiber and 19-core Erbium-doped fiber amplifier (EDFA). A new 19-core fiber with an improved core arrangement was employed to achieve a low aggregated inter-core crosstalk of -42 dB at 1550 nm over 30 km. The EDFA uses shared free-space optics for pump beam combining and isolation, thus is SDM transparent and has some potential for cost reduction. 19.6 dB to 23.3 dB gain and 6.0 dB to 7.0 dB noise figure were obtained for each SDM channel at 1550 nm. System feasibility for SDM transmission over 1200 km was demonstrated with 100 Gb/s PDM-QPSK signals.

  19. Aperture averaging in multiple-input single-output free-space optical systems using partially coherent radial array beams.

    Science.gov (United States)

    Gökçe, Muhsin Caner; Baykal, Yahya; Uysal, Murat

    2016-06-01

    Multiple-input single-output (MISO) techniques are employed in free-space optical (FSO) links to mitigate the degrading effects of atmospheric turbulence. In this paper, for the MISO FSO system, a partially coherent radial array and a finite-sized receiver aperture are used at the transmitter and the receiver, respectively. Using the extended Huygens-Fresnel principle, we formulate the average power and the power correlation at the finite-sized slow detector in weak atmospheric turbulence. System performance indicators such as the power scintillation index and the aperture averaging factor are determined. Effects of the source size, ring radius, receiver aperture radius, link distance, and structure constant and the degree of source coherence are analyzed on the performance of the MISO FSO system. In the limiting cases, the numerical results are found to be the same when compared to the existing coherent and partially coherent Gaussian beam scintillation indices.

  20. Opto-VLSI-based reconfigurable free-space optical interconnects architecture

    DEFF Research Database (Denmark)

    Aljada, Muhsen; Alameh, Kamal; Chung, Il-Sug;

    2007-01-01

    is the Opto-VLSI processor which can be driven by digital phase steering and multicasting holograms that reconfigure the optical interconnects between the input and output ports. The optical interconnects architecture is experimentally demonstrated at 2.5 Gbps using high-speed 1×3 VCSEL array and 1......This paper presents a short-distance reconfigurable high-speed optical interconnects architecture employing a Vertical Cavity Surface Emitting Laser (VCSEL) array, Opto-very-large-scale-integrated (Opto-VLSI) processors, and a photodetector (PD) array. The core component of the architecture......×3 photoreceiver array in conjunction with two 1×4096 pixel Opto-VLSI processors. The minimisation of the crosstalk between the output ports is achieved by appropriately aligning the VCSEL and PD elements with respect to the Opto-VLSI processors and driving the latter with optimal steering phase holograms....

  1. Packaging a free-space intra-chip optical interconnect module: Monte Carlo tolerance study and assembly results

    Science.gov (United States)

    Vervaeke, Michael; Lahti, Markku; Karpinnen, Mikko; Debaes, Christof; Volckaerts, Bart; Karioja, Pentti; Thienpont, Hugo

    2006-04-01

    In this paper we give an overview of the fabrication and assembly induced performance degradation of an intra-multi-chip-module free-space optical interconnect, integrating micro-lenses and a deflection prism above a dense opto-electronic chip. The proposed component is used to demonstrate the capabilities of an accurate micro-optical rapid prototype technique, namely the Deep Proton Writing (DPW). To evaluate the accuracy of DPW and to assess whether our assembly scheme will provide us with a reasonable process yield, we have built a simulation framework combining mechanical Monte Carlo analysis with optical simulations. Both the technological requirements to ensure a high process yield, and the specifications of our in-house DPW technology are discussed. Therefore, we first conduct a sensitivity analysis and we subsequently simulate the effect of combined errors using a Monte Carlo simulation. We are able to investigate the effect of a technology accuracy enhancement on the fabrication and assembly yield by scaling the standard deviation of the errors proportionally to each sensitivity interval. We estimate that 40% of the systems fabricated with DPW will show an optical transmission efficiency above -4.32 dB, which is -3 dB below the theoretical obtainable value. We also discuss our efforts to implement an opto-mechanical Monte Carlo simulator. It enables us to address specific issues not directly related with the micro-optical or DPW components, such as the influence of glueing layers and structures that allow for self-alignment, by combining mechanical tolerancing algorithms with optical simulation software. More in particular we determined that DPW provides ample accuracy to meet the requirements to obtain a high manufacturing yield. Finally, we shortly highlight the basic layout of a completed demonstrator. The adhesive bonding of opto-electronic devices in their package is subject to further improvement to enhance the tilt accuracy of the devices with

  2. Chip-interleaved optical code division multiple access relying on a photon-counting iterative successive interference canceller for free-space optical channels.

    Science.gov (United States)

    Zhou, Xiaolin; Zheng, Xiaowei; Zhang, Rong; Hanzo, Lajos

    2013-07-01

    In this paper, we design a novel Poisson photon-counting based iterative successive interference cancellation (SIC) scheme for transmission over free-space optical (FSO) channels in the presence of both multiple access interference (MAI) as well as Gamma-Gamma atmospheric turbulence fading, shot-noise and background light. Our simulation results demonstrate that the proposed scheme exhibits a strong MAI suppression capability. Importantly, an order of magnitude of BER improvements may be achieved compared to the conventional chip-level optical code-division multiple-access (OCDMA) photon-counting detector.

  3. Free-space optics technology employed in an UMTS release 4 bearer independent core network access part

    Science.gov (United States)

    Bibac, Ionut

    2005-08-01

    The UMTS Bearer Independent Core Network program introduced the 3rd Generation Partnership Program Release 4 BICN architecture into the legacy UMTS TDM-switched network. BICN is the application of calI server archltecture for voice and circuit switched data, enabling the provisioning of traditional circuit-switched services using a packet-switched transport network. Today"s business climate has made it essential for service providers to develop a comprehensive networking strategy that means introduction of RCBICN networks. The R4-BICN solution to the evolution of the Core Network in UMTS will enable operators to significantly reduce the capital and operational costs of delivering both traditional voice sewices and new multimedia services. To build the optical backbone, which can support the third generation (3G) packetized infrastructure, the operators could choose a fibre connection, or they could retain the benefits of a wireless connectivity by using a FSO - Free Space Optical lmk, the only wireless technology available that is capable of achieving data rates up to 2.4 Gbit/s. FSO offers viable alternatives for both core transmission networks and for replacing microwaves links in NodeB - RNC access networks. The paper and presentation aim to demonstrate the manner in which FSO products and networks are employed into R4-BICN design solutions.

  4. Blood pulse wave velocity and pressure sensing via fiber based and free space based optical sensors

    Science.gov (United States)

    Sirkis, Talia; Beiderman, Yevgeny; Agdarov, Sergey; Beiderman, Yafim; Zalevsky, Zeev

    2017-02-01

    Continuous noninvasive measurement of vital bio-signs, such as cardiopulmonary parameters, is an important tool in evaluation of the patient's physiological condition and health monitoring. On the demand of new enabling technologies, some works have been done in continuous monitoring of blood pressure and pulse wave velocity. In this paper, we introduce two techniques for non-contact sensing of vital bio signs. In the first approach the optical sensor is based on single mode in-fibers Mach-Zehnder interferometer (MZI) to detect heartbeat, respiration and pulse wave velocity (PWV). The introduced interferometer is based on a new implanted scheme. It replaces the conventional MZI realized by inserting of discontinuities in the fiber to break the total internal reflection and scatter/collect light. The proposed fiber sensor was successfully incorporated into shirt to produce smart clothing. The measurements obtained from the smart clothing could be obtained in comfortable manner and there is no need to have an initial calibration or a direct contact between the sensor and the skin of the tested individual. In the second concept we show a remote noncontact blood pulse wave velocity and pressure measurement based on tracking the temporal changes of reflected secondary speckle patterns produced in human skin when illuminated by a laser beams. In both concept experimental validation of the proposed schemes is shown and analyzed.

  5. On the Performance of Free-Space Optical Systems over Generalized Atmospheric Turbulence Channels with Pointing Errors

    KAUST Repository

    Ansari, Imran Shafique

    2015-03-01

    Generalized fading has been an imminent part and parcel of wireless communications. It not only characterizes the wireless channel appropriately but also allows its utilization for further performance analysis of various types of wireless communication systems. Under the umbrella of generalized fading channels, a unified performance analysis of a free-space optical (FSO) link over the Malaga (M) atmospheric turbulence channel that accounts for pointing errors and both types of detection techniques (i.e. indirect modulation/direct detection (IM/DD) as well as heterodyne detection) is presented. Specifically, unified exact closed-form expressions for the probability density function (PDF), the cumulative distribution function (CDF), the moment generating function (MGF), and the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system are presented, all in terms of the Meijer\\'s G function except for the moments that is in terms of simple elementary functions. Then capitalizing on these unified results, unified exact closed-form expressions for various performance metrics of FSO link transmission systems are offered, such as, the outage probability (OP), the higher-order amount of fading (AF), the average error rate for binary and M-ary modulation schemes, and the ergodic capacity (except for IM/DD technique, where closed-form lower bound results are presented), all in terms of Meijer\\'s G functions except for the higher-order AF that is in terms of simple elementary functions. Additionally, the asymptotic results are derived for all the expressions derived earlier in terms of the Meijer\\'s G function in the high SNR regime in terms of simple elementary functions via an asymptotic expansion of the Meijer\\'s G function. Furthermore, new asymptotic expressions for the ergodic capacity in the low as well as high SNR regimes are derived in terms of simple elementary functions via utilizing moments. All the presented results are

  6. Effects of aperture averaging and beam width on a partially coherent Gaussian beam over free-space optical links with turbulence and pointing errors.

    Science.gov (United States)

    Lee, It Ee; Ghassemlooy, Zabih; Ng, Wai Pang; Khalighi, Mohammad-Ali; Liaw, Shien-Kuei

    2016-01-01

    Joint effects of aperture averaging and beam width on the performance of free-space optical communication links, under the impairments of atmospheric loss, turbulence, and pointing errors (PEs), are investigated from an information theory perspective. The propagation of a spatially partially coherent Gaussian-beam wave through a random turbulent medium is characterized, taking into account the diverging and focusing properties of the optical beam as well as the scintillation and beam wander effects. Results show that a noticeable improvement in the average channel capacity can be achieved with an enlarged receiver aperture in the moderate-to-strong turbulence regime, even without knowledge of the channel state information. In particular, it is observed that the optimum beam width can be reduced to improve the channel capacity, albeit the presence of scintillation and PEs, given that either one or both of these adverse effects are least dominant. We show that, under strong turbulence conditions, the beam width increases linearly with the Rytov variance for a relatively smaller PE loss but changes exponentially with steeper increments for higher PE losses. Our findings conclude that the optimal beam width is dependent on the combined effects of turbulence and PEs, and this parameter should be adjusted according to the varying atmospheric channel conditions. Therefore, we demonstrate that the maximum channel capacity is best achieved through the introduction of a larger receiver aperture and a beam-width optimization technique.

  7. A PSAM-based estimator of noise and fading statistics for optimum receivers of free space optics signals

    Science.gov (United States)

    Moradi, Hassan; Refai, Hazem H.; LoPresti, Peter G.; Atiquzzaman, Mohammed

    2010-02-01

    Incoherent receivers of Free Space Optical (FSO) signals have no knowledge of instantaneous channel state. Thus, the receiver requires some information about the noise and fading statistics for a maximum likelihood (ML)-based optimal detection. Using pilot-aided symbols, we develop a simple multi slot averaging (MSA) estimation technique to approximate the values of parameters required at the incoherent detector. No channel state information (CSI) is available at the receiver side and this work will not be also trying to estimate it. But the estimation of noise and fading statistics will be practically investigated. We evaluate the bit error rate (BER) performance of FSO links with MSA estimation over both Gaussian and lognormal atmospheric turbulence fading (scintillation) channels. Numerical simulation will be completed to evaluate the estimation error of the MSA estimator. We will see that at signal to noise ratio (SNR)=13dB, the performance loss of the Gaussian estimator improves from 3dB to 0.4dB when we increase the number of pilot symbols from 16 to 64. This paper also presents the hardware design of the estimator using Xilinx system generator.

  8. Experimental verification of long-term evolution radio transmissions over dual-polarization combined fiber and free-space optics optical infrastructures.

    Science.gov (United States)

    Bohata, J; Zvanovec, S; Pesek, P; Korinek, T; Mansour Abadi, M; Ghassemlooy, Z

    2016-03-10

    This paper describes the experimental verification of the utilization of long-term evolution radio over fiber (RoF) and radio over free space optics (RoFSO) systems using dual-polarization signals for cloud radio access network applications determining the specific utilization limits. A number of free space optics configurations are proposed and investigated under different atmospheric turbulence regimes in order to recommend the best setup configuration. We show that the performance of the proposed link, based on the combination of RoF and RoFSO for 64 QAM at 2.6 GHz, is more affected by the turbulence based on the measured difference error vector magnitude value of 5.5%. It is further demonstrated the proposed systems can offer higher noise immunity under particular scenarios with the signal-to-noise ratio reliability limit of 5 dB in the radio frequency domain for RoF and 19.3 dB in the optical domain for a combination of RoF and RoFSO links.

  9. Performance of free-space laser communication systems as a function of the sampling rate in the tracking loop

    Science.gov (United States)

    Nikulin, V.; Sofka, J.; Khandekar, R.

    2005-08-01

    Laser technology plays an ever-increasing role in aerospace and communication systems and is often viewed as a technology that has the potential for providing the material base for high-bandwidth applications. Laser provides the most logical connectivity channel for mobile systems requiring high data rates, low power consumption, covert operation, and high resistance to jamming. While advancements in modern opto-electronics have resulted in small size, reliable and power efficient lasers and modulators, successful operation of any communication technology hinges upon the ability to develop an equally advanced beam steering/positioning system. In many aerospace applications, when the transmitting optical platform is placed on board of an airplane, the ability to track the target is affected by the complex high-speed maneuvers performed by the aircraft and the resident vibration of the airframe. The tracking system must assure that in spite of the relative motion of both the transmitting and receiving stations and adverse environments, such as vibration, mutual alignment of two systems will be maintained to minimize communication errors. The work presented in this paper concentrates on the development of agile beam steering systems for laser communication terminals. Acousto-optic Bragg cells are used as deflectors while feedback information is generated by a quadrant detector. The control system is synthesized using a relatively simple constant-gain controller augmented with an adaptive Kalman filter to mitigate the effects of measurement noise in the tracking system. Laboratory experiments are conducted to investigate communication performance as a function of the sampling rate in the beam position feedback.

  10. Practical free-space quantum key distribution over 1 km

    CERN Document Server

    Buttler, W T; Kwiat, P G; Lamoreaux, S K; Luther, G G; Morgan, G L; Nordholt, J E; Peterson, C G; Simmons, C M

    1998-01-01

    A working free-space quantum key distribution (QKD) system has been developed and tested over an outdoor optical path of ~1 km at Los Alamos National Laboratory under nighttime conditions. Results show that QKD can provide secure real-time key distribution between parties who have a need to communicate secretly. Finally, we examine the feasibility of surface to satellite QKD.

  11. Effects of source spatial partial coherence on temporal fade statistics of irradiance flux in free-space optical links through atmospheric turbulence.

    Science.gov (United States)

    Chen, Chunyi; Yang, Huamin; Zhou, Zhou; Zhang, Weizhi; Kavehrad, Mohsen; Tong, Shoufeng; Wang, Tianshu

    2013-12-01

    The temporal covariance function of irradiance-flux fluctua-tions for Gaussian Schell-model (GSM) beams propagating in atmospheric turbulence is theoretically formulated by making use of the method of effective beam parameters. Based on this formulation, new expressions for the root-mean-square (RMS) bandwidth of the irradiance-flux temporal spectrum due to GSM beams passing through atmospheric turbulence are derived. With the help of these expressions, the temporal fade statistics of the irradiance flux in free-space optical (FSO) communication systems, using spatially partially coherent sources, impaired by atmospheric turbulence are further calculated. Results show that with a given receiver aperture size, the use of a spatially partially coherent source can reduce both the fractional fade time and average fade duration of the received light signal; however, when atmospheric turbulence grows strong, the reduction in the fractional fade time becomes insignificant for both large and small receiver apertures and in the average fade duration turns inconsiderable for small receiver apertures. It is also illustrated that if the receiver aperture size is fixed, changing the transverse correlation length of the source from a larger value to a smaller one can reduce the average fade frequency of the received light signal only when a threshold parameter in decibels greater than the critical threshold level is specified.

  12. High-speed reconfigurable card-to-card optical interconnects based on hybrid free-space and multi-mode fiber propagations.

    Science.gov (United States)

    Wang, Ke; Nirmalathas, Ampalavanapillai; Lim, Christina; Skafidas, Efstratios; Alameh, Kamal

    2013-12-16

    In this paper, a high-speed reconfigurable card-to-card optical interconnect architecture based on hybrid free-space and multi-mode fiber (MMF) propagation is proposed. The use of free-space signal transmission provides flexibility and reconfigurability and the MMF extends the achievable interconnection range. A printed-circuit-board (PCB) based integrated optical interconnect module is designed and developed and proof-of-concept demonstration experiments are carried out. Results show that 3 × 10 Gb/s reconfigurable optical interconnect is realized with ~12 cm free-space propagation and a 10 m MMF length. In addition, since air turbulence due to high temperature of electronic components and heat dissipation fans always exists in typical interconnect environments and it normally results in system performance degradation, its impact on the proposed reconfigurable optical interconnect scheme is also experimentally investigated. Results indicate that even with comparatively strong air turbulence, 3 × 10 Gb/s optical interconnects with flexibility can still be achieved and the power penalty is <0.7 dB.

  13. A Unified Performance Analysis of Free-Space Optical Links over Gamma-Gamma Turbulence Channels with Pointing Errors

    KAUST Repository

    Ansari, Imran Shafique

    2013-11-13

    In this work, we present a unified performance analysis of a free-space optical (FSO) link that accounts for pointing errors and both types of detection techniques (i.e. intensity modulation/direct detection as well as heterodyne detection). More specifically, we present unified exact closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function, and the moments of the end-to-end signal-to-noise ratio (SNR) of a single link FSO transmission system, all in terms of the Meijer\\'s G function except for the moments that is in terms of simple elementary functions. We then capitalize on these unified results to offer unified exact closed-form expressions for various performance metrics of FSO link transmission systems, such as, the outage probability, the higher-order amount of fading (AF), the average error rate for binary and M-ary modulation schemes, and the ergodic capacity, all in terms of Meijer\\'s G functions except for the higher-order AF that is in terms of simple elementary functions. Additionally, we derive the asymptotic results for all the expressions derived earlier in terms of Meijer\\'s G function in the high SNR regime in terms of simple elementary functions via an asymptotic expansion of the Meijer\\'s G function. We also derive new asymptotic expressions for the ergodic capacity in the low as well as high SNR regimes in terms of simple elementary functions via utilizing moments. All the presented results are verified via computer-based Monte-Carlo simulations.

  14. Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

    Science.gov (United States)

    Farr, William H.

    2009-01-01

    Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

  15. Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

    Science.gov (United States)

    Farr, William H.

    2009-01-01

    Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

  16. Enhanced quantum communication via optical refocusing

    Energy Technology Data Exchange (ETDEWEB)

    Lupo, Cosmo [School of Science and Technology, University of Camerino, I-62032 Camerino (Italy); Giovannetti, Vittorio [National Enterprise for Nanoscience and Nanotechnology (NEST), Scuola Normale Superiore and Istituto Nanoscienze, Consiglio Nazionale delle Ricerche (CNR), I-56126 Pisa (Italy); Pirandola, Stefano [Department of Computer Science, University of York, York YO10 5GH (United Kingdom); Mancini, Stefano [School of Science and Technology, University of Camerino, I-62032 Camerino (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Perugia, I-06123 Perugia (Italy); Lloyd, Seth [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2011-07-15

    We consider the problem of quantum communication mediated by a passive optical refocusing system. The model captures the basic features of all those situations in which a signal is either refocused by a repeater for long-distance communication, or it is focused on a detector prior to the information decoding process. Introducing a general method for linear passive optical systems, we determine the conditions under which optical refocusing implies information transmission gain. Although the finite aperture of the repeater may cause loss of information, we show that the presence of the refocusing system can substantially enhance the rate of reliable communication with respect to the free-space propagation. We explicitly address the transferring of classical messages over the quantum channel, but the results can be easily extended to include the case of transferring quantum messages as well.

  17. Enhanced quantum communication via optical refocusing

    Science.gov (United States)

    Lupo, Cosmo; Giovannetti, Vittorio; Pirandola, Stefano; Mancini, Stefano; Lloyd, Seth

    2011-07-01

    We consider the problem of quantum communication mediated by a passive optical refocusing system. The model captures the basic features of all those situations in which a signal is either refocused by a repeater for long-distance communication, or it is focused on a detector prior to the information decoding process. Introducing a general method for linear passive optical systems, we determine the conditions under which optical refocusing implies information transmission gain. Although the finite aperture of the repeater may cause loss of information, we show that the presence of the refocusing system can substantially enhance the rate of reliable communication with respect to the free-space propagation. We explicitly address the transferring of classical messages over the quantum channel, but the results can be easily extended to include the case of transferring quantum messages as well.

  18. Three-dimensional reconstruction in free-space whole-body fluorescence tomography of mice using optically reconstructed surface and atlas anatomy

    Science.gov (United States)

    Zhang, Xiaofeng; Badea, Cristian T.; Johnson, G. Allan

    2009-11-01

    We present a 3-D image reconstruction method for free-space fluorescence tomography of mice using hybrid anatomical prior information. Specifically, we use an optically reconstructed surface of the experimental animal and a digital mouse atlas to approximate the anatomy of the animal as structural priors to assist image reconstruction. Experiments are carried out on a cadaver of a nude mouse with a fluorescent inclusion (2.4-mm-diam cylinder) implanted in the chest cavity. Tomographic fluorescence images are reconstructed using an iterative algorithm based on a finite element method. Coregistration of the fluorescence reconstruction and micro-CT (computed tomography) data acquired afterward show good localization accuracy (localization error 1.2+/-0.6 mm). Using the optically reconstructed surface, but without the atlas anatomy, image reconstruction fails to show the fluorescent inclusion correctly. The method demonstrates the utility of anatomical priors in support of free-space fluorescence tomography.

  19. Enhanced Quantum Communication via Optical Refocusing

    CERN Document Server

    Lupo, Cosmo; Pirandola, Stefano; Mancini, Stefano; Lloyd, Seth

    2011-01-01

    We consider the problem of quantum communication mediated by an optical refocusing system, which is schematized as a thin lens with a finite pupil. This model captures the basic features of all those situations in which a signal is either refocused by a repeater for long distance communication, or it is focused on a detector prior to the information decoding process. Introducing a general method for linear optical systems, we compute the communication capacity of the refocusing apparatus. Although the finite extension of the pupil may cause loss of information, we show that the presence of the refocusing system can substantially enhance the rate of reliable communication with respect to the free-space propagation.

  20. 4 x 10 Gb/s terrestrial optical free space transmission over 1.2 km using an EDFA preamplifier with 100 GHz channel spacing.

    Science.gov (United States)

    Song, D Y; Hurh, Y S; Cho, J W; Lim, J H; Lee, D W; Lee, J S; Chung, Y

    2000-10-09

    We demonstrate a transmission of 4 x 10 Gb/s WDM channels over 1.2 km of free space in 1.55-microm band. The transmitted beam is coupled into a single-mode fiber through a fiber-pigtailed collimator, which enables the use of standard 100-GHz channel spacing and an optical preamplifier at the receiver. All the received channels have Q values higher than 6.

  1. Quantum cryptography in free space.

    Science.gov (United States)

    Jacobs, B C; Franson, J D

    1996-11-15

    The range of quantum cryptography systems using optical fibers is limited to roughly 30 km because amplifiers cannot be used. A fully operational system for quantum cryptography based on the transmission of single photons in free space under daylight conditions has been demonstrated. The feasibility of a global system for quantum cryptography based on a network of ground stations and satellites is discussed.

  2. Advanced digital optical communications

    CERN Document Server

    Binh, Le Nguyen

    2015-01-01

    This book provides a fundamental understanding of digital communication applications in optical communication technologies. Emphasizing operation principles versus mathematical analysis, the Second Edition includes new coverage of superchannel optical transmission systems, metropolitan and long-haul optical systems and networks, and Nyquist pulse shaping and high spectral efficiency of optical transmission systems, as well as new homework problems and examples. Featuring theoretical foundations as well as practical case studies, the text focuses on enhancements to digital technologies that are

  3. 全双工逆向调制回复空间光通信系统性能评价%Performance evaluation of full-duplex free space laser communication system based on modulating retro-reflector

    Institute of Scientific and Technical Information of China (English)

    张鹏; 王天枢; 杨国伟; 贾青松; 马万卓; 张立中; 佟首峰; 姜会林

    2015-01-01

    基于逆向调制反射器(MRR)的空间光通信系统因其结构紧凑、可免去链路一端的捕跟(APT)系统、功耗低等优点,是空间光通信系统研究热点之一。提出采用双波长激光发射实现全双工逆向调制回复空间光通信结构,并基于该结构对强度调制解调模式,通信距离为300 km ,通信速率为1 GHz下的地面站对近地小卫星全双工通信链路进行了链路计算及通信误码率的分析。当MRR端口径为0.1 m时,通信链路余量大于5 dB ,通信误码率优于10-15,满足通信链路的要求。并进一步分析了仿真结果存在的缺陷。结果表明所提出的空间光通信结构在小卫星对地面站全双工激光通信是可行的,是未来空间光通信系统发展趋势之一。%Free space optical communication based on modulating retro-reflector (MRR) is research hotspots of future wireless optical communication because of less power, compact structure and without Acquisition, Pointing and Tracking (APT) requirement at system based on MRR. Full-duplex free space laser communication system based on MRR and double-wavelength laser is proposed. The link budget between small satellite under low orbit and ground station and bit error rate (BER) of optical communication are calculated when Communication distance and rate are 300 km and 1 GHz. It can be found that the link budge is more than 5 dB, and BER is less than 10-15. The results show that the budge and BER meet the communication requirement. Then limitation of the emulation is also analyzed. In conclusion, the proposed system can be used between light-weight full-duplex laser communication of small satellite under low orbit and ground station. It may be one of the future development trends of space optical communication system.

  4. 海浪中船载激光通讯机运动模拟%Study and Experiments of Ship Movement Simulation for Free Space Laser Communication

    Institute of Scientific and Technical Information of China (English)

    安翔

    2011-01-01

    大气激光通信具有抗电磁干扰能力强、保密性高等优点,是船舶间通信的一个重要手段.根据船舶的运动方程,采用线性系统理论分析,给出了船载激光通讯机在风浪中的运动规律,对于进一步实验研制船载激光通信系统有重要意义.%Free space laser communication (FSOC), which features high anti-EM interference capability, good security, is the important method of the communication between ships. According to the ship motion equations, this paper mainly discusses the motion law of the FSOC equipment on a ship in the wind waves by using linear system theory, that is very important for the research and development of ship-bome free space laser communication.

  5. Fibre-optic communications

    CERN Document Server

    Lecoy, Pierre

    2010-01-01

    This book describes in a comprehensive manner the components and systems of fiber optic communications and networks. The first section explains the theory of multimode and single-mode fibers, then the technological features, including manufacturing, cabling, and connecting. The second section describes the various components (passive and active optical components, integrated optics, opto-electronic transmitters and receivers, and optical amplifiers) used in fiber optic systems. Finally, the optical transmission system design is explained, and applications to optical networks and fiber optic se

  6. Statistical analysis on the optical fading in free space optical channel for RoFSO link design

    Science.gov (United States)

    Kim, Kyung-Hwan; Higashino, Takeshi; Tsukamoto, Katsutoshi; Komaki, Shozo; Kazaura, Kamugisha; Matsumoto, Mitsuji

    2010-01-01

    This paper presents empirical probability density functions (p.d.fs) of variance and fluctuation speed of scintillation, through analyzing a number of experimental data measured in Japan by a statistical model. The model enables us to treat scintillation speed by one parameter of cut-off frequency in the power spectral density (PDS). By using the model and based on the two p.d.fs, we also present simulation results on the level crossing rate (LCR) and average fade duration (AFD). Combined the two results, an outage probabilities corresponding to a threshold optical intensity can be derived.

  7. Optical communications beyond orbital angular momentum

    Science.gov (United States)

    Rosales-Guzmán, Carmelo; Trichili, Abderrahmen; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

    2016-09-01

    Current optical communication technologies are predicted to face a bandwidth capacity limit in the near future. The nature of the limitation is fundamental rather than technological and is set by nonlinearities in optical fibers. One solution, suggested over 30 years ago, comprises the use of spatial modes of light as information carriers. Along this direction, light beams endowed with orbital angular momentum (OAM) have been demonstrated as potential information carriers in both, free space and fibres. However, recent studies suggest that purely OAM modes does not increase the bandwidth of optical communication systems. In fact, in all work to date, only the azimuthal component of transverse spatial modes has been used. Crucially, all transverse spatial modes require two degrees of freedom to be described; in the context of Laguerre-Gaussian (LGp`) beams these are azimuthal (l) and radial (p), the former responsible for OAM. Here, we demonstrate a technique where both degrees of freedom of LG modes are used as information carrier over free space. We transfer images encoded using 100 spatial modes in three wavelengths as our basis, and employ a spatial demultiplexing scheme that detects all 100 modes simultaneously. Our scheme is a hybrid of MIMO and SMM, and serves as a proof-of-principle demonstration. The cross-talk between the modes is small and independent of whether OAM modes are used or not.

  8. An Optical Receiver Post-Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

    Science.gov (United States)

    Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

    2016-01-01

    The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

  9. Experimental characterization of a 400  Gbit/s orbital angular momentum multiplexed free-space optical link over 120 m

    OpenAIRE

    Ren, Yongxiong; WANG Zhe; Liao, Peicheng; Li, Long; Xie, Guodong; Huang, Hao; Zhao, Zhe; Yan, Yan; Ahmed, Nisar; Willner, Asher; Lavery, Martin P. J.; Ashrafi, Nima; Ashrafi, Solyman; Bock, Robert; Tur, Moshe

    2016-01-01

    We experimentally demonstrate and characterize the\\ud performance of a 400-Gbit/s orbital angular momentum\\ud (OAM) multiplexed free-space optical link over 120-\\ud meters on the roof of a building. Four OAM beams, each\\ud carrying a 100-Gbit/s QPSK channel are multiplexed and\\ud transmitted. We investigate the influence of channel\\ud impairments on the received power, inter-modal\\ud crosstalk among channels, and system power penalties.\\ud Without laser tracking and compensation systems, the\\...

  10. Experimental characterization of a 400  Gbit/s orbital angular momentum multiplexed free-space optical link over 120 m

    OpenAIRE

    Ren, Yongxiong; Wang, Zhe; Liao, Peicheng; LI, Long; Xie, Guodong; Huang, Hao; Zhao, Zhe; Yan, Yan; Ahmed, Nisar; Willner, Asher; Lavery, Martin P. J.; Ashrafi, Nima; Ashrafi, Solyman; Bock, Robert; Tur, Moshe

    2016-01-01

    We experimentally demonstrate and characterize the\\ud performance of a 400-Gbit/s orbital angular momentum\\ud (OAM) multiplexed free-space optical link over 120-\\ud meters on the roof of a building. Four OAM beams, each\\ud carrying a 100-Gbit/s QPSK channel are multiplexed and\\ud transmitted. We investigate the influence of channel\\ud impairments on the received power, inter-modal\\ud crosstalk among channels, and system power penalties.\\ud Without laser tracking and compensation systems, the\\...

  11. 自由空间光通信低功率激光干扰实验%Experiment of low-power laser jamming free space optical system

    Institute of Scientific and Technical Information of China (English)

    陈静; 薛海中; 刘学文; 魏龙超; 毛登森; 冯茜

    2012-01-01

    The free space optical communication (FSO) based on IM/DD is the most mature technology and widely used recently. The way that how the low power pulse infrared laser jammed the FSO system which was developed independently based on IM/DD was researched. To approach the reality jamming application, laser was diffused by a white paper which was placed out of the FSO' s field of view. Amount of experiments were carried out by using laser diode and diode-pumped solid-state laser (DPL) with different repetition rates and different pulse widthes. The results show that the FSO based on IM/DD can be jammed by a low-power infrared laser, and the relationship between the efficiency of jamming and the parameters of jamming laser such as repetition rate and pulse width is gained. Moreover, the experiment phenomena is explained by using theoretical analysis, concluded the conditions of the FSO jamming by low power and pulse infrared laser.%以目前技术最为成熟、应用最为广泛的强度调制/直接检测(IM/DD)体制的自由空间激光通信体制为例,利用自主研发的无线激光通信系统,采用漫反射的方法,研究了小功率脉冲激光对自由空间激光通信的干扰效果.利用不同调制频率、不同脉宽的半导体激光器和固体激光器分别进行了多次激光干扰实验,证明了干扰的可行性,得出了调制频率、脉宽与干扰效果的关系,并结合自由空间激光通信原理和通信设备的工作流程对实验现象加以解释和分析,提出了低功率脉冲激光对通信系统实现干扰的条件.

  12. Average BER analysis of SCM-based free-space optical systems by considering the effect of IM3 with OSSB signals under turbulence channels.

    Science.gov (United States)

    Lim, Wansu; Cho, Tae-Sik; Yun, Changho; Kim, Kiseon

    2009-11-09

    In this paper, we derive the average bit error rate (BER) of subcarrier multiplexing (SCM)-based free space optics (FSO) systems using a dual-drive Mach-Zehnder modulator (DD-MZM) for optical single-sideband (OSSB) signals under atmospheric turbulence channels. In particular, we consider the third-order intermodulation (IM3), a significant performance degradation factor, in the case of high input signal power systems. The derived average BER, as a function of the input signal power and the scintillation index, is employed to determine the optimum number of SCM users upon the designing FSO systems. For instance, when the user number doubles, the input signal power decreases by almost 2 dBm under the log-normal and exponential turbulence channels at a given average BER.

  13. Fiber-wireless integrated mobile backhaul network based on a hybrid millimeter-wave and free-space-optics architecture with an adaptive diversity combining technique.

    Science.gov (United States)

    Zhang, Junwen; Wang, Jing; Xu, Yuming; Xu, Mu; Lu, Feng; Cheng, Lin; Yu, Jianjun; Chang, Gee-Kung

    2016-05-01

    We propose and experimentally demonstrate a novel fiber-wireless integrated mobile backhaul network based on a hybrid millimeter-wave (MMW) and free-space-optics (FSO) architecture using an adaptive combining technique. Both 60 GHz MMW and FSO links are demonstrated and fully integrated with optical fibers in a scalable and cost-effective backhaul system setup. Joint signal processing with an adaptive diversity combining technique (ADCT) is utilized at the receiver side based on a maximum ratio combining algorithm. Mobile backhaul transportation of 4-Gb/s 16 quadrature amplitude modulation frequency-division multiplexing (QAM-OFDM) data is experimentally demonstrated and tested under various weather conditions synthesized in the lab. Performance improvement in terms of reduced error vector magnitude (EVM) and enhanced link reliability are validated under fog, rain, and turbulence conditions.

  14. Roadmap of optical communications

    Science.gov (United States)

    Agrell, Erik; Karlsson, Magnus; Chraplyvy, A. R.; Richardson, David J.; Krummrich, Peter M.; Winzer, Peter; Roberts, Kim; Fischer, Johannes Karl; Savory, Seb J.; Eggleton, Benjamin J.; Secondini, Marco; Kschischang, Frank R.; Lord, Andrew; Prat, Josep; Tomkos, Ioannis; Bowers, John E.; Srinivasan, Sudha; Brandt-Pearce, Maïté; Gisin, Nicolas

    2016-06-01

    Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.

  15. High-performance two-axis gimbal system for free space laser communications onboard unmanned aircraft systems

    Science.gov (United States)

    Locke, Michael; Czarnomski, Mariusz; Qadir, Ashraf; Setness, Brock; Baer, Nicolai; Meyer, Jennifer; Semke, William H.

    2011-03-01

    A custom designed and manufactured gimbal with a wide field-of-view and fast response time is developed. This enhanced custom design is a 24 volt system with integrated motor controllers and drivers which offers a full 180o fieldof- view in both azimuth and elevation; this provides a more continuous tracking capability as well as increased velocities of up to 479° per second. The addition of active high-frequency vibration control, to complement the passive vibration isolation system, is also in development. The ultimate goal of this research is to achieve affordable, reliable, and secure air-to-air laser communications between two separate remotely piloted aircraft. As a proof-of-concept, the practical implementation of an air-to-ground laserbased video communications payload system flown by a small Unmanned Aerial Vehicle (UAV) will be demonstrated. A numerical tracking algorithm has been written, tested, and used to aim the airborne laser transmitter at a stationary ground-based receiver with known GPS coordinates; however, further refinement of the tracking capabilities is dependent on an improved gimbal design for precision pointing of the airborne laser transmitter. The current gimbal pointing system is a two-axis, commercial-off-the-shelf component, which is limited in both range and velocity. The current design is capable of 360o of pan and 78o of tilt at a velocity of 60o per second. The control algorithm used for aiming the gimbal is executed on a PC-104 format embedded computer onboard the payload to accurately track a stationary ground-based receiver. This algorithm autonomously calculates a line-of-sight vector in real-time by using the UAV autopilot's Differential Global Positioning System (DGPS) which provides latitude, longitude, and altitude and Inertial Measurement Unit (IMU) which provides the roll, pitch, and yaw data, along with the known Global Positioning System (GPS) location of the ground-based photodiode array receiver.

  16. Three-dimensional optoelectronic stacked processor by use of free-space optical interconnection and three-dimensional VLSI chip stacks.

    Science.gov (United States)

    Li, Guoqiang; Huang, Dawei; Yuceturk, Emel; Marchand, Philippe J; Esener, Sadik C; Ozguz, Volkan H; Liu, Yue

    2002-01-10

    We present a demonstration system under the three-dimensional (3D) optoelectronic stacked processor consortium. The processor combines the advantages of optics in global, high-density, high-speed parallel interconnections with the density and computational power of 3D chip stacks. In particular, a compact and scalable optoelectronic switching system with a high bandwidth is designed. The system consists of three silicon chip stacks, each integrated with a single vertical-cavity-surface-emitting-laser-metal-semiconductor-metal detector array and an optical interconnection module. Any input signal at one end stack can be switched through the central crossbar stack to any output channel on the opposite end stack. The crossbar bandwidth is designed to be 256 Gb/s. For the free-space optical interconnection, a novel folded hybrid micro-macro optical system with a concave reflection mirror has been designed. The optics module can provide a high resolution, a large field of view, a high link efficiency, and low optical cross talk. It is also symmetric and modular. Off-the-shelf macro-optical components are used. The concave reflection mirror can significantly improve the image quality and tolerate a large misalignment of the optical components, and it can also compensate for the lateral shift of the chip stacks. Scaling of the macrolens can be used to adjust the interconnection length between the chip stacks or make the system more compact. The components are easy to align, and only passive alignment is required. Optics and electronics are separated until the final assembly step, and the optomechanic module can be removed and replaced. By use of 3D chip stacks, commercially available optical components, and simple passive packaging techniques, it is possible to achieve a high-performance optoelectronic switching system.

  17. A Low-Cost, Man-Portable, Free-Space Optics Communications Device for Ethernet Applications

    Science.gov (United States)

    2004-12-01

    routing delays, and the delays caused by the reading and writing latencies of the disk drives. However, this method would suffice to eventually reach...wien.ac.at/~dusty/ projekte /laserlink/files/ne5211.pdf , last accessed December 2004. 22. “1.25 Gbps High Speed limiting Post Amplifier

  18. Nonlinear Detection, Estimation, and Control for Free-Space Optical Communication

    Science.gov (United States)

    2008-08-17

    6.4.1, we can achieve Cit x̂ i t = 0, t > 0, using the control law uα,it dt = − ( CitB α,i t )−1 { ( CitA i t + Ċ i t ) x̂itdt+ C i tM i t ∫ R2 rN i (dt...given by F it = −     I2×2 02×2 ( LitHtB β,i t )−1 LitHtB α,i t I2×2     −1     ( CitB α,i t )−1( CitA i t + Ċ i t ) ( LitHtB β,i t )−1

  19. Free-space quantum cryptography

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.J.; Buttler, W.T.; Kwiat, P.G.; Lamoreaux, S.K.; Morgan, G.L.; Nordholt, J.E.; Peterson, C.G.

    1998-12-31

    An experimental free-space quantum key distribution (QKD) system has been tested over an outdoor optical path of {approximately}1 km under nighttime conditions at Los Alamos National Laboratory. This system employs the Bennett 92 protocol; here the authors give a brief overview of this protocol, and describe the experimental implementation of it. An analysis of the system efficiency is presented, as well as a description of the error detection protocol, which employs a two-dimensional parity check scheme. Finally, the susceptibility of this system to eavesdropping by various techniques is determined. Possible applications include the rekeying of satellites in low earth orbit.

  20. Performance Analysis of Heterodyne-Detected OCDMA Systems Using PolSK Modulation over a Free-Space Optical Turbulence Channel

    Directory of Open Access Journals (Sweden)

    Fan Bai

    2015-10-01

    Full Text Available This paper presents a novel model of heterodyne-detected optical code-division multiple-access (OCDMA systems employing polarization shift keying (PolSK modulation over a free-space optical (FSO turbulence channel. In this article, a new transceiver configuration and detailed analytical model for the proposed system are provided and discussed, taking into consideration the potential of heterodyne detection on mitigating the impact of turbulence-induced irradiance fluctuation on the performance of the proposed system under the gamma-gamma turbulence channel. Furthermore, we derived the closed-form expressions for the system error probability and outage probability, respectively. We determine the advantages of the proposed modeling by performing a comparison with a direct detection scheme obtained from an evaluation of link performance under the same environment conditions. The presented work also shows the most significant impact factor that degrades the performance of the proposed system and indicates that the proposed approach offers an optimum link performance compared to conventional cases.

  1. Physical and statistical modeling of attenuation due to atmospheric hydrometeors on free-space optical links at 850 and 1550 nm

    Science.gov (United States)

    Grabner, Martin; Kvicera, Vaclav

    2012-10-01

    Atmospheric hydrometeors such as rain and fog may cause attenuation of an optical signal and degrade the performance of free-space optical (FSO) systems. For efficient design of the FSO links, attenuation characteristics must be predicted by sufficiently reliable models that have been tested on experimental data. A long term experiment on the FSO links operating at 850 and 1550 nm wavelengths is conducted in Prague. The path lengths are 100 and 853 m. Received power fluctuations on the FSO links and relevant meteorological quantities such as rain intensity and liquid water content of fog are measured simultaneously. The relationships between the physical parameters of hydrometeors and path attenuation are analyzed and compared with theoretical relations derived using the Mie scattering theory together with some natural assumptions about the physical properties of scattering particles such as droplet size distribution of different types of hydrometeors. Long term statistics of attenuation are obtained and availability performance of the experimental FSO links is assessed. The method for predicting attenuation statistics based on physical and statistical models is introduced and the errors of the proposed models with respect to measured data are analyzed. The models are compared with the existing empirical relationships derived from other FSO experiments and differences are discussed.

  2. Optical communication components

    Science.gov (United States)

    Eldada, Louay

    2004-03-01

    We review and contrast key technologies developed to address the optical components market for communication applications. We first review the component requirements from a network perspective. We then look at different material systems, compare their properties, and describe the functions achieved to date in each of them. The material systems reviewed include silica fiber, silica on silicon, silicon on insulator, silicon oxynitride, sol-gels, polymers, thin-film dielectrics, lithium niobate, indium phosphide, gallium arsenide, magneto-optic materials, and birefringent crystals. We then describe the most commonly used classes of optical device technology and present their pros and cons as well as the functions achieved to date in each of them. The technologies reviewed include passive, actuation, and active technologies. The passive technologies described include fused fibers, dispersion-compensating fiber, beam steering, Bragg gratings, diffraction gratings, holographic elements, thin-film filters, photonic crystals, microrings, and birefringent elements. The actuation technologies include thermo-optics, electro-optics, acousto-optics, magneto-optics, electroabsorption, liquid crystals, total internal reflection technologies, and mechanical actuation. The active technologies include heterostructures, quantum wells, rare-earth doping, dye doping, Raman amplification, and semiconductor amplification. We also investigate the use of different material systems and device technologies to achieve building-block functions, including lasers, amplifiers, detectors, modulators, polarization controllers, couplers, filters, switches, attenuators, isolators, circulators, wavelength converters, chromatic dispersion compensators, and polarization mode dispersion compensators. Some of the technologies presented are well established in the industry and in some cases have reached the commodity stage, others have recently become ready for commercial introduction, while some others

  3. Design of an omnidirectional optical antenna for ultraviolet communication.

    Science.gov (United States)

    Zhang, Xuebin; Tang, Yi; Huang, Heqing; Zhang, Lijun; Bai, Tingzhu

    2014-05-20

    In this paper we propose an omnidirectional large field-optical antenna with a dual-mirror structure and field devices and demonstrate its utilization in ultraviolet (UV) communications. Theoretical analysis shows that it is suitable for short-range UV communication. Simulation indicates that the optical gain is 32, and the system has a good spot uniformity. Additionally, incident angles of incident ray meet the requirement of the interference filter (±10°). Outdoor experiments show that the angle of FOV is in the range of ±20°~±80° and a SNR increase of 31 dB compared with bare tube is observed, demonstrating the effectiveness of the omnidirectional optical antenna structure for free-space UV communication.

  4. On the Performance Analysis of Hybrid ARQ With Incremental Redundancy and With Code Combining Over Free-Space Optical Channels With Pointing Errors

    KAUST Repository

    Zedini, Emna

    2014-07-16

    In this paper, we investigate the performance of hybrid automatic repeat request (HARQ) with incremental redundancy (IR) and with code combining (CC) from an information-theoretic perspective over a point-to-point free-space optical (FSO) system. First, we introduce new closed-form expressions for the probability density function, the cumulative distribution function, the moment generating function, and the moments of an FSO link modeled by the Gamma fading channel subject to pointing errors and using intensity modulation with direct detection technique at the receiver. Based on these formulas, we derive exact results for the average bit error rate and the capacity in terms of Meijer\\'s G functions. Moreover, we present asymptotic expressions by utilizing the Meijer\\'s G function expansion and using the moments method, too, for the ergodic capacity approximations. Then, we provide novel analytical expressions for the outage probability, the average number of transmissions, and the average transmission rate for HARQ with IR, assuming a maximum number of rounds for the HARQ protocol. Besides, we offer asymptotic expressions for these results in terms of simple elementary functions. Additionally, we compare the performance of HARQ with IR and HARQ with CC. Our analysis demonstrates that HARQ with IR outperforms HARQ with CC.

  5. Product Codes for Optical Communication

    DEFF Research Database (Denmark)

    Andersen, Jakob Dahl

    2002-01-01

    Many optical communicaton systems might benefit from forward-error-correction. We present a hard-decision decoding algorithm for the "Block Turbo Codes", suitable for optical communication, which makes this coding-scheme an alternative to Reed-Solomon codes.......Many optical communicaton systems might benefit from forward-error-correction. We present a hard-decision decoding algorithm for the "Block Turbo Codes", suitable for optical communication, which makes this coding-scheme an alternative to Reed-Solomon codes....

  6. Free-space to few-mode-fiber coupling under atmospheric turbulence.

    Science.gov (United States)

    Zheng, Donghao; Li, Yan; Chen, Erhu; Li, Beibei; Kong, Deming; Li, Wei; Wu, Jian

    2016-08-01

    High speed free space optical communication (FSOC) has taken advantages of components developed for fiber-optic communication systems. Recently, with the rapid development of few-mode-fiber based fiber communication systems, few-mode-fiber components might further promote their applications in FSOC system. The coupling efficiency between free space optical beam and few-mode fibers under atmospheric turbulence effect are investigated in this paper. Both simulation and experimental results show that, compared with single-mode fiber, the coupling efficiencies for a 2-mode fiber and a 4-mode fiber are improved by ~4 dB and ~7 dB respectively in the presence of medium moderate and strong turbulence. Compared with single-mode fiber, the relative standard deviation of received power is restrained by 51% and 66% respectively with a 4-mode and 2-mode fiber.

  7. 3D optical vortices generated by micro-optical elements and its novel applications

    Institute of Scientific and Technical Information of China (English)

    BU J.; LIN J.; K. J. Moh; B. P. S. Ahluwalia; CHEN H. L.; PENG X.; NIU H. B.; YUAN X.C.

    2007-01-01

    In this paper we report on recent development in the areas of optical vortices generated by micro-optical elements and applications of optical vortices, including optical manipulation, radial polarization and secure free space optical communication

  8. Performance Metrics and Design Parameters for a Free-space Communication Link Based on Multiplexing of Multiple Orbital-Angular-Momentum Beams

    CERN Document Server

    Xie, Guodong; Ren, Yongxiong; Huang, Hao; Yan, Yan; Ahmed, Nisar; Zhao, Zhe; Lavery, Martin P J; Ashrafi, Nima; Ashrafi, Solyman; Tur, Moshe; Molisch, Andreas F; Willner, Alan E

    2014-01-01

    We study the design parameters for an orbital angular momentum (OAM) multiplexed free-space data link. Power loss, channel crosstalk and power penalty of the link are analyzed in the case of misalignment between the transmitter and receiver (lateral displacement, receiver angular error, or transmitter pointing error). The relationship among the system power loss and link distance, transmitted beam size and receiver aperture size are discussed based on the beam divergence due to free space propagation. We also describe the trade-offs for different receiver aperture sizes and mode spacing of the transmitted OAM beams under given lateral displacements or receiver angular errors. Through simulations and some experiments, we show that (1) a system with a larger transmitted beam size and a larger receiver aperture is more tolerant to the lateral displacement but less tolerant to the receiver angular error; (2) a system with a larger mode spacing, which uses larger OAM charges, suffers more system power loss but les...

  9. Investigation of Atmospheric Laser Optics Test bed (A_LOT) Optical Turbulence Intensity for Free-Space Laser Communications

    Science.gov (United States)

    2006-12-01

    data include mean temperature, wind speed (small three- cup anemometer ), barometric pressure, relative humidity, and rainfall amount. We have also...integrated a single three-axis sonic anemometer (R.M. Young Company1, Model 81000) alongside the rooftop weather station. The sonic sensor provides...and mean and fluctuating temperature data). Basically, a sonic anemometer determines wind speed and wind direction by measuring the change in the

  10. Design of an optical-communication link with Mars

    CERN Document Server

    Carrasco-Casado, Alberto

    2016-01-01

    The possibility of using optical communications in free-space as an improvement of current RF communication systems was analyzed in this Project. The particular case of a link Mars-Earth was studied and a link based in the future NASA's MLCD project, which is currently being developed, was designed. For this, an orbit simulator was programmed, evaluating the transfer orbit, analyzing the losses that occur in the transmission channel, using several atmospheric models, selecting the most adequate elements for the transmitter and the receiver, calculating the Doppler effect during the mission, and performing a budget link for the different orbit positions. From these results, the maximum bitrate through the MLCD mission was evaluated for the different astronomical observatories chosen as optical ground stations.

  11. Fibre optic communication key devices

    CERN Document Server

    Grote, Norbert

    2017-01-01

    The book gives an in-depth description of key devices of current and next generation fibre optic communication networks. Devices treated include semiconductor lasers, optical amplifiers, modulators, wavelength filters and other passives, detectors, all-optical switches, but relevant properties of optical fibres and network aspects are included as well. The presentations include the physical principles underlying the various devices, technologies used for their realization, typical performance characteristics and limitations, but development trends towards more advanced components are also illustrated. This new edition of a successful book was expanded and updated extensively. The new edition covers among others lasers for optical communication, optical switches, hybrid integration, monolithic integration and silicon photonics. The main focus is on Indium phosphide-based structures but silicon photonics is included as well. The book covers relevant principles, state-of-the-art implementations, status of curren...

  12. Research of Three-Wave-Band Filters Used in Free Space Communication System%空间光通信系统三波段滤光膜的研究

    Institute of Scientific and Technical Information of China (English)

    潘永刚; 刘冬梅; 张静; 付秀华; 杨道奇

    2012-01-01

    Filter is often used to interfere the spectral spectrum into different bands in free space laser communication. This article mainly introduces the research and preparation of a three-band near infrared optical filter. According to the design theory, TiO2 is selected as the material of high refractive index and SiQ2 as the low one to realize high transmittance in two bands of 770~860 nm and 1530~1575 nm, and high reflection in the band of 1615~1700 nm. The film stack is designed by film design software, and electron gun and ion-assisted deposition system are used for film preparation. The process flow is optimized through the adjustment of process parameters to get a good thickness uniformity of less than 3% by adjusting the compensation bezel. Although the film is thick, it meets the use requirement as shown by the tests of optical properties, mechanical properties and resistance to the environment. In addition, the quality of the coating surface successfully passes the test of the surface profile instrument, meanwhile, the variation of profile peak-to-valley (P-V) value can meet the design requirements.%空间激光通信常采用干涉截止滤光膜对不同波段的光谱进行分光.着重介绍了近红外三波段光学滤光片的研究与制备.根据膜系设计理论,分别选择TiO2和SiO2作为高、低折射率材料,借助膜系设计软件设计优化了合理的膜系,实现了770~860 nm及1530~1575 nm光谱范围双波段的高透过和1615~1700 nm波段的高反射.采用电子枪离子辅助沉积系统进行制备.优化工艺参数,通过调整补偿挡板使膜厚均匀性控制在3%以内.虽然制备膜层较厚,但经检测其光学性能、机械性能及耐环境能力均满足使用要求.用轮廓仪检测所制备膜层的面形,其峰谷值变化达到预期要求.

  13. Optical fiber communications

    CERN Document Server

    Keiser, Gerd

    2008-01-01

    The fourth edition of this popular text and reference book presents the fundamental principles for understanding and applying optical fiber technology to sophisticated modern telecommunication systems. Optical-fiber-based telecommunication networks have become a major information-transmission-system, with high capacity links encircling the globe in both terrestrial and undersea installations. Numerous passive and active optical devices within these links perform complex transmission and networking functions in the optical domain, such as signal amplification, restoration, routing, and switching. Along with the need to understand the functions of these devices comes the necessity to measure both component and network performance, and to model and stimulate the complex behavior of reliable high-capacity networks.

  14. Application of Single-Mode Fiber-Coupled Receivers in Optical Satellite to High-Altitude Platform Communications

    Directory of Open Access Journals (Sweden)

    Oswald Wallner

    2008-05-01

    Full Text Available In a free-space optical communication system employing fiber-optic components, the phasefront distortions induced by atmospheric turbulence limit the efficiency with which the laser beam is coupled into a single-mode fiber. We analyze different link scenarios including a geostationary (GEO satellite, a high-altitude platform (HAP, and an optical ground station (OGS. Single-mode coupled optically preamplified receivers allow for efficient suppression of background noise and highly sensitive detection. While GEO-to-OGS communication suffers from atmospheric turbulence, we demonstrate that GEO-to-HAP communication allows for close to diffraction-limited performance when applying tip-tilt correction.

  15. Application of Single-Mode Fiber-Coupled Receivers in Optical Satellite to High-Altitude Platform Communications

    Directory of Open Access Journals (Sweden)

    Fidler Franz

    2008-01-01

    Full Text Available Abstract In a free-space optical communication system employing fiber-optic components, the phasefront distortions induced by atmospheric turbulence limit the efficiency with which the laser beam is coupled into a single-mode fiber. We analyze different link scenarios including a geostationary (GEO satellite, a high-altitude platform (HAP, and an optical ground station (OGS. Single-mode coupled optically preamplified receivers allow for efficient suppression of background noise and highly sensitive detection. While GEO-to-OGS communication suffers from atmospheric turbulence, we demonstrate that GEO-to-HAP communication allows for close to diffraction-limited performance when applying tip-tilt correction.

  16. A COTS RF/Optical Software Defined Radio for the Integrated Radio and Optical Communications Test Bed

    Science.gov (United States)

    Nappier, Jennifer M.; Zeleznikar, Daniel J.; Wroblewski, Adam C.; Tokars, Roger P.; Schoenholz, Bryan L.; Lantz, Nicholas C.

    2017-01-01

    The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration (NASA) is investigating the merits of a hybrid radio frequency (RF) and optical communication system for deep space missions. In an effort to demonstrate the feasibility and advantages of a hybrid RF/Optical software defined radio (SDR), a laboratory prototype was assembled from primarily commercial-off-the-shelf (COTS) hardware components. This COTS platform has been used to demonstrate simultaneous transmission of the radio and optical communications waveforms through to the physical layer (telescope and antenna). This paper details the hardware and software used in the platform and various measures of its performance. A laboratory optical receiver platform has also been assembled in order to demonstrate hybrid free space links in combination with the transmitter.

  17. Practical free-space quantum cryptography

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.J.; Buttler, W.T.; Kwiat, P.G.; Lamoreaux, S.K.; Luther, G.G.; Morgan, G.L.; Nordholt, J.E.; Peterson, C.G.; Simmons, C.M.

    1998-12-01

    An experimental free-space quantum key distribution (QKD) system has been tested over an outdoor optical path of {approx} 1 km under nighttime conditions at Los Alamos National Laboratory. This system employs the Bennett 92 protocol; here the authors give a brief overview of this protocol, and describe the experimental implementation of it. An analysis of the system efficiency is presented, as well as a description of the error detection protocol, which employs a two-dimensional parity check scheme. Finally, the susceptibility of this system to eavesdropping by various techniques is determined, and the effectiveness of privacy amplification procedures is discussed. The conclusions are that free-space QKD is both effective and secure; possible applications include the rekeying of satellites in low earth orbit.

  18. Fiber-optic communication systems

    CERN Document Server

    Agrawal, Govind P

    2010-01-01

    This book provides a comprehensive account of fiber-optic communication systems. The 3rd edition of this book is used worldwide as a textbook in many universities. This 4th edition incorporates recent advances that have occurred, in particular two new chapters. One deals with the advanced modulation formats (such as DPSK, QPSK, and QAM) that are increasingly being used for improving spectral efficiency of WDM lightwave systems. The second chapter focuses on new techniques such as all-optical regeneration that are under development and likely to be used in future communication systems. All othe

  19. Underwater optical wireless communication network

    Science.gov (United States)

    Arnon, Shlomi

    2010-01-01

    The growing need for underwater observation and subsea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, biogeochemical, evolutionary, and ecological changes in the sea, ocean, and lake environments, and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. Models are presented for three kinds of optical wireless communication links: (a) a line-of-sight link, (b) a modulating retroreflector link, and (c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered light it was possible to mitigate this decrease in some cases. It is concluded from the analysis that a high-data-rate underwater optical wireless network is a feasible solution for emerging applications such as UUV-to-UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  20. Beam divergence changing mechanism for short-range inter-unmanned aerial vehicle optical communications.

    Science.gov (United States)

    Heng, Kiang Huat; Zhong, Wen-De; Cheng, Tee Hiang; Liu, Ning; He, Yingjie

    2009-03-10

    The problems associated with using a single fixed beam divergence for short-range inter-unmanned aerial vehicle free-space optical communications are discussed. To overcome the problems, a beam divergence changing mechanism is proposed. Four different methods are then proposed to implement the beam divergence changing mechanism. The performance of these methods is evaluated in terms of transmission distance under adverse weather conditions. The results show that the performance is greatly improved when the beam divergence changing mechanism is used.

  1. Fibre Optic Communication Key Devices

    CERN Document Server

    Grote, Norbert

    2012-01-01

    The book gives an in-depth description of the key devices of current and next generation fibre optic communication networks. In particular, the book covers devices such as semiconductor lasers, optical amplifiers, modulators, wavelength filters, and detectors but the relevant properties of optical fibres as well. The presentations include the physical principles underlying the various devices, the technologies used for the realization of the different devices, typical performance characteristics and limitations, and development trends towards more advanced components are also illustrated. Thus the scope of the book spans relevant principles, state-of-the-art implementations, the status of current research and expected future components.

  2. Chaotic systems in optical communications

    Science.gov (United States)

    Siuzdak, J.

    2016-09-01

    Communications application of chaotic oscillations of lasers with optoelectronic feedback was discussed. The possibility of eavesdropping of the transmission was analyzed. It was proved that if the rogue party precisely knows parameters of the chaotic system it may recreate the entire signals solely by observation of the optical signal power causing security breach.

  3. Teleporting independent qubits through a 97 km free-space channel

    CERN Document Server

    Yin, Juan; Ren, Ji-Gang; Cao, Yuan; Yong, Hai-Lin; Wu, Yu-Ping; Liu, Chang; Liao, Sheng-Kai; Jiang, Yan; Cai, Xin-Dong; Xu, Ping; Pan, Ge-Sheng; Wang, Jian-Yu; Chen, Yu-Ao; Peng, Cheng-Zhi; Pan, Jian-Wei

    2012-01-01

    With the help of quantum entanglement, quantum communication can be achieved between arbitrarily distant places without passing through intermediate locations by quantum teleportation. In the laboratory, quantum teleportation has been demonstrated over short distance by photonic and atomic qubits. Using fiber links, quantum teleportation has been achieved over kilometer distances. Long distance quantum teleportation is of particular interest and has been one of the holy grails of practical quantum communication. Most recently, quantum teleportation over 16 km free-space link was demonstrated. However, a major restriction in this experiment is that the unknown quantum state cannot directly come from outside. Here, based on an ultra-bright multi-photon entanglement source, we demonstrate quantum teleportation, closely following the original scheme, for any unknown state created outside, between two optical free-space links separated by 97 km. Over a 35-53 dB high-loss quantum channel, an average fidelity of 80....

  4. Optical wireless communications: Theory and applications

    Science.gov (United States)

    Aminikashani, Mohammadreza

    This dissertation focuses on optical communications having recently attracted sig- nificant attentions as a promising complementary technique for radio frequency (RF) in both short- and long-range communications. These systems offer signifi- cant technical and operational advantages such as higher capacity, virtually unlim- ited reuse, unregulated spectrum and robustness to electromagnetic interference. Optical wireless communication (OWC) can be used both indoors and outdoors. Part of the dissertation contains novel results on terrestrial free-space optical (FSO) communications. FSO communication is a line-of sight technique that uses lasers for high rate wireless communication over distances up to several kilometers. In comparison to RF counterparts, a FSO link has a very high optical bandwidth available, allowing aggregate data rates on the order of Tera bits per second (1 Tera bits per second is 1000 Giga bites per second). However, FSO suffers limitations. The major limitation of the terrestrial FSO communication systems is the atmo- spheric turbulence, which produces fluctuations in the irradiance of the transmitted optical beam, as a result of random variations in the refractive index through the link. The existence of atmospheric-induced turbulence degrades the performance of FSO links particularly with a transmission distance longer than 1 kilometer. The identification of a tractable probability density function (pdf) to describe at- mospheric turbulence under all irradiance fluctuation regimes is crucial in order to study the reliability of a terrestrial FSO system. This dissertation addresses this daunting problem and proposes a novel statistical model that accurately de- scribes turbulence-induced fading under all irradiance conditions and unifies most of the proposed statistical models derived until now in the literature. The proposed model is important for the research community working on FSO communications because it allows them to fully capitalize

  5. Encoding information using Laguerre Gaussian modes over free space turbulence media.

    Science.gov (United States)

    Trichili, Abderrahmen; Salem, Amine Ben; Dudley, Angela; Zghal, Mourad; Forbes, Andrew

    2016-07-01

    We experimentally demonstrate an efficient information transmission technique using Laguerre Gaussian (LG) modes. This technique is based on multiplexing and demultiplexing multiple LG modes with different azimuthal and radial components. At the reception, the initially sent modes encoding the information are extracted with high fidelity using a complete decomposition allowing to identify a particular mode from a set of modes within a unique iteration. Importantly, we investigate the effects of the atmospheric turbulence on the proposed communication system. We believe that the proposed technique is promising for high-bit-rate spatial division multiplexing in optical fiber and free space communication systems.

  6. N-slit Interferometer for Secure Free-Space Optical Communications: 527 m Intra Interferometric Path Length

    Science.gov (United States)

    2011-01-01

    7] Feynman R P, Leighton R B and Sands M 1965 The Feynman Lectures on Physics vol 3 (Reading, MA: Addison Wesley) [8] Dirac P A M 1978 The Principles...by Newton [5] and N-slit diffraction was discussed by Michelson [6]. In a more contemporaneous setting, Feynman [7] applied Dirac’s quantum notation [8...the integrity of the interferometric characters is protected by the fundamental physics of interference [2, 7], which Figure 8. Interferogram registered

  7. Design challenges and guidelines for free-space optical communication links using orbital-angular-momentum multiplexing of multiple beams

    Science.gov (United States)

    Willner, Alan E.; Xie, Guodong; Li, Long; Ren, Yongxiong; Yan, Yan; Ahmed, Nisar; Zhao, Zhe; Wang, Zhe; Liu, Cong; Willner, Asher J.; Ashrafi, Nima; Ashrafi, Solyman; Tur, Moshe; Molisch, Andreas F.

    2016-07-01

    In this paper, recent studies on the potential challenges for an orbital angular momentum (OAM) multiplexing system were reviewed. The design guideline for a practical OAM multiplexing system were investigated in term of (i) the power loss due to the beam divergence and limited-size receiver, and (ii) the channel crosstalk due to the misalignment between the transmitter and receiver.

  8. Performance of the optical communication adaptive optics testbed

    Science.gov (United States)

    Troy, Mitchell; Roberts, Jennifer; Guiwits, Steve; Azevedo, Steve; Bikkannavar, Siddarayappa; Brack, Gary; Garkanian, Vachik; Palmer, Dean; Platt, Benjamin; Truong, Tuan; Wilson, Keith; Wallace, Kent

    2005-01-01

    We describe the current performance of an adaptive optics testbed for optical communication. This adaptive optics system allows for simulation of night and day-time observing on a 1 meter telescope with a 97 actuator deformable mirror.

  9. Phase-Modulated Optical Communication Systems

    CERN Document Server

    Ho, Keang-Po

    2005-01-01

    Fiber-optic communication systems have revolutionized our telecommunication infrastructures – currently, almost all telephone land-line, cellular, and internet communications must travel via some form of optical fibers. In these transmission systems, neither the phase nor frequency of the optical signal carries information – only the intensity of the signal is used. To transmit more information in a single optical carrier, the phase of the optical carrier must be explored. As a result, there is renewed interest in phase-modulated optical communications, mainly in direct-detection DPSK signals for long-haul optical communication systems. When optical amplifiers are used to maintain certain signal level among the fiber link, the system is limited by amplifier noises and fiber nonlinearities. Phase-Modulated Optical Communication Systems surveys this newly popular area, covering the following topics: The transmitter and receiver for phase-modulated coherent lightwave systems Method for performance analysis o...

  10. LLCD operations using the Optical Communications Telescope Laboratory (OCTL)

    Science.gov (United States)

    Biswas, Abhijit; Kovalik, Joseph M.; Wright, Malcolm W.; Roberts, William T.; Cheng, Michael K.; Quirk, Kevin J.; Srinivasan, Meera; Shaw, Matthew D.; Birnbaum, Kevin M.

    2014-03-01

    The Optical Communications Telescope Laboratory (OCTL) located on Table Mountain near Wrightwood, CA served as an alternate ground terminal to the Lunar Laser Communications Demonstration (LLCD), the first free-space laser communication demonstration from lunar distances. The Lunar Lasercom OCTL Terminal (LLOT) Project utilized the existing 1m diameter OCTL telescope by retrofitting: (i) a multi-beam 1568 nm laser beacon transmitter; (ii) a tungsten silicide (WSi) superconducting nanowire single photon detector (SNSPD) receiver for 1550 nm downlink; (iii) a telescope control system with the functionality required for laser communication operations; and (iv) a secure network connection to the Lunar Lasercom Operations Center (LLOC) located at the Lincoln Laboratory, Massachusetts Institute of Technology (LL-MIT). The laser beacon transmitted from Table Mountain was acquired by the Lunar Lasercom Space Terminal (LLST) on-board the Lunar Atmospheric Dust Environment Explorer (LADEE) spacecraft and a 1550 nm downlink at 39 and 78 Mb/s was returned to LLOT. Link operations were coordinated by LLOC. During October and November of 2013, twenty successful links were accomplished under diverse conditions. In this paper, a brief system level description of LLOT along with the concept of operations and selected results are presented.

  11. MEMS/MOEMS application to optical communication

    Science.gov (United States)

    Fujita, Hiroyuki

    2001-09-01

    The paper describes brief summary of current MEMS technology and its application to optics. The optical application is one of the most important applications of MEMS because of two reasons; one is that the micromachine technology can provide high performances and new functionalities for optical systems and the other is that those optical microsystems can satisfy market demands for optical communication networks, displays, data storage and sensors. Opportunities for MEMS-based devices in optical communication networks are discussed. Some specific examples of MEMS optical switches are described.

  12. Free space millimeter wave-coupled electro-optic high speed nonlinear polymer phase modulator with in-plane slotted patch antennas.

    Science.gov (United States)

    Park, D H; Pagán, V R; Murphy, T E; Luo, J; Jen, A K-Y; Herman, W N

    2015-04-06

    We report in-plane slotted patch antenna-coupled electro-optic phase modulators with a carrier-to-sideband ratio (CSR) of 22 dB under an RF power density of 120 W/m(2) and a figure of merit of 2.0 W(-1/2) at the millimeter wave frequencies of 36-37 GHz based on guest-host type of second-order nonlinear polymer SEO125. CSR was improved more than 20 dB by using a SiO(2) protection layer. We demonstrate detection of 3 GHz modulation of the RF carrier. We also derive closed-form expressions for the modulated phase of optical wave and carrier-to-sideband ratio. Design, simulation, fabrication, and experimental results are discussed.

  13. Optical Refractive Index Sensing Based on High-Q Bound States in the Continuum in Free-Space Coupled Photonic Crystal Slabs.

    Science.gov (United States)

    Liu, Yonghao; Zhou, Weidong; Sun, Yuze

    2017-08-11

    High sensitivity (S) and high quality factor (Q) are desirable to achieve low detection limit in label-free optical sensors. In this paper, we theoretically demonstrate that single-layer and coupled bi-layer photonic crystal slabs (PCS) possess simultaneously high S and high Q near the bound states in the continuum (BIC). We theoretically achieved S > 800 nm/RIU and Q > 10⁷ in refractive index sensing in the 1400-1600 nm telecom optical wavelength bands. We experimentally demonstrated an S of 94 nm/RIU and a Q of 1.2 × 10⁴, with a detection limit of 6 × 10(-5) refractive index unit. These sensor designs can find applications in biochemical sensing, environmental monitoring, and healthcare.

  14. Spectral and spatial characterization of perfluorinated graded-index polymer optical fibers for the distribution of optical wireless communication cells.

    Science.gov (United States)

    Hajjar, Hani Al; Montero, David S; Lallana, Pedro C; Vázquez, Carmen; Fracasso, Bruno

    2015-02-10

    In this paper, the characterization of a perfluorinated graded-index polymer optical fiber (PF-GIPOF) for a high-bitrate indoor optical wireless system is reported. PF-GIPOF is used here to interconnect different optical wireless access points that distribute optical free-space high-bitrate wireless communication cells. The PF-GIPOF channel is first studied in terms of transmission attenuation and frequency response and, in a second step, the spatial power profile distribution at the fiber output is analyzed. Both characterizations are performed under varying restricted mode launch conditions, enabling us to assess the transmission channel performance subject to potential connectorization errors within an environment where the end users may intervene by themselves on the home network infrastructure.

  15. Study on the Repetition Space-Time Codes for Multiple-Input Multiple-Output Free-Space Optical Systems%多输入多输出空间光通信中的循环空时编码研究

    Institute of Scientific and Technical Information of China (English)

    黎明; 曹阳; 李书明; 杨绍文

    2013-01-01

    多输入多输出(MIMO)技术是消除大气闪烁对空间光通信的影响和降低误码率(SER)的有效手段之一.针对2×2空间光通信系统,将Alamouti空时码与跳时超宽带技术(TH-UWB)结合,提出一种适合脉冲位置调制(PPM)的循环空时编码(RSTC)方法,推导了等增益合并(EGC)最大似然检测(MLD)和相关矩阵检测(CMD)的两种解码算法,最后分析了系统误码性能.在弱湍流和准静态衰落信道条件下仿真,结果表明,无论是在信道信息(CSI)已知还是未知情况下,编码2×2系统的误码率高于未编码的.该编码方法获得了空间和时间分集,相关矩阵检测法取得相似于信道最大比值合并(MRC)的效果,但随信道间相关性增加其误码性能下降明显.%The multiple-input-multiple-output (MIMO) technique is one of the effective means to mitigate the effects of atmospheric scintillation and reduce the symbol error rate (SER) for free-space optical communications. Considering the combinatin of Alamouti space-time code and time topping ultra-wide band ( TH-UWB) communications, a novel repetition space-time codes (RSTC) method for 2×2 free-space optical communications with pulse position modulation (PPM) is developed. In particular, two decoding methods of equal gain combining (EGC) maximum likelihood detection (MLD) and correlation matrix detection (CMD) are derived. When a quasi-static fading and weak turbulence channel model is considered, simulation is conducted. Simulation results show that whether the channel state information (CSI) is known or unknown, the coding system demonstrates more significant performance of the SER than the uncoding. In other words, transmitting diversity can be achieved while conveying the information only through the time delays of the modulated signals transmitted from the different antennas. CMD has almost the same effect of signal combing with maximal ratio combining (MRC). However, when the channel correlation increases

  16. Essentials of modern optical fiber communication

    CERN Document Server

    Noé, Reinhold

    2016-01-01

    This is a concise introduction into optical fiber communication. It covers important aspects from the physics of optical wave propagation and amplification to the essentials of modulation formats and receivers. The combination of a solid coverage of necessary fundamental theory with an in-depth discussion of recent relevant research results enables the reader to design modern optical fiber communication systems. The book serves both graduate students and professionals. It includes many worked examples with solutions for lecturers. For the second edition, Reinhold Noé made many changes and additions throughout the text so that this concise book presents the essentials of optical fiber communication in an easy readable and understandable way.

  17. Fiber Optic Communications Technology. A Status Report.

    Science.gov (United States)

    Hull, Joseph A.

    Fiber optic communications (communications over very pure glass transmission channels of diameter comparable to a human hair) is an emerging technology which promises most improvements in communications capacity at reasonable cost. The fiber transmission system offers many desirable characteristics representing improvements over conventional…

  18. Atmospheric-Fade-Tolerant Tracking and Pointing in Wireless Optical Communication

    Science.gov (United States)

    Ortiz, Gerardo; Lee, Shinhak

    2003-01-01

    An acquisition, tracking, and pointing (ATP) system, under development at the time of reporting the information for this article, is intended to enable a terminal in a free-space optical communication system to continue to aim its transmitting laser beam toward a receiver at a remote terminal when the laser beacon signal from the remote terminal temporarily fades or drops out of sight altogether. Such fades and dropouts can be caused by adverse atmospheric conditions (e.g., rain or clouds). They can also occur when intervening objects block the line of sight between terminals as a result of motions of those objects or of either or both terminals

  19. Optical communication beyond orbital angular momentum

    Science.gov (United States)

    Trichili, Abderrahmen; Rosales-Guzmán, Carmelo; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

    2016-06-01

    Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks.

  20. Optical smart card using semipassive communication.

    Science.gov (United States)

    Glaser, I; Green, Shlomo; Dimkov, Ilan

    2006-03-15

    An optical secure short-range communication system is presented. The mobile unit (optical smart card) of this system utilizes a retroreflector with an optical modulator, using light from the stationary unit; this mobile unit has very low power consumption and can be as small as a credit card. Such optical smart cards offer better security than RF-based solutions, yet do not require physical contact. Results from a feasibility study model are included.

  1. Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

    Science.gov (United States)

    Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

    2015-12-28

    An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network.

  2. Deep Space Optical Communication (DSOC) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop key technologies that enable operational deep space optical communications.Spacecraft disturbance isolation platform for sub-microradian pointing with...

  3. V-shape liquid crystal-based retromodulator air to ground optical communications

    CERN Document Server

    Geday, Morten A; Carrasco-Casado, Alberto; Bennis, Noureddine; Quintana, Xabier; Hernandez, Francisco Lopez; Sanchez, Jose Manuel Oton

    2015-01-01

    This paper describes the use of a 2D liquid crystal retro-modulator as a free space, wireless, optical link. The retro-modulator is made up of a retro-reflecting cornercube onto which 2 cascaded V-shape smectics liquid crystal modulators are mounted. The communication link differs with respect to more conventional optical links in not using amplitude (nor frequency) modulation, but instead state-of-polarisation (SOP) modulation known as Polarisation Shift Keying (PolSK). PolSK has the advantage over amplitude modulation, that it is less sensitive to changes in the visibility of the atmosphere, and increases inherently the bandwidth of the link. The implementation of PolSK both in liquid crystal based and in retro-modulated communication are novelties.

  4. Free-space quantum key distribution with entangled photons

    CERN Document Server

    Marcikic, I; Kurtsiefer, C; Marcikic, Ivan; Lamas-Linares, Antia; Kurtsiefer, Christian

    2006-01-01

    We report on a complete experimental implementation of a quantum key distribution protocol through a free space link using polarization-entangled photon pairs from a compact parametric down-conversion source. Over 10 hours of uninterrupted communication between sites 1.5 km apart, we observe average key generation rates of 630 per second after error correction and privacy amplification. Our scheme requires no specific hardware channel for synchronization apart from a classical wireless link, and no explicit random number generator.

  5. Characterization of a High-SpeedHigh-Power Semiconductor Master-Oscillator Power-Amplifier (MOPA) Laser as a Free-Space Transmitter

    Science.gov (United States)

    Wright, M. W.

    2000-04-01

    Semiconductor lasers offer promise as high-speed transmitters for free-space optical communication systems. This article examines the performance of a semiconductor laser system in a master-oscillator power-amplifier (MOPA) geometry developed through a Small Business Innovation Research (SBIR) contract with SDL, Inc. The compact thermo-electric cooler (TEC) packaged device is capable of 1-W output optical power at greater than 2-Gb/s data rates and a wavelength of 960 nm. In particular, we have investigated the effects of amplified spontaneous emission on the modulation extinction ratio and bit-error rate (BER) performance. BERs of up to 10^(-9) were possible at 1.4 Gb/s; however, the modulation extinction ratio was limited to 6 dB. Other key parameters for a free-space optical transmitter, such as the electrical-optical efficiency (24 percent) and beam quality, also were measured.

  6. All-optical signal processing technique for secure optical communication

    Science.gov (United States)

    Qian, Feng-chen; Su, Bing; Ye, Ya-lin; Zhang, Qian; Lin, Shao-feng; Duan, Tao; Duan, Jie

    2015-10-01

    Secure optical communication technologies are important means to solve the physical layer security for optical network. We present a scheme of secure optical communication system by all-optical signal processing technique. The scheme consists of three parts, as all-optical signal processing unit, optical key sequence generator, and synchronous control unit. In the paper, all-optical signal processing method is key technology using all-optical exclusive disjunction (XOR) gate based on optical cross-gain modulation effect, has advantages of wide dynamic range of input optical signal, simple structure and so on. All-optical XOR gate composed of two semiconductor optical amplifiers (SOA) is a symmetrical structure. By controlling injection current, input signal power, delay and filter bandwidth, the extinction ratio of XOR can be greater than 8dB. Finally, some performance parameters are calculated and the results are analyzed. The simulation and experimental results show that the proposed method can be achieved over 10Gbps optical signal encryption and decryption, which is simple, easy to implement, and error-free diffusion.

  7. A Review on Inter-satellite Link in Inter-satellite Optical Wireless Communication

    Science.gov (United States)

    Arora, Heena; Goyal, Rakesh

    2017-06-01

    In this paper, inter-satellite optical wireless communication (IsOWC) system is proposed, one of the imperative utilizations of free space optics/wireless space optics (FSO)/WSO innovation. IsOWC frameworks give a high bandwidth, small size, small weight, low power and minimal effort different option for present microwave satellite frameworks. Optical communications systems have evolved from lengthy fibers to powerful wireless system. This has hence resulted in the use of optical wireless communication system in space communications. As the quantity of satellites circling the Earth expands year by year, a system between the satellites gives a strategy to them to correspond with one another. This is vital for satellites to send data to each other furthermore to hand off the data starting with one satellite then onto the next satellite and after that to the ground stations. By utilizing laser satellite correspondence, the satellites can be joined with information rates up to a few Gbps. The system performance including bit rates, input power, wavelength and distance on an inter-satellite link was analyzed. Various issues such as bit rates, input power, wavelength and distance were presented in IsOWC.

  8. The handbook of optical communication networks

    CERN Document Server

    Ilyas, Mohammad

    2003-01-01

    The Handbook of Optical Communication Networks presents comprehensive, up-to-date technical information on integrated, state-of-the-art optical networks. Beginning with an in-depth intoduction to the field, top international authorities explore every major aspect of optical networks, from basic concepts to research grade material. Their discussions cover all of the essential topics, including protocols, resource management, routing and wavelength assignment in WDM networks, connection management, survivability, enabling technologies, and future trends.

  9. AlGaAs phased array laser for optical communications

    Science.gov (United States)

    Carlson, N. W.

    1989-01-01

    Phased locked arrays of multiple AlGaAs diode laser emitters were investigated both in edge emitting and surface emitting configurations. CSP edge emitter structures, coupled by either evanescent waves or Y-guides, could not achieve the required powers (greater than or similar to 500 mW) while maintaining a diffraction limited, single lobed output beam. Indeed, although the diffraction limit was achieved in this type of device, it was at low powers and in the double lobed radiation pattern characteristic of out-of-phase coupling. Grating surface emitting (GSE) arrays were, therefore, investigated with more promising results. The incorporation of second order gratings in distribute Bragg reflector (DBR) structures allows surface emission, and can be configured to allow injection locking and lateral coupling to populate 2-D arrays that should be able to reach power levels commensurate with the needs of high performance, free space optical communications levels. Also, a new amplitude modulation scheme was developed for GSE array operation.

  10. Quantum Limits of Space-to-Ground Optical Communications

    Science.gov (United States)

    Hemmati, H.; Dolinar, S.

    2012-01-01

    For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission

  11. Quantum Limits of Space-to-Ground Optical Communications

    Science.gov (United States)

    Hemmati, H.; Dolinar, S.

    2012-01-01

    For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission

  12. High Spectral Density Optical Communication Technologies

    CERN Document Server

    Nakazawa, Masataka; Miyazaki, Tetsuya

    2010-01-01

    The latest hot topics of high-spectral density optical communication systems using digital coherent optical fibre communication technologies are covered by this book. History and meaning of a "renaissance" of the technology, requirements to the Peta-bit/s class "new generation network" are also covered in the first part of this book. The main topics treated are electronic and optical devices, digital signal processing including forward error correction, modulation formats as well as transmission and application systems. The book serves as a reference to researchers and engineers.

  13. Fiber optic communications fundamentals and applications

    CERN Document Server

    Kumar, Shiva

    2014-01-01

    Fiber-optic communication systems have advanced dramatically over the last four decades, since the era of copper cables, resulting in low-cost and high-bandwidth transmission. Fiber optics is now the backbone of the internet and long-distance telecommunication. Without it we would not enjoy the benefits of high-speed internet, or low-rate international telephone calls. This book introduces the basic concepts of fiber-optic communication in a pedagogical way. The important mathematical results are derived by first principles rather than citing research articles. In addition, physical interpre

  14. Initial Characterization of Optical Communications with Disruption-Tolerant Network Protocols

    Science.gov (United States)

    Schoolcraft, Joshua; Wilson, Keith

    2011-01-01

    Disruption-tolerant networks (DTNs) are groups of network assets connected with a suite of communication protocol technologies designed to mitigate the effects of link delay and disruption. Application of DTN protocols to diverse groups of network resources in multiple sub-networks results in an overlay network-of-networks with autonomous data routing capability. In space environments where delay or disruption is expected, performance of this type of architecture (such as an interplanetary internet) can increase with the inclusion of new communications mediums and techniques. Space-based optical communication links are therefore an excellent building block of space DTN architectures. When compared to traditional radio frequency (RF) communications, optical systems can provide extremely power-efficient and high bandwidth links bridging sub-networks. Because optical links are more susceptible to link disruption and experience the same light-speed delays as RF, optical-enabled DTN architectures can lessen potential drawbacks and maintain the benefits of autonomous optical communications over deep space distances. These environment-driven expectations - link delay and interruption, along with asymmetric data rates - are the purpose of the proof-of-concept experiment outlined herein. In recognizing the potential of these two technologies, we report an initial experiment and characterization of the performance of a DTN-enabled space optical link. The experiment design employs a point-to-point free-space optical link configured to have asymmetric bandwidth. This link connects two networked systems running a DTN protocol implementation designed and written at JPL for use on spacecraft, and further configured for higher bandwidth performance. Comparing baseline data transmission metrics with and without periodic optical link interruptions, the experiment confirmed the DTN protocols' ability to handle real-world unexpected link outages while maintaining capability of

  15. 3D micro-lenses for free space intra-chip coupling in photonic-integrated circuits (Conference Presentation)

    Science.gov (United States)

    Thomas, Robert; Williams, Gwilym I.; Ladak, Sam; Smowton, Peter M.

    2017-02-01

    The integration of multiple optical elements on a common substrate to create photonic integrated circuits (PIC) has been successfully applied in: fibre-optic communications, photonic computing and optical sensing. The push towards III-Vs on silicon promises a new generation of integrated devices that combine the advantages of both integrated electronics and optics in a single substrate. III-V edge emitting laser diodes offer high efficiency and low threshold currents making them ideal candidates for the optically active elements of the next generation of PICs. Nevertheless, the highly divergent and asymmetric beam shapes intrinsic to these devices limits the efficiency with which optical elements can be free space coupled intra-chip; a capability particularly desirable for optical sensing applications e.g. [1]. Furthermore, the monolithic nature of the integrated approach prohibits the use of macroscopic lenses to improve coupling. However, with the advent of 3D direct laser writing, three dimensional lenses can now be manufactured on a microscopic-scale [2], making the use of micro-lens technology for enhanced free space coupling of integrated optical elements feasible. Here we demonstrate the first use of 3D micro-lenses to improve the coupling efficiency of monolithically integrated lasers. Fabricated from IP-dip photoresist using a Nanoscribe GmbH 3D lithography tool, the lenses are embedded directly onto a structured GaInP/AlGaInP substrate containing arrays of ridge lasers free space coupled to one another via a 200 μm air gap. We compare the coupling efficiency of these lasers with and without micro-lenses through photo-voltage and beam profile measurements and discuss optimisation of lens design.

  16. Design of a holographic tracking module for long-range retroreflector free-space systems.

    Science.gov (United States)

    Quintana, C; Erry, G; Gomez, A; Thueux, Y; Faulkner, G E; O'Brien, D C

    2016-09-01

    Weight reduction and low power consumption are key requirements in the next generation of unmanned aerial vehicles (UAVs). To communicate with an operator, a secured link between the UAV and a ground-based station is desirable. To realize these links, retroreflecting free-space optics is potentially attractive as it offers light weight and low complexity at the UAV. However, the base station requires a high-performance tracking module to enable a steady illumination of the UAV retroreflector. In this paper, we present the design and implementation of a tracking system, which consists of coarse tracking and holographic fine tracking modules working cooperatively. Using this system, experimental field trials were carried out by mounting a multiple-quantum-well-based modulated retroreflector on a commercial UAV. A 2 Mbps optical link was achieved with a bit error rate of ∼2×10-4 at a link range of 300 m.

  17. Long distance free-space quantum key distribution

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt-Manderbach, T.

    2007-10-16

    The aim of the presented experiment was to investigate the feasibility of satellite-based global quantum key distribution. In this context, a free-space quantum key distribution experiment over a real distance of 144 km was performed. The transmitter and the receiver were situated in 2500 m altitude on the Canary Islands of La Palma and Tenerife, respectively. The small and compact transmitter unit generated attenuated laser pulses, that were sent to the receiver via a 15-cm optical telescope. The receiver unit for polarisation analysis and detection of the sent pulses was integrated into an existing mirror telescope designed for classical optical satellite communications. To ensure the required stability and efficiency of the optical link in the presence of atmospheric turbulence, the two telescopes were equipped with a bi-directional automatic tracking system. Still, due to stray light and high optical attenuation, secure key exchange would not be possible using attenuated pulses in connection with the standard BB84 protocol. The photon number statistics of attenuated pulses follows a Poissonian distribution. Hence, by removing a photon from all pulses containing two or more photons, an eavesdropper could measure its polarisation without disturbing the polarisation state of the remaining pulse. In this way, he can gain information about the key without introducing detectable errors. To protect against such attacks, the presented experiment employed the recently developed method of using additional 'decoy' states, i.e., the the intensity of the pulses created by the transmitter were varied in a random manner. By analysing the detection probabilities of the different pulses individually, a photon-number-splitting attack can be detected. Thanks to the decoy-state analysis, the secrecy of the resulting quantum key could be ensured despite the Poissonian nature of the emitted pulses. For a channel attenuation as high as 35 dB, a secret key rate of up to 250

  18. Experimental validation of an undersea free space laser network simulator in turbid coastal conditions

    Science.gov (United States)

    Rashkin, David; Dalgleish, Fraser; Cardei, Ionut; Ouyang, Bing; Vuorenkoski, Anni; Cardei, Mihaela

    2013-06-01

    Mobile, high throughput mid-range data communications and robust real-time data networking in the subsea environment that can accommodate high bandwidth sensors such as optical imagers have a potentially high impact as enabling technologies for a variety of future subsea operations in the areas of distributed sensing and real-time wireless feedback and control of unmanned undersea vehicles. Although much work has been done recently in the field of undersea optical free space communications and networking, to date there has yet to be an implementation of a complete multi-node undersea wireless optical data communications network. The deployment and testing of optical wireless network equipment in the undersea environment is expensive and time-consuming, and there is a clear need for a network simulation framework that will allow researchers to evaluate the performances of different networking concepts/configurations under realistic operational and environmental constraints. This paper describes a network simulation approach that uses an accurate time dependent Monte Carlo channel model to simulate the networking physical layer, which can be used in conjunction with higher network layer protocols to simulate larger scale network performance and to help determine hardware requirements for overall network system design in a variety of undersea channel conditions.

  19. Technology Development for High Efficiency Optical Communications

    Science.gov (United States)

    Farr, William H.

    2012-01-01

    Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency telecommunications system that will enable greater than 10X the data rate of a state-of-the-art deep space RF system (Ka-band) for similar transceiver mass and power burden on the spacecraft. These technologies are a low mass spacecraft disturbance isolation assembly, a flight qualified photon counting detector array, a high efficiency flight laser amplifier and a high efficiency photon counting detector array for the ground-based receiver.

  20. Maximizing the security of chaotic optical communications.

    Science.gov (United States)

    Hou, T T; Yi, L L; Yang, X L; Ke, J X; Hu, Y; Yang, Q; Zhou, P; Hu, W S

    2016-10-03

    The practical application of chaotic optical communications has been limited by two aspects: the difficulty in concealing the time delay - a critical security parameter in feedback chaotic systems, and the difficulty of significantly enlarging the key space without complicating the implementation. Here we propose an architecture to break the above limits. By introducing a frequency-dependent group delay module with frequency tuning resolution of 1 MHz into the chaotic feedback loop, we demonstrate excellent time delay concealment effect, and an additional huge key space of 1048 can be achieved at the same time. The effectiveness is proved by both numerical simulation and experiment. Besides, the proposed scheme is compatible with the existing commercial optical communication systems, thus pave the way for high-speed secure optical communications.

  1. MX optical fiber communication system

    Science.gov (United States)

    Keiser, G.

    The fiber optic (FO) network for the proposed MX mobile basing scheme is described. C3 operations would be implemented through 15,000 km of FO links between 4800 sites. Burying the cables would ensure continued C3 operations in a hostile environment, although protection would be needed from burrowing rodents. Technology development criteria, such as optical sources and photodetectors for the 1300-1600 nm long wavelength region, are noted, together with construction of a test site at an Air Force base in California.

  2. Optical Antenna System in Free Space Optical Communication System%自由空间光通信系统中的光学天线系统

    Institute of Scientific and Technical Information of China (English)

    高瞻; 张一波

    2003-01-01

    自由空间光通信是新近发展起来的一种宽带接入方式.作为一种独特的通信方式,它在许多场合可以发挥作用,已成为现有几种宽带接入方式很好的补充.光学天线系统是自由空间光通信系统的重要组成部分.简要介绍了自由空间光通信系统的用途,对透射式和反射式光学天线进行了分析和比较.

  3. Free-space quantum key distribution at night

    Energy Technology Data Exchange (ETDEWEB)

    Buttler, W.T.; Hughes, R.J.; Kwiat, P.G.; Lamoreaux, S.K.; Luther, G.G.; Morgan, G.L.; Nordholt, J.E.; Peterson, C.G.; Simmons, C.M.

    1998-09-01

    An experimental free-space quantum key distribution (QKD) system has been tested over an outdoor optical path of {approximately} 1 km under nighttime conditions at Los Alamos National Laboratory. This system employs the Bennett 92 protocol; in this paper, the authors give a brief overview of this protocol, and describe the experimental implementation of it. An analysis of the system efficiency is presented, as well as a description of the error detection protocol which employs a two-dimensional parity check scheme. Finally, the susceptibility of this system to eavesdropping by various techniques is determined, and the effectiveness of privacy amplification procedures is discussed. The conclusions are that free-space QKD is both effective and secure; possible applications include the rekeying of satellites in low earth orbit.

  4. Multilevel Modulation formats for Optical Communication

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee

    2008-01-01

    This thesis studies the use of multilevel modulation formats for optical communication systems. Multilevel modulation is an attractive method of increasing the spectral efficiency of optical communication systems. Various modulation formats employing phase modulation, amplitude modulation...... or a combination of the two have been studied. The use of polarization multiplexing (PolMux) to double the bit rate has also been investigated. The impact of transmission impairments such as chromatic dispersion, self phase modulation and cross phase modulation has been investigated. The feasibility of multilevel...... modulation for network oriented scenarios has been demonstrated....

  5. Research on diversity receive technology for wireless optical communication using PPM in weak turbulence atmosphere channel

    Science.gov (United States)

    Liu, Yang; Zhang, Guo-an

    2014-09-01

    In order to mitigate atmospheric turbulence, the free space optical (FSO) system model with spatial diversity is analyzed based on intensity detection pulse position modulation (PPM) in the weak turbulence atmosphere. The slot error rate (SER) calculating formula of the system without diversity is derived under pulse position modulation firstly. Then as a benchmark, independent of identical distribution, the average slot error rates of the three linear combining technologies, which are the maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SelC), are compared. Simulation results show that the performance of system is the best improved by MRC, followed by EGC, and is poor by SelC, but SelC is simpler and more convenient. Spatial diversity is efficient to improve the performance and has strong ability on resistance to atmospheric channel decline. The above scheme is more suitable for optical wireless communication systems.

  6. Avalanche Photodiode Arrays for Optical Communications Receivers

    Science.gov (United States)

    Srinivasan, M.; Vilnrotter, V.

    2001-01-01

    An avalanche photodiode (APD) array for ground-based optical communications receivers is investigated for the reception of optical signals through the turbulent atmosphere. Kolmogorov phase screen simulations are used to generate realistic spatial distributions of the received optical field. It is shown that use of an APD array for pulse-position modulation detection can improve performance by up to 4 dB over single APD detection in the presence of turbulence, but that photon-counting detector arrays yield even greater gains.

  7. Inter-satellite coherent optical communication locked frequency analysis and method

    Science.gov (United States)

    Guo, Haichao; She, Shang; Xiaojun, Li; Song, Dawei

    2014-10-01

    In free space optical homodyne receiver that analyze Residual carrier COSTAS loop, Inter-satellite LEO-GEO laser communication link frequency analysis, result from Doppler frequency shift 10GHz in the maximum range, LEO-GEO inter-satellite laser links between Doppler rate of change in the 20MHz/s. The optical homodyne COSTAS receiver is the application in inter-satellite optical link coherent communication system. The homodyne receiver is the three processes: Scanning frequency, Locked frequency and Locked phase, before the homodyne coherent communication. The processes are validated in lab., and the paper presents the locked frequency data and chart, LO laser frequency with triangle control scanning and receiving optical frequency is mixed less 100MHz intermediate frequency, locked frequency range between 100MHz and 1MHz basically, discriminator method determines mixing intermediate frequency less 1MHz between the signal laser and the LO laser with the low-pass filter due to frequency loop and phase loop noise. When two loops are running, the boundary frequency of laser tuning is fuzzy, so that we must be decoupling internal PID parameters. In the Locked frequency and phase COSTAS loop homodyne receiver gave the eye-diagram with Bit error rate 10E-7.

  8. Impact of nonlinearities on fiber optic communications

    CERN Document Server

    2011-01-01

    This book covers the recent progress in fiber-optic communication systems with a main focus on the impact of fiber nonlinearities on system performance. There has been significant progress in coherent communication systems in the past few years due to the advances in digital signal processing techniques. This has led to renewed interest in fiber linear and nonlinear impairments as well as techniques to mitigate them in the electrical domain. In this book, the reader will find all the important topics of fiber optic communication systems in one place, with in-depth coverage by the experts of each sub-topic. Pioneers from each of the sub-topics have been invited to contribute. Each chapter will have a section on fundamentals as well as reviews of literature and of recent developments. Readers will benefit from this approach since many of the conference proceedings and journal articles mainly focus on the authors’ research, without spending space on preliminaries.

  9. Space Optical Communications Using Laser Beam Amplification

    Science.gov (United States)

    Agrawal, Govind

    2015-01-01

    The Space Optical Communications Using Laser Beam Amplification (SOCLBA) project will provide a capability to amplify a laser beam that is received in a modulating retro-reflector (MRR) located in a satellite in low Earth orbit. It will also improve the pointing procedure between Earth and spacecraft terminals. The technology uses laser arrays to strengthen the reflected laser beam from the spacecraft. The results of first year's work (2014) show amplification factors of 60 times the power of the signal beam. MMRs are mirrors that reflect light beams back to the source. In space optical communications, a high-powered laser interrogator beam is directed from the ground to a satellite. Within the satellite, the beam is redirected back to ground using the MMR. In the MMR, the beam passes through modulators, which encode a data signal onto the returning beam. MMRs can be used in small spacecraft for optical communications. The SOCLBA project is significant to NASA and small spacecraft due to its application to CubeSats for optical data transmission to ground stations, as well as possible application to spacecraft for optical data transmission.

  10. Gigahertz Optical Data Transmitters for Laser Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Wireless optical communication systems have gone through considerable development in the past few years, as optical components have experiences important technologic...

  11. Secure optical communication using stimulated Brillouin scattering in optical fiber

    Science.gov (United States)

    Yi, Lilin; Zhang, Tao; Li, Zhengxuan; Zhou, Junhe; Dong, Yi; Hu, Weisheng

    2013-03-01

    We propose to encrypt/decrypt high-speed optical signal using stimulated Brillouin scattering (SBS) effect in optical fiber for the first time. The broadened SBS gain or loss distorts the amplitude and phase of the optical signal so as to realize all-optical encryption. The corresponding SBS loss or gain with the same bandwidth and amplitude recovers the distorted signal to implement optical decryption. The encryption/decryption keys could be the SBS gain amplitude, bandwidth, central wavelength and the spectral shape, which are configurable and can be flexibly controlled by the users. The operation principle of the SBS based encryption and decryption is explained in detail. Complete encryption and error-free decryption for a 10.86-Gb/s on-off-keying signal has been experimentally demonstrated using broadband SBS amplification and absorption. The immunity of the proposed encryption method to the eavesdropper's attack is also analyzed. The SBS based secure optical communication is compatible with the current optical communication systems.

  12. Education kits for fiber optics, optoelectronics, and optical communications

    Science.gov (United States)

    Hájek, Martin; Švrček, Miroslav

    2007-04-01

    Our company MIKROKOM, s.r.o. is engaged for many years in development of education equipment and kits for fiber optics, optoelectronics and optical communications. We would like to inform competitors of conference about results of this long-time development. Requirements on education kits and equipment in a modern and dynamic area as is optical communications and fiber optics are quite difficult. The education kits should to clearly introduce students to given issue - the most important physical principles and technical approaches, but it should to introduce also to new and modern technologies, which are quickly changing and developing. On the other hand should be these tools and kits reasonable for the schools. In our paper we would like to describe possible ways of development of this education kits and equipment and present our results of long-time work, which covers very wide range. On the one hand we developed equipment and kits for clear demonstration of physical effects using plastic optical fibers POF, next we prepare kits with a glass fibers, which are the most used fibers in practice and after as much as the kits, which covers broad range of passive and active elements of the optical networks and systems and which makes possible to create complex optical transmission connection. This kind of systems with using corresponding tools and equipment introduce the students to properties, manipulation, measurement and usage of optical fibers, traces and many active and passive components. Furthermore, with using different sorts of optical sources, photodetectors, fiber optics couplers etc., students can get acquainted with all optoelectronics transmission system, which uses different sorts of signals. Special part will be devoted also to effort mentioned before - to implement modern technologies such as e.g. Wavelength Division Multiplex (WDM) into the education kits. Our presentation will inform auditors about development of mentioned education kits and

  13. Optical wireless communications an emerging technology

    CERN Document Server

    Capsoni, Carlo; Ghassemlooy, Zabih; Boucouvalas, Anthony; Udvary, Eszter

    2016-01-01

    This book focuses on optical wireless communications (OWC), an emerging technology with huge potential for the provision of pervasive and reliable next-generation communications networks. It shows how the development of novel and efficient wireless technologies can contribute to a range of transmission links essential for the heterogeneous networks of the future to support various communications services and traffic patterns with ever-increasing demands for higher data-transfer rates. The book starts with a chapter reviewing the OWC field, which explains different sub-technologies (visible-light, ultraviolet (UV) and infrared (IR) communications) and introduces the spectrum of application areas (indoor, vehicular, terrestrial, underwater, intersatellite, deep space, etc.). This provides readers with the necessary background information to understand the specialist material in the main body of the book, which is in four parts. The first of these deals with propagation modelling and channel characterization of ...

  14. Performance analysis of dual-hop optical wireless communication systems over k-distribution turbulence channel with pointing error

    Science.gov (United States)

    Mishra, Neha; Sriram Kumar, D.; Jha, Pranav Kumar

    2017-06-01

    In this paper, we investigate the performance of the dual-hop free space optical (FSO) communication systems under the effect of strong atmospheric turbulence together with misalignment effects (pointing error). We consider a relay assisted link using decode and forward (DF) relaying protocol between source and destination with the assumption that Channel State Information is available at both transmitting and receiving terminals. The atmospheric turbulence channels are modeled by k-distribution with pointing error impairment. The exact closed form expression is derived for outage probability and bit error rate and illustrated through numerical plots. Further BER results are compared for the different modulation schemes.

  15. Optical Wireless Communications and Autonomous Beam Control Moving User Terminal

    OpenAIRE

    Tangtrongbenchasil, Charoen; HAMADA, Yoichi; KATO, Toshihiro; Nonaka, Koji

    2007-01-01

    Optical wireless communications is a research topic of extreme interest since it offers high data rate (Gbps data rate), security, and RF interference immunity. However, optical wireless communications places severe restrictions on the communications paths; they must be direct beam connections. To increase the number of users and link robustness, optical wireless communications must be able to operate even when obstacles are placed between transmitters and receivers, so optical micro-cell (OM...

  16. Radio Science from an Optical Communications Signal

    Science.gov (United States)

    Moision, Bruce; Asmar, Sami; Oudrhiri, Kamal

    2013-01-01

    NASA is currently developing the capability to deploy deep space optical communications links. This creates the opportunity to utilize the optical link to obtain range, doppler, and signal intensity estimates. These may, in turn, be used to complement or extend the capabilities of current radio science. In this paper we illustrate the achievable precision in estimating range, doppler, and received signal intensity of an non-coherent optical link (the current state-of-the-art for a deep-space link). We provide a joint estimation algorithm with performance close to the bound. We draw comparisons to estimates based on a coherent radio frequency signal, illustrating that large gains in either precision or observation time are possible with an optical link.

  17. Affordable underwater wireless optical communication using LEDs

    Science.gov (United States)

    Pilipenko, Vladimir; Arnon, Shlomi

    2013-09-01

    In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

  18. Scalable Optical-Fiber Communication Networks

    Science.gov (United States)

    Chow, Edward T.; Peterson, John C.

    1993-01-01

    Scalable arbitrary fiber extension network (SAFEnet) is conceptual fiber-optic communication network passing digital signals among variety of computers and input/output devices at rates from 200 Mb/s to more than 100 Gb/s. Intended for use with very-high-speed computers and other data-processing and communication systems in which message-passing delays must be kept short. Inherent flexibility makes it possible to match performance of network to computers by optimizing configuration of interconnections. In addition, interconnections made redundant to provide tolerance to faults.

  19. Discovery deep space optical communications (DSOC) transceiver

    Science.gov (United States)

    Roberts, W. Thomas

    2017-02-01

    NASA's 22 cm diameter Deep Space Optical Communications (DSOC) Transceiver is designed to provide a bidirectional optical link between a spacecraft in the inner solar system and an Earth-based optical ground station. This design, optimized for operation across a wide range of illumination conditions, is focused on minimizing blinding from stray light, and providing reliable, accurate attitude information to point its narrow communication beam accurately to the future location of the ground terminal. Though our transceiver will transmit in the 1550 nm waveband and receive in the 1064 nm waveband, the system design relies heavily on reflective optical elements, extending flexibility to be modified for use at different wavebands. The design makes use of common path propagation among transmit, receive and pointing verification optical channels to maintain precise alignment among its components, and to naturally correct for element misalignment resulting from launch or thermal element perturbations. This paper presents the results of trade studies showing the evolution of the design, unique operational characteristics of the design, elements that help to maintain minimal stray light contamination, and preliminary results from development and initial testing of a functional aluminum test model.

  20. Soliton coding for secured optical communication link

    CERN Document Server

    Amiri, Iraj Sadegh; Idrus, Sevia Mahdaliza

    2015-01-01

    Nonlinear behavior of light such as chaos can be observed during propagation of a laser beam inside the microring resonator (MRR) systems. This Brief highlights the design of a system of MRRs to generate a series of logic codes. An optical soliton is used to generate an entangled photon. The ultra-short soliton pulses provide the required communication signals to generate a pair of polarization entangled photons required for quantum keys. In the frequency domain, MRRs can be used to generate optical millimetre-wave solitons with a broadband frequency of 0?100 GHz. The soliton signals are multi

  1. On-chip Optical Communication Using

    Directory of Open Access Journals (Sweden)

    Graphene M.Sankar

    2015-05-01

    Full Text Available Advancement in technology is increasing day by day. Accordance to Moore‟s Law, the number of transistors per square inch on integrated circuits had doubled every year. In this way, Graphene research so far has focused on electronics and photonic applications, in spite of its impressive optical properties, graphene can be used as optical communication devices which are more efficient than any other materials. It has as unique photonic and electronic extraordinary properties. This leads to remarkable high bandwidth, zero source-drain bias, better modulation of light, and good internal quantum efficiency.

  2. Fiber optical parametric amplifiers in optical communication systems

    DEFF Research Database (Denmark)

    Marhic, Michel E.; Andrekson, Peter A.; Petropoulos, Periklis

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-...... in excess of 14,000 Tb/s x km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed.......The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time......-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512Gb/s have been transmitted over 6,000km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products...

  3. Range Dependence of the Optical Communications Channel

    Science.gov (United States)

    Moision, B.; Farr, W.

    2014-11-01

    We show the capacity of a pulse-position-modulated (PPM) direct-detected optical communications link goes as 1/R^2 at high signal-to-noise ratio (SNR) and 1/R^4 at low SNR, where R is the range, and illustrate some consequences of this change in slope. First, we show the capacity is unaffected when the receive diameter is increased and the effective isotropic radiated power (EIRP) decreased in equal proportions, only up to a critical diameter, and that when the receive diameter is larger than this threshold, the receive diameter-EIRP trade-off is unequal (2:1, in dB). Second, we show that this transition in slope implies a crossover in optical and RF capacities as a function of the range, demonstrating the transition for sample deep-space communications links.

  4. Quantum stream cipher based on optical communications

    OpenAIRE

    Hirota, Osamu; Kato, Kentaro; Sohma, Masaki; Usuda, Tsuyoshi S.; HARASAWA, Katsuyoshi

    2004-01-01

    In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse:$ = 1000 \\sim 10000$. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no class...

  5. Fast Asynchronous Data Communication Via Fiber Optics

    Science.gov (United States)

    Bergman, Larry A.; Tell, Robert G.

    1989-01-01

    Transmitter and receiver devised for asynchronous digital communication via optical fiber at rates above 100 Mb/s. Transmitter converts parallel data to serial for high-speed transmission; receiver recovers clock signal and converts data back to parallel. No phase-lock loops used. New receiver design avoids over-sampling altogether. Local sampling oscillator operating nominally at clock frequency generates N clock signals of equally spaced phase, used to clock incoming data into N separate shift registers.

  6. Cost effective optical coupling for polymer optical fiber communication

    Science.gov (United States)

    Chandrappan, Jayakrishnan; Zhang, Jing; Mohan, Ramkumar V.; Gomez, Philbert Oliver; Aung, Than Aye; Xiao, Yongfei; Ramana, Pamidighantam V.; Lau, John Hon Shing; Kwong, Dim Lee

    2008-02-01

    Polymer Optical Fiber (POF) optical modules are gaining momentum due to their applications in short distance communications. POFs offer more flexibility for plug and play applications and provide cost advantages. They also offer significant weight advantage in automotive and avionic networks. One of the most interesting field of application is home networking. Low cost optical components are required, since cost is a major concern in local and home networks. In this publication, a fast and easy to install, low cost solution for efficient light coupling in and out of Step Index- POF is explored. The efficient coupling of light from a large core POF to a small area detector is the major challenge faced. We simulated direct coupling, lens coupling and bend losses for step index POF using ZEMAX R optical simulation software. Simulations show that a lensed fiber tip particularly at the receiver side improves the coupling efficiency. The design is optimized for 85% coupling efficiency and explored the low cost fabrication method to implement it in the system level. The two methods followed for lens fabrication is described here in detail. The fabricated fiber lenses are characterized using a beam analyzer. The fabrication process was reiterated to optimize the lens performance. It is observed that, the fabricated lenses converge the POF output spot size by one fourth, there by enabling a higher coupling efficiency. This low cost method proves to be highly efficient and effective optical coupling scheme in POF communications.

  7. Quantum Communication Experiments Over Optical Fiber

    Science.gov (United States)

    Takesue, Hiroki

    Quantum key distribution (QKD) is expected to be the first application of quantum information to be realized as a practical system. In the last decade, research on QKD made significant progress both in concept and technology. In this chapter, we review the progress of technologies designed to realize high-speed and long-distance quantum communication over optical fiber, focusing on the results obtained by NTT. The first section describes a roadmap towards scalable quantum communications, which is composed of three phases. The second section reviews our effort to realize phase 1 quantum communication systems, namely point-to-point QKD systems based on the differential phase shift QKD (DPS-QKD) protocol. The third section describes entanglement generation and application in the telecom band, which are the key technologies for realizing phase 2 and 3 systems. The final section provides a summary and describes the future outlook.

  8. Free-space and underwater GHz data transmission using AlGaInN laser diode technology

    Science.gov (United States)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.

    2016-05-01

    Laser diodes fabricated from the AlGaInN material system is an emerging technology for defence and security applications; in particular for free space laser communication. Conventional underwater communication is done acoustically with very slow data rates, short reach, and vulnurable for interception. AlGaInN blue-green laser diode technology allows the possibility of both airbourne links and underwater telecom that operate at very fast data rates (GHz), long reach (100's of metres underwater) and can also be quantum encrypted. The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Galliumnitride (GaN) blue laser diode is reported in free-space and underwater.

  9. BER performance of MSK in ground-to-satellite uplink optical communication under the influence of atmospheric turbulence and detector noise.

    Science.gov (United States)

    Ding, Jiachen; Li, Mi; Tang, Minghui; Li, Yan; Song, Yuejiang

    2013-09-15

    Minimum shift keying (MSK) has been widely used in fiber optical communication and free-space optical communication. In order to introduce MSK into satellite laser communication, the bit-error rate (BER) performance of the MSK scheme is investigated in uplink communications under the influence of atmospheric turbulence consisting of weak fluctuation and beam wander. Numerical results indicate that the BER performance of MSK is much better than the performance of on-off keying (OOK). With the laser power being 4 W, the improvement is 5 dB in coherent demodulation and 15 dB in delay coherent demodulation. Furthermore, compared with OOK, optimal values of the divergence angle, receiver diameter, and transmitter beam radius are easier and more practical to achieve in the MSK scheme. The work can benefit ground-to-satellite laser uplink communication system design.

  10. Development level of space optical transceiver and the design of network communication on optical transceiver

    Science.gov (United States)

    Zhang, Tao; Wang, Bo; Jiang, Huilin

    2015-08-01

    Compared with traditional communication technology, laser communication technology has great advantages and broad application prospects. And the optical transceiver is the main of the space laser communication system. This paper discusses achievements on the optical transceiver among developed countries in recent years, discussing the trend of optical transceiver. Under the background of laser communication for the future platform among more types network, optical transceiver on one-many communication of optical antenna has been reported, assessing the advantages and disadvantages of all kinds of design scheme from several aspects. Finally, some new thought and analysis of optical antenna of network communication technology have been put forward.

  11. Hemispherical Optical Dome for Underwater Communication

    Science.gov (United States)

    Shiri, Ron S.; Lunde, Emily L.; Coronado, Patrick L.; Quijada, Manuel A.

    2017-01-01

    For many years, acoustic systems have been used as the primary method for underwater communication; however, the data transfer rate of such systems is low because sound propagates slowly through the water. A higher throughput can be achieved using visible light to transmit data underwater. The first issue with using this approach is that there is generally a large loss of the light signal due to scattering and absorption in water even though there is an optimal wavelength for transmission in the blue or green wavelengths of the visible spectrum. The second issue is that a simple system consisting only of a highly directional source transmitter and small optical detector receiver has a very narrow field of view. The goal of this project is to improve an optical, underwater communication system by increasing the effective field of view of the receiving optics. To this end, we make two changes to the simple system: (1) An optical dome was added near the receiver. An array of lenses is placed radially on the surface of the dome, reminiscent of the compound eye of an insect. The lenses make the source and detector planes conjugate, and each lens adds a new region of the source plane to the instrument's total field of view. (2) The receiver was expanded to include multiple photodiodes. With these two changes, the receiver has much more tolerance to misalignments (in position and angle) of the transmitter.Two versions of the optical dome (with 6 and 8 diameters) were designed using the CREO CAD software and modeled using the CODE V optical design software. A series of these transparent hemispherical domes, with both design diameters, were manufactured using a 5-axis mill. The prototype was then retrofitted with lenses and compared with the computer-generated model to demonstrate the effectiveness of this solution. This work shows the dome design improves the optical field of view of the underwater communication system considerably. Furthermore, with the experimental test

  12. Grating-based real-time smart optics for biomedicine and communications

    Science.gov (United States)

    Yaqoob, Zahid

    Novel photonic systems are proposed and experimentally validated using active as well as passive wavelength dispersive optical devices in unique fashions to solve important system level application problems in biomedicine and laser communications. Specifically for the first time are proposed, high dynamic range variable optical attenuators (VOAs) using bulk acousto-optics (AO). These AO-based architectures have excellent characteristics such as high laser damage threshold (e.g., 1 Watt CW laser power operations), large (e.g., >40 dB) dynamic range, and microsecond domain attenuation setting speed. The demonstrated architectures show potentials for compact, low static insertion loss, and low power VOA designs for wavelength division multiplexed (WDM) fiber-optic communication networks and high speed photonic signal processing for optical and radio frequency (RF) radar and electronic warfare (EW). Acoustic diffraction of light in isotropic media has been manipulated to design and demonstrate on a proof-of-principle basis, the first bulk AO-based optical coherence tomography (OCT) system for high-resolution sub-surface tissue diagnostics. As opposed to the current OCT systems that use mechanical means to generate optical delays, both free-space as well as fiber-optic AO-based OCT systems utilize unique electronically-controlled acousto-optically switched no-moving parts optical delay lines and therefore promise microsecond speed OCT data acquisition rates. The proposed OCT systems also feature high (e.g., >100 MHz) intermediate frequency for low 1/f noise heterodyne detection. For the first time, two agile laser beam steering schemes that are members of a new beam steering technology known as Multiplexed-Optical Scanner Technology (MOST) are theoretically investigated and experimentally demonstrated. The new scanner technologies are based on wavelength and space manipulations and possess remarkable features such as a no-moving parts fast (e.g., microseconds domain or

  13. Fiber optical parametric amplifiers in optical communication systems.

    Science.gov (United States)

    Marhic, Michel E; Andrekson, Peter A; Petropoulos, Periklis; Radic, Stojan; Peucheret, Christophe; Jazayerifar, Mahmoud

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed. [Formula: see text].

  14. Strategies for Dense Optical CDMA Communication Systems

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-bao; LIN Jin-tong

    2005-01-01

    In this paper,we have formulated a strategy that the limited available code sequences in pure Direct-Sequence(DS)or Frequency-Hopping(FH)system can be reused to realize dense optical CDMA:the strategy of novel hybrid DS/FH system.In which,the case that there are n users employing the same FH pattern but different DS code patterns is considered.On the condition that the impact of channel noises is neglected,the upper bound probability of error is evaluated based on the stationary random process theory.The results show that the hybrid system is suitable for Dense Optical CDMA(DOCDMA)communication.Moreover,the problems such as the link-impairment,dispersion of group velocity,etc.in the pure(DS or FH)system can be solved effectively.

  15. Free-Space Quantum Key Distribution using Polarization Entangled Photons

    Science.gov (United States)

    Kurtsiefer, Christian

    2007-06-01

    We report on a complete experimental implementation of a quantum key distribution protocol through a free space link using polarization-entangled photon pairs from a compact parametric down-conversion source [1]. Based on a BB84-equivalent protocol, we generated without interruption over 10 hours a secret key free-space optical link distance of 1.5 km with a rate up to 950 bits per second after error correction and privacy amplification. Our system is based on two time stamp units and relies on no specific hardware channel for coincidence identification besides an IP link. For that, initial clock synchronization with an accuracy of better than 2 ns is achieved, based on a conventional NTP protocol and a tiered cross correlation of time tags on both sides. Time tags are used to servo a local clock, allowing a streamed measurement on correctly identified photon pairs. Contrary to the majority of quantum key distribution systems, this approach does not require a trusted large-bandwidth random number generator, but integrates that into the physical key generation process. We discuss our current progress of implementing a key distribution via an atmospherical link during daylight conditions, and possible attack scenarios on a physical timing information side channel to a entanglement-based key distribution system. [1] I. Marcikic, A. Lamas-Linares, C. Kurtsiefer, Appl. Phys. Lett. 89, 101122 (2006).

  16. Hybrid optical CDMA-FSO communications network under spatially correlated gamma-gamma scintillation

    DEFF Research Database (Denmark)

    Jurado-Navas, Antonio; Raddo, Thiago R.; Garrido-Balsells, José María

    2016-01-01

    In this paper, we propose a new hybrid network solution based on asynchronous optical code-division multiple-access (OCDMA) and free-space optical (FSO) technologies for last-mile access networks, where fiber deployment is impractical. The architecture of the proposed hybrid OCDMA-FSO network is ...

  17. Optical fiber communication — An overview

    Indian Academy of Sciences (India)

    M Arumugam

    2001-11-01

    This paper deals with the historical development of optical communication systems and their failures initially. Then the different generations in optical fiber communication along with their features are discussed. Some aspects of total internal reflection, different types of fibers along with their size and refractive index profile, dispersion and loss mechanisms are also mentioned. Finally the general system of optical fiber communication is briefly mentioned along with its advantages and limitations. Future soliton based optical fiber communication is also highlighted.

  18. Photorealistic ray tracing of free-space invisibility cloaks made of uniaxial dielectrics

    CERN Document Server

    Halimeh, Jad C

    2012-01-01

    The design rules of transformation optics generally lead to spatially inhomogeneous and anisotropic impedance-matched magneto-dielectric material distributions for, e.g., free-space invisibility cloaks. Recently, simplified anisotropic non-magnetic free-space cloaks made of a locally uniaxial dielectric material (calcite) have been realized experimentally. In a two-dimensional setting and for in-plane polarized light propagating in this plane, the cloaking performance can still be perfect for light rays. However, for general views in three dimensions, various imperfections are expected. In this paper, we study two different purely dielectric uniaxial cylindrical free-space cloaks. For one, the optic axis is along the radial direction, for the other one it is along the azimuthal direction. The azimuthal uniaxial cloak has not been suggested previously to the best of our knowledge. We visualize the cloaking performance of both by calculating photorealistic images rendered by ray tracing. Following and complemen...

  19. Commercialization and Standardization Progress Towards an Optical Communications Earth Relay

    Science.gov (United States)

    Edwards, Bernard L.; Israel, David J.

    2015-01-01

    NASA is planning to launch the next generation of a space based Earth relay in 2025 to join the current Space Network, consisting of Tracking and Data Relay Satellites in space and the corresponding infrastructure on Earth. While the requirements and architecture for that relay satellite are unknown at this time, NASA is investing in communications technologies that could be deployed to provide new communications services. One of those new technologies is optical communications. The Laser Communications Relay Demonstration (LCRD) project, scheduled for launch in 2018 as a hosted payload on a commercial communications satellite, is a critical pathfinder towards NASA providing optical communications services on the next generation space based relay. This paper will describe NASA efforts in the on-going commercialization of optical communications and the development of inter-operability standards. Both are seen as critical to making optical communications a reality on future NASA science and exploration missions. Commercialization is important because NASA would like to eventually be able to simply purchase an entire optical communications terminal from a commercial provider. Inter-operability standards are needed to ensure that optical communications terminals developed by one vendor are compatible with the terminals of another. International standards in optical communications would also allow the space missions of one nation to use the infrastructure of another.

  20. Reduction of ETS-VI Laser Communication Equipment Optical-Downlink Telemetry Collected During GOLD

    Science.gov (United States)

    Toyoshima, M.; Araki, K.; Arimoto, Y.; Toyoda, M.; Jeganathan, M.; Wilson, K.; Lesh, J. R.

    1997-01-01

    Free-space laser communications experiments were conducted between the laser communication equipment (LCE) on board the Japanese Engineering Test Satellite VI (ETS-VI) and the ground station located at the Table Mountain Facility (TMF) during late 1995 and early 1996. This article describes the on-line data reduction process used to decode LCE telemetry (called E2) downlinked on the optical carrier during the Ground/Orbiter Lasercomm Demonstration (GOLD) experiments. The LCE has the capability of transmitting real-time sensor and status information at 128 kbps by modulating the onboard diode laser. The optical downlink was detected on the ground, bit synchronized, and the resulting data stream stored on a data recorder. The recorded data were subsequently decoded by on-line data processing that included cross-correlation of the known telemetry data format and the downlink data stream. Signals obtained from the processing can be useful not only in evaluating the characteristics of the LCE but also in understanding uplink and downlink signal quality.

  1. Turbulence Mitigation Scheme for Optical Communications using Orbital Angular Momentum Multiplexing Based on Channel Coding and Wavefront Correction

    CERN Document Server

    Zhao, Shengmei; Zhou, Li; Gong, Longyan; Cheng, Wenwen; Sheng, Yubo; Zheng, Baoyu

    2014-01-01

    The free-space optical (FSO) communication links with orbital angular momentum (OAM) multiplexing have been demonstrated that they can largely enhance the systems' capacity without a corresponding increase in spectral bandwidth, but the performance of the system is unavoidably disturbed by atmospheric turbulence (AT). Different from the existed AT disturbance, the OAM-multiplexed systems will cause both the burst and random errors for a single OAM state carrier and the `crosstalk' interference between the different OAM states carriers. In this paper, we propose a turbulence mitigation method to improve AT tolerance of OAM-multiplexed FSO communication links. In the proposed scheme, we use channel codes to correct the burst and random errors caused by AT for a single OAM state carrier; And we use wavefront correction method to correct the `crosstalk' interference between the different OAM states carriers. The improvements of AT tolerance are discussed by comparing the performance of OAM-multiplexed FSO communi...

  2. VCSELs for optical communication at Fuji Xerox

    Science.gov (United States)

    Kondo, Takashi; Hayakawa, Junichiro; Jogan, Naoki; Murakami, Akemi; Sakurai, Jun; Gu, Xiaodong; Koyama, Fumio

    2017-02-01

    We introduce the characteristics of vertical-cavity surface-emitting lasers (VCSELs) for use in optical communications. In the field of optical interconnections and networks, 850 nm VCSELs are key optical transmitters due to their high-speed modulation and low power consumption. One promising candidate for achieving high-speed modulations exceeding 50 Gbps is the transverse-coupled-cavity (TCC) VCSEL. In this talk, we demonstrate the characteristics of 850 nm transverse-coupled-cavity VCSELs, which helped us achieve a high 3dB modulation bandwidth (30 GHz) at 0 °C and realize eye-opening at the large-signal modulation rate of 48 Gbps. The VCSEL's epilayer structure was grown by MOCVD. The active region consists of three strained InGaAs QWs surrounded by AlGaAs barriers. The n-type and p-type DBRs are composed of AlGaAs/AlGaAs, respectively. A line-shaped H+ ion was implanted at the center of the bowtie-shaped post, dividing it into two cavities. The threshold current of the TCC VCSEL with an oxide aperture of 3.6 μm is 0.33 mA. Only the left-side cavity is pumped, while the right cavity is unpumped. The effect of modulation bandwidth enhancement was observed over a wide temperature range of 120K thanks to an optical feedback in the coupled cavities. These results show the possibility of achieving high-speed VCSELs without any temperature or bias control. We also demonstrate an ultra-compact photodetector-integrated VCSEL with two laterally-coupled cavities. An output power and a photocurrent exhibit similar tendencies under a wide range of temperature changes. This device could be also used for monitoring output power without a conventional photodetector mounted separately.

  3. Analysis of optical amplifier noise in coherent optical communication systems with optical image rejection receivers

    DEFF Research Database (Denmark)

    Jørgensen, Bo Foged; Mikkelsen, Benny; Mahon, Cathal J.

    1992-01-01

    performance. Two types of optical image rejection receivers are investigated: a novel, all-optical configuration and the conventional, microwave-based configuration. The analysis shows that local oscillator-spontaneous emission beat noise (LO-SP), signal-spontaneous emission beat noise (S-SP), and spontaneous......A detailed theoretical analysis of optical amplifier noise in coherent optical communication systems with heterodyne receivers is presented. The analysis quantifies in particular how optical image rejection receiver configurations reduce the influence of optical amplifier noise on system......-spontaneous beat noise (SP-SP) can all be reduced by 3 dB, thereby doubling the dynamic range of the optical amplifier. A 2.5-dB improvement in dynamic range has been demonstrated experimentally with the all-optical image rejection configuration. The implications of the increased dynamic range thus obtained...

  4. Raman amplification in optical communication systems

    DEFF Research Database (Denmark)

    Kjær, Rasmus

    2008-01-01

    Fiber Raman amplifiers are investigated with the purpose of identifying new applications and limitations for their use in optical communication systems. Three main topics are investigated, namely: New applications of dispersion compensating Raman amplifiers, the use Raman amplification to increase...... fiberbaserede Raman-forstærkere med henblik på at identificere både deres begrænsninger og nye anvendelsesmuligheder i optiske kommunikationssystemer. En numerisk forstærkermodel er blevet udviklet for bedre at forstå forstærkerens dynamik, dens gain- og støjbegrænsninger. Modellen bruges til at forudsige...... forstærkerens statiske og dynamiske egenskaber, og det eftervises at dens resultater er i god overensstemmelse med eksperimentelle forstærkermålinger. Dispersions-kompenserende fiber er på grund af sin store udbredelse og fiberens høje Raman gain effektivitet et meget velegnet Raman gain-medium. Tre nye...

  5. Optical communications. V - Light emitting diodes /LED/

    Science.gov (United States)

    Best, S. W.

    1980-10-01

    The process of assembling diode chips is discussed, along with their application in optical communications. Metal plating is performed with an evaporation technique using primarily AuGe on the back side and Al or AuZn on the front side. The assembling of LED-chips with metal casings is illustrated. The chip is mounted on a flat bottom plate and electrical contact is established by means of an alloying or adhesion procedure. A glass fiber can be attached to the diode and then fitted with a casing, or the diode can be assembled with a metal cap and a lense, or with an open cap that is sealed with a clear synthetic resin plastic. The typical emission spectra of an LED and a semiconductor laser are compared. Limitations in the operation of an LED in a photoconductor are examined, taking into account spectral line width and radiated power criteria.

  6. Mitigating Photon Jitter in Optical PPM Communication

    Science.gov (United States)

    Moision, Bruce

    2008-01-01

    A theoretical analysis of photon-arrival jitter in an optical pulse-position-modulation (PPM) communication channel has been performed, and now constitutes the basis of a methodology for designing receivers to compensate so that errors attributable to photon-arrival jitter would be minimized or nearly minimized. Photon-arrival jitter is an uncertainty in the estimated time of arrival of a photon relative to the boundaries of a PPM time slot. Photon-arrival jitter is attributable to two main causes: (1) receiver synchronization error [error in the receiver operation of partitioning time into PPM slots] and (2) random delay between the time of arrival of a photon at a detector and the generation, by the detector circuitry, of a pulse in response to the photon. For channels with sufficiently long time slots, photon-arrival jitter is negligible. However, as durations of PPM time slots are reduced in efforts to increase throughputs of optical PPM communication channels, photon-arrival jitter becomes a significant source of error, leading to significant degradation of performance if not taken into account in design. For the purpose of the analysis, a receiver was assumed to operate in a photon- starved regime, in which photon counts follow a Poisson distribution. The analysis included derivation of exact equations for symbol likelihoods in the presence of photon-arrival jitter. These equations describe what is well known in the art as a matched filter for a channel containing Gaussian noise. These equations would yield an optimum receiver if they could be implemented in practice. Because the exact equations may be too complex to implement in practice, approximations that would yield suboptimal receivers were also derived.

  7. Quantum stream cipher based on optical communications

    CERN Document Server

    Hirota, O; Sohma, M; Usuda, T S; Harasawa, K; Hirota, Osamu; Kato, Kentaro; Sohma, Masaki; Usuda, Tsuyoshi S.; Harasawa, Katsuyoshi

    2004-01-01

    In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse:$ = 1000 \\sim 10000$. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no classical analogue. That is, one can provide secure communication, even the system has $H(K) << H(X)$. In this paper, first, we give a brief review on the general logic of Yuen's theory. Then, we show concrete security analysis of quantum stream cipher to quantum individual measurement attacks. Especially by showing the analysis of Lo-Ko known plaintext attack, the feature of Y-00 is clarified. In addition, we give a simple experimental result on the advantage distillation by scheme consisting of intensity modulation/dir...

  8. Laser-based satellite communication systems stabilized by non-mechanical electro-optic scanners

    Science.gov (United States)

    Ziemkiewicz, Michael; Davis, Scott R.; Rommel, Scott D.; Gann, Derek; Luey, Benjamin; Gamble, Joseph D.; Anderson, Mike

    2016-05-01

    Laser communications systems provide numerous advantages for establishing satellite-to-ground data links. As a carrier for information, lasers are characterized by high bandwidth and directionality, allowing for fast and secure transfer of data. These systems are also highly resistant to RF influences since they operate in the infrared portion of the electromagnetic spectrum, far from radio bands. In this paper we will discuss an entirely non-mechanical electro-optic (EO) laser beam steering technology, with no moving parts, which we have used to form robust 400 Mbps optical data connections through air. This technology will enable low cost, compact, and rugged free space optical (FSO) communication modules for small satellite applications. The EO beam-steerer at the heart of this system is used to maintain beam pointing as the satellite orbits. It is characterized by extremely low values for size, weight and power consumption (SWaP) - approximately 300 cm3, 300 g, and 5 W respectively, which represents a marked improvement compared to heavy, and power-consuming gimbal mechanisms. It is capable of steering a 500 mW, 1 mm short wave infrared (SWIR) beam over a field of view (FOV) of up to 50° x 15°, a range which can be increased by adding polarization gratings, which provide a coarse adjust stage at the EO beam scanner output. We have integrated this device into a communication system and demonstrated the capability to lock on and transmit a high quality data stream by modulation of SWIR power.

  9. Integrated Radio and Optical Communication (iROC)

    Science.gov (United States)

    Raible, Daniel; Romanofsky, Robert; Pease, Gary; Kacpura, Thomas

    2016-01-01

    This is an overview of the Integrated Radio and Optical Communication (iROC) Project for Space Communication and Navigation Industry Days. The Goal is to develop and demonstrate new, high payoff space technologies that will promote mission utilization of optical communications, thereby expanding the capabilities of NASA's exploration, science, and discovery missions. This is an overview that combines the paramount features of select deep space RF and optical communications elements into an integrated system, scalable from deep space to near earth. It will realize Ka-band RF and 1550 nanometer optical capability. The approach is to prototype and demonstrate performance of key components to increase to TRL-5, leading to integrated hybrid communications system demonstration to increase to TRL-5, leading to integrated hybrid communications system demonstration.

  10. Coherent optical communication using polarization multiple-input-multiple-output.

    Science.gov (United States)

    Han, Yan; Li, Guifang

    2005-09-19

    Polarization-division multiplexed (PDM) optical signals can potentially be demultiplexed by coherent detection and digital signal processing without using optical dynamic polarization control at the receiver. In this paper, we show that optical communications using PDM is analogous to wireless communications using multiple-input-multiple-output (MIMO) antennae and thus algorithms for channel estimation in wireless MIMO can be ready applied to optical polarization MIMO (PMIMO). Combined with frequency offset and phase estimation algorithms, simulations show that PDM quadrature phase-shift keying signals can be coherently detected by the proposed scheme using commercial semiconductor lasers while no optical phase locking and polarization control are required. This analogy further suggests the potential application of space-time coding in wireless communications to optical polarization MIMO systems and relates the problem of polarization-mode dispersion in fiber transmission to the multi-path propagation in wireless communications.

  11. Improved Climatological Characterization of Optical Turbulence for Space Optical Imaging and Communications

    Science.gov (United States)

    Alliss, R.; Felton, B.

    2010-09-01

    Optical turbulence (OT) acts to distort light in the atmosphere, degrading imagery from astronomical or other telescopes. In addition, the quality of service of a free space optical communications link may also be impacted. Some of the degradation due to turbulence can be corrected by adaptive optics. However, the severity of optical turbulence, and thus the amount of correction required, is largely dependent upon the turbulence at the location of interest. Therefore, it is vital to understand the climatology of optical turbulence at such locations. In many cases, it is impractical and expensive to setup instrumentation to characterize the climatology of OT, particularly for OCONUS locations, so simulations become a less expensive and convenient alternative. The strength of OT is characterized by the refractive index structure function Cn2, which in turn is used to calculate atmospheric seeing parameters. While attempts have been made to characterize Cn2 using empirical models, Cn2 can be calculated more directly from Numerical Weather Prediction (NWP) simulations using pressure, temperature, thermal stability, vertical wind shear, turbulent Prandtl number, and turbulence kinetic energy (TKE). In this work we use the Weather Research and Forecast (WRF) NWP model to generate Cn2 climatologies in the planetary boundary layer and free atmosphere, allowing for both point-to-point and ground-to-space seeing estimates of the Fried Coherence length (ro) and other seeing parameters. Simulations are performed using the Maui High Performance Computing Centers (MHPCC) Mana cluster. The WRF model is configured to run at 1km horizontal resolution over a domain covering several hundreds of kilometers. The vertical resolution varies from 25 meters in the boundary layer to 500 meters in the stratosphere. The model top is 20 km. We are interested in the variations in Cn2 and the Fried Coherence Length (ro). Nearly two years of simulations have been performed over various regions

  12. FREE-SPACE QUANTUM CRYPTOGRAPHY IN DAYLIGHT

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, R.J.; Buttler, W.T. [and others

    2000-01-01

    Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. The security of these transmissions is based on the inviolability of the laws of quantum mechanics and information-theoretically secure post-processing methods. An adversary can neither successfully tap the quantum transmissions, nor evade detection, owing to Heisenberg's uncertainty principle. In this paper we describe the theory of quantum cryptography, and the most recent results from our experimental free-space system with which we have demonstrated for the first time the feasibility of quantum key generation over a point-to-point outdoor atmospheric path in daylight. We achieved a transmission distance of 0.5 km, which was limited only by the length of the test range. Our results provide strong evidence that cryptographic key material could be generated on demand between a ground station and a satellite (or between two satellites), allowing a satellite to be securely re-keyed on orbit. We present a feasibility analysis of surface-to-satellite quantum key generation.

  13. Propagation of Gaussian Schell-model Array beams in free space and atmospheric turbulence

    Science.gov (United States)

    Mao, Yonghua; Mei, Zhangrong; Gu, Juguan

    2016-12-01

    Based on the extended Huygens-Fresnel principle, the evolution behavior of the spectral density and the spectral degree of coherence of the beam produced by a recently introduced novel class of Gaussian Schell-model Arrays (GSMA) source in free space and turbulence atmospheric are explored and comparatively analyzed. And the influence of the fractal constant of the atmospheric power spectrum and refractive-index structure constant on the spectral density and the spectral degree of coherence of beams are analyzed. It is shown that the optical lattice profile is stable when beams propagate in free space, but the spectral density eventually is suppressed and transformed into a Gaussian profiles when it passes at sufficiently large distances through the turbulent atmosphere. The distributions of the spectral degree of coherence in far field eventually transformed into a shrink Gaussian profile relative to free space which means that the degree of spatial coherence turns worse.

  14. Digital coherent transceiver for optical communications: from design to implementation

    OpenAIRE

    Anzuola Valencia, Esdras

    2012-01-01

    Establishing the basis of optical coherent transmission and detection which exploit digital signal processing (DSP) to optimize the performance of optical communication systems. [ANGLÈS] In this project we analyze the theoretical models of optical coherent communication systems as well as the front-end arquitectures used to implement them. Key concepts as balanced photo detection and quantum limit are explained and studied. Complex modulation schemes maximize spectral efficiency and power ...

  15. A Study of Synchronization Techniques for Optical Communication Systems

    Science.gov (United States)

    Gagliardi, R. M.

    1975-01-01

    The study of synchronization techniques and related topics in the design of high data rate, deep space, optical communication systems was reported. Data cover: (1) effects of timing errors in narrow pulsed digital optical systems, (2) accuracy of microwave timing systems operating in low powered optical systems, (3) development of improved tracking systems for the optical channel and determination of their tracking performance, (4) development of usable photodetector mathematical models for application to analysis and performance design in communication receivers, and (5) study application of multi-level block encoding to optical transmission of digital data.

  16. Optical coherent and envelope detection for photonic wireless communication links

    DEFF Research Database (Denmark)

    Prince, Kamau; Zibar, Darko; Yu, Xianbin;

    We present two novel optical detection techniques for radio over fiber (RoF) communication links. Firstly, we present recent results obtained with optical digital coherent detection of optical phase-modulated ROF signals supporting error-free transmission over 25 km standard SMF with BPSK and QPSK...

  17. Recent progress on planar lightwave circuit technology for optical communication

    Science.gov (United States)

    Takahashi, Hiroshi

    2009-11-01

    Silica waveguide planar lightwave circuit (PLC) technology is very useful for fabricating compact and high performance optical devices for optical communication. Wavelength multiplexers and optical switches for ROADM and OXC are still being developed to improve performance further. New devices for an advanced modulation format can also be fabricated with PLC technology.

  18. Experimental demonstration of multi-aperture digital coherent combining over a 3.2-km free-space link

    Science.gov (United States)

    Geisler, D. J.; Yarnall, T. M.; Schieler, C. M.; Stevens, M. L.; Robinson, B. S.; Hamilton, S. A.

    2017-02-01

    The next generation free-space optical communications infrastructure will need to support a wide variety of space-to-ground links. As a result of the limited size, weight, and power on space-borne assets, the ground terminals need to scale efficiently to large collection areas to support extremely long link distances or high data rates. Recent advances in integrated digital coherent receivers enable the coherent combining (i.e., full-field addition) of signals from several small apertures to synthesize an effective single large aperture. In this work, we experimentally demonstrate the coherent combining of signals received by four independent receive chains after propagation through a 3:2-km atmospheric channel. Measured results show the practicality of coherently combining the four received signals via digital signal processing after transmission through a turbulent atmosphere. In particular, near-lossless combining is demonstrated using the technique of maximal ratio combining.

  19. Secure Communications in High Speed Fiber Optical Networks Using Code Division Multiple Access (CDMA) Transmission

    Energy Technology Data Exchange (ETDEWEB)

    Han, I; Bond, S; Welty, R; Du, Y; Yoo, S; Reinhardt, C; Behymer, E; Sperry, V; Kobayashi, N

    2004-02-12

    , as opposed to field dynamics of liquid crystal molecules, enable phase codes at GHz rates. The semiconductor arrayed waveguide grating (AWG) is the building block of the encoder/decoder device. A monolithically integrated AWG is developed in this LDRD. Using this building block, the AWG can be integrated with phase modulators to create temporally varying phase codes; this allows superior physical level encoding technology. The breadth of this project is wide, covering a free space optic demonstration (large optic at the meter scale) of the encoding system. This was done as a proof-of-principal exercise and to investigate the time varying phase codes (''locks'' and ''keys''). Then a monolithically integrated AWG implemented at the millimeter was investigated. The mono lithically integrated AWG has the same functionality as the table top free space optic but reduced down in size to be easily embedded in fiber optic networks.

  20. Holographic tool kit for optical communication beyond orbital angular momentum

    CERN Document Server

    Trichili, Abderrahmen; Dudley, Angela; Ndagano, Bienvenu; Salem, Amine Ben; Zghal, Mourad; Forbes, Andrew

    2016-01-01

    Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realising higher bit rates for next generation optical networks.

  1. Optical communications and a comparison of optical technologies for a high data rate return link from Mars

    Science.gov (United States)

    Spence, Rodney L.

    1993-01-01

    The important principles of direct- and heterodyne-detection optical free-space communications are reviewed. Signal-to-noise-ratio (SNR) and bit-error-rate (BER) expressions are derived for both the direct-detection and heterodyne-detection optical receivers. For the heterodyne system, performance degradation resulting from received-signal and local oscillator-beam misalignment and laser phase noise is analyzed. Determination of interfering background power from local and extended background sources is discussed. The BER performance of direct- and heterodyne-detection optical links in the presence of Rayleigh-distributed random pointing and tracking errors is described. Finally, several optical systems employing Nd:YAG, GaAs, and CO2 laser sources are evaluated and compared to assess their feasibility in providing high-data-rate (10- to 1000-Mbps) Mars-to-Earth communications. It is shown that the root mean square (rms) pointing and tracking accuracy is a critical factor in defining the system transmitting laser-power requirements and telescope size and that, for a given rms error, there is an optimum telescope aperture size that minimizes the required power. The results of the analysis conducted indicate that, barring the achievement of extremely small rms pointing and tracking errors (less than 0.2 microrad), the two most promising types of optical systems are those that use an Nd:YAG laser (lambda = 1.064 microns) and high-order pulse position modulator (PPM) and direct detection, and those that use a CO2 laser (lambda = 10.6 microns) and phase shifting keying homodyne modulation and coherent detection. For example, for a PPM order of M = 64 and an rms pointing accuracy of 0.4 microrad, an Nd:YAG system can be used to implement a 100-Mbps Mars link with a 40-cm transmitting telescope, a 20-W laser, and a 10-m receiving photon bucket. Under the same conditions, a CO2 system would require 3-m transmitting and receiving telescopes and a 32-W laser to implement such

  2. Rapid Polarization Activity in Optical Communication Systems

    Science.gov (United States)

    Yevick, David; Reimer, Michael; Soliman, George

    2010-03-01

    We have recently analyzed the high-speed polarization and polarization-mode-dispersion (PMD) transients associated with mechanical impacts on a dispersion compensation module consisting of several km of optical fiber. These generate in our experiments rotational frequencies of up to several hundred radians/sec on the Poincare sphere that can severely degrade the performance of both standard and non-conventional communications systems. Accordingly, we implemented several procedures for performing high-speed polarization measurements, employed these to analyze small and large amplitude excitations and compared the results with a heuristic fiber model. Theoretically, we extended our previous work on applying the Magnus expansion to the analysis of the dependence of the PMD and polarization-dependent-loss (PDL) on frequency. From these, we obtained simple procedures for modeling polarization behavior over a wide frequency range from a small number of experimental measurements. Finally, we analyzed the applicability of various models of stochastic time-dependent refractive index variations to system outage prediction.

  3. A novel approach for simulating the optical misalignment caused by satellite platform vibration in the ground test of satellite optical communication systems.

    Science.gov (United States)

    Wang, Qiang; Tan, Liying; Ma, Jing; Yu, Siyuan; Jiang, Yijun

    2012-01-16

    Satellite platform vibration causes the misalignment between incident direction of the beacon and optical axis of the satellite optical communication system, which also leads to the instability of the laser link and reduces the precision of the system. So how to simulate the satellite platform vibration is a very important work in the ground test of satellite optical communication systems. In general, a vibration device is used for simulating the satellite platform vibration, but the simulation effect is not ideal because of the limited randomness. An approach is reasonable, which uses a natural random process for simulating the satellite platform vibration. In this paper, we discuss feasibility of the concept that the effect of angle of arrival fluctuation is taken as an effective simulation of satellite platform vibration in the ground test of the satellite optical communication system. Spectrum characteristic of satellite platform vibration is introduced, referring to the model used by the European Space Agency (ESA) in the SILEX program and that given by National Aeronautics and Space Development Agency (NASDA) of Japan. Spectrum characteristic of angle of arrival fluctuation is analyzed based on the measured data from an 11.16km bi-directional free space laser transmission experiment. Spectrum characteristic of these two effects is compared. The results show that spectra of these two effects have similar variation trend with the variation of frequency and feasibility of the concept is proved by the comparison results. At last the procedure of this method is proposed, which uses the power spectra of angle of arrival fluctuation to simulate that of the satellite platform vibration. The new approach is good for the ground test of satellite optical communication systems.

  4. Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

  5. Serial optical communications and ultra-fast optical signal processing of Tbit/s data signals

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Hu, Hao;

    2010-01-01

    This paper reviews our recent advances in ultra-high speed serial optical communications. It describes Tbit/s optical signal processing and various materials allowing for this, as well as network scenarios embracing this technology......This paper reviews our recent advances in ultra-high speed serial optical communications. It describes Tbit/s optical signal processing and various materials allowing for this, as well as network scenarios embracing this technology...

  6. All-optical virtual private network and ONUs communication in optical OFDM-based PON system.

    Science.gov (United States)

    Zhang, Chongfu; Huang, Jian; Chen, Chen; Qiu, Kun

    2011-11-21

    We propose and demonstrate a novel scheme, which enables all-optical virtual private network (VPN) and all-optical optical network units (ONUs) inter-communications in optical orthogonal frequency-division multiplexing-based passive optical network (OFDM-PON) system using the subcarrier bands allocation for the first time (to our knowledge). We consider the intra-VPN and inter-VPN communications which correspond to two different cases: VPN communication among ONUs in one group and in different groups. The proposed scheme can provide the enhanced security and a more flexible configuration for VPN users compared to the VPN in WDM-PON or TDM-PON systems. The all-optical VPN and inter-ONU communications at 10-Gbit/s with 16 quadrature amplitude modulation (16 QAM) for the proposed optical OFDM-PON system are demonstrated. These results verify that the proposed scheme is feasible.

  7. Isolation Platform for Long Range Optical Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical communication links provide higher data transfer rates with lower mass, power, and volume than conventional radio-frequency links. For deep space...

  8. Networked Operations of Hybrid Radio Optical Communications Satellites

    Science.gov (United States)

    Hylton, Alan; Raible, Daniel

    2014-01-01

    In order to address the increasing communications needs of modern equipment in space, and to address the increasing number of objects in space, NASA is demonstrating the potential capability of optical communications for both deep space and near-Earth applications. The Integrated Radio Optical Communications (iROC) is a hybrid communications system that capitalizes on the best of both the optical and RF domains while using each technology to compensate for the other's shortcomings. Specifically, the data rates of the optical links can be higher than their RF counterparts, whereas the RF links have greater link availability. The focus of this paper is twofold: to consider the operations of one or more iROC nodes from a networking point of view, and to suggest specific areas of research to further the field. We consider the utility of Disruption Tolerant Networking (DTN) and the Virtual Mission Operation Center (VMOC) model.

  9. Vibration Isolation Platform for Long Range Optical Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical communication links provide higher data transfer rates with lower mass, power, and volume than conventional radio-frequency links. For deep space...

  10. Research on the standards of indicators associated with maintain time in bidirectional beam tracking in inter-satellites optical communication links.

    Science.gov (United States)

    Yu, Siyuan; Wu, Feng; Tan, Liying; Guo, Pengzhen; Ma, Jing

    2015-10-19

    We report on a novel technology for high-speed inter-satellites optical communication by bidirectional beam tracking. By establishing the relation between the compensation effect and the parameters of response time and overshoot situation, the stability can be well compensated simply by the control system. Thus the relation between compensation effect and maintain time can be predicted from ground tests, and the certain evaluation standard could be established to meet the requirements of system. The other critical factors, such as signal-to-noise ratio and pointing angle error, have also been considered to improve the stability. The general approach can provide us a powerful path to overcome the performance limitation of bidirectional beam tracking, which can be expected to be widely applied in Free Space optics communications in future.

  11. Feasibility Study on Acquisition, Tracking, and Pointing Using Earth Thermal Images for Deep-Space Ka-Band and Optical Communications

    Science.gov (United States)

    Lee, S.; Ortiz, G. G.; Roberts, W. T.; Alexander, J. W.

    2003-11-01

    The feasibility of using long-wavelength Earth thermal (infrared) images for antenna/ telescope tracking/pointing applications for both deep-space Ka-band (18 to 35 GHz) and free-space optical communications has been investigated and is reported on here. The advantage of this technology rests on using full Earth images in this band that yield more accurate estimates of geometric centroids than those of Earth images in the visible band. Furthermore, these images are nearly independent of Earth phase angle. The results of the study show that, at a Mars range with currently available sensors, a noise equivalent angle of 10 to 150 nrad and a bias error of better than 80 nrad can be obtained. This would enable precise pointing of both the optical and Ka-band communications beams.

  12. Wireless optical telecommunications

    CERN Document Server

    Bouchet, Olivier

    2013-01-01

    Wireless optical communication refers to communication based on the unguided propagation of optical waves. The past 30 years have seen significant improvements in this technique - a wireless communication solution for the current millennium - that offers an alternative to radio systems; a technique that could gain attractiveness due to recent concerns regarding the potential effects of radiofrequency waves on human health.The aim of this book is to look at the free space optics that are already used for the exchange of current information; its many benefits, such as incorporating chan

  13. Machine learning concepts in coherent optical communication systems

    DEFF Research Database (Denmark)

    Zibar, Darko; Schäffer, Christian G.

    2014-01-01

    Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA.......Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA....

  14. Mode-Locked Semiconductor Lasers for Optical Communication Systems

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Oxenløwe, Leif Katsuo

    2005-01-01

    We present investigations on 10 and 40 GHz monolithic mode-locked lasers for applications in optical communications systems. New all-active lasers with one to three quantum wells have been designed, fabricated and characterized.......We present investigations on 10 and 40 GHz monolithic mode-locked lasers for applications in optical communications systems. New all-active lasers with one to three quantum wells have been designed, fabricated and characterized....

  15. Ultrahigh Capacity Optical Communications Beyond Pb/s

    DEFF Research Database (Denmark)

    Morioka, Toshio

    2013-01-01

    Recent progress in ultrahigh capacity optical communication technologies based on space-division multiplexing is described including one Pb/s transmission in a newly developed multi-core fiber with future perspectives for more capacity.......Recent progress in ultrahigh capacity optical communication technologies based on space-division multiplexing is described including one Pb/s transmission in a newly developed multi-core fiber with future perspectives for more capacity....

  16. Application of Beyond Bound Decoding for High Speed Optical Communications

    DEFF Research Database (Denmark)

    Li, Bomin; Larsen, Knud J.; Vegas Olmos, Juan José;

    2013-01-01

    This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB.......This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB....

  17. Machine learning concepts in coherent optical communication systems

    DEFF Research Database (Denmark)

    Zibar, Darko; Schäffer, Christian G.

    2014-01-01

    Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA.......Powerful statistical signal processing methods, used by the machine learning community, are addressed and linked to current problems in coherent optical communication. Bayesian filtering methods are presented and applied for nonlinear dynamic state tracking. © 2014 OSA....

  18. Multimedial CD for an Education in Optical Communications

    Directory of Open Access Journals (Sweden)

    Roman Psanecky

    2003-01-01

    Full Text Available This article deals with an e-learning in optical communications. Ways of e-learning include learning by education software, multimedial CD and Internet on the www address http://fel.utc.sk/~psanecky/.An aim of multimedial CD development was to develop an didactic tools for the course Fotonics at the Department of Telecommunications, and also for anybody who interested in optical communication and e-learning through Internet.

  19. BANDWIDTH OF QUANTUM OPTICAL COMMUNICATION SYSTEM

    Directory of Open Access Journals (Sweden)

    I. R. Gulakov

    2012-01-01

    Full Text Available Impact of registered optical radiation intensity, overvoltage, dimensions of photosensitive surface, structure of p-n junction and avalanche photodetectors dead time operating in the photon counting mode on quantum optical system capacity has been carried out in this investigation. As a result, the quantum optical system maximum capacity of 81 kbit/s has been obtained.

  20. All-optical signal processing data communication and storage applications

    CERN Document Server

    Eggleton, Benjamin

    2015-01-01

    This book provides a comprehensive review of the state-of-the art of optical signal processing technologies and devices. It presents breakthrough solutions for enabling a pervasive use of optics in data communication and signal storage applications. It presents presents optical signal processing as solution to overcome the capacity crunch in communication networks. The book content ranges from the development of innovative materials and devices, such as graphene and slow light structures, to the use of nonlinear optics for secure quantum information processing and overcoming the classical Shannon limit on channel capacity and microwave signal processing. Although it holds the promise for a substantial speed improvement, today’s communication infrastructure optics remains largely confined to the signal transport layer, as it lags behind electronics as far as signal processing is concerned. This situation will change in the near future as the tremendous growth of data traffic requires energy efficient and ful...

  1. NASA's optical communications program for 2015 and beyond

    Science.gov (United States)

    Cornwell, Donald M.

    2015-03-01

    NASA's Space Communications and Navigation (SCaN) program at NASA headquarters is pursuing a vibrant and wide-ranging optical communications program for further planetary and near-Earth missions following the spectacular success of NASA's Lunar Laser Communication Demonstration (LLCD) from the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft orbiting the moon in 2013. This invited paper will discuss NASA's new laser communication missions, key scenarios and details, and the plans to infuse this new technology into NASA's existing communications networks.

  2. Interactive educational technologies as a method of communicative competency development of optical and fiber optic communication systems specialists

    Science.gov (United States)

    Matveeva, Tatiana U.; Osadchiy, Igor S.; Husnutdinova, Marina N.

    2017-04-01

    The article examines the process of formation of communicative competencies of optic and fiber optic communication systems specialists; the role of communicative competencies is examined in the structure of professionally important skills, together with the contents of professional activity. The stages of empirical research into formation of communicative competencies have been presented, and the values of statistical reliability of data have been provided. The model of formation of communicative competency using interactive technology has been developed based on the research done, and main stages of model implementation and motives of formation of communicative competency have been highlighted. A scheme of "Communicative competence as a base of future success" training session has been suggested as one of the basic interactive technologies. Main components of education that are used during the stages of the training cycle have been examined. The statistical data on the effectiveness of use of interactive educational technologies has been presented; it allowed development of communicative competency of specialists in the field of optical and fiber optic communication system.

  3. Site survey for optimum location of Optical Communication Experimental Facility

    Science.gov (United States)

    1968-01-01

    Site survey was made to determine the optimum location for an Optical Communication Experimental Facility /OCEF/ and to recommend several sites, graded according to preference. A site was desired which could perform two-way laser communication with a spacecraft and laser tracking with a minimum of interruption by weather effects.

  4. Investigation and Demonstration of High Speed Full-Optical Hybrid FSO/Fiber Communication System under Light Sand Storm Condition

    KAUST Repository

    Esmail, Maged Abdullah

    2016-12-19

    In contrast to traditional free space optical (FSO) systems, the new generation is aimed to be transparent to optical fiber where protocols, high signal bandwidths, and high data rates over fiber are all maintained. In this paper, we experimentally demonstrate a high speed outdoor full-optical FSO communication system over 100 m link. We first describe the design of our transmitter, which consists of a comb generator and a flexible multiformat transmitter. Our measurements are performed in arid desert area under a light dust storm. In this environment, we use a 12 subcarrier comb generator, each of which is modulated by a quadrature-amplitude modulation (QAM) signal. We achieved a 1.08 Tbps error free data rate with 3.6 b/s/Hz spectral efficiency. We place long optical fiber rolls in the transmitter side and the receiver side to mimic real FSO deployments. Furthermore, we investigated the effect of receiver misalignment in outdoor conditions and the effect of background noise. We find that full-optical FSO system is sensitive to the misalignment effect. However, the background noise has negligible effect. Finally, we find that solar heating of the transceiver causes collimator deviation, which requires using a cooling unit or auto tracking system.

  5. Free-Space Quantum Signatures Using Heterodyne Measurements

    Science.gov (United States)

    Croal, Callum; Peuntinger, Christian; Heim, Bettina; Khan, Imran; Marquardt, Christoph; Leuchs, Gerd; Wallden, Petros; Andersson, Erika; Korolkova, Natalia

    2016-09-01

    Digital signatures guarantee the authorship of electronic communications. Currently used "classical" signature schemes rely on unproven computational assumptions for security, while quantum signatures rely only on the laws of quantum mechanics to sign a classical message. Previous quantum signature schemes have used unambiguous quantum measurements. Such measurements, however, sometimes give no result, reducing the efficiency of the protocol. Here, we instead use heterodyne detection, which always gives a result, although there is always some uncertainty. We experimentally demonstrate feasibility in a real environment by distributing signature states through a noisy 1.6 km free-space channel. Our results show that continuous-variable heterodyne detection improves the signature rate for this type of scheme and therefore represents an interesting direction in the search for practical quantum signature schemes. For transmission values ranging from 100% to 10%, but otherwise assuming an ideal implementation with no other imperfections, the signature length is shorter by a factor of 2 to 10. As compared with previous relevant experimental realizations, the signature length in this implementation is several orders of magnitude shorter.

  6. Free-Space Quantum Signatures Using Heterodyne Measurements.

    Science.gov (United States)

    Croal, Callum; Peuntinger, Christian; Heim, Bettina; Khan, Imran; Marquardt, Christoph; Leuchs, Gerd; Wallden, Petros; Andersson, Erika; Korolkova, Natalia

    2016-09-02

    Digital signatures guarantee the authorship of electronic communications. Currently used "classical" signature schemes rely on unproven computational assumptions for security, while quantum signatures rely only on the laws of quantum mechanics to sign a classical message. Previous quantum signature schemes have used unambiguous quantum measurements. Such measurements, however, sometimes give no result, reducing the efficiency of the protocol. Here, we instead use heterodyne detection, which always gives a result, although there is always some uncertainty. We experimentally demonstrate feasibility in a real environment by distributing signature states through a noisy 1.6 km free-space channel. Our results show that continuous-variable heterodyne detection improves the signature rate for this type of scheme and therefore represents an interesting direction in the search for practical quantum signature schemes. For transmission values ranging from 100% to 10%, but otherwise assuming an ideal implementation with no other imperfections, the signature length is shorter by a factor of 2 to 10. As compared with previous relevant experimental realizations, the signature length in this implementation is several orders of magnitude shorter.

  7. Exo-atmospheric telescopes for deep space optical communications

    Science.gov (United States)

    Hurd, William J.; MacNeal, Bruce E.; Ortiz, Gerardo G.; Cheng, Edward S.; Moe, Rud V.; Walker, Jon Z.; Fairbrother, Debora A.; Dennis, Michael L.; Eegholm, Bente; Kasunic, Keith J.

    2006-01-01

    For deep space optical communications, optical telescopes located above the Earth's atmosphere would have significant performance advantages over telescopes mounted on the Earth's surface. Link outages due to could cover would be eliminated, atmospheric attenuation would be eliminated, and signal degradation due to stray light would be reduced.

  8. European IST-programme roadmap for Optical Communications

    DEFF Research Database (Denmark)

    Ackaert, Ann; Demeester, Piet; Lagasse, Paul;

    2003-01-01

    On the basis of European IST project results in the field of photonics, the OPTIMIST thematic network has produced a roadmap for optical communications. This work is described in the present article which provides scenarios for the evolution of the optical network in the coming 10 years. Predicta...

  9. Fiber-Optic Terahertz Data-Communication Networks

    Science.gov (United States)

    Chua, Peter L.; Lambert, James L.; Morookian, John M.; Bergman, Larry A.

    1994-01-01

    Network protocols implemented in optical domain. Fiber-optic data-communication networks utilize fully available bandwidth of single-mode optical fibers. Two key features of method: use of subpicosecond laser pulses as carrier signals and spectral phase modulation of pulses for optical implementation of code-division multiple access as multiplexing network protocol. Local-area network designed according to concept offers full crossbar functionality, security of data in transit through network, and capacity about 100 times that of typical fiber-optic local-area network in current use.

  10. Communications, tracking, and docking on the Space Station

    Science.gov (United States)

    Erwin, H. O.; Coden, M. H.; Scholl, F. W.

    1982-01-01

    Many of the communications, tracking, and docking functions on a large manned orbiting Space Station - one that is modular and made of metal - will have to be performed by optical systems out of necessity. This paper discusses four practical approaches to accomplishing Space Station functions using optical communications technology. It also provides the results of preliminary experiments involved in the design of particular systems. Major operational factors considered in each system design include: (a) electromagnetic interference problems, (b) data bandwidth requirements, (c) zero-gravity operations, (d) free-space operations, (e) data security, and (f) modular expansion of the Space Station structure. The technologies discussed are the following: (a) local infrared communications, (b) optical tracking and docking techniques, (c) long distance free space optical communications, and (d) local area optical networks.

  11. Exo-atmospheric telescopes for Deep Space Optical Communications

    Science.gov (United States)

    Hurd, William J.; Moe, Rud V.; Dennis, Michael L.; MacNeal, Bruce E.; Walker, Jon Z.; Ortiz, Gerardo G.; Eegholm, Bente; Fairbrother, debora A.; Cheng, Edward S.; Kasunic, Keith J.

    2006-01-01

    For deep space optical communications, optical telescopes located above the Earth's atmosphere would have significant performance advantages over telescopes mounted on the Earth's surface. Link outages due to cloud cover would be eliminated, atmospheric attenuation would be eliminated, and signal degradation due to stray light would be reduced. A study has been conducted to compare various exo-atmospheric platforms for the Earth end of the optical link.

  12. On Approaching the Ultimate Limits of Photon-Efficient and Bandwidth-Efficient Optical Communication

    CERN Document Server

    Dolinar, Sam; Erkmen, Baris I; Moision, Bruce

    2011-01-01

    It is well known that ideal free-space optical communication at the quantum limit can have unbounded photon information efficiency (PIE), measured in bits per photon. High PIE comes at a price of low dimensional information efficiency (DIE), measured in bits per spatio-temporal-polarization mode. If only temporal modes are used, then DIE translates directly to bandwidth efficiency. In this paper, the DIE vs. PIE tradeoffs for known modulations and receiver structures are compared to the ultimate quantum limit, and analytic approximations are found in the limit of high PIE. This analysis shows that known structures fall short of the maximum attainable DIE by a factor that increases linearly with PIE for high PIE. The capacity of the Dolinar receiver is derived for binary coherent-state modulations and computed for the case of on-off keying (OOK). The DIE vs. PIE tradeoff for this case is improved only slightly compared to OOK with photon counting. An adaptive rule is derived for an additive local oscillator th...

  13. Crossbar Switches For Optical Data-Communication Networks

    Science.gov (United States)

    Monacos, Steve P.

    1994-01-01

    Optoelectronic and electro-optical crossbar switches called "permutation engines" (PE's) developed to route packets of data through fiber-optic communication networks. Basic network concept described in "High-Speed Optical Wide-Area Data-Communication Network" (NPO-18983). Nonblocking operation achieved by decentralized switching and control scheme. Each packet routed up or down in each column of this 5-input/5-output permutation engine. Routing algorithm ensures each packet arrives at its designated output port without blocking any other packet that does not contend for same output port.

  14. Crossbar Switches For Optical Data-Communication Networks

    Science.gov (United States)

    Monacos, Steve P.

    1994-01-01

    Optoelectronic and electro-optical crossbar switches called "permutation engines" (PE's) developed to route packets of data through fiber-optic communication networks. Basic network concept described in "High-Speed Optical Wide-Area Data-Communication Network" (NPO-18983). Nonblocking operation achieved by decentralized switching and control scheme. Each packet routed up or down in each column of this 5-input/5-output permutation engine. Routing algorithm ensures each packet arrives at its designated output port without blocking any other packet that does not contend for same output port.

  15. Experimental validation of phase-only pre-compensation over 494  m free-space propagation.

    Science.gov (United States)

    Brady, Aoife; Berlich, René; Leonhard, Nina; Kopf, Teresa; Böttner, Paul; Eberhardt, Ramona; Reinlein, Claudia

    2017-07-15

    It is anticipated that ground-to-geostationary orbit (GEO) laser communication will benefit from pre-compensation of atmospheric turbulence for laser beam propagation through the atmosphere. Theoretical simulations and laboratory experiments have determined its feasibility; extensive free-space experimental validation has, however, yet to be fulfilled. Therefore, we designed and implemented an adaptive optical (AO)-box which pre-compensates an outgoing laser beam (uplink) using the measurements of an incoming beam (downlink). The setup was designed to approximate the baseline scenario over a horizontal test range of 0.5 km and consisted of a ground terminal with the AO-box and a simplified approximation of a satellite terminal. Our results confirmed that we could focus the uplink beam on the satellite terminal using AO under a point-ahead angle of 28 μrad. Furthermore, we demonstrated a considerable increase in the intensity received at the satellite. These results are further testimony to AO pre-compensation being a viable technique to enhance Earth-to-GEO optical communication.

  16. Invariant integral and statistical equations of paraxial light beam transmission in free space

    Institute of Scientific and Technical Information of China (English)

    邓锡铭; 郭弘; 曹清

    1997-01-01

    The statistical behavior of arbitrary paraxial light beams propagating in free space is investigated by using the Hermite-Gaussian expansion method and Fock’s representation. A series of equivalent Gaussian parameters for paraxial beam and the statistical equations for these parameters are presented. The optical transmission problem in quasi-far field region is studied. The so-called general Hermite-Gaussian beam is defined.

  17. Digital Signal Processing for Optical Coherent Communication Systems

    DEFF Research Database (Denmark)

    Zhang, Xu

    In this thesis, digital signal processing (DSP) algorithms are studied to compensate for physical layer impairments in optical fiber coherent communication systems. The physical layer impairments investigated in this thesis include optical fiber chromatic dispersion, polarization demultiplexing......, light sources frequency and phase offset and phase noise. The studied DSP algorithms are considered as key building blocks in digital coherent receivers for the next generation of optical communication systems such as 112-Gb/s dual polarization (DP) quadrature phase shift keying (QPSK) optical...... spectrum narrowing tolerance 112-Gb/s DP-QPSK optical coherent systems using digital adaptive equalizer. The demonstrated results show that off-line DSP algorithms are able to reduce the bit error rate (BER) penalty induced by signal spectrum narrowing. Third, we also investigate bi...

  18. Network Communication by Optical Directional Link

    Directory of Open Access Journals (Sweden)

    V. Biolkova

    1999-04-01

    Full Text Available In this article, infrared point-to-point technologies (optical directional links are discussed which are designed for digital transmissions. Optical directional links (ODLs are transparent for the SDH/ATM, FDDI-II, Ethernet, and Token Ring protocols. Depending on type, ODL ranges are 300 m, 500 m, 1000 m and 2000 m. Steady and statistical models of ODL are presented as well as the measuring ODL arrangement and the graphs concerning the fluctuations of the received signal.

  19. Passive, free-space laser gyroscope

    CERN Document Server

    Korth, W Zach; Hall, Evan D; Arai, Koji; Gustafson, Eric K; Adhikari, Rana X

    2015-01-01

    Laser gyroscopes making use of the Sagnac effect have been used as highly accurate rotation sensors for many years. First used in aerospace and defense applications, these devices have more recently been used for precision seismology and in other research settings. In particular, mid-sized (~1 m-scale) laser gyros have been under development as tilt sensors to augment the adaptive active seismic isolation systems in terrestrial interferometric gravitational wave detectors. The most prevalent design is the "active" gyroscope, in which the optical ring cavity used to measure the Sagnac degeneracy breaking is itself a laser resonator. In this article, we describe another topology: a "passive" gyroscope, in which the sensing cavity is not itself a laser but is instead tracked using external laser beams. While subject to its own limitations, this design is free from the deleterious lock-in effects observed in active systems, and has the advantage that it can be constructed using commercially available components. ...

  20. A Space-Based Optical Communication System Utilizing Fiber Optics

    Science.gov (United States)

    1989-11-09

    single mode elliptic core fibers," Opt. Commun., 49, 3, 178-183 (1984). 35 15. B.J. Klein and J.J. Degnan, " Optical antenna gain. 1: Transmitting...antennas," Appl. Opt., 13,9,2134- 2141 (1974). 16. B.J. Klein and J.J. Degnan, " Optical antenna gain. 2: Receiving antennas," Appl. Opt., 13, 10,2397- 2401...1974). 17. B.J. Klein and J.J. Degnan, " Optical antenna gain. 3: The effect of secondary element support struts on transmitter gain," Appl. Opt., 15

  1. The design of space optical communications terminal with high efficient

    Science.gov (United States)

    Deng, Xiaoguo; Li, Gang; Jiang, Bo; Yang, Xiaoxu; Yan, Peipei

    2015-02-01

    In order to improve high-speed laser space optical communications terminal receive energy and emission energy, meet the demand of mini-type and light-type for space-based bear platform, based on multiple-reflect coaxial optical receiving antenna structure, while considering the installation difficulty, a high-efficient optical system had been designed, which aperture is off-axial, both signal-receiving sub-optical system and emission sub-optical system share a same primary optical path. By the separating light lens behind the primary optical path, the received light with little energy will be filtered and shaped and then transmitted to each detector, at the same time, by the coupling element, the high-power laser will be coupling into optical antenna, and then emitted to outside. Applied the power-detected optical system evaluate principle, the optimized off-axial optical system's efficiency had been compared with the coaxial optical system. While, analyzed the Gauss beam energy distribution by numerical theory, discussed that whether off-axis optical system can be an emission terminal, verify the feasibility of the theory of the design of the system.

  2. Hybrid Ground Station Technology for RF and Optical Communication Links

    Science.gov (United States)

    Davarian, Faramaz; Hoppe, D.; Charles, J.; Vilnrotter, V.; Sehic, A.; Hanson, T.; Gam, E.

    2012-01-01

    To support future enhancements of NASA's deep space and planetary communications and tracking services, the Jet Propulsion Laboratory is developing a hybrid ground station that will be capable of simultaneously supporting RF and optical communications. The main reason for adding optical links to the existing RF links is to significantly increase the capacity of deep space communications in support of future solar system exploration. It is envisioned that a mission employing an optical link will also use an RF link for telemetry and emergency purposes, hence the need for a hybrid ground station. A hybrid station may also reduce operations cost by requiring fewer staff than would be required to operate two stations. A number of approaches and techniques have been examined. The most promising ones have been prototyped for field examination and validation.

  3. Ultrafast Long-Distance Quantum Communication with Static Linear Optics

    Science.gov (United States)

    Ewert, Fabian; Bergmann, Marcel; van Loock, Peter

    2016-11-01

    We propose a projection measurement onto encoded Bell states with a static network of linear optical elements. By increasing the size of the quantum error correction code, both Bell measurement efficiency and photon-loss tolerance can be made arbitrarily high at the same time. As a main application, we show that all-optical quantum communication over large distances with communication rates similar to those of classical communication is possible solely based on local state teleportations using optical sources of encoded Bell states, fixed arrays of beam splitters, and photon detectors. As another application, generalizing state teleportation to gate teleportation for quantum computation, we find that in order to achieve universality the intrinsic loss tolerance must be sacrificed and a minimal amount of feedforward has to be added.

  4. Solutes in the free space of growing stem tissues

    Energy Technology Data Exchange (ETDEWEB)

    Cosgrove, D.J.; Cleland, R.E.

    1983-01-01

    The concentration of osmotically active solutes in the cell wall free space of young stem tissues was studied using a variety of extraction methods. When the intercellular air spaces of etiolated pea (Pisum sativum L.) internodes were perfused with distilled H/sub 2/O, the resulting solution contained a solute concentration of about 70 milliosmoles per kilogram. A second procedure involving vacuum infiltration of segments followed by centrifugation to collect the free space solution gave similar results. Apical stem segments yielded free space extracts about twice as concentrated as those from basal portions of the stem. After correcting for dilution of the free space solution by the infiltrated water, the osmotic pressure of the undiluted free space in pea stem tissue was estimated to be 2.9 bars for apical segments, 1.8 bars for basal regions. These values may be somewhat overestimated due to solute efflux from intracellular pools during the extraction procedure. Similar results were obtained for stem regions of etiolated soybean (Glycine max (L.) Merr.) and cucumber (Cucumis sativus L.) seedlings. From measurements of the electrical conductivity and refractive index of free space extracts before and after ashing, it appears that 25% of the solutes are inorganic electrolytes and 75% are organic nonelectrolytes with an average size similar to that of glucose. A significant osmotic pressure in the wall space offers an explanation for the frequent observation that nontranspiring plants have negative water potentials. Calculations of hydraulic resistance from water potential data must take into account solutes in the free space, else apparent, but unreal, changes in resistance may be calculated. 27 references, 4 tables.

  5. Communication issues in parallel systems with optical interconnections

    Science.gov (United States)

    Berthome, Pascal; Ferreira, A.

    1995-02-01

    In classical massively parallel computers, the complexity of the interconnection networks is much higher than the complexity of the processing elements themselves. Optical interconnections may provide a way to reconsider very large parallel architectures. We compare some optically interconnected parallel multicomputer models with regard to their communication capabilities. We first establish a distinction of such systems, based on the independence of the communication elements embedded in the processors (transmitters and receivers). Then, motivated by the fact that in multicomputers some communication operations have to be very efficiently performed, we study two fundamental communication problems, namely, one-to-all and all-to-all, under the hypothesis of bounded fanout. Our results take also into account a bounded number of available wavelengths.

  6. MEMS Lens Scanners for Free-Space Optical Interconnects

    Science.gov (United States)

    2011-12-15

    89 Fig. 8.7. Matlab Simulink simulation of the optoelectronic PLL . (a) Shows the block diagram of the feedback loop. (b) Shows the linear...with a 20 kHz sample rate on a personal computer running the Labview real-time operating system. Fig. 4.12. Block diagram setup with... PLL ) circuit has been demonstrated by Satyan et. al, to linearize the frequency to current relationship, as shown in Fig. 8.6 [116]. Chapter 8

  7. Synchronization and a secure communication scheme using optical star network

    Science.gov (United States)

    Jeeva Sathya Theesar, S.; Ariffin, M. R. K.; Banerjee, Santo

    2013-12-01

    This work aims to show the effect of synchronization phenomena in multi-nodal star optical network topology as well as to develop an efficient symmetric cryptosystem utilizing available parameters. The optical network is based on chaotic semiconductor laser (SL) systems described by dimensionless modified Lang-Kobayashi's (L-K) delay differential equations. The network nodes are mutually connected with a central semiconductor laser hub with bidirectional linear optical feedback. It has been observed that the laser output can be modulated using a star network setup. The laser intensity increases with the number of nodes and its much more higher than the same for solitary laser, keeping all other inputs as constant. So the network topology is an effective way to optimize the output power. The process by each nodes into the network is illustrated graphically for three, five and seven SLs, respectively. Also the whole network can be implemented as an optical communication system for transmission of signals. Each SL can act as a transceiver during communication. The communication process is examined using a chaotic signal as a plaintext connected with the SL hub and successfully provided a symmetrically secure mechanism upon the communication protocol. The result shows the optimization of output power with the increment of the number of nodes. Also the communication scheme can successfully decode the encrypted signal from SL Hub, at each other nodes.

  8. Research on optic antenna of space laser communication networking

    Science.gov (United States)

    Meng, Li-Xin; Li, Long; Zhang, Li-zhong; Zhao, Shan-shan; Jiang, Hui-lin

    2013-08-01

    With the highlights of the high transmission rate, large capacity, strong anti-interference and anti-capture ability, good security and small light, space laser communication becomes an important hotspot. At present, the focus of research of the laser communication system is point to point communication structure. However, from the application point of view, both the realization of space laser communication among multiple points and the establishment of the information transmission network can really have the practical value. Aiming at the problem of space laser communication network, this article puts forward the general idea about optical antenna to achieve multiple tracking goals at the same time. Through the analysis of the optical antenna, and the comparing of the current commonly used mirror driving mechanism, a new mirror driving mechanism is designed. The azimuth motion, containing circular grating feedback, is driven by torque motor,voice coil motor of fan produces pitch motion that has fan-shaped grating feedback, so that compression of the structure size to improve the efficiency of the reflector assembly. Through the establishment of the driving mechanism and the kinematic model of 3D entity, the relationship between the single drive azimuth and pitch angle following the angle of incident light is explained. The biggest ideal view area affecting the optical antenna is obtained by the simulation analysis of the kinematics model using MATLAB. The several factors of field overlap area and blind area offers a theoretical basis for structure optimization and control system for the subsequent optical antenna design.

  9. Ring resonator systems to perform optical communication enhancement using soliton

    CERN Document Server

    Amiri, Iraj Sadegh

    2014-01-01

    The title explain new technique of secured and high capacity optical communication signals generation by using the micro and nano ring resonators. The pulses are known as soliton pulses which are more secured due to having the properties of chaotic and dark soliton signals with ultra short bandwidth. They have high capacity due to the fact that ring resonators are able to generate pulses in the form of solitons in multiples and train form. These pulses generated by ring resonators are suitable in optical communication due to use the compact and integrated rings system, easy to control, flexibi

  10. Fibre optic communications: past, present and future

    Directory of Open Access Journals (Sweden)

    B. M. Lacquet

    2000-07-01

    Full Text Available The exponential increase in the use of the Internet and the consequent growing need for higher bandwidth demand that the telecommu­nications industry expand the laid networks at a much faster rate. Optical fibre is the only transmission medium that has the potential of unlimited bandwidth and the ability to handle very high data rates.

  11. Soliton-based ultra-high speed optical communications

    Indian Academy of Sciences (India)

    Akira Hasegawa

    2001-11-01

    Multi-terabit/s, ultra-high speed optical transmissions over several thousands kilometers on fibers are becoming a reality. Most use RZ (Return to Zero) format in dispersion-managed fibers. This format is the only stable waveform in the presence of fiber Kerr nonlinearity and dispersion in all optical transmission lines with loss compensated by periodic amplifications. The nonlinear Schrödinger equation assisted by the split step numerical solutions is commonly used as the master equation to describe the information transfer in optical fibers. All these facts are the outcome of research on optical solitons in fibers in spite of the fact that the commonly used RZ format is not always called a soliton format. The overview presented here attempts to incorporate the role of soliton-based communications research in present day ultra-high speed communications.

  12. Time domain dispersion of underwater optical wireless communication

    Institute of Scientific and Technical Information of China (English)

    Wei Wei; Xiaohui Zhang; Jionghui Rao; Wenbo Wang

    2011-01-01

    @@ A new method to count the expected value and variance of time dispersion is presented for time dispersion of underwater optical wireless communication.Instead of the typically used Gamma distribution, inverse-Gaussian distribution is suggested for underwater optical impulse response time waveform function.The expectation of this method is in good agreement with experimental data.Future works may include water absorption to the model.%A new method to count the expected value and variance of time dispersion is presented for time dispersion of underwater optical wireless communication.Instead of the typically used Gamma distribution, inverseGaussian distribution is suggested for underwater optical impulse response time waveform function.The expectation of this method is in good agreement with experimental data.Future works may include water absorption to the model.

  13. Microresonator solitons for massively parallel coherent optical communications

    CERN Document Server

    Marin-Palomo, Pablo; Karpov, Maxim; Kordts, Arne; Pfeifle, Joerg; Pfeiffer, Martin H P; Trocha, Philipp; Wolf, Stefan; Brasch, Victor; Rosenberger, Ralf; Vijayan, Kovendhan; Freude, Wolfgang; Kippenberg, Tobias J; Koos, Christian

    2016-01-01

    Optical solitons are waveforms that preserve their shape while travelling, relying on a balance of dispersion and nonlinearity. Data transmission schemes using solitons were heavily investigated in the 1980s promising to overcome the limitations imposed by dispersion of optical fibers. These approaches, however, were eventually abandoned in favour of WDM schemes, that are easier to implement and offer much better scalability to higher data rates. Here, we show that optical solitons may experience a comeback in optical terabit communications, this time not as a competitor, but as a key element of massively parallel WDM. Instead of encoding data on the soliton itself, we exploit continuously circulating solitons in Kerr-nonlinear microresonators to generate broadband optical frequency combs. In our experiments, we use two interleaved Kerr combs to transmit data on a total of 179 individual optical carriers that span the entire C and L bands. Using higher-order modulation formats (16QAM), net data rates exceedin...

  14. Hybrid RF/Optical Communications via 34-meter DSN Antennas

    Science.gov (United States)

    Vilnrotter, V.

    2010-02-01

    There is considerable interest in determining whether suitably modified versions of existing 34-m antennas at NASA's Goldstone Communications Complex, originally designed for X-band (nominally 8 GHz) and Ka-band (32 GHz) operation, could also be used to receive near-infrared optical signals. The robust backup structure of these antennas, together with extremely large collecting apertures and millidegree pointing capabilities, suggest that dual RF/optical communications may indeed be possible, at optical data rates approaching 1 gigabit per second (GBPS) from typical Mars distances. Several design concepts have emerged as possible candidates, requiring modifications ranging from polishing and coating of the existing aluminum panels of the main reflector, to significant redesign involving replacement of the panels with optical reflectors. Optical receiver parameters such as collecting area, field of view (FOV), and immunity to reflected sunlight differ markedly for each design concept, hence will likely lead to different levels of performance in terms of data throughput at a given error probability, and in terms of the ability to point close to the Sun. The communications performance of two candidate design concepts operating under realistic daytime conditions is evaluated, with particular emphasis on spatial and temporal acquisition algorithms and receiver optimization to achieve the best possible communication performance at high data rates.

  15. Leo-Based Optical/Microwave Terrestrial Communications

    CERN Document Server

    Meulenberg, Andrew; Ramanathan, Shivram

    2010-01-01

    We propose a LEO-based communication system that is built by deploying circum-terra, optic fibers connecting hundreds of small (perhaps) phased-array-communications and RF-signal-transfer antennas around the earth on multiple rings. The proposed LEO-earth connection will be through microwave links (Ku or low-Ka band) and many of the ISL's through the optic-fiber rings. Inter-ring connectivity could be with either high-Ka band or optical (laser) links. The initial ring would serve to complement existing terrestrial fiber networks; but, the system would expand with additional rings into non-equatorial planes to provide global connectivity. The proposed system would make use of connectivity & broadcasting capability of satellite constellations as well as the high throughput point-to-point capability of optic-fiber systems. The advantages, options, and economics of the proposed LEO optic-fiber / microwave communication system over existing terrestrial- and space-communication systems (of similar functionality...

  16. Both channel coding and wavefront correction on the turbulence mitigation of optical communications using orbital angular momentum multiplexing

    Science.gov (United States)

    Zhao, Shengmei; Wang, Le; Zou, Li; Gong, Longyan; Cheng, Weiwen; Zheng, Baoyu; Chen, Hanwu

    2016-10-01

    A free-space optical (FSO) communication link with multiplexed orbital angular momentum (OAM) modes has been demonstrated to largely enhance the system capacity without a corresponding increase in spectral bandwidth, but the performance of the link is unavoidably degraded by atmospheric turbulence (AT). In this paper, we propose a turbulence mitigation scheme to improve AT tolerance of the OAM-multiplexed FSO communication link using both channel coding and wavefront correction. In the scheme, we utilize a wavefront correction method to mitigate the phase distortion first, and then we use a channel code to further correct the errors in each OAM mode. The improvement of AT tolerance is discussed over the performance of the link with or without channel coding/wavefront correction. The results show that the bit error rate performance has been improved greatly. The detrimental effect of AT on the OAM-multiplexed FSO communication link could be removed by the proposed scheme even in the relatively strong turbulence regime, such as Cn2 = 3.6 ×10-14m - 2 / 3.

  17. Dynamics and Synchronization of Semiconductor Lasers for Chaotic Optical Communications

    Science.gov (United States)

    Liu, Jia-Ming; Chen, How-Foo; Tang, Shuo

    The objective of this chapter is to provide a complete picture of the nonlinear dynamics and chaos synchronization of single-mode semiconductor lasers for chaotic optical communications. Basic concepts and theoretical framework are reviewed. Experimental results are presented to demonstrate the fundamental concepts. Numerical computations are employed for mapping the dynamical states and for illustrating certain detailed characteristics of the chaotic states. Three different semiconductor laser systems, namely, the optical injection system, the optical feedback system, and the optoelectronic feedback system, that are of most interest for high-bit-rate chaotic optical communications are considered. The optical injection system is a nonautonomous system that follows a period-doubling route to chaos. The optical feedback system is a phase-sensitive delayed-feedback autonomous system for which all three known routes, namely, period-doubling, quasiperiodicity, and intermittency, to chaos can be found. The optical feedback system is a phase-insensitive delayed-feedback autonomous system that follows a quasiperiodicity route to chaotic pulsing. Identical synchronization in unidirectionally coupled configurations is the focus of discussions for chaotic communications. For optical injection and optical feedback systems, the frequency, phase, and amplitude of the optical fields of both transmitter and receiver lasers are all locked in synchronism when complete synchronization is accomplished. For the optoelectronic feedback system, chaos synchronization involves neither the locking of the optical frequency nor the synchronization of the optical phase. For both optical feedback and optoelectronic feedback systems, where the transmitter is configured with a delayed feedback loop, anticipated and retarded synchronization can be observed as the difference between the feedback delay time and the propagation time from the transmitter laser to the receiver laser is varied. For a

  18. Acemind new indoor full duplex optical wireless communication prototype

    Science.gov (United States)

    Bouchet, Olivier; Perrufel, Micheline; Topsu, Suat; Guan, Hongyu

    2016-09-01

    For over a century and Mr. Guglielmo Marconi invention, systems using radio waves have controlled over wireless telecommunication solutions; from Amplitude Modulation (AM) radio products to satellite communications for instance. But beyond an increasingly negative opinion face to radio waves and radio spectrum availability more and more reduced; there is an unprecedented opportunity with LED installation in displays and lighting to provide optical wireless communication solutions. As a result, technologically mature solutions are already commercially available for services such as Location Based Services (LBS), broadcast diffusion or Intelligent Transport Services (ITS). Pending finalization of the standard review process IEEE 802.15.7 r1, our paper presents the results of the European collaborative project named "ACEMIND". It offers an indoor bilateral optical wireless communication prototype having the following characteristics: use of the existing electrical infrastructure, through judicious combination with Light Fidelity (LiFi), Power Line Communication (PLC) and Ethernet to reduce the implementation cost. We propose a bilateral optical wireless communication even when the light is switched off by using Visible Light Communication (VLC) and Infra-Red Communication (IRC) combined to a remote optical switch. Dimensionally optimized LiFi module is presented in order to offer the possibility for integration inside a laptop. Finally, there is operational mechanism implementation such as OFDM/DMT to increase throughput. After the introduction, we will present the results of a market study from Orange Labs customers about their opinion on LiFi components. Then we will detail the LiFi prototype, from the physical layer aspect to MAC layer before concluding on commercial development prospects.

  19. Applications of expectation maximization algorithm for coherent optical communication

    DEFF Research Database (Denmark)

    Carvalho, L.; Oliveira, J.; Zibar, Darko

    2014-01-01

    In this invited paper, we present powerful statistical signal processing methods, used by machine learning community, and link them to current problems in optical communication. In particular, we will look into iterative maximum likelihood parameter estimation based on expectation maximization al...

  20. Kansas Communication and Instruction System through Fiber-Optic Transmission.

    Science.gov (United States)

    Kansas State Dept. of Education, Topeka.

    Schools and communities will restructure as they move into the next decade. The success of this restructuring will be dependent upon access to and sharing of quality teaching and information through an expanded communication system. One of the major two-way interactive technologies is the fiber-optic cable: a delivery system that will provide…

  1. Enhancing Optical Communications with Brand New Fibers

    DEFF Research Database (Denmark)

    Morioka, Toshio; Awaji, Yoshinari; Ryf, Roland

    2012-01-01

    Optical fibers have often been considered to offer effectively infinite capacity to support the rapid traffic growth essential to our information society. However, as demand has grown and technology has developed, we have begun to realize that there is a fundamental limit to fiber capacity of ~ 100....... This article reviews the most recent research efforts around the globe launched over the past few years with a view to overcome these limitations and substantially increase capacity by exploring the last degree of freedom available: the spatial domain. Central to this effort has been the development of brand...

  2. Quantum dot devices for optical communications

    DEFF Research Database (Denmark)

    Mørk, Jesper

    2005-01-01

    . The main property of semiconductor quantum dots compared to bulk material or even quantum well structures is the discrete nature of the allowed states, which means that inversion of the medium can be obtained for very low electron densities. This has led to the fabrication of quantum dot lasers with record......-low threshold currents and amplifiers with record-high power levels. In this tutorial we will review the basic properties of quantum dots, emphasizing the properties which are important for laser and amplifier applications, as well as devices for all-optical signal processing. The high-speed properties...

  3. Effects of unwanted feedback on synchronized chaotic optical communications.

    Science.gov (United States)

    Li, Xiaofeng; Pan, Wei; Luo, Bin; Ma, Dong

    2006-04-10

    The effects of unwanted external optical feedback on synchronized chaotic optical communication systems are studied numerically. We consider an open-loop configuration consisting of a transmitter laser with double external optical feedbacks and a receiver laser with optical injection from the transmitter laser. First, including the effects of unwanted optical feedback, the synchronization performances of both the complete synchronization and the generalized synchronization are examined. Then the encoding and decoding performances of the generalized synchronization and the effects of the introduced feedback are investigated, respectively. Finally, we study the control of the unwanted feedback on the dynamics of the transmitter laser and briefly discuss the system security when the transmitter laser is driven to operate in a steady state or periodic oscillation state by the additional feedback.

  4. The 2004 Latsis Symposium: Quantum optics for Communication and Computing

    CERN Multimedia

    2004-01-01

    1-3 March 2004 Ecole Polytechnique Fédérale de Lausanne Auditoire SG1 The field of Quantum Optics covers topics that extend from basic physical concepts, regarding the quantum description of light, matter, and light-matter interaction, to the applications of these concepts in future information and communication technologies. This field is of primary importance for science and society for two reasons. Firstly, it brings a deeper physical understanding of the fundamental aspects of modern quantum physics. Secondly, it offers perspectives for the invention and implementation of new devices and systems in the fields of communications, information management and computing. The themes that will be addressed in the Latsis Symposium on Quantum Optics are quantum communications, quantum computation, and quantum photonic devices. The objective of the symposium is to give an overview of this fascinating and rapidly evolving field. The different talks will establish links between new fundamental c...

  5. The 2004 Latsis Symposium: Quantum optics for Communication and Computing

    CERN Multimedia

    2004-01-01

    1-3 March 2004 Ecole Polytechnique Fédérale de Lausanne Auditoire SG1 The field of Quantum Optics covers topics that extend from basic physical concepts, regarding the quantum description of light, matter, and light-matter interaction, to the applications of these concepts in future information and communication technologies. This field is of primary importance for science and society for two reasons. Firstly, it brings a deeper physical understanding of the fundamental aspects of modern quantum physics. Secondly, it offers perspectives for the invention and implementation of new devices and systems in the fields of communications, information management and computing. The themes that will be addressed in the Latsis Symposium on Quantum Optics are quantum communications, quantum computation, and quantum photonic devices. The objective of the symposium is to give an overview of this fascinating and rapidly evolving field. The different talks will establish links between new fundamental ...

  6. The 2004 Latsis Symposium: Quantum optics for Communication and Computing

    CERN Multimedia

    2004-01-01

    1-3 March 2004 Ecole Polytechnique Fédérale de Lausanne Auditoire SG1 The field of Quantum Optics covers topics that extend from basic physical concepts, regarding the quantum description of light, matter, and light-matter interaction, to the applications of these concepts in future information and communication technologies. This field is of primary importance for science and society for two reasons. Firstly, it brings a deeper physical understanding of the fundamental aspects of modern quantum physics. Secondly, it offers perspectives for the invention and implementation of new devices and systems in the fields of communications, information management and computing. The themes that will be addressed in the Latsis Symposium on Quantum Optics are quantum communications, quantum computation, and quantum photonic devices. The objective of the symposium is to give an overview of this fascinating and rapidly evolving field. The different talks will establish links between new fundamental...

  7. Effectiveness of adaptive optics system in satellite-to-ground coherent optical communication.

    Science.gov (United States)

    Jian, Huang; Ke, Deng; Chao, Liu; Peng, Zhang; Dagang, Jiang; Zhoushi, Yao

    2014-06-30

    Adaptive optics (AO) systems can suppress the signal fade induced by atmospheric turbulence in satellite-to-ground coherent optical communication. The lower bound of the signal fade under AO compensation was investigated by analyzing the pattern of aberration modes for a one-stage imaging AO system. The distribution of the root mean square of the residual aberration is discussed on the basis of the spatial and temporal characteristics of the residual aberration of the AO system. The effectiveness of the AO system for improving the performance of coherent optical communication is presented in terms of the bit error rate and system availability.

  8. Secure Communication System Basedon Chaosin Optical Fibre

    Institute of Scientific and Technical Information of China (English)

    Pak L Chu; Fan Zhang; William Mak; Robust Lai

    2003-01-01

    @@ 1 Introduction Recently, there have been intense research activities on the study of synchronized chaos generated by fibre lasers [1] and its application to secure communication systems . So far, all studies concentrate on two aspects:[2].So far,all studies concentrate on two aspects:(1) the effect of the transmission channel between the transmitter and the receiver has been neglected, and (2)the chaos and the signal are carried by one wavelength.Both theoretical and experimental investigations make these two assumptions. In the experiments, the transmission fibre is invariably short, in the order of tens of metres. Hence its dispersion and nonlinear effects are negligible. The fibre laser responsible for the generation of chaos is often designed to lase at one wavelength only.

  9. Design Reference Missions for Deep-Space Optical Communication

    Science.gov (United States)

    Breidenthal, J.; Abraham, D.

    2016-05-01

    We examined the potential, but uncertain, NASA mission portfolio out to a time horizon of 20 years, to identify mission concepts that potentially could benefit from optical communication, considering their communications needs, the environments in which they would operate, and their notional size, weight, and power constraints. A set of 12 design reference missions was selected to represent the full range of potential missions. These design reference missions span the space of potential customer requirements, and encompass the wide range of applications that an optical ground segment might eventually be called upon to serve. The design reference missions encompass a range of orbit types, terminal sizes, and positions in the solar system that reveal the chief system performance variables of an optical ground segment, and may be used to enable assessments of the ability of alternative systems to meet various types of customer needs.

  10. High-speed analog fiber optic links for satellite communication

    Science.gov (United States)

    Daryoush, A. S.; Herczfeld, P. R.; Kunath, R. R.

    1988-01-01

    Large-aperture phased array antennas operating at millimeter wave frequencies are designed for space-based communications and imaging. Array elements are comprised of active transmit/receive (T/R) modules which are linked to the central processing unit through a high-speed fiberoptic network. This paper demonstrates optical control of active modules for satellite communication at 24 GHz. An approach called T/R level data mixing, which utilizes fiberoptic transmission of a data signal to individual T/R modules to be upconverted by an optically synchronized local oscillator, is demonstrated at 24 GHz. A free-running HEMT oscillator, used as local oscillator at 24 GHz, is synchronized using indirect subharmonic optical injection locking over a locking range of 14 MHz. Results of data link performance over 500-1000 MHz is also reported in terms of gain-bandwidth, linearity and third-order intercept, sensitivity, and dynamic range.

  11. Quantum dot devices for optical communications

    DEFF Research Database (Denmark)

    Mørk, Jesper

    2005-01-01

    Semiconductor quantum dots are often described as "artificial atoms": They are small nanometre-sized structures in which electrons only are allowed to exist at certain discrete levels due to size quantization, thus allowing the engineering of fundamental properties such as the coupling to light....... The main property of semiconductor quantum dots compared to bulk material or even quantum well structures is the discrete nature of the allowed states, which means that inversion of the medium can be obtained for very low electron densities. This has led to the fabrication of quantum dot lasers with record......-low threshold currents and amplifiers with record-high power levels. In this tutorial we will review the basic properties of quantum dots, emphasizing the properties which are important for laser and amplifier applications, as well as devices for all-optical signal processing. The high-speed properties...

  12. Compact and Economical MMI Optical Power Splitter for Optical Communication

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A 1 X 8 GaAs/GaAlAs optical power splitter based on a MultiMode Interference (MMI) coupler is presented. The input and output single mode waveguides are optimized by the Discrete Spectral Index Method (DSIM) and a moderate square spot on the output in deepetched rib waveguides is obtained. The fabrication tolerance has been analyzed by the Finite Difference Beam Propagation Method (FDBPM). The device was fabricated by the dry etching technique and the near-field output obtained. The device shows polarization-insensitive, large fabrication tolerance, low theoretical excess loss and low power imbalance.

  13. Optical Filters, Modulators and Interconnects for Optical Communication Systems

    Science.gov (United States)

    Han, Sang-Kook

    This dissertation describes the theoretical and experimental studies on the guided wave optical devices in the InGaAlAs/InP material system and the integration of the optical devices which utilize single quantum well (SQW) as well as multi-quantum well (MQW) structures. This study encompasses the fabrication and characterization of passive ridge waveguides, efficient phase modulators using the quadratic electro-optic effect, as well as efficient, narrow bandwidth wavelength filters. For the purpose of the monolithic integration of an SQW laser diode with an MQW modulator in GaAs/AlGaAs without a complex regrowth process, an impurity-induced layer disordering (IILD) technique is used to facilitate a novel tapered waveguide interconnect structure. The narrow bandwidth and widely tunable wavelength filters are essential for the implementation of highly dense wavelength-division-multiplexers/demultiplexers (WDM) in multi-wavelength optical networks and systems. The vertically stacked directional coupler structure wavelength filter device operating at 1.55 μm which permits the maximum asymmetry possible in directional coupler devices to achieve a narrow bandwidth is presented. The quaternary InGaAlAs layers grown on InP substrate are used and it facilitates larger tunability due to material dispersion. The spectral index method and coupled mode theory are used for theoretical calculations of the filter response. The characteristics of the filter are measured and the tunability of the device is discussed. An array of many filters with different center wavelength in a single chip is studied and a relatively broad range of center wavelength is easily obtained by a small variation in the design of the structure. To achieve an integration of a high gain SQW laser diode and an MQW electroabsorption intensity modulator with a high on/off ratio, we utilize a tapered waveguide interconnect using an IILD technique which permits transfer of the energy generated in an SQW laser

  14. Hyperbolic-metamaterial antennas for broadband enhancement of dipole emission to free space

    Energy Technology Data Exchange (ETDEWEB)

    Valagiannopoulos, C. A. [Department of Radio Science and Engineering, School of Electrical Engineering, Aalto University, P.O. Box 13000, FI-00076 Aalto (Finland); Department of Electrical and Computer Engineering, University of Texas at Austin, 1616 Guadalupe St., Texas 78712 (United States); Mirmoosa, M. S.; Nefedov, I. S.; Tretyakov, S. A.; Simovski, C. R. [Department of Radio Science and Engineering, School of Electrical Engineering, Aalto University, P.O. Box 13000, FI-00076 Aalto (Finland)

    2014-10-28

    Dipole emitters used in nano optics and nanophotonics (e.g., fluorescent molecules or quantum dots) are weak radiators and thus detecting the radiation of a single emitter gets possible only if it is significantly enhanced. For this enhancement, one often utilizes resonant nanoantennas (Purcell's effect); this method, however, requires the exact knowledge of source location and radiation frequency which constitute a significant drawback. One known possibility for broadband location-insensitive radiation enhancement is to use a layer of the so-called hyperbolic metamaterial. However, the enhanced radiated energy is mainly directed into the volume of the lossy medium, where it is lost to heating. In this work, we suggest specific shapes of macroscopic hyperbolic metamaterial samples to open radiation windows for enhanced radiation to free space. We show that hyperbolic media slabs with properly shaped macroscopic grooves convert the evanescent waves produced by a dipole into waves traveling in free space, which results in the enhancement of useful radiation by one to two orders of magnitude. That level of enhancement of radiation into free-space which is also wideband and of non-resonant nature has not been reported up to now. These results may open possibilities for realization of broadband and directive antennas, where the primary radiators are randomly positioned fluorescent molecules or quantum dots.

  15. Fiber Optic Infrastructure for Wireless Communication Networks

    Science.gov (United States)

    Lau, Kam Y.; Cutrer, David M.; Georges, John B.; Yeung, Simon

    It is clear that to meet the new demands of wireless customers, conventional cellular service providers and upcoming Personal Communication Service (PCS) providers for conventional phone service and high bandwidth wireless LAN must upgrade their networks to provide complete radio coverage. This evolution has motivated the need for low-cost systems that transport radio signals to and from areas of poor signal coverage. The most important area where this problem must be solved is inside of buildings, since this is where people spend most of their time. Unfortunately, the in-building environment is also the most challenging area to provide radio coverage due to severe attenuation and multi-path effects. The problem must be tackled from the viewpoint of optimization of performance/cost ratio of the network. In this paper, we describe a system-level approach to tackle this problem. We demonstrate how one can trade-off hardware performance, which represent cost, with proper choice of system architecture which includes, among other factors, in-building radio environment, to arrive at an optimum network solution technically and economically.

  16. Identifying free space in a robot bird-eye view

    NARCIS (Netherlands)

    Maillette de Buy Wenniger, G.E.; Schmits, T.; Visser, A.; Petrović, I.; Lilienthal, A.J.

    2009-01-01

    Free space detection based on visual clues is an upcoming approach in robotics. Our working domain is the Virtual Rescue League of the RoboCup. In this domain efficient obstacle avoidance is crucial to find victims under challenging conditions. In this study a machine-learning approach is applied to

  17. Wavelength-Multiplexed Solitons in Optical Communications Networks.

    Science.gov (United States)

    Benner, Alan Frederic

    1992-01-01

    Solitons in optical fibers have proved exceedingly useful for counteracting dispersive pulse spreading in ultra-long distance data transmission in optical fibers. However, optical solitons have only been used for point-to-point communication, and have only utilized 1 [ THz] transmission bandwidth available in low-loss optical fiber. An extremely promising proposed system architecture for high-capacity multi-node communication utilizes generation, transmission, and detection of ensembles of pulses denoting data packets, encoded at 1 bit per wavelength. The use of optical solitons in such a wavelength-multiplexed packet switching network promises extremely high long distance capacity, but is complicated by nonlinear interactions between solitons during transmission. We investigate the generation, propagation, and detection of wavelength multiplexed optical soliton data packets through a combination of theoretical analysis utilizing the Inverse Scattering Transform technique, computational numerical analysis, and laboratory experimentation. The optical waveform envelopes evolve by the Nonlinear Schrodinger equation, an integrable nonlinear partial differential equation. There exists an invariant parameter domain, termed the scattering domain, which is nonlinearly related to the spatial domain, where the parameters describing a nonlinear evolving waveform either evolve linearly with time or are constant. Data may therefore be encoded upon these invariant parameters for transmission and effective detection. Through a series of four techniques, ranging from purely theoretical and exact to approximate and highly practical, we demonstrate that, given the expected restrictions on possible pulse parameters for optical communications systems, the information denoted by an ensemble of strongly interacting, wavelength-multiplexed solitons may be extracted from the frequency domain data for the waveform. This demonstrates that it is quite feasible to use solitons for long

  18. Holographic optical receiver front end for wireless infrared indoor communications.

    Science.gov (United States)

    Jivkova, S; Kavehrad, M

    2001-06-10

    Multispot diffuse configuration (MSDC) for indoor wireless optical communications, utilizing multibeam transmitter and angle diversity detection, is one of the most promising ways of achieving high capacities for use in high-bandwidth islands such as classrooms, hotel lobbies, shopping malls, and train stations. Typically, the optical front end of the receiver consists of an optical concentrator to increase the received optical signal power and an optical bandpass filter to reject the ambient light. Using the unique properties of holographic optical elements (HOE), we propose a novel design for the receiver optical subsystem used in MSDC. With a holographic curved mirror as an optical front end, the receiver would achieve more than an 10-dB improvement in the electrical signal-to-noise ratio compared with a bare photodetector. Features such as multifunctionality of the HOE and the receiver's small size, light weight, and low cost make the receiver front end a promising candidate for a user's portable equipment in broadband indoor wireless multimedia access.

  19. Experimental multiplexing of quantum key distribution with classical optical communication

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Liu-Jun; Chen, Luo-Kan; Ju, Lei [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Xu, Mu-Lan; Zhao, Yong [Quantum Communication Technology Co., Ltd., Anhui, Hefei, Anhui 230088 (China); Chen, Kai; Chen, Zeng-Bing; Chen, Teng-Yun, E-mail: tychen@ustc.edu.cn; Pan, Jian-Wei [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-02-23

    We demonstrate the realization of quantum key distribution (QKD) when combined with classical optical communication, and synchronous signals within a single optical fiber. In the experiment, the classical communication sources use Fabry-Pérot (FP) lasers, which are implemented extensively in optical access networks. To perform QKD, multistage band-stop filtering techniques are developed, and a wavelength-division multiplexing scheme is designed for the multi-longitudinal-mode FP lasers. We have managed to maintain sufficient isolation among the quantum channel, the synchronous channel and the classical channels to guarantee good QKD performance. Finally, the quantum bit error rate remains below a level of 2% across the entire practical application range. The proposed multiplexing scheme can ensure low classical light loss, and enables QKD over fiber lengths of up to 45 km simultaneously when the fibers are populated with bidirectional FP laser communications. Our demonstration paves the way for application of QKD to current optical access networks, where FP lasers are widely used by the end users.

  20. Engineering trade studies for a quantum key distribution system over a 30  km free-space maritime channel.

    Science.gov (United States)

    Gariano, John; Neifeld, Mark; Djordjevic, Ivan

    2017-01-20

    Here, we present the engineering trade studies of a free-space optical communication system operating over a 30 km maritime channel for the months of January and July. The system under study follows the BB84 protocol with the following assumptions: a weak coherent source is used, Eve is performing the intercept resend attack and photon number splitting attack, prior knowledge of Eve's location is known, and Eve is allowed to know a small percentage of the final key. In this system, we examine the effect of changing several parameters in the following areas: the implementation of the BB84 protocol over the public channel, the technology in the receiver, and our assumptions about Eve. For each parameter, we examine how different values impact the secure key rate for a constant brightness. Additionally, we will optimize the brightness of the source for each parameter to study the improvement in the secure key rate.

  1. Multi-platform laser communication networking optical antenna system design

    Science.gov (United States)

    Zhang, Tao

    2016-10-01

    In this paper, a new conclusion based on rotating parabolic model and a different scheme of laser communication networking antenna system has been put forward in the paper. Based on rotating parabolic antenna, a new theory of the optical properties have been deduced, which can realize larger dynamic, duplex, networking communications among multiple platforms in 360° azimuth and pitch range. Meanwhile, depending on the operation mode of the system, multiple mathematical optimization models have been established. Tracking communication range, emission energy efficiency and receiving energy efficiency have been analyzed and optimized. Relationship among opening up and low apertures, the lens unit aperture, focal length of lens unit as well as rotating parabolic focal length have been analyzed. Tracking pitching range and emission energy utilization has carried on the theoretical derivation and optimization and networking platform link between energy receiver and transmitter has been analyzed. Taking some parameters of this new system into calculation, optimized results can be utilized with MATLAB software for its application and system of communication engineering. The rotating parabolic internal can form a hollow structure, which is utilized for miniaturization, light-weighted design and realize duplex communication in a wide range and distance. Circular orbit guidance is the modern way used in dynamic tracking system. The new theory and optical antenna system has widespread applications value as well.

  2. Optical PPM-CDMA Communication System with Optical Hard-Limiter

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An optical PPM-CDMA communication system with an opticalhard-limiter in front of the correlator of a receiver is proposed in order to reduce multi-user interference. The performance of the system is evaluated when the effects of both multi-user interference and photo detector shot noise are considered. An upper bound on the bit error rate is derived. The comparison of the performance of the above receiver with that of the optical PPM-CDMA system without an optical hard-limiter is made. Simulation results show that the performance of the system with an optical hard-limiter is superior to that of the conventional one.

  3. Optical Communication for Coping the UAS Data Deluge

    Science.gov (United States)

    Griethe, Wolfgang; Heine, Frank; Seel, Stefan; Alberty, Thomas

    2012-08-01

    Hardly any technology has retained a greater recovery in recent years than that of the Unmanned Aerial Systems (UAS). The rationale for this is manifold. UAS are currently operated by many countries around the world. Upcoming sensors and raised numbers of operated vehicles create an increased bandwidth demand for Unmanned Aerial Vehicle (UA V) to ground communication bandwidth in the near future, exceeding currently installed RF communication capabilities. A high bandwidth optical link between an above-the-weather UAV and a GEO spacecraft offers a secure, jamming resistant, non-ITU regulated alternative to existing and envisaged Ku- and Ka- band UAV data and TM/TC links.

  4. Continuous variable quantum communication with bright entangled optical beams

    Institute of Scientific and Technical Information of China (English)

    XIE Chang-de; ZHANG Jing; PAN Qing; JIA Xiao-jun; PENG Kun-chi

    2006-01-01

    In this paper,we briefly introduce the basic concepts and protocols of continuous variable quantum communication,and then summarize the experimental researches accomplished by our group in this field.The main features of quantum communication systems used in our experiments are:(1) The bright entangled optical beams with the anticorrelated amplitude quadratures and the correlated phase quadratures that serve as the entanglement resources and (2) The Bell-state direct detection systems are utilized in the measurements of quantum entanglement and transmitted signals instead of the usually balanced homodyne detectors.

  5. Optical fiber communication systems with Matlab and Simulink models

    CERN Document Server

    Binh, Le Nguyen

    2014-01-01

    ""This book adds an aspect of programming and simulation not so well developed in other books. It is complete in this sense and enables directly linking the physics of optical components and systems to realistic results.""-Martin Rochette, Associate Professor, McGill University, Quebec, Canada""…this will be an excellent textbook since it has all new development and information on optical communication systems…I think this book can easily replace many other textbooks in this field.""-Massoud Moussavi, California State Polytechnic University-Pomona""The book is well written. It describes the fu

  6. Optical intersatellite links - Application to commercial satellite communications

    Science.gov (United States)

    Paul, D.; Faris, F.; Garlow, R.; Inukai, T.; Pontano, B.; Razdan, R.; Ganz, Aura; Caudill, L.

    1992-01-01

    Application of optical intersatellite links for commercial satellite communications services is addressed in this paper. The feasibility of commercialization centers around basic issues such as the need and derived benefits, implementation complexity and overall cost. In this paper, commercialization of optical ISLs is assessed in terms of the services provided, systems requirements and feasibility of appropriate technology. Both long- and short-range ISLs for GEO-GEO, GEO-LEO and LEO applications are considered. Impact of systems requirements on the payload design and use of advanced technology in reducing its mass, power, and volume requirements are discussed.

  7. Subcarrier Intensity Modulated Optical Wireless Communications:A Survey from Communication Theory Perspective

    Institute of Scientific and Technical Information of China (English)

    Md Zoheb Hassan; Md Jahangir Hossain; Julian Cheng; Victor C M Leung

    2016-01-01

    Subcarrier intensity modulation with direct detection is a modulation/detection technique for optical wireless communication sys⁃tems, where a pre⁃modulated and properly biased radio frequency signal is modulated on the intensity of the optical carrier. The most important benefits of subcarrier intensity modulation are as follows: 1) it does not provide irreducible error floor like the con⁃ventional on⁃off keying intensity modulation with a fixed detection threshold; 2) it provides improved spectral efficiency and sup⁃ports higher order modulation schemes; and 3) it has much less implementation complexity compared to coherent optical wireless communications with heterodyne or homodyne detection. In this paper, we present an up⁃to⁃date review of subcarrier intensity modulated optical wireless communication systems. We survey the error rate and outage performance of subcarrier intensity modu⁃lations in the atmospheric turbulence channels considering different modulation and coding schemes. We also explore different contemporary atmospheric turbulence fading mitigation solutions that can be employed for subcarrier intensity modulation. These solutions include diversity combining, adaptive transmission, relay assisted transmission, multiple⁃subcarrier intensity modulations, and optical orthogonal frequency division multiplexing. Moreover, we review the performance of subcarrier intensity modulations due to the pointing error and synchronization error.

  8. All-optical OFDM network coding scheme for all-optical virtual private communication in PON

    Science.gov (United States)

    Li, Lijun; Gu, Rentao; Ji, Yuefeng; Bai, Lin; Huang, Zhitong

    2014-03-01

    A novel optical orthogonal frequency division multiplexing (OFDM) network coding scheme is proposed over passive optical network (PON) system. The proposed scheme for all-optical virtual private network (VPN) does not only improve transmission efficiency, but also realize full-duplex communication mode in a single fiber. Compared with the traditional all-optical VPN architectures, the all-optical OFDM network coding scheme can support higher speed, more flexible bandwidth allocation, and higher spectrum efficiency. In order to reduce the difficulty of alignment for encoding operation between inter-communication traffic, the width of OFDM subcarrier pulse is stretched in our proposed scheme. The feasibility of all-optical OFDM network coding scheme for VPN is verified, and the relevant simulation results show that the full-duplex inter-communication traffic stream can be transmitted successfully. Furthermore, the tolerance of misalignment existing in inter-ONUs traffic is investigated and analyzed for all-optical encoding operation, and the difficulty of pulse alignment is proved to be lower.

  9. Numerical modelling of multimode fibre-optic communication lines

    Energy Technology Data Exchange (ETDEWEB)

    Sidelnikov, O S; Fedoruk, M P [Novosibirsk State University, Novosibirsk (Russian Federation); Sygletos, S; Ferreira, F [Aston University, England, Birmingham, B4 7ET (United Kingdom)

    2016-01-31

    The results of numerical modelling of nonlinear propagation of an optical signal in multimode fibres with a small differential group delay are presented. It is found that the dependence of the error vector magnitude (EVM) on the differential group delay can be reduced by increasing the number of ADC samples per symbol in the numerical implementation of the differential group delay compensation algorithm in the receiver. The possibility of using multimode fibres with a small differential group delay for data transmission in modern digital communication systems is demonstrated. It is shown that with increasing number of modes the strong coupling regime provides a lower EVM level than the weak coupling one. (fibre-optic communication lines)

  10. Advancing Unmanned Aircraft Sensor Collection and Communication Capabilities with Optical Communications

    Science.gov (United States)

    Lukaczyk, T.

    2015-12-01

    Unmanned aircraft systems (UAS) are now being used for monitoring climate change over both land and seas. Their uses include monitoring of cloud conditions and atmospheric composition of chemicals and aerosols due to pollution, dust storms, fires, volcanic activity and air-sea fluxes. Additional studies of carbon flux are important for various ecosystem studies of both marine and terrestrial environments specifically, and can be related to climate change dynamics. Many measurements are becoming more complex as additional sensors become small enough to operate on more widely available small UAS. These include interferometric radars as well as scanning and fan-beam lidar systems which produce data streams even greater than those of high resolution video. These can be used to precisely map surfaces of the earth, ocean or ice features that are important for a variety of earth system studies. As these additional sensor capabilities are added to UAS the ability to transmit data back to ground or ship monitoring sites is limited by traditional wireless communication protocols. We describe results of tests of optical communication systems that provide significantly greater communication bandwidths for UAS, and discuss both the bandwidth and effective range of these systems, as well as their power and weight requirements both for systems on UAS, as well as those of ground-based receiver stations. We justify our additional use of Delay and Disruption Tolerant Networking (DTN) communication protocols with optical communication methods to ensure security and continuity of command and control operations. Finally, we discuss the implications for receiving, geo-referencing, archiving and displaying data streams from sensors communicated via optical communication to better enable real-time anomaly detection and adaptive sampling capabilities using multiple UAS or other unmanned or manned systems.

  11. Ultra-high-speed serial optical communications: Enabling technologies

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2008-01-01

    This paper will present recently identified and demonstrated key technologies for ultra-high-speed serial communications. Certain key components such as stabilised highly non-linear fibre switches, periodically poled Lithium Niobate devices and semiconductor optical amplifiers will be described...... with demonstrations of 640 Gb/s transmission, clock recovery, demultiplexing, add/drop, wavelength conversion and channel identification. Timing jitter tolerance is addressed through techniques to create flat-top pulses....

  12. Plastic optical fiber serial communications link for distributed control system

    Science.gov (United States)

    Saxena, Piyush; Sharangpani, K. K.; Vora, H. S.; Nakhe, S. V.; Jain, R.; Shenoy, N. M.; Bhatnagar, R.; Shirke, N. D.

    2001-09-01

    One of the most common interface for communications specified is RS 232C standard. Though widely accepted, RS232 has limited transmission speed, range and networking capabilities. RS 422 standard overcomes limitations by using differential signal lines. In automation of the operation of gas discharge lasers, multiple processors are used for control of lasers, cooling system, vacuum system etc. High EMI generated by lasers interfere through galvanic transmission or by radiation over the length of cables, and hang up operation of processors or control PC. A serial communications link was designed eliminating copper transmission media, using plastic optical fiber cables and components, to connect local controllers with the master PC working on RS232 protocols. The paper discusses the design and implementation of a high ly reliable EMI harden serial communications link.

  13. Simulation of a Rowland spectrometer for optical communication over POF

    Science.gov (United States)

    Haupt, M.; Fischer, U. H. P.

    2008-09-01

    Standard polymer optical fibers (POFs) are used in various fields of applications. As a medium for communication systems, they offer many advantages in comparison with copper or glass. POFs are applied for short-distance communication in the automotive. They are also used for communication in the house. All these applications have high demand on bandwidth. Standard communication via POF is limited in bandwidth, because only one wavelength is used to carry information over the fiber. One promising attempt is to use wavelength division multiplexing (WDM). There instead of one wavelength many wavelengths carry information over one single fiber. So WDM over POF has the power to force this limitation. Therefore the design and the development of a demultiplexer, which is required for WDM, will be shown in the paper. The development is done by means of an optical simulation program. This is a fast and inexpensive way to obtain satisfying results. The principle structure of the MUX/DEMUX element is a Rowland spectrometer. This device separates the monochromatic parts of light by means of a high dispersive grating on a mirror. The shape of the mirror and the parameters of the grating have to be developed and optimized in several steps to reach the demands. These process steps will be presented.

  14. Secure communication in fiber optic systems via transmission of broad-band optical noise.

    Science.gov (United States)

    Buskila, O; Eyal, A; Shtaif, M

    2008-03-03

    We propose a new scheme for data encryption in the physical layer. Our scheme is based on the distribution of a broadband optical noise-like signal between Alice and Bob. The broadband signal is used for the establishment of a secret key that can be used for the secure transmission of information by using the one-time-pad method. We characterize the proposed scheme and study its applicability to the existing fiber-optics communications infrastructure.

  15. 4 X 20 Gbit/s mode division multiplexing over free space using vector modes and a q-plate mode (de)multiplexer

    CERN Document Server

    Milione, Giovanni; Huang, Hao; Ren, Yongxiong; Xie, Guodong; Nguyen, Thien An; Karimi, Ebrahim; Marrucci, Lorenzo; Nolan, Daniel A; Alfano, Robert R; Willner, Alan E

    2014-01-01

    Vector modes are spatial modes that have spatially inhomogeneous states of polarization, such as, radial and azimuthal polarization. They can produce smaller spot sizes and stronger longitudinal polarization components upon focusing. As a result, they are used for many applications, including optical trapping and nanoscale imaging. In this work, vector modes are used to increase the information capacity of free space optical communication via the method of optical communication referred to as mode division multiplexing. A mode (de)multiplexer for vector modes based on a liquid crystal technology referred to as a q-plate is introduced. As a proof of principle, using the mode (de)multiplexer four vector modes each carrying a 20 Gbit/s quadrature phase shift keying signal on a single wavelength channel (~1550nm), comprising an aggregate 80 Gbit/s, were transmitted ~1m over the lab table with <-16.4 dB (<2%) mode crosstalk. Bit error rates for all vector modes were measured at the forward error correction t...

  16. Free-Space Nanometer Wiring via Nanotip Manipulation

    Science.gov (United States)

    Kizuka, Tokushi; Ashida, Shin

    2015-08-01

    Relentless efforts in semiconductor technology have driven nanometer-scale miniaturization of transistors, diodes, and interconnections in electronic chips. Free-space writing enables interconnections of stacked modules separated by an arbitrary distance, leading to ultimate integration of electronics. We have developed a free-space method for nanometer-scale wiring on the basis of manipulating a metallic nanotip while applying a bias voltage without radiative heating, lithography, etching, or electrodeposition. The method is capable of fabricating wires with widths as low as 1-6 nm and lengths exceeding 200 nm with a breakdown current density of 8 TA/m2. Structural evolution and conduction during wire formation were analyzed by direct atomistic visualization using in situ high-resolution transmission electron microscopy.

  17. Detection of free spaces for mobile robot navigation

    Science.gov (United States)

    Azzizi, Norelhouda; Zaatri, Abdelouahab; Rahmani, Fouad Lazhar

    2014-10-01

    This work is situated within the framework of the semi-autonomous and autonomous navigation of mobile robots in unknown environments with obstacles occurrence. It is based on the implementation of a vision-based system using an embedded monocular CCD camera. The vision system is designed to dynamically determine the free space in which the robot can move without obstacle collisions. This system is composed of a sequel of image processing operations: contour detection by Canny's filter, connection of neighborhood pixels, elimination of small contours which are considered as noise. The free space is determined by analyzing the perceived area and checking the presence of obstacles. Finally, obstacle borders are delimited enabling to prevent obstacles. Some experimental results are presented to illustrate the effective possibility of use of our system.

  18. Interaction of two edge dislocations in free-space propagation

    Institute of Scientific and Technical Information of China (English)

    He De; Gao Zeng-Hui; Yan Hong-Wei; Lü Bai-Da

    2011-01-01

    This paper studies in detail the interaction of two edge dislocations nested in a Gaussian beam propagating in free space. It shows that in free-space propagation the edge dislocations are unstable and vanish, and two noncanonical vortices with opposite topological charge take place when off-axis distances c1 and c2 of two edge dislocations are nonzero, and the condition k2w80 + 32c1c2(w20 - 2c1c2)z2 > 0 is fulfilled (k-wave number, w0-waist width). A noncanonical vortex appears when one off-axis distance is zero. However, one edge dislocation is stable when two edge dislocations are perpendicular and one off-axis distance is zero. Two perpendicular edge dislocations both with zero off-axis distance are also stable. The analytical results are illustrated by numerical examples.

  19. Stokes-vector direct detection for optical communications

    Science.gov (United States)

    Shieh, William; Li, An; Che, Di; Yuan, Feng; Khodakarami, Hamid

    2017-01-01

    To cope with the exponential growth of the Internet traffic, optical communications has advanced by leaps and bounds. For several decades, Intensity modulation with direct detection (IM-DD) dominates the commercial short-reach optical communications. However, when upgrading the data-rate distance product to 1000 Gb/s·km per wavelength and beyond, IM-DD faces severe performance barrier. Aiming to improve the electrical SE and extend the transmission distance, advanced DD modulation formats have been proposed through a so-called self-coherent (SCOH) approach, where a carrier is transmitted together with the signal to achieve a linear mapping between the electrical baseband signal and the optical field. In that way, the impact of the CD can be removed from the received signal, greatly extending the transmission distance of the DD system. Particularly, Stokes-vector direct detection (SV-DD) has been proposed to realize linear complex optical channels as well as enhance the electrical spectral efficiency and transmission reach. In this talk, we present the principle and discuss the performance of SV-DD systems.

  20. Data acquisition remote node powered over the communications optical fiber

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Antonio J.N., E-mail: toquim@ipfn.tecnico.ulisboa.pt; Sousa, Jorge; Gonçalves, Bruno

    2015-10-15

    Large nuclear fusion reactors, like ITER, will have harsh electromagnetic environments nearby the machine. Foreseeing the necessity for special data acquisition remote nodes, on difficult access locations and as close as possible to the experimental devices, motivated the system design. The architecture is based on the power-over-fiber technology recent advancements and respective implementation aim is to attain a proof of concept for the fusion technology field and others, e.g., high energy physics, industry, etc. The design intends the replacement of traditional copper cables and power supplies, vulnerable to electromagnetic interference, by the communications optical fiber of the data acquisition remote node. Optical fibers provide galvanic isolation, immunity to noisy electromagnetic environments and simultaneously can supply power to the remote node electronics. System architecture uses a laser power converter (array of photovoltaic cells) to convert the laser light, from the optical fiber, into electricity. The generated electrical power is enough for powering the remote node electronics and optoelectronics, such as an ADC, a low power FPGA and an optical transmitter. The laser power converter is also used as the communications receiver and from which the acquisition clock is recovered, providing synchronism between remote data acquisition nodes. Descriptions of the system architecture, tested implementations and future improvements are presented.