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Sample records for cavity-enhanced optical frequency

  1. Cavity-enhanced optical frequency combspectroscopy

    DEFF Research Database (Denmark)

    Balslev-Clausen, David Morten; Thorpe, M. J.; Kirchner, M. S.;

    2008-01-01

    Broad-bandwidth, high-spectral-resolution optical detection of human breath has identified multiple important biomarkers correlated with specific diseases and metabolic processes. This optical-frequency-comb-based breath analysis system comes with excellent performance in all criteria: high...

  2. Signal line shapes of Fourier transform cavity-enhanced frequency modulation spectroscopy with optical frequency combs

    CERN Document Server

    Johansson, Alexandra C; Khodabakhsh, Amir; Foltynowicz, Aleksandra

    2016-01-01

    We present a thorough analysis of the signal line shapes of Fourier transform-based noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS). We discuss the signal dependence on the ratio of the modulation frequency, f${_m}$, to the molecular line width, {\\Gamma}. We compare a full model of the signals and a simplified absorption-like analytical model that has high accuracy for low f${_m}$/{\\Gamma} ratios and is much faster to compute. We verify the theory experimentally by measuring and fitting NICE-OFCS spectra of CO${_2}$ at 1575 nm using a system based on an Er:fiber femtosecond laser and a cavity with a finesse of ~11000.

  3. Continuous Vernier filtering of an optical frequency comb for broadband cavity-enhanced molecular spectroscopy

    CERN Document Server

    Rutkowski, Lucile

    2016-01-01

    We have recently introduced the Vernier-based Direct Frequency Comb Cavity-Enhanced Spectroscopy technique and we present the corresponding formalism for quantitative broadband spectroscopy. We achieve high sensitivity and broadband performance by acquiring spectra covering more than 2000 cm$^{-1}$ around 12600 cm$^{-1}$ (800 nm), resolving the 3$\

  4. Characteristic analysis of the optical delay in frequency response of resonant cavity enhanced (RCE) photodetectors

    Institute of Scientific and Technical Information of China (English)

    Guo Jian-Chuan; Zuo Yu-Hua; Zhang Yun; Ding Wu-Chang; Cheng Bu-Wen; Yu Jin-Zhong; Wang Qi-Ming

    2009-01-01

    With consideration of the modulation frequency of the input lightwave itself, we present a new model to calculate the quantum efficiency of RCE p-i-n photodetectors (PD) by superimposition of multiple reflected lightwaves. For the first time, the optical delay, another important factor limiting the electrical bandwidth of RCE p-i-n PD excluding the transit time of the carriers and RCd response of the photodetector, is analyzed and discussed in detail. The optical delay dominates the bandwidth of RCE p-i-n PD when its active layer is thinner than several 10 nm. These three limiting factors must be considered exactly for design of ultra-high-speed RCE p-i-n PD.

  5. Noise-immune cavity-enhanced optical frequency comb spectroscopy: A sensitive technique for high-resolution broadband molecular detection

    CERN Document Server

    Khodabakhsh, Amir; Foltynowicz, Aleksandra

    2014-01-01

    Noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS) is a recently developed technique that utilizes phase modulation to obtain immunity to frequency-to-amplitude noise conversion by the cavity modes and yields high absorption sensitivity over a broad spectral range. We describe the principles of the technique and discuss possible comb-cavity matching solutions. We present a theoretical description of NICE-OFCS signals detected with a Fourier transform spectrometer (FTS), and validate the model by comparing it to experimental CO2 spectra around 1575 nm. Our system is based on an Er:fiber femtosecond laser locked to a cavity and phase-modulated at a frequency equal to a multiple of the cavity free spectral range (FSR). The NICE-OFCS signal is detected by a fast-scanning FTS equipped with a high-bandwidth commercial detector. We demonstrate a simple method of passive locking of the modulation frequency to the cavity FSR that significantly improves the long term stability of the system, a...

  6. Human breath analysis via cavity-enhanced optical frequency comb spectroscopy

    CERN Document Server

    Thorpe, Michael J; Kirchner, Matthew S; Ye, Jun

    2007-01-01

    To date, researchers have identified over 1000 different compounds contained in human breath. These molecules have both endogenous and exogenous origins and provide information about physiological processes occurring in the body as well as environment-related ingestion or absorption of contaminants1,2. While the presence and concentration of many of these molecules are poorly understood, many 'biomarker' molecules have been correlated to specific diseases and metabolic processes. Such correlations can result in non-invasive methods of health screening for a wide variety of medical conditions. In this article we present human breath analysis using an optical-frequency-comb-based trace detection system with excellent performance in all criteria: detection sensitivity, ability to identify and distinguish a large number of biomarkers, and measurement time. We demonstrate a minimum detectable absorption of 8 x 10-10 cm-1, a spectral resolution of 800 MHz, and 200 nm of spectral coverage from 1.5 to 1.7 micron wher...

  7. Cavity-Enhanced Frequency-Agile Rapid Scanning (fars) Spectroscopy: Measurement Principles

    Science.gov (United States)

    Hodges, Joseph T.; Long, David A.; Truong, Gar-Wing; Douglass, Kevin O.; Maxwell, Stephen E.; Zee, Roger Van; Plusquellic, David F.

    2013-06-01

    We present the principles of frequency-agile, rapid scanning (FARS) spectroscopy, a new technique for high-bandwidth, cavity-enhanced, laser absorption measurements. This method enables a visible or near-infrared probe laser beam to be frequency tuned over several tens of GHz using a microwave source, a waveguide phase modulator and a filter cavity. For the types of cavity-enhanced methods discussed here, the optical resonator itself is used to select a single sideband of the modulated laser spectrum, obviating the need for a separate filter cavity. FARS offers several important advantages over conventional cw laser tuning methods based on thermal or mechanical methods. These include, high speed tuning with sub-ms switching times, the ability to select arbitrary frequency steps or chirp rates, and the realization of a spectrum detuning axis with sub-kHz level precision. We discuss how FARS can be applied to cavity ring-down spectroscopy and other cavity-enhanced methods to enable rapid and accurate measurements of line parameters and to give noise-equivalent absorption coefficients at the 10^{-12} cm^{-1} Hz^{-1/2} level.

  8. Optical re-injection in cavity-enhanced absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Leen, J. Brian, E-mail: b.leen@lgrinc.com; O’Keefe, Anthony [Los Gatos Research, 67 E. Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)

    2014-09-15

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  9. Cavity-enhanced spectroscopies

    CERN Document Server

    van Zee, Roger

    2003-01-01

    ""Cavity-Enhanced Spectroscopy"" discusses the use of optical resonators and lasers to make sensitive spectroscopic measurements. This volume is written by the researcchers who pioneered these methods. The book reviews both the theory and practice behind these spectroscopic tools and discusses the scientific discoveries uncovered by these techniques. It begins with a chapter on the use of optical resonators for frequency stabilization of lasers, which is followed by in-depth chapters discussing cavity ring-down spectroscopy, frequency-modulated, cavity-enhanced spectroscopy, intracavity spectr

  10. Cavity-enhanced optical detection of carbon nanotube Brownian motion

    CERN Document Server

    Stapfner, S; Hunger, D; Weig, E M; Reichel, J; Favero, I

    2012-01-01

    Optical cavities with small mode volume are well-suited to detect the vibration of sub-wavelength sized objects. Here we employ a fiber-based, high-finesse optical microcavity to detect the Brownian motion of a freely suspended carbon nanotube at room temperature under vacuum. The optical detection resolves deflections of the oscillating tube down to 50pm/Hz^1/2. A full vibrational spectrum of the carbon nanotube is obtained and confirmed by characterization of the same device in a scanning electron microscope. Our work successfully extends the principles of high-sensitivity optomechanical detection to molecular scale nanomechanical systems.

  11. Cavity-enhanced single frequency synthesis via DFG of mode-locked pulse trains

    OpenAIRE

    Ferrari, Gabriele; Carusotto, Iacopo

    2005-01-01

    We show how to synthesize a CW, single-frequency optical field from the frequency-dispersed, pulsed field of a mode-locked laser. This process, which relies on difference frequency generation in an optical cavity, is efficient and can be considered as an optical rectification. Quantitative estimates for the output power and amplitude noise properties of a realistic system are given. Possible applications to optical frequency synthesis and optical metrology are envisaged.

  12. Walk-off-induced modulation instability, temporal pattern formation, and frequency comb generation in cavity-enhanced second-harmonic generation

    CERN Document Server

    Leo, F; Ricciardi, I; De Rosa, M; Coen, S; Wabnitz, S; Erkintalo, M

    2016-01-01

    We derive a time-domain mean-field equation to model the full temporal and spectral dynamics of light in singly resonant cavity-enhanced second-harmonic generation systems. We show that the temporal walk-off between the fundamental and the second-harmonic fields plays a decisive role under realistic conditions, giving rise to rich, previously unidentified nonlinear behaviour. Through linear stability analysis and numerical simulations, we discover a new kind of quadratic modulation instability which leads to the formation of optical frequency combs and associated time-domain dissipative structures. Our numerical simulations show excellent agreement with recent experimental observations of frequency combs in quadratic nonlinear media [Phys. Rev. A 91, 063839 (2015)]. Thus, in addition to unveiling a new, experimentally accessible regime of nonlinear dynamics, our work enables predictive modeling of frequency comb generation in cavity-enhanced second-harmonic generation systems.

  13. Cavity-enhanced parity-nonconserving optical rotation in metastable Xe and Hg.

    Science.gov (United States)

    Bougas, L; Katsoprinakis, G E; von Klitzing, W; Sapirstein, J; Rakitzis, T P

    2012-05-25

    We propose the measurement of cavity-enhanced parity-nonconserving (PNC) optical rotation in several transitions of metastable Xe and Hg, including Xe (2P(3/2)(o))6s(2)[3/2](2)(o)→(2P(1/2)(o))6s(2)[1/2](1)(o) and Hg 6s6p (3)P(2)(o)→6s6p (1)P(1)(o), with calculated amplitude ratios of E(1)(PNC)/M1=11×10(-8) and 10×10(-8), respectively. We demonstrate the use of a high-finesse bow-tie cavity with counterpropagating beams and a longitudinal magnetic field, which allows the absolute measurement of chiral optical rotation, with a path length enhancement of about 10(4), necessary for PNC measurement from available column densities of 10(14) cm(-2) for metastable Xe or Hg. Rapid PNC-signal reversal, allowing robust background subtraction, is achieved by shifting the cavity resonance to an opposite polarization mode or by inverting the magnetic field. The precise measurement of isotope and nuclear-spin dependent E(1)(PNC) amplitudes provides a sensitive low-energy test of the standard model. PMID:23003234

  14. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    Science.gov (United States)

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

  15. Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS – applicability and corrections

    Directory of Open Access Journals (Sweden)

    D. Pöhler

    2009-11-01

    Full Text Available Atmospheric trace gas measurements by cavity assisted long-path absorption spectroscopy are an emerging technology. An interesting approach is the combination of CEAS with broadband light sources, the broadband CEAS (BB-CEAS. BB-CEAS lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light path by the trace gas absorption, since cavity losses due to absorption by gases reduce the quality (Q of the cavity. In fact, at wavelength, where the quality of the BB-CEAS cavity is dominated by the trace gas absorption (especially at very high mirror reflectivity, the average light path will vary nearly inversely with the trace gas concentration and the strength of the band will become only weakly dependent on the trace gas concentration c in the cavity, (the differential optical density being proportional to the logarithm of the trace gas concentration. Only in the limiting case where the mirror reflectivity determines Q at all wavelength, the strength of the band as seen by the CE-DOAS instrument becomes directly proportional to the concentration c. We investigate these relationships in detail and present methods to correct for the cases between the two above extremes, which are of course the important ones in practice.

  16. A novel instrument for measurements of BrO with LED based Cavity-Enhanced Differential Optical Absorption Spectoscopy

    Science.gov (United States)

    Hoch, D. J.; Buxmann, J.; Sihler, H.; Pöhler, D.; Zetzsch, C.; Platt, U.

    2013-07-01

    The chemistry of the troposphere and specifically the global tropospheric ozone budget is affected by reactive halogen species like Bromine monoxide (BrO) or Chlorine monoxide (ClO). Especially BrO plays an important role in the processes of ozone destruction, disturbance of NOx and HOx chemistry, oxidation of DMS, and the deposition of elementary mercury. In the troposphere BrO has been detected in polar regions, at salt lakes, in volcanic plumes, and in the marine boundary layer. For a better understanding of these processes field measurements as well as reaction-chamber studies are performed. In both cases instruments with high spatial resolution and high sensitivity are necessary. A Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) instrument with an open path measurement cell was designed and applied. For the first time, a CE-DOAS instrument is presented using an UV-LED in the 325-365 nm wavelength range. In laboratory studies, BrO as well as HONO, HCHO, O3, and O4, could be reliable determined at detection limits of 20 ppt for BrO, 9.1 ppb for HCHO, 970 ppt for HONO, and 91 ppb for O3, for five minutes integration time, respectively. The best detection limits were achieved for BrO (11 ppt), HCHO (5.1 ppb), HONO (490 ppt), and O3 (59 ppb) for integration times of 81 min or less. Comparison with established White-System DOAS and O3 monitor demonstrate the reliability of the instrument.

  17. A novel instrument for measurements of BrO with LED based Cavity-Enhanced Differential Optical Absorption Spectoscopy

    Directory of Open Access Journals (Sweden)

    D. J. Hoch

    2013-07-01

    Full Text Available The chemistry of the troposphere and specifically the global tropospheric ozone budget is affected by reactive halogen species like Bromine monoxide (BrO or Chlorine monoxide (ClO. Especially BrO plays an important role in the processes of ozone destruction, disturbance of NOx and HOx chemistry, oxidation of DMS, and the deposition of elementary mercury. In the troposphere BrO has been detected in polar regions, at salt lakes, in volcanic plumes, and in the marine boundary layer. For a better understanding of these processes field measurements as well as reaction-chamber studies are performed. In both cases instruments with high spatial resolution and high sensitivity are necessary. A Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS instrument with an open path measurement cell was designed and applied. For the first time, a CE-DOAS instrument is presented using an UV-LED in the 325–365 nm wavelength range. In laboratory studies, BrO as well as HONO, HCHO, O3, and O4, could be reliable determined at detection limits of 20 ppt for BrO, 9.1 ppb for HCHO, 970 ppt for HONO, and 91 ppb for O3, for five minutes integration time, respectively. The best detection limits were achieved for BrO (11 ppt, HCHO (5.1 ppb, HONO (490 ppt, and O3 (59 ppb for integration times of 81 min or less. Comparison with established White-System DOAS and O3 monitor demonstrate the reliability of the instrument.

  18. An instrument for measurements of BrO with LED-based Cavity-Enhanced Differential Optical Absorption Spectroscopy

    Science.gov (United States)

    Hoch, D. J.; Buxmann, J.; Sihler, H.; Pöhler, D.; Zetzsch, C.; Platt, U.

    2014-01-01

    The chemistry of the troposphere and specifically the global tropospheric ozone budget is affected by reactive halogen species such as bromine monoxide (BrO) or chlorine monoxide (ClO). Especially BrO plays an important role in the processes of ozone destruction, disturbance of NOx and HOx chemistry, oxidation of dimethyl sulfide (DMS), and the deposition of elementary mercury. In the troposphere BrO has been detected in polar regions, at salt lakes, in volcanic plumes, and in the marine boundary layer. For a better understanding of these processes, field measurements as well as reaction chamber studies are performed. In both cases instruments with high spatial resolution and high sensitivity are necessary. A Cavity-Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) instrument with an open path measurement cell was designed and applied. For the first time, a CE-DOAS instrument is presented using an UV LED in the 325-365 nm wavelength range. In laboratory studies, BrO as well as HONO, HCHO, O3, and O4 could be reliably determined at detection limits of 20 ppt for BrO, 9.1 ppb for HCHO, 970 ppt for HONO, and 91 ppb for O3, for five minutes integration time. The best detection limits were achieved for BrO (11 ppt), HCHO (5.1 ppb), HONO (490 ppt), and O3 (59 ppb) for integration times of 81 minutes or less. Comparison with established White system (WS) DOAS and O3 monitor measurements demonstrate the reliability of the instrument.

  19. SPECIES: a versatile spectrometer based on optical-feedback cavity-enhanced absorption for in situ balloon-borne and airborne measurements

    Science.gov (United States)

    Jacquet, Patrick; Catoire, Valery; Robert, Claude; Chartier, Michel; Huret, Nathalie; Desbois, Thibault; Marocco, Nicola; Kassi, Samir; Kerstel, Eric; Romanini, Daniele

    2015-04-01

    Over the last twenty years, thanks to significant technological advances in measurement techniques, our understanding of the chemistry and dynamics of the upper troposphere and stratosphere has progressed significantly. However some key questions remain unsolved, and new ones arise in the changing climate context. The full recovery of the ozone layer and the delay of recovery, the impact of the climate change on the stratosphere and the role of this one as a feedback are almost unknown. To address these challenges, one needs instruments able to measure a wide variety of trace gas species simultaneously with a wide vertical range. In this context, LPC2E and LIPHY are developing a new balloon-borne and airborne instrument: SPECIES (SPECtromètre Infrarouge à lasErs in Situ, i.e. in-Situ Infrared lasEr SPECtrometer). Based on the Optical Feedback Cavity Enhanced Spectroscopy technique, combined with mid-infrared quantum cascade lasers, this instrument will offer unprecedented performances in terms of the vertical extent of the measurements, from ground to the middle stratosphere, and the number of molecular species simultaneously measured with sub-ppb detection limits (among others: NO, N2O, HNO3, H2O2, HCl, HOCl, CH3Cl, COF2, HCHO, HCOOH, O3, NH3 NO2, H2O, OCS, SO2). Due to high frequency measurement (>0.5 Hz) it shall offer very high spatial resolution (a few meters).

  20. Cavity-enhanced ultrafast two-dimensional spectroscopy using higher-order modes

    CERN Document Server

    Allison, Thomas K

    2016-01-01

    We describe methods using frequency combs and optical resonators for recording two-dimensional (2D) ultrafast spectroscopy signals with high sensitivity. By coupling multiple frequency combs to higher-order modes of one or more optical cavities, background-free, cavity-enhanced 2D spectroscopy signals are naturally generated via phase cycling. As in cavity-enhanced ultrafast transient absorption spectroscopy (CE-TAS), the signal to noise is enhanced by a factor proportional to the cavity finesse squared, so even using cavities of modest finesse, a very high sensitivity is expected, enabling ultrafast 2D spectroscopy experiments in dilute molecular beams.

  1. Mid-infrared concentration-modulated noise-immune cavity-enhanced optical heterodyne molecular spectroscopy of a continuous supersonic expansion discharge source

    Science.gov (United States)

    Talicska, Courtney N.; Porambo, Michael W.; Perry, Adam J.; McCall, Benjamin J.

    2016-06-01

    Concentration-modulated noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) is implemented for the first time on a continuous gas-flow pinhole supersonic expansion discharge source for the study of cooled molecular ions. The instrument utilizes a continuous-wave optical parametric oscillator easily tunable from 2.5 to 3.9 μm and demonstrates a noise equivalent absorption of ˜1 × 10-9 cm-1. The effectiveness of concentration-modulated NICE-OHMS is tested through the acquisition of transitions in the ν1 fundamental band of HN2+ centered near 3234 cm-1, with a signal-to-noise of ˜40 obtained for the strongest transitions. The technique is used to characterize the cooling abilities of the supersonic expansion discharge source itself, and a Boltzmann analysis determines a rotational temperature of ˜29 K for low rotational states of HN2+. Further improvements are discussed that will enable concentration-modulated NICE-OHMS to reach its full potential for the detection of molecular ions formed in supersonic expansion discharges.

  2. Long Wave Infrared Cavity Enhanced Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Taubman, Matthew S.; Scott, David C.; Cannon, Bret D.; Myers, Tanya L.; Bonebrake, Christopher A.; Aker, Pam M.; Wojcik, Michael D.; Munley, John T.; Nguyen, Vinh T.; Schultz, John F.

    2004-10-01

    The principal goal of Pacific Northwest National Laboratory's (PNNL's) long wave infrared (LWIR) cavity enhanced sensor (CES) project is to explore ultra-sensitive spectroscopic techniques and apply them to the development of LWIR chemical sensors needed for detecting weapons proliferation. This includes detecting not only the weapons of mass destruction (WMDs) themselves, but also signatures of their production and/or detonation. The LWIR CES project is concerned exclusively with developing point sensors; other portions of PNNL's IR Sensors program address stand off detection. PNNL's LWIR CES research is distinguished from that done by others by the use quantum cascade lasers (QCLs) as the light source. QCLs are novel devices, and a significant fraction of our research has been devoted to developing the procedures and hardware required to implement them most effectively for chemical sensing. This report details the progress we have made on our LWIR CES sensor development. During FY02, PNNL investigated three LWIR CES implementations beginning with the easiest to implement, direct cavity-enhanced detection (simple CES), including a technique of intermediate difficulty, cavity-dithered phase-sensitive detection (FM recovery CES) through to the most complex technique, that of resonant sideband cavity-enhanced detection also known as noise-immune cavity-enhanced optical heterodyne molecular spectroscopy, or NICE-OHMS.

  3. Cavity-enhanced dual-comb spectroscopy

    CERN Document Server

    Bernhardt, Birgitta; Jacquet, Patrick; Jacquey, Marion; Kobayashi, Yohei; Udem, Thomas; Holzwarth, Ronald; Guelachvili, Guy; Hänsch, Theodor W; Picqué, Nathalie

    2009-01-01

    The sensitivity of molecular fingerprinting is dramatically improved when placing the absorbing sample in a high-finesse optical cavity, thanks to the large increase of the effective path-length. As demonstrated recently, when the equidistant lines from a laser frequency comb are simultaneously injected into the cavity over a large spectral range, multiple trace-gases may be identified within a few milliseconds. Analyzing efficiently the light transmitted through the cavity however still remains challenging. Here, a novel approach, cavity-enhanced frequency comb Fourier transform spectroscopy, fully overcomes this difficulty and measures ultrasensitive, broad-bandwidth, high-resolution spectra within a few tens of $\\mu$s. It could be implemented from the Terahertz to the ultraviolet regions without any need for detector arrays. We recorded, within 18 $\\mu$s, spectra of the 1.0 $\\mu$m overtone bands of ammonia spanning 20 nm with 4.5 GHz resolution and a noise-equivalent-absorption at one-second-averaging per ...

  4. Cavity-enhanced frequency doubling from 795nm to 397.5nm ultra-violet coherent radiation with PPKTP crystals in the low pump power regime.

    Science.gov (United States)

    Wen, Xin; Han, Yashuai; Bai, Jiandong; He, Jun; Wang, Yanhua; Yang, Baodong; Wang, Junmin

    2014-12-29

    We demonstrate a simple, compact and cost-efficient diode laser pumped frequency doubling system at 795 nm in the low power regime. In two configurations, a bow-tie four-mirror ring enhancement cavity with a PPKTP crystal inside and a semi-monolithic PPKTP enhancement cavity, we obtain 397.5nm ultra-violet coherent radiation of 35mW and 47mW respectively with a mode-matched fundamental power of about 110mW, corresponding to a conversion efficiency of 32% and 41%. The low loss semi-monolithic cavity leads to the better results. The constructed ultra-violet coherent radiation has good power stability and beam quality, and the system has huge potential in quantum optics and cold atom physics. PMID:25607194

  5. Light emitting diode cavity enhanced differential optical absorption spectroscopy (LED-CE-DOAS): a novel technique for monitoring atmospheric trace gases

    Science.gov (United States)

    Thalman, Ryan M.; Volkamer, Rainer M.

    2009-08-01

    The combination of Cavity Enhanced Absorption Spectroscopy (CEAS) with broad-band light sources (e.g. Light- Emitting Diodes, LEDs) lends itself to the application of cavity enhanced DOAS (CE-DOAS) to perform sensitive and selective point measurements of multiple trace gases with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e., does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0). We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420-490nm) to measure nitrogen dioxide (NO2), glyoxal (CHOCHO), iodine monoxide (IO), water (H2O) and oxygen dimers (O4). Aerosol extinction is retrieved at two wavelengths by means of observing water and O4 and measuring pressure, temperature and relative humidity independently. The instrument components are presented, and the approach to measure aerosol extinction is demonstrated by means of a set of experiments where laboratory generated monodisperse aerosols are added to the cavity. The aerosol extinction cross section agrees well with Mie calculations, demonstrating that our setup enables measurements of the above gases in open cavity mode.

  6. Development of a cavity enhanced aerosol albedometer

    Directory of Open Access Journals (Sweden)

    W. Zhao

    2014-03-01

    Full Text Available We report on the development of a cavity enhanced aerosol single scattering albedometer incorporating incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS approach and an integrating sphere (IS for simultaneous in situ measurements of aerosol scattering and extinction coefficients in the exact same sample volume. The cavity enhanced albedometer employed a blue light-emitting diode (LED based IBBCEAS approach for the measurement of wavelength-resolved aerosol optical extinction over the spectral range of 445–480 nm. An integrating sphere nephelometer coupled to the IBBCEAS setup was used for the measurement of aerosol scattering. The scattering signal was measured with a single channel photomultiplier tube (PMT, providing an integrated value over a narrow bandwidth (FWHM ~ 9 nm in the spectral region of 465–474 nm. A scattering coefficient at a wavelength of 470 nm was deduced as an averaged scattering value and used for data analysis and instrumental performance comparison. Performance evaluation of the albedometer was carried out using laboratory-generated particles and ambient aerosol. The scattering and extinction measurements of monodisperse polystyrene latex (PSL spheres generated in laboratory proved excellent correlation between two channels of the albedometer. The retrieved refractive index (RI from the measured scattering and extinction efficiencies agreed well with the values reported in previously published papers. Aerosol light scattering and extinction coefficients, single scattering albedo (SSA and NO2 concentrations in an ambient sample were directly and simultaneously measured using the developed albedometer. The developed instrument was validated via an intercomparison of the measured aerosol scattering coefficient and NO2 trace concentration against a TSI 3563 integrating nephelometer and a chemiluminescence detector, respectively.

  7. Cavity-enhanced Raman Microscopy of Individual Carbon Nanotubes

    CERN Document Server

    Hümmer, Thomas; Hofmann, Matthias S; Hänsch, Theodor W; Högele, Alexander; Hunger, David

    2015-01-01

    Raman spectroscopy reveals chemically specific information, and combined with imaging provides label-free insight into the molecular world. However, the signals are intrinsically weak and call for enhancement techniques. Here we use a tunable high-finesse optical microcavity to demonstrate Purcell enhancement of Raman scattering in combination with high-resolution scanning-cavity imaging. We detect cavity-enhanced Raman spectra of individual single-walled carbon nanotubes, expand the technique to hyperspectral imaging, and co-localize measurements with cavity-enhanced absorption microscopy. Direct comparison with confocal Raman microscopy yields a 550-times enhanced collectable Raman scattering spectral density and a 11-fold enhancement of the integrated count rate. The quantitative character, the inherent spectral filtering, and the absence of intrinsic background in cavity-vacuum stimulated Raman scattering renders our technique a promising tool for molecular imaging. Furthermore, cavity-enhanced Raman tran...

  8. Development of a cavity enhanced aerosol albedometer

    OpenAIRE

    Zhao, W.; Xu, X.; Dong, M.; Chen, W.; X. Gu; Hu, C; Huang, Y.; Gao, X; Huang, W.; Zhang, W

    2014-01-01

    We report on the development of a cavity enhanced aerosol single scattering albedometer incorporating incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS) approach and an integrating sphere (IS) for simultaneous in situ measurements of aerosol scattering and extinction coefficients in the exact same sample volume. The cavity enhanced albedometer employed a blue light-emitting diode (LED) based IBBCEAS approach for the measurement of wavelength-resolv...

  9. Dilute nitride resonant cavity enhanced photodetector with internal gain for the λ ∼ 1.3 μm optical communications window

    Science.gov (United States)

    Balkan, N.; Erol, A.; Sarcan, F.; Al-Ghuraibawi, L. F. F.; Nordin, M. S.

    2015-10-01

    We report on a novel dilute nitride-based resonant cavity enhanced photodetector (RCEPD) operating at 1.286 μm. The RCEPD was fabricated using 21 pairs top and 24 pairs bottom GaAs/AlGaAs distributed Bragg reflectors for mirrors and 7 nm thick nine GaAs/Ga0.65In0.35N0.02 As0.98 quantum wells as the absorption region. For a 15 μm diameter window, the photocurrent at 1.286 μm is 27 μA and 42 μA, at V = 0 and -1 V, respectively, whereas the dark current is as low as 1.7 nA at -1 V. At the operating wavelength, an excellent wavelength selectivity with a full width at half maximum (FWHM) of 5 nm, and a high quantum efficiency of 43% are demonstrated. The device exhibits significant internal gain at very small reverse bias voltages of V ⩾ -2 V with an overall quantum efficiency of 67%. These are the best ever recorded values for a dilute nitride RCEPD.

  10. New Developments of Broadband Cavity Enhanced Spectroscopic Techniques

    Science.gov (United States)

    Walsh, A.; Zhao, D.; Linnartz, H.; Ubachs, W.

    2013-06-01

    In recent years, cavity enhanced spectroscopic techniques, such as cavity ring-down spectroscopy (CRDS), cavity enhanced absorption spectroscopy (CEAS), and broadband cavity enhanced absorption spectroscopy (BBCEAS), have been widely employed as ultra-sensitive methods for the measurement of weak absorptions and in the real-time detection of trace species. In this contribution, we introduce two new cavity enhanced spectroscopic concepts: a) Optomechanical shutter modulated BBCEAS, a variant of BBCEAS capable of measuring optical absorption in pulsed systems with typically low duty cycles. In conventional BBCEAS applications, the latter substantially reduces the signal-to-noise ratio (S/N), consequently also reducing the detection sensitivity. To overcome this, we incorporate a fast optomechanical shutter as a time gate, modulating the detection scheme of BBCEAS and increasing the effective duty cycle reaches a value close to unity. This extends the applications of BBCEAS into pulsed samples and also in time-resolved studies. b) Cavity enhanced self-absorption spectroscopy (CESAS), a new spectroscopic concept capable of studying light emitting matter (plasma, flames, combustion samples) simultaneously in absorption and emission. In CESAS, a sample (plasma, flame or combustion source) is located in an optically stable cavity consisting of two high reflectivity mirrors, and here it acts both as light source and absorbing medium. A high detection sensitivity of weak absorption is reached without the need of an external light source, such as a laser or broadband lamp. The performance is illustrated by the first CESAS result on a supersonically expanding hydrocarbon plasma. We expect CESAS to become a generally applicable analytical tool for real time and in situ diagnostics. A. Walsh, D. Zhao, W. Ubachs, H. Linnartz, J. Phys. Chem. A, {dx.doi.org/10.1021/jp310392n}, in press, 2013. A. Walsh, D. Zhao, H. Linnartz Rev. Sci. Instrum. {84}(2), 021608 2013. A. Walsh, D. Zhao

  11. Optical frequency combs generated mechanically

    CERN Document Server

    Sumetsky, M

    2016-01-01

    It is shown that a highly equidistant optical frequency comb can be generated by the parametric excitation of an optical bottle microresonator with nanoscale effective radius variation by its natural mechanical vibrations.

  12. Cavity-enhanced field-free molecular alignment at high repetition rate

    CERN Document Server

    Benko, Craig; Allison, Thomas K; Labaye, François; Ye, Jun

    2015-01-01

    Extreme ultraviolet frequency combs are a versatile tool with applications including precision measurement, strong-field physics, and solid-state physics. Here we report on an application of extreme ultraviolet frequency combs and their driving lasers to studying strong-field effects in molecular systems. We perform field-free molecular alignment and high-order hamonic generation with aligned molecules in a gas jet at 154 MHz repetition rate using a high-powered optical frequency comb inside a femtosecond enhancement cavity. The cavity-enhanced system provides means to reach suitable intensities to study field-free molecular alignment and enhance the observable effects of the molecule-field interaction. We observe modulations of the driving field, arising from the nature of impulsive stimulated Raman scattering responsible for coherent molecular rotations. We foresee impact of this work on the study of molecule-based strong-field physics, with improved precision and a more fundamental understanding of the int...

  13. Active Faraday optical frequency standards

    CERN Document Server

    Zhuang, Wei

    2014-01-01

    We propose the mechanism of active Faraday optical clock, and experimentally demonstrate active Faraday optical frequency standards based on 852 nm narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standards is determined by the cesium 6 $^{2}S_{1/2}$ $F$ = 4 to 6 $^{2}P_{3/2}$ $F'$ = 4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 996(26) Hz, which is 5.3 $\\times$ 10$^{3}$ times smaller than the natural linewidth of the cesium 852 nm transition line. The maximum emitted light power reaches 75 $\\upmu$W. The active Faraday optical frequency standards reported here have advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for...

  14. Cavity-enhanced resonant tunneling photodetector at telecommunication wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Pfenning, Andreas, E-mail: Andreas.Pfenning@physik.uni-wuerzburg.de; Hartmann, Fabian; Langer, Fabian; Höfling, Sven; Kamp, Martin; Worschech, Lukas [Technische Physik, Physikalisches Institut, Universität Würzburg and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Am Hubland, D-97074 Würzburg (Germany)

    2014-03-10

    An AlGaAs/GaAs double barrier resonant tunneling diode (RTD) with a nearby lattice-matched GaInNAs absorption layer was integrated into an optical cavity consisting of five and seven GaAs/AlAs layers to demonstrate cavity enhanced photodetection at the telecommunication wavelength 1.3 μm. The samples were grown by molecular beam epitaxy and RTD-mesas with ring-shaped contacts were fabricated. Electrical and optical properties were investigated at room temperature. The detector shows maximum photocurrent for the optical resonance at a wavelength of 1.29 μm. At resonance a high sensitivity of 3.1×10{sup 4} A/W and a response up to several pA per photon at room temperature were found.

  15. Cavity-enhanced resonant tunneling photodetector at telecommunication wavelengths

    International Nuclear Information System (INIS)

    An AlGaAs/GaAs double barrier resonant tunneling diode (RTD) with a nearby lattice-matched GaInNAs absorption layer was integrated into an optical cavity consisting of five and seven GaAs/AlAs layers to demonstrate cavity enhanced photodetection at the telecommunication wavelength 1.3 μm. The samples were grown by molecular beam epitaxy and RTD-mesas with ring-shaped contacts were fabricated. Electrical and optical properties were investigated at room temperature. The detector shows maximum photocurrent for the optical resonance at a wavelength of 1.29 μm. At resonance a high sensitivity of 3.1×104 A/W and a response up to several pA per photon at room temperature were found

  16. Long Wave Infrared Cavity Enhanced Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Taubman, Matthew S.; Scott, David C.; Cannon, Bret D.; Myers, Tanya L.; Munley, John T.; Nguyen, Vinh T.; Schultz, John F.

    2005-12-01

    The principal goal of Pacific Northwest National Laboratory's (PNNL's) long wave infrared (LWIR) cavity enhanced sensor (CES) task is to explore ultra-sensitive spectroscopic chemical sensing techniques and apply them to detecting proliferation of weapons of mass destruction (WMD). Our primary application is detecting signatures of WMD production, but LWIR CES techniques are also capable of detecting chemical weapons. The LWIR CES task is concerned exclusively with developing novel point sensors; stand-off detection is addressed by other PNNL tasks and projects. PNNL's LWIR CES research is distinguished from that done by others by the use quantum cascade lasers (QCLs) as the light source. QCLs are novel devices, and a significant fraction of our research has been devoted to developing the procedures and hardware required to implement them most effectively for chemical sensing. This report details the progress we have made on LWIR CES sensor development.

  17. Cavity-Enhanced Ultrafast Transient Absorption Spectroscopy

    CERN Document Server

    Reber, Melanie A R; Allison, Thomas K

    2015-01-01

    We present a new technique using a frequency comb laser and optical cavities for performing ultrafast transient absorption spectroscopy with improved sensitivity. Resonantly enhancing the probe pulses, we demonstrate a sensitivity of $\\Delta$OD $ = 1 \\times 10^{-9}/\\sqrt{\\mbox{Hz}}$ for averaging times as long as 30 s per delay point ($\\Delta$OD$_{min} = 2 \\times 10^{-10}$). Resonantly enhancing the pump pulses allows us to produce a high excitation fraction at high repetition-rate, so that signals can be recorded from samples with optical densities as low as OD $\\approx 10^{-8}$, or column densities $< 10^{10}$ molecules/cm$^2$. This high sensitivity enables new directions for ultrafast spectroscopy.

  18. Electronic tunneling currents at optical frequencies

    Science.gov (United States)

    Faris, S. M.; Fan, B.; Gustafson, T. K.

    1975-01-01

    Rectification characteristics of nonsuperconducting metal-barrier-metal junctions as deduced from electronic tunneling theory have been observed experimentally for optical frequency irradiation of the junction.

  19. Broadband cavity enhanced spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    OpenAIRE

    Washenfelder, R. A.; A. R. Attwood; Flores, J. M.; Rudich, Y.; S. S. Brown

    2015-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity enhanced spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and ...

  20. Ac electronic tunneling at optical frequencies

    Science.gov (United States)

    Faris, S. M.; Fan, B.; Gustafson, T. K.

    1974-01-01

    Rectification characteristics of non-superconducting metal-barrier-metal junctions deduced from electronic tunneling have been observed experimentally for optical frequency irradiation of the junction. The results provide verification of optical frequency Fermi level modulation and electronic tunneling current modulation.

  1. Transfer of optical frequency combs over optical fibre links

    OpenAIRE

    Marra, Giuseppe

    2013-01-01

    In just over a decade the optical frequency comb technique has completely transformed the field of frequency metrology. These devices have made the measurement of the frequency of light a much easier and affordable task when compared to with earlier techniques. With both research and technology development on these devices becoming more mature, optical frequency combs have been affecting other science areas. Applications are already found in spectroscopy, attosecond physics and astrophysics a...

  2. Hermetic optical-fiber iodine frequency standard.

    Science.gov (United States)

    Light, Philip S; Anstie, James D; Benabid, Fetah; Luiten, Andre N

    2015-06-15

    We have built an optical-frequency standard based on interrogating iodine vapor that has been trapped within the hollow core of a hermetically sealed kagome-lattice photonic crystal fiber. A frequency-doubled Nd:YAG laser locked to a hyperfine component of the P(142)37-0 I2127 transition using modulation transfer spectroscopy shows a frequency stability of 3×10(-11) at 100 s. We discuss the impediments in integrating this all-fiber standard into a fully optical-fiber-based system, and suggest approaches that could improve performance of the frequency standard substantially.

  3. Cavity-enhanced frequency up-conversion in rubidium vapour

    CERN Document Server

    Offer, Rachel F; Riis, Erling; Franke-Arnold, Sonja; Arnold, Aidan S

    2016-01-01

    We report the first use of a ring cavity to both enhance the output power and dramatically narrow the linewidth ($<1\\,$MHz) of blue light generated by four wave mixing in a rubidium vapour cell. We find that the high output power available in our cavity-free system leads to power broadening of the generated blue light linewidth. Our ring cavity removes this limitation, allowing high output power and narrow linewidth to be achieved concurrently. As the cavity blue light is widely tunable over the $^{85}$Rb 5S$_{1/2} \\,\\,F=3$ $\\rightarrow$ 6P$_{3/2}$ transition, this narrow linewidth light would be suitable for second-stage laser cooling, which could be valuable for efficient $^{85}$Rb BEC production.

  4. Pump-probe differencing technique for cavity-enhanced, noise-canceling saturation laser spectroscopy

    CERN Document Server

    De Vine, G; Close, J D; Gray, M B; Vine, Glenn de; Clelland, David E. Mc; Close, John D.; Gray, Malcolm B.

    2004-01-01

    We present an experimental technique enabling mechanical-noise free, cavity-enhanced frequency measurements of an atomic transition and its hyperfine structure. We employ the 532nm frequency doubled output from a Nd:YAG laser and an iodine vapour cell. The cell is placed in a traveling-wave Fabry-Perot interferometer (FPI) with counter-propagating pump and probe beams. The FPI is locked using the Pound-Drever-Hall (PDH) technique. Mechanical noise is rejected by differencing pump and probe signals. In addition, this differenced error signal gives a sensitive measure of differential non-linearity within the FPI.

  5. Hybrid III-V/SOI resonant cavity enhanced photodetector

    DEFF Research Database (Denmark)

    Learkthanakhachon, Supannee; Taghizadeh, Alireza; Park, Gyeong Cheol;

    2016-01-01

    A hybrid III–V/SOI resonant-cavity-enhanced photodetector (RCE-PD) structure comprising a high-contrast grating (HCG) reflector, a hybrid grating (HG) reflector, and an air cavity between them, has been proposed and investigated. In the proposed structure, a light absorbing material is integrated...

  6. Line-Parameter Measurements and Stringent Tests of Line-Shape Models Based on Cavity-Enhanced Absorption Spectroscopy

    Science.gov (United States)

    Bielska, Katarzyna; Fleisher, Adam J.; Hodges, Joseph T.; Lin, Hong; Long, David A.; Reed, Zachary D.; Sironneau, Vincent; Truong, Gar-Wing; Wójtewicz, Szymon

    2014-06-01

    Laser methods that are based on cavity-enhanced absorption spectroscopy (CEAS) are well-suited for measuring molecular line parameters under conditions of low optical density, and as such they are complementary to broadband Fourier-transform spectroscopy (FTS) techniques. Attributes of CEAS include relatively low detection limits, accurate and precise detuning axes and high fidelity measurements of line shape. In many cases these performance criteria are superior to those obtained using direct laser absorption spectroscopy and FTS-based systems. In this presentation we will survey several examples of frequency-stabilized cavity ring-down spectroscopy (FS-CRDS)1 measurements obtained with laser spectrometers developed at the National Institute of Standards and Technology (NIST) in Gaithersburg Maryland. These experiments, which are motivated by atmospheric monitoring and remote-sensing applications that require high-precision and accuracy, involve nearinfrared transitions of carbon dioxide, water, oxygen and methane. We discuss spectra with signal-to-noise ratios exceeding 106, frequency axes with absolute uncertainties in the 10 kHz to 100 kHz range and linked to a Cs clock, line parameters with relative uncertainties at the 0.2 % level and isotopic ratios measured with a precision of 0.03 %. We also present FS-CRDS measurements of CO2 line intensities which are measured at atmospheric concentration levels and linked to gravimetric standards for CO2 in air, and we quantify pressure-dependent deviations between various theoretical line profiles and measured line shapes. Finally we also present recent efforts to increase data throughput and spectral coverage in CEAS experiments. We describe three new high-bandwidth CEAS techniques including frequency-agile, rapid scanning spectroscopy (FARS)2, which enables continuous-wave measurements of cavity mode linewidth and acquisition of ringdown decays with no dead time during laser frequency tuning, heterodyne

  7. Slow light based optical frequency shifter

    CERN Document Server

    Li, Qian; Thuresson, Axel; Nilsson, Adam N; Rippe, Lars; Kröll, Stefan

    2016-01-01

    We demonstrate experimentally and theoretically a controllable way of shifting the frequency of an optical pulse by using a combination of spectral hole burning, slow light effect, and linear Stark effect in a rare-earth-ion doped crystal. We claim that the solid angle of acceptance of a frequency shift structure can be close to $2\\pi$, which means that the frequency shifter could work not only for optical pulses propagating in a specific spatial mode but also for randomly scattered light. As the frequency shift is controlled solely by an external electric field, it works also for weak coherent light fields, and can e.g. be used as a frequency shifter for quantum memory devices in quantum communication.

  8. Slow-light-based optical frequency shifter

    Science.gov (United States)

    Li, Qian; Bao, Yupan; Thuresson, Axel; Nilsson, Adam N.; Rippe, Lars; Kröll, Stefan

    2016-04-01

    We demonstrate experimentally and theoretically a controllable way of shifting the frequency of an optical pulse by using a combination of spectral hole burning, slow light effect, and linear Stark effect in a rare-earth-ion-doped crystal. We claim that the solid angle of acceptance of a frequency shift structure can be close to 2 π , which means that the frequency shifter could work not only for optical pulses propagating in a specific spatial mode but also for randomly scattered light. As the frequency shift is controlled solely by an external electric field, it works also for weak coherent light fields and can be used, for example, as a frequency shifter for quantum memory devices in quantum communication.

  9. A microresonator frequency comb optical clock

    CERN Document Server

    Papp, Scott B; DelHaye, Pascal; Quinlan, Franklyn; Lee, Hansuek; Vahala, Kerry J; Diddams, Scott A

    2013-01-01

    Optical-frequency combs enable measurement precision at the 20th digit, and accuracy entirely commensurate with their reference oscillator. A new direction in experiments is the creation of ultracompact frequency combs by way of nonlinear parametric optics in microresonators. We refer to these as microcombs, and here we report a silicon-chip-based microcomb optical clock that phase-coherently converts an optical-frequency reference to a microwave signal. A low-noise comb spectrum with 25 THz span is generated with a 2 mm diameter silica disk and broadening in nonlinear fiber. This spectrum is stabilized to rubidium frequency references separated by 3.5 THz by controlling two teeth 108 modes apart. The optical clocks output is the electronically countable 33 GHz microcomb line spacing, which features an absolute stability better than the rubidium transitions by the expected factor of 108. Our work demonstrates the comprehensive set of tools needed for interfacing microcombs to state-of-the-art optical clocks.

  10. Nobel Lecture: Defining and measuring optical frequencies

    Science.gov (United States)

    Hall, John L.

    2006-10-01

    Four long-running currents in laser technology met and merged in 1999-2000. Two of these were the quest toward a stable repetitive sequence of ever-shorter optical pulses and, on the other hand, the quest for the most time-stable, unvarying optical frequency possible. The marriage of UltraFast and UltraStable lasers was brokered mainly by two international teams and became exciting when a special “designer” microstructure optical fiber was shown to be nonlinear enough to produce “white light” from the femtosecond laser pulses, such that the output spectrum embraced a full optical octave. Then, for the first time, one could realize an optical frequency interval equal to the comb’s lowest frequency, and count out this interval as a multiple of the repetition rate of the femtosecond pulse laser. This “gear-box” connection between the radio frequency standard and any/all optical frequency standards came just as Sensitivity-Enhancing ideas were maturing. The four-way Union empowered an explosion of accurate frequency measurement results in the standards field and prepares the way for refined tests of some of our cherished physical principles, such as the time-stability of some of the basic numbers in physics (e.g., the “fine-structure” constant, the speed of light, certain atomic mass ratios etc.), and the equivalence of time-keeping by clocks based on different physics. The stable laser technology also allows time-synchronization between two independent femtosecond lasers so exact they can be made to appear as if the source were a single laser. By improving pump/probe experiments, one important application will be in bond-specific spatial scanning of biological samples. This next decade in optical physics should be a blast.

  11. Resonant cavity enhanced light harvesting in flexible thin-film organic solar cells

    KAUST Repository

    Sergeant, Nicholas P.

    2013-04-24

    Dielectric/metal/dielectric (DMD) electrodes have the potential to significantly increase the absorption efficiency and photocurrent in flexible organic solar cells. We demonstrate that this enhancement is attributed to a broadband cavity resonance. Silver-based semitransparent DMD electrodes with sheet resistances below 10 ohm/sq. are fabricated on flexible polyethylene terephthalate (PET) substrates in a high-throughput roll-to-roll sputtering tool. We carefully study the effect of the semitransparent DMD electrode (here composed of ZnxSnyOz/Ag/InxSn yOz) on the optical device performance of a copper phthalocyanine (CuPc)/fullerene (C60) bilayer cell and illustrate that a resonant cavity enhanced light trapping effect dominates the optical behavior of the device. © 2013 Optical Society of America.

  12. Interfacing whispering-gallery microresonators and free space light with cavity enhanced Rayleigh scattering

    CERN Document Server

    Zhu, Jiangang; Yilmaz, Huzeyfe; Peng, Bo; Dong, Mark; Tomes, Matthew; Carmon, Tal; Yang, Lan

    2014-01-01

    Whispering gallery mode resonators (WGMRs) take advantage of strong light confinement and long photon lifetime for applications in sensing, optomechanics, microlasers and quantum optics. However, their rotational symmetry and low radiation loss impede energy exchange between WGMs and the surrounding. As a result, free-space coupling of light into and from WGMRs is very challenging. In previous schemes, resonators are intentionally deformed to break circular symmetry to enable free-space coupling of carefully aligned focused light, which comes with bulky size and alignment issue that hinder the realization of compact WGMR applications. Here, we report a new class of nanocouplers based on cavity enhanced Rayleigh scattering from nano-scatterer(s) on resonator surface, and demonstrate whispering gallery microlaser by free-space optical pumping of an Ytterbium doped silica microtoroid via the scatterers. This new scheme will not only expand the range of applications enabled by WGMRs, but also provide a possible r...

  13. Noise-immune cavity-enhanced analytical atomic spectrometry - NICE-AAS - A technique for detection of elements down to zeptogram amounts

    Science.gov (United States)

    Axner, Ove; Ehlers, Patrick; Hausmaninger, Thomas; Silander, Isak; Ma, Weiguang

    2014-10-01

    Noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) is a powerful technique for detection of molecular compounds in gas phase that is based on a combination of two important concepts: frequency modulation spectroscopy (FMS) for reduction of noise, and cavity enhancement, for prolongation of the interaction length between the light and the sample. Due to its unique properties, it has demonstrated unparalleled detection sensitivity when it comes to detection of molecular constituents in the gas phase. However, despite these, it has so far not been used for detection of atoms, i.e. for elemental analysis. The present work presents an assessment of the expected performance of Doppler-broadened (Db) NICE-OHMS for analytical atomic spectrometry, then referred to as noise-immune cavity-enhanced analytical atomic spectrometry (NICE-AAS). After a description of the basic principles of Db-NICE-OHMS, the modulation and detection conditions for optimum performance are identified. Based on a previous demonstrated detection sensitivity of Db-NICE-OHMS of 5 × 10- 12 cm- 1 Hz- 1/2 (corresponding to a single-pass absorbance of 7 × 10- 11 over 10 s), the expected limits of detection (LODs) of Hg and Na by NICE-AAS are estimated. Hg is assumed to be detected in gas phase directly while Na is considered to be atomized in a graphite furnace (GF) prior to detection. It is shown that in the absence of spectral interferences, contaminated sample compartments, and optical saturation, it should be feasible to detect Hg down to 10 zg/cm3 (10 fg/m3 or 10- 5 ng/m3), which corresponds to 25 atoms/cm3, and Na down to 0.5 zg (zg = zeptogram = 10- 21 g), representing 50 zg/mL (parts-per-sextillion, pps, 1:1021) in liquid solution (assuming a sample of 10 μL) or solely 15 atoms injected into the GF, respectively. These LODs are several orders of magnitude lower (better) than any previous laser-based absorption technique previously demonstrated under atmospheric

  14. Generation of multiple optical frequencies referenced to a frequency comb for precision free-space frequency transfer

    Science.gov (United States)

    Chun, Byung Jae; Kang, Hyun Jay; Kim, Young-Jin; Kim, Seung-Woo

    2016-03-01

    Generating multiple optical frequencies referenced to the frequency standard is an important task in optical clock dissemination and optical communication. An apparatus for frequency-comb-referenced generation of multiple optical frequencies is demonstrated for high-precision free-space transfer of multiple optical frequencies. The relative linewidth and frequency instability at each channel corresponds to sub-1 Hz and 1.06×10-15 at 10 s averaging time, respectively. During the free-space transfer, the refractive index change of transmission media caused by atmospheric turbulences induces phase and frequency noise on optical frequencies. These phase and frequency noise causes induced linewidth broadening and frequency shift in optical frequencies which can disturb the accurate frequency transfer. The proposed feedback loop with acousto-optic modulator can monitor and compensate phase/frequency noise on optical frequencies. As a result, a frequency-comb-referenced single optical mode is compensated with a high signal to noise ratio (SNR) of 80 dB. By sharing the same optical paths, this feedback loop is confirmed to be successfully transferred to the neighboring wavelength channels (a 100 GHz spaced channel). This result confirms our proposed system can transfer optical frequencies to the remote site in free-space without performance degradation.

  15. Noise-immune cavity-enhanced analytical atomic spectrometry — NICE-AAS — A technique for detection of elements down to zeptogram amounts

    International Nuclear Information System (INIS)

    Noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) is a powerful technique for detection of molecular compounds in gas phase that is based on a combination of two important concepts: frequency modulation spectroscopy (FMS) for reduction of noise, and cavity enhancement, for prolongation of the interaction length between the light and the sample. Due to its unique properties, it has demonstrated unparalleled detection sensitivity when it comes to detection of molecular constituents in the gas phase. However, despite these, it has so far not been used for detection of atoms, i.e. for elemental analysis. The present work presents an assessment of the expected performance of Doppler-broadened (Db) NICE-OHMS for analytical atomic spectrometry, then referred to as noise-immune cavity-enhanced analytical atomic spectrometry (NICE-AAS). After a description of the basic principles of Db-NICE-OHMS, the modulation and detection conditions for optimum performance are identified. Based on a previous demonstrated detection sensitivity of Db-NICE-OHMS of 5 × 10−12 cm−1 Hz−1∕2 (corresponding to a single-pass absorbance of 7 × 10−11 over 10 s), the expected limits of detection (LODs) of Hg and Na by NICE-AAS are estimated. Hg is assumed to be detected in gas phase directly while Na is considered to be atomized in a graphite furnace (GF) prior to detection. It is shown that in the absence of spectral interferences, contaminated sample compartments, and optical saturation, it should be feasible to detect Hg down to 10 zg/cm3 (10 fg/m3 or 10−5 ng/m3), which corresponds to 25 atoms/cm3, and Na down to 0.5 zg (zg = zeptogram = 10−21 g), representing 50 zg/mL (parts-per-sextillion, pps, 1:1021) in liquid solution (assuming a sample of 10 μL) or solely 15 atoms injected into the GF, respectively. These LODs are several orders of magnitude lower (better) than any previous laser-based absorption technique previously demonstrated under

  16. Optical frequency-modulated continuous-wave interferometers.

    Science.gov (United States)

    Zheng, Jesse

    2006-04-20

    I discuss optical frequency-modulated continuous-wave (FMCW) interferometers, including their principles, characteristics, specific requirements, procedure for their construction, optical configurations, primary applications, optical sources, resolution, measurement range, and stability. PMID:16633422

  17. Cavity-Enhanced Ultrafast Spectroscopy: Ultrafast Meets Ultrasensitive

    Science.gov (United States)

    Allison, Thomas K.; Reber, Melanie Roberts; Chen, Yuning

    2016-06-01

    Ultrafast optical spectroscopy methods, such as transient absorption spectroscopy and 2D-spectroscopy, are widely used across many disciplines. However, these techniques are typically restricted to optically thick samples, such as solids and liquid solutions. Using a frequency comb laser and optical cavities, we present a new technique for performing ultrafast optical spectroscopy with high sensitivity, enabling work in dilute gas-phase molecular beams. Resonantly enhancing the probe pulses, we demonstrate transient absorption measurements with a detection limit of ΔOD = 2 × 10-10 (1 × 10-9/√{Hz}). Resonantly enhancing the pump pulses allows us to produce a high excitation fraction at high repetition-rate, so that signals can be recorded from samples with optical densities as low as OD ≈ 10-8, or column densities green squares show the average of the Allan deviations obtained independently for each delay point. Error bars here are the standard deviation (not the uncertainty in the mean) of this ensemble, to represent the spread in the data. The blue diamond is the average of the error bars of (a), along with their standard deviation. The grey line has a slope of -1/2 on the log-log plot, the expected slope for white noise performance

  18. Tunable optical frequency division using a phase-locked optical parametric oscillator.

    Science.gov (United States)

    Lee, D; Wong, N C

    1992-01-01

    We report the experimental demonstration of a novel optical parametric oscillator approach to tunable optical frequency division. The beat frequency of the signal and idler subharmonic outputs of a tunable cw KTP optical parametric oscillator was phase locked to a microwave reference frequency source, which thus permitted precise determination of the output frequencies at approximately half the input pump frequency.

  19. Optical generation of radio-frequency power

    International Nuclear Information System (INIS)

    An optical technique for high-power radio-frequency (RF) signal generation is described. The technique uses a unique photodetector based on a traveling-wave design driven by an appropriately modulated light source. The traveling-wave photodetector (TWPD) exhibits simultaneously a theoretical quantum efficiency approaching 100 % and a very large electrical bandwidth. Additionally, it is capable of dissipating the high-power levels required for the RF generation technique. The modulated light source is formed by either the beating together of two lasers or by the direct modulation of a light source. A system example is given which predicts RF power levels of 100's of mW's at millimeter wave frequencies with a theoretical ''wall-plug'' efficiency approaching 34%

  20. Broadband cavity enhanced spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    Science.gov (United States)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Rudich, Y.; Brown, S. S.

    2015-09-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity enhanced spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99933 ± 0.00003 (670 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.49 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device (CCD) array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity enhanced spectroscopy and cavity ringdown spectroscopy agree within 2 % (slope for linear fit = 0.98 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity enhanced spectroscopy and calculated based on flow dilution are also well-correlated, with r2 = 0.9998. During constant, mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1-min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically-based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to trace gases, this approach will be appropriate for

  1. Optical Frequency Comb Generation based on Erbium Fiber Lasers

    Directory of Open Access Journals (Sweden)

    Droste Stefan

    2016-06-01

    Full Text Available Optical frequency combs have revolutionized optical frequency metrology and are being actively investigated in a number of applications outside of pure optical frequency metrology. For reasons of cost, robustness, performance, and flexibility, the erbium fiber laser frequency comb has emerged as the most commonly used frequency comb system and many different designs of erbium fiber frequency combs have been demonstrated. We review the different approaches taken in the design of erbium fiber frequency combs, including the major building blocks of the underlying mode-locked laser, amplifier, supercontinuum generation and actuators for stabilization of the frequency comb.

  2. Optical Frequency Comb Generation based on Erbium Fiber Lasers

    Science.gov (United States)

    Droste, Stefan; Ycas, Gabriel; Washburn, Brian R.; Coddington, Ian; Newbury, Nathan R.

    2016-06-01

    Optical frequency combs have revolutionized optical frequency metrology and are being actively investigated in a number of applications outside of pure optical frequency metrology. For reasons of cost, robustness, performance, and flexibility, the erbium fiber laser frequency comb has emerged as the most commonly used frequency comb system and many different designs of erbium fiber frequency combs have been demonstrated. We review the different approaches taken in the design of erbium fiber frequency combs, including the major building blocks of the underlying mode-locked laser, amplifier, supercontinuum generation and actuators for stabilization of the frequency comb.

  3. Cavity-enhanced Raman microscopy of individual carbon nanotubes

    Science.gov (United States)

    Hümmer, Thomas; Noe, Jonathan; Hofmann, Matthias S.; Hänsch, Theodor W.; Högele, Alexander; Hunger, David

    2016-07-01

    Raman spectroscopy reveals chemically specific information and provides label-free insight into the molecular world. However, the signals are intrinsically weak and call for enhancement techniques. Here, we demonstrate Purcell enhancement of Raman scattering in a tunable high-finesse microcavity, and utilize it for molecular diagnostics by combined Raman and absorption imaging. Studying individual single-wall carbon nanotubes, we identify crucial structural parameters such as nanotube radius, electronic structure and extinction cross-section. We observe a 320-times enhanced Raman scattering spectral density and an effective Purcell factor of 6.2, together with a collection efficiency of 60%. Potential for significantly higher enhancement, quantitative signals, inherent spectral filtering and absence of intrinsic background in cavity-vacuum stimulated Raman scattering render the technique a promising tool for molecular imaging. Furthermore, cavity-enhanced Raman transitions involving localized excitons could potentially be used for gaining quantum control over nanomechanical motion and open a route for molecular cavity optomechanics.

  4. Time-resolved broadband cavity-enhanced absorption spectroscopy for chemical kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Sheps, Leonid; Chandler, David W.

    2013-04-01

    Experimental measurements of elementary reaction rate coefficients and product branching ratios are essential to our understanding of many fundamentally important processes in Combustion Chemistry. However, such measurements are often impossible because of a lack of adequate detection techniques. Some of the largest gaps in our knowledge concern some of the most important radical species, because their short lifetimes and low steady-state concentrations make them particularly difficult to detect. To address this challenge, we propose a novel general detection method for gas-phase chemical kinetics: time-resolved broadband cavity-enhanced absorption spectroscopy (TR-BB-CEAS). This all-optical, non-intrusive, multiplexed method enables sensitive direct probing of transient reaction intermediates in a simple, inexpensive, and robust experimental package.

  5. Steering optical comb frequency by rotating polarization state

    CERN Document Server

    Zhang, Y; Zhang, X F; Zhang, L; Han, W; Guo, W; Jiang, H; Zhang, S

    2016-01-01

    Optical frequency combs, with precise control of repetition rate and carrier-envelope-offset frequency, have revolutionized many fields, such as fine optical spectroscopy, optical frequency standards, ultra-fast science research, ultra-stable microwave generation and precise ranging measurement. However, existing high bandwidth frequency control methods have small dynamic range, requiring complex hybrid control techniques. To overcome this limitation, we develop a new approach, where a home-made intra-cavity electro-optic modulator tunes polarization state of laser signal rather than only optical length of the cavity, to steer frequencies of a nonlinear-polarization-rotation mode-locked laser. By taking advantage of birefringence of the whole cavity, this approach results in not only broadband but also relative large-dynamic frequency control. Experimental results show that frequency control dynamic range increase at least one order in comparison with the traditional intra-cavity electro-optic modulator techn...

  6. Mid-Infrared Tunable Resonant Cavity Enhanced Detectors

    Directory of Open Access Journals (Sweden)

    Hans Zogg

    2008-09-01

    Full Text Available Mid-infrared detectors that are sensitive only in a tunable narrow spectral band are presented. They are based on the Resonant Cavity Enhanced Detector (RCED principle and employing a thin active region using IV-VI narrow gap semiconductor layers. A Fabry-Pérot cavity is formed by two mirrors. The active layer is grown onto one mirror, while the second mirror can be displaced. This changes the cavity length thus shifting the resonances where the detector is sensitive. Using electrostatically actuated MEMS micromirrors, a very compact tunable detector system has been fabricated. Mirror movements of more than 3 μm at 30V are obtained. With these mirrors, detectors with a wavelength tuning range of about 0.7 μm have been realized. Single detectors can be used in mid-infrared micro spectrometers, while a detector arrangement in an array makes it possible to realize Adaptive Focal Plane Arrays (AFPA.

  7. Optical Transmitter Terminal for Selective RF High Frequency Bans Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the proposal work is to investigate the highly innovative conceptual design of an optical communication selective frequency transmitter terminal...

  8. Trapping of a microsphere pendulum resonator in an optical potential

    OpenAIRE

    Jonathan M. Ward; Wu, Yuqiang; Minogin, V. G.; Nic Chormaic, Síle

    2009-01-01

    We propose a method to spatially confine or corral the movements of a micropendulum via the optical forces produced by two simultaneously excited optical modes of a photonic molecule comprising two microspherical cavities. We discuss how the cavity enhanced optical force generated in the photonic molecule can create an optomechanical potential of about 10 eV deep and 30 pm wide, which can be used to trap the pendulum at any given equilibrium position by a simple choice of laser frequencies. T...

  9. Analysis of optical frequency-modulated continuous-wave interference.

    Science.gov (United States)

    Zheng, Jesse

    2004-07-20

    I systematically analyze the theory of optical frequency-modulated continuous-wave (FMCW) interference. There are three different versions of optical FMCW interference, discussed in detail: sawtooth-wave optical FMCW interference, triangular-wave optical FMCW interference, and sinusoidal-wave optical FMCW interference. The essential concepts and technical terms are clearly defined, the necessary simplifications are introduced according to the characteristics of optical waves, and the formulas used to calculate the signal intensities under two different situations (static and dynamic) are properly derived. Advantages and limitations of each version of optical FMCW interference are also discussed. PMID:15291063

  10. Optical frequency comb technology for ultra-broadband radio-frequency photonics

    CERN Document Server

    Torres-Company, Victor

    2014-01-01

    The outstanding phase-noise performance of optical frequency combs has led to a revolution in optical synthesis and metrology, covering a myriad of applications, from molecular spectroscopy to laser ranging and optical communications. However, the ideal characteristics of an optical frequency comb are application dependent. In this review, the different techniques for the generation and processing of high-repetition-rate (>10 GHz) optical frequency combs with technologies compatible with optical communication equipment are covered. Particular emphasis is put on the benefits and prospects of this technology in the general field of radio-frequency photonics, including applications in high-performance microwave photonic filtering, ultra-broadband coherent communications, and radio-frequency arbitrary waveform generation.

  11. Full stabilization of a microresonator-based optical frequency comb.

    Science.gov (United States)

    Del'Haye, P; Arcizet, O; Schliesser, A; Holzwarth, R; Kippenberg, T J

    2008-08-01

    We demonstrate control and stabilization of an optical frequency comb generated by four-wave mixing in a monolithic microresonator with a mode spacing in the microwave regime (86 GHz). The comb parameters (mode spacing and offset frequency) are controlled via the power and the frequency of the pump laser, which constitutes one of the comb modes. Furthermore, generation of a microwave beat note at the comb's mode spacing frequency is demonstrated, enabling direct stabilization to a microwave frequency standard.

  12. Wide and stable optical frequency comb in an intensity-modulated continuous wave pumped optical fiber

    International Nuclear Information System (INIS)

    This paper investigates how to obtain a wide and stable optical frequency comb in an intensity-modulated continuous-wave pumped optical fiber by straightforwardly characterizing the signal-to-noise ratio and analyzing the optimal fiber length. The stability of the obtained optical frequency comb is analyzed by a method which is similar to the eye pattern. The prospect for obtaining wider and more stable optical frequency combs is discussed. (paper)

  13. Incoherent Optical Frequency Domain Reflectometry for Distributed Thermal Sensing

    OpenAIRE

    Karamehmedovic, Emir; Jeppesen, Palle; Peucheret, Christophe; Bjarklev, Anders Overgaard

    2006-01-01

    This thesis reports the main results from an investigation of a fibre-optic distributed temperature sensor based on spontaneous Raman scattering. The technique used for spatial resolving is the incoherent optical frequency domain reflectometry, where a pump laser is sine modulated with a stepwise increasing frequency, after which the inverse Fourier transform is applied to the signal from the backscattered light. This technique is compared with the more conventional optical time domain reflec...

  14. Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference

    CERN Document Server

    Chanteau, Bruno; Zhang, Wei; Santarelli, Giorgio; Coq, Yann Le; Auguste, Frédéric; Darquié, Benoît; Chardonnet, Christian; Amy-Klein, Anne

    2012-01-01

    We have built a frequency chain which enables to measure the absolute frequency of a laser emitting in the 28-31 THz frequency range and stabilized onto a molecular absorption line. The set-up uses an optical frequency comb and an ultrastable 1.55 $\\mu$m frequency reference signal, transferred from LNE-SYRTE to LPL through an optical link. We are now progressing towards the stabilization of the mid-IR laser via the frequency comb and the extension of this technique to quantum cascade lasers. Such a development is very challenging for ultrahigh resolution molecular spectroscopy and fundamental tests of physics with molecules.

  15. Cavity enhanced second-order nonlinear quantum photonic logic circuits

    CERN Document Server

    Trivedi, Rahul; Majumdar, Arka

    2015-01-01

    A large obstacle for realizing quantum photonic logic is the weak optical nonlinearity of available materials, which results in large power consumption. In this paper, we argue that second order ($\\chi^{(2)}$) nonlinear optical devices are more suitable for achieving low power photonic logic. We present the theoretical design of all-optical logic with $\\chi^{(2)}$ nonlinear bimodal cavities and their networks. Using semiclassical models derived from the Wigner quasi-probability distribution function, we analyze the power consumption of networks implementing an optical AND gate and an optical latch. Comparison between the second and third order $(\\chi^{(3)})$ optical logic reveals that the $\\chi^{(2)}$ design outperforms the corresponding $\\chi^{(3)}$ design in terms of the gate power consumption at high quality factors. Specifically, using realistic estimates for the $\\chi^{(2)}$ and $\\chi^{(3)}$ susceptibilities of available materials we show that at cavity quality factors $\\sim 10^4$, optical logic designed...

  16. Generation of optical frequencies out of the frequency comb of a femtosecond laser for DWDM telecommunication

    International Nuclear Information System (INIS)

    We exploit the frequency comb of a fs laser as the frequency ruler to generate reference optical frequencies for multi-channel DWDM (dense wavelength-division-multiplexing) telecommunication. Our fiber-based scheme of single-mode extraction enables on-demand generation of optical frequencies within the telecommunication band with an absolute frequency uncertainty of 9.1×10-13. The linewidth of extracted optical modes is less than 1 Hz, and the instability is measured 2.3×10-15 at 10 s averaging. This outstanding performance of optical frequency generation would lead to a drastic improvement of the spectral efficiency for the next-generation DWDM telecommunication

  17. Frequency modulation via the Doppler effect in optical fibers.

    Science.gov (United States)

    Oberson, P; Huttner, B; Gisin, N

    1999-04-01

    We present the principle of optical frequency modulation via the Doppler effect obtained by rapidly stretching an optical fiber and thus modifying the optical path of the light propagating in the fiber. This procedure creates a pure frequency shift, with no degradation of the spectrum. Moreover, the effect is wavelength independent and can therefore be applied to any type of light source. We show an experimental realization in which a frequency excursion of ~100 MHz was obtained with a bobbin vibrating at 180 Hz.

  18. The 87Sr optical frequency standard at PTB

    International Nuclear Information System (INIS)

    With 87Sr atoms confined in a one-dimensional optical lattice, the frequency of the optical clock transition 5s21S0-5s5p3P0 has been determined to be 429 228 004 229 872.9(5) Hz. The transition frequency was measured with the help of a femtosecond-frequency comb against one of Physikalisch-Technische Bundesanstalt (PTB's) H-masers whose frequency was measured simultaneously by the PTB Cs-fountain clock CSF1. The Sr optical frequency standard contributes with a fractional uncertainty of 1.5 * 10-16 to the total uncertainty. The agreement of the measured transition frequency with previous measurements at other institutes supports the status of this transition as the secondary representation of the second with the currently smallest uncertainty. (authors)

  19. Optical frequency tripling with improved suppression and sideband selection.

    Science.gov (United States)

    Thakur, Manoj P; Medeiros, Maria C R; Laurêncio, Paula; Mitchell, John E

    2011-12-12

    A novel optical dispersion tolerant millimetre-wave radio-over-fibre system using optical frequency tripling technique with enhanced and selectable sideband suppression is demonstrated. The implementation utilises cascaded optical modulators to achieve either an optical single sideband (OSSB) or double sideband-suppressed carrier (DSB-SC) signal with high sideband suppression. Our analysis and simulation results indicate that the achievable suppression ratio of this configuration is only limited by other system factors such as optical noise and drifting of the operational conditions. The OSSB transmission system performance is assessed experimentally by the transport of 4 WiMax channels modulating a 10 GHz optical upconverted RF carrier as well as for optical frequency doubling and tripling. The 10 GHz and tripled carrier at 30 GHz are dispersion tolerant resulting both in an average relative constellation error (RCE) of -28.7 dB after 40 km of fibre. PMID:22274056

  20. Optical frequency tripling with improved suppression and sideband selection.

    Science.gov (United States)

    Thakur, Manoj P; Medeiros, Maria C R; Laurêncio, Paula; Mitchell, John E

    2011-12-12

    A novel optical dispersion tolerant millimetre-wave radio-over-fibre system using optical frequency tripling technique with enhanced and selectable sideband suppression is demonstrated. The implementation utilises cascaded optical modulators to achieve either an optical single sideband (OSSB) or double sideband-suppressed carrier (DSB-SC) signal with high sideband suppression. Our analysis and simulation results indicate that the achievable suppression ratio of this configuration is only limited by other system factors such as optical noise and drifting of the operational conditions. The OSSB transmission system performance is assessed experimentally by the transport of 4 WiMax channels modulating a 10 GHz optical upconverted RF carrier as well as for optical frequency doubling and tripling. The 10 GHz and tripled carrier at 30 GHz are dispersion tolerant resulting both in an average relative constellation error (RCE) of -28.7 dB after 40 km of fibre.

  1. Progress on indium and barium single ion optical frequency standards

    CERN Document Server

    Sherman, J A; Metz, S; Nagourney, W; Fortson, N; Sherman, Jeff A.; Trimble, William; Metz, Steven; Nagourney, Warren; Fortson, Norval

    2005-01-01

    We report progress on 115In+ and 137Ba+ single ion optical frequency standards using all solid-state sources. Both are free from quadrupole field shifts and together enable a search for drift in fundamental constants.

  2. Multiplexed sub-Doppler spectroscopy with an optical frequency comb

    CERN Document Server

    Long, David A; Plusquellic, David F; Hodges, Joseph T

    2016-01-01

    An optical frequency comb generated with an electro-optic phase modulator and a chirped radiofrequency waveform is used to perform saturation and pump-probe spectroscopy on the $D_1$ and $D_2$ transitions of atomic potassium. With a comb tooth spacing of 200 kHz and an optical bandwidth of 2 GHz the hyperfine transitions can be simultaneously observed. Interferograms are recorded in as little as 5 $\\mu$s (a timescale corresponding to the inverse of the comb tooth spacing). Importantly, the sub-Doppler features can be measured as long as the laser carrier frequency lies within the Doppler profile, thus removing the need for slow scanning or a priori knowledge of the frequencies of the sub-Doppler features. Sub-Doppler optical frequency comb spectroscopy has the potential to dramatically reduce acquisition times and allow for rapid and accurate assignment of complex molecular and atomic spectra which are presently intractable.

  3. Evanescent-wave and open-air chiral sensing via signal-reversing cavity-enhanced polarimetry

    CERN Document Server

    Sofikitis, Dimitris; Katsoprinakis, Georgios E; Spiliotis, Alexandros K; Loppinet, Benoit; Rakitzis, T Peter

    2014-01-01

    Sensing chirality is of fundamental importance to many fields, including analytical and biological chemistry, pharmacology, and fundamental physics. Recent developments have extended optical chiral sensing using microwaves, fs pulses, superchiral light, and photoionization. The most widely used methods are the traditional methods of circular dichroism and optical rotation (OR). However, chiral signals are typically very weak, and their measurement is limited by larger time-dependent backgrounds and by imperfect and slow subtraction procedures. Here, we demonstrate a pulsed-laser bowtie-cavity-enhanced polarimeter with counter-propagating beams, which solves these background problems: the chiral signals are enhanced by the number of cavity passes; the effects of linear birefringence are suppressed by a large induced intracavity Faraday rotation; and rapid signal reversals are effected by reversing the Faraday rotation and subtracting signals from the counter-propagating beams. These advantages allow measuremen...

  4. All-optical orthogonal frequency division multiplexing (OFDM) transmitter

    DEFF Research Database (Denmark)

    2015-01-01

    The invention relates to an all-optical orthogonal frequency division multiplexing (OFDM) transmitter for generating an OFDM output signal. The transmitter comprises a first time-domain optical Fourier transform (OFT) assembly, the first OFT assembly is of a K-D-K configuration and comprises...

  5. Noise-free quantum optical frequency shifting driven by mechanics

    CERN Document Server

    Fan, Linran; Poot, Menno; Cheng, Risheng; Guo, Xiang; Han, Xu; Tang, Hong X

    2016-01-01

    The ability to manipulate single photons is of critical importance for fundamental quantum optics studies and practical implementations of quantum communications. While extraordinary progresses have been made in controlling spatial, temporal, spin and orbit angular momentum degrees of freedom, frequency-domain control of single photons so far relies on nonlinear optical effects, which have faced obstacles such as noise photons, narrow bandwidth and demanding optical filtering. Here we demonstrate the first integrated near-unity efficiency frequency manipulation of single photons, by stretching and compressing a waveguide at 8.3 billion cycles per second. Frequency shift up to 150 GHz at telecom wavelength is realized without measurable added noise and the preservation of quantum coherence is verified through quantum interference between twin photons of different colors. This single photon frequency control approach will be invaluable for increasing the channel capacity of quantum communications and compensati...

  6. Mid-Infrared Optical Frequency Combs based on Crystalline Microresonators

    CERN Document Server

    Wang, C Y; Del'Haye, P; Schliesser, A; Hofer, J; Holzwarth, R; Hänsch, T W; Picqué, N; Kippenberg, T J

    2011-01-01

    The mid-infrared spectral range (\\lambda ~ 2 \\mu m to 20 \\mu m) is known as the "molecular fingerprint" region as many molecules have their highly characteristic, fundamental ro-vibrational bands in this part of the electromagnetic spectrum. Broadband mid-infrared spectroscopy therefore constitutes a powerful and ubiquitous tool for optical analysis of chemical components that is used in biochemistry, astronomy, pharmaceutical monitoring and material science. Optical frequency combs, i.e. broad spectral bandwidth coherent light sources consisting of equally spaced sharp lines, have revolutionized optical frequency metrology one decade ago. They now demonstrate dramatically improved acquisition rates, resolution and sensitivity for molecular spectroscopy mostly in the visible and near-infrared ranges. Mid-infrared frequency combs have therefore become highly desirable and recent progress in generating such combs by nonlinear frequency conversion has opened access to this spectral region. Here we report on a pr...

  7. Cavity-Enhanced Measurements of Defect Spins in Silicon Carbide

    Science.gov (United States)

    Calusine, Greg; Politi, Alberto; Awschalom, David D.

    2016-07-01

    The identification of new solid-state defect-qubit candidates in widely used semiconductors has the potential to enable the use of nanofabricated devices for enhanced qubit measurement and control operations. In particular, the recent discovery of optically active spin states in silicon carbide thin films offers a scalable route for incorporating defect qubits into on-chip photonic devices. Here, we demonstrate the use of 3C silicon carbide photonic crystal cavities for enhanced excitation of color-center defect spin ensembles in order to increase measured photoluminescence signal count rates, optically detected magnetic-resonance signal intensities, and optical spin initialization rates. We observe an up to a factor of 30 increase in the photoluminescence and optically detected magnetic-resonance signals from Ky5 color centers excited by cavity-resonant excitation and increase the rate of ground-state spin initialization by approximately a factor of 2. Furthermore, we show that the 705-fold reduction in excitation mode volume and enhanced excitation and collection efficiencies provided by the structures can be used to overcome inhomogenous broadening in order to facilitate the study of defect-qubit subensemble properties. These results highlight some of the benefits that nanofabricated devices offer for engineering the local photonic environment of color-center defect qubits to enable applications in quantum information and sensing.

  8. Precise Stabilization of the Optical Frequency of WGMRs

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey; Matsko, Andrey; Yu, Nan; Maleki, Lute; Iltchenko, Vladimir

    2009-01-01

    Crystalline whispering gallery mode resonators (CWGMRs) made of crystals with axial symmetry have ordinary and extraordinary families of optical modes. These modes have substantially different thermo-refractive constants. This results in a very sharp dependence of differential detuning of optical frequency on effective temperature. This frequency difference compared with clock gives an error signal for precise compensation of the random fluctuations of optical frequency. Certain crystals, like MgF2, have turnover points where the thermo-refractive effect is completely nullified. An advantage for applications using WGMRs for frequency stabilization is in the possibility of manufacturing resonators out of practically any optically transparent crystal. It is known that there are crystals with negative and zero thermal expansion at some specific temperatures. Doping changes properties of the crystals and it is possible to create an optically transparent crystal with zero thermal expansion at room temperature. With this innovation s stabilization technique, the resultant WGMR will have absolute frequency stability The expansion of the resonator s body can be completely compensated for by nonlinear elements. This results in compensation of linear thermal expansion (see figure). In three-mode, the MgF2 resonator, if tuned at the turnover thermal point, can compensate for all types of random thermal-related frequency drift. Simplified dual-mode method is also available. This creates miniature optical resonators with good short- and long-term stability for passive secondary frequency ethalon and an active resonator for active secondary frequency standard (a narrowband laser with long-term stability).

  9. Optical Frequency-Modulated Continuous-Wave (FMCW) Interferometry

    CERN Document Server

    Zheng, Jesse

    2005-01-01

    This book introduces the optical frequency-modulated continuous-wave (FMCW) interferometry - a new field of optics that is derived from radar. The study of optical FMCW interference not only updates our knowledge about the nature of light, but also creates an advanced technology for precision measurements. The principles, applications and signal processing of optical FMCW interference are systematically discussed. This book is intended for scientists and engineers in both academia and industry. It is especially suited to professionals who are working in the field of measurement instruments.

  10. Frequency comb metrology with an optical parametric oscillator.

    Science.gov (United States)

    Balskus, K; Schilt, S; Wittwer, V J; Brochard, P; Ploetzing, T; Jornod, N; McCracken, R A; Zhang, Z; Bartels, A; Reid, D T; Südmeyer, T

    2016-04-18

    We report on the first demonstration of absolute frequency comb metrology with an optical parametric oscillator (OPO) frequency comb. The synchronously-pumped OPO operated in the 1.5-µm spectral region and was referenced to an H-maser atomic clock. Using different techniques, we thoroughly characterized the frequency noise power spectral density (PSD) of the repetition rate frep, of the carrier-envelope offset frequency fCEO, and of an optical comb line νN. The comb mode optical linewidth at 1557 nm was determined to be ~70 kHz for an observation time of 1 s from the measured frequency noise PSD, and was limited by the stability of the microwave frequency standard available for the stabilization of the comb repetition rate. We achieved a tight lock of the carrier envelope offset frequency with only ~300 mrad residual integrated phase noise, which makes its contribution to the optical linewidth negligible. The OPO comb was used to measure the absolute optical frequency of a near-infrared laser whose second-harmonic component was locked to the F = 2→3 transition of the 87Rb D2 line at 780 nm, leading to a measured transition frequency of νRb = 384,228,115,346 ± 16 kHz. We performed the same measurement with a commercial fiber-laser comb operating in the 1.5-µm region. Both the OPO comb and the commercial fiber comb achieved similar performance. The measurement accuracy was limited by interferometric noise in the fibered setup of the Rb-stabilized laser. PMID:27137274

  11. Cavity-enhanced light emission from electrically driven carbon nanotubes

    Science.gov (United States)

    Pyatkov, Felix; Fütterling, Valentin; Khasminskaya, Svetlana; Flavel, Benjamin S.; Hennrich, Frank; Kappes, Manfred M.; Krupke, Ralph; Pernice, Wolfram H. P.

    2016-06-01

    An important advancement towards optical communication on a chip would be the development of integratable, nanoscale photonic emitters with tailored optical properties. Here we demonstrate the use of carbon nanotubes as electrically driven high-speed emitters in combination with a nanophotonic cavity that allows for exceptionally narrow linewidths. The one-dimensional photonic crystal cavities are shown to spectrally select desired emission wavelengths, enhance intensity and efficiently couple light into the underlying photonic network with high reproducibility. Under pulsed voltage excitation, we realize on-chip modulation rates in the GHz range, compatible with active photonic networks. Because the linewidth of the molecular emitter is determined by the quality factor of the photonic crystal, our approach effectively eliminates linewidth broadening due to temperature, surface interaction and hot-carrier injection.

  12. Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    Science.gov (United States)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Zarzana, K. J.; Rudich, Y.; Brown, S. S.

    2016-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1- reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to

  13. Frequency domain optical tomography using a Monte Carlo perturbation method

    Science.gov (United States)

    Yamamoto, Toshihiro; Sakamoto, Hiroki

    2016-04-01

    A frequency domain Monte Carlo method is applied to near-infrared optical tomography, where an intensity-modulated light source with a given modulation frequency is used to reconstruct optical properties. The frequency domain reconstruction technique allows for better separation between the scattering and absorption properties of inclusions, even for ill-posed inverse problems, due to cross-talk between the scattering and absorption reconstructions. The frequency domain Monte Carlo calculation for light transport in an absorbing and scattering medium has thus far been analyzed mostly for the reconstruction of optical properties in simple layered tissues. This study applies a Monte Carlo calculation algorithm, which can handle complex-valued particle weights for solving a frequency domain transport equation, to optical tomography in two-dimensional heterogeneous tissues. The Jacobian matrix that is needed to reconstruct the optical properties is obtained by a first-order "differential operator" technique, which involves less variance than the conventional "correlated sampling" technique. The numerical examples in this paper indicate that the newly proposed Monte Carlo method provides reconstructed results for the scattering and absorption coefficients that compare favorably with the results obtained from conventional deterministic or Monte Carlo methods.

  14. A broadband cavity enhanced absorption spectrometer for aircraft measurements of glyoxal, methylglyoxal, nitrous acid, nitrogen dioxide, and water vapor

    Science.gov (United States)

    Min, K.-E.; Washenfelder, R. A.; Dubé, W. P.; Langford, A. O.; Edwards, P. M.; Zarzana, K. J.; Stutz, J.; Lu, K.; Rohrer, F.; Zhang, Y.; Brown, S. S.

    2016-02-01

    We describe a two-channel broadband cavity enhanced absorption spectrometer (BBCEAS) for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water (H2O). The instrument spans 361-389 and 438-468 nm, using two light-emitting diodes (LEDs) and a single grating spectrometer with a charge-coupled device (CCD) detector. Robust performance is achieved using a custom optical mounting system, high-power LEDs with electronic on/off modulation, high-reflectivity cavity mirrors, and materials that minimize analyte surface losses. We have successfully deployed this instrument during two aircraft and two ground-based field campaigns to date. The demonstrated precision (2σ) for retrievals of CHOCHO, HONO and NO2 are 34, 350, and 80 parts per trillion (pptv) in 5 s. The accuracy is 5.8, 9.0, and 5.0 %, limited mainly by the available absorption cross sections.

  15. High Performance Small Optically Pumped Caesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-Wei; YANG Dong-Hai

    2007-01-01

    An experiment of a high performance small optically pumped caesium (Cs) beam frequency standard is reported. An extended cavity diode laser works as the probing laser, of which the frequency is stabilized by the Zeeman modulation method. The running parameters of the frequency standard are dynamically optimized via digital servo electronics. The experimental setup improves the frequency stability up to 1.8 × 10-12 atτ= 1 s and about 1.0 × 10~13 at τ= 105 s (Allan deviation).

  16. High sensitivity liquid phase measurements using broadband cavity enhanced absorption spectroscopy (BBCEAS) featuring a low cost webcam based prism spectrometer.

    Science.gov (United States)

    Qu, Zhechao; Engstrom, Julia; Wong, Donald; Islam, Meez; Kaminski, Clemens F

    2013-11-01

    Cavity enhanced techniques enable high sensitivity absorption measurements in the liquid phase but are typically more complex, and much more expensive, to perform than conventional absorption methods. The latter attributes have so far prevented a wide spread use of these methods in the analytical sciences. In this study we demonstrate a novel BBCEAS instrument that is sensitive, yet simple and economical to set up and operate. We use a prism spectrometer with a low cost webcam as the detector in conjunction with an optical cavity consisting of two R = 0.99 dielectric mirrors and a white light LED source for illumination. High sensitivity liquid phase measurements were made on samples contained in 1 cm quartz cuvettes placed at normal incidence to the light beam in the optical cavity. The cavity enhancement factor (CEF) with water as the solvent was determined directly by phase shift cavity ring down spectroscopy (PS-CRDS) and also by calibration with Rhodamine 6G solutions. Both methods yielded closely matching CEF values of ~60. The minimum detectable change in absorption (αmin) was determined to be 6.5 × 10(-5) cm(-1) at 527 nm and was limited only by the 8 bit resolution of the particular webcam detector used, thus offering scope for further improvement. The instrument was used to make representative measurements on dye solutions and in the determination of nitrite concentrations in a variation of the widely used Griess Assay. Limits of detection (LOD) were ~850 pM for Rhodamine 6G and 3.7 nM for nitrite, respectively. The sensitivity of the instrument compares favourably with previous cavity based liquid phase studies whilst being achieved at a small fraction of the cost hitherto reported, thus opening the door to widespread use in the community. Further means of improving sensitivity are discussed in the paper. PMID:24049768

  17. Optical Frequency Measurements Relying on a Mid-Infrared Frequency Standard

    Science.gov (United States)

    Rovera, G. Daniele; Acef, Ouali

    Only a small number of groups are capable of measuring optical frequencies throughout the world. In this contribution we present some of the underlying philosophy of such frequency measurement systems, including some important theoretical hints. In particular, we concentrate on the approach that has been used with the BNM-LPTF frequency chain, where a separate secondary frequency standard in the mid-infrared has been used. The low-frequency section of the chain is characterized by a measurement of the phase noise spectral density Sφ at 716GHz.Most of the significant measurements performed in the last decade are briefly presented, together with a report on the actual stability and reproducibility of the CO2/ OsO4 frequency standard.Measuring the frequency of an optical frequency standard by direct comparison with the signal available at the output of a primary frequency standard (usually between 5MHz and 100MHz) requires a multiplication factor greater than 107. A number of possible configurations, using harmonic generation, sum or difference frequency generation, have been proposed and realized in the past [1,2,3,4,5,6] and in more recent times [7]. A new technique, employing a femtosecond laser, is presently giving its first impressive results [8].All of the classical frequency chains require a large amount of manpower, together with a great deal of simultaneously operating hardware. This has the consequence that only a very few systems are actually in an operating condition throughout the world.

  18. Coherent cavity-enhanced dual-comb spectroscopy

    CERN Document Server

    Fleisher, Adam J; Reed, Zachary D; Hodges, Joseph T; Plusquellic, David F

    2016-01-01

    Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without the need for moving parts or low-resolution dispersive optics. This method of broadband spectroscopy is most often accomplished via tight phase locking of two mode-locked lasers, or via sophisticated signal processing algorithms, and therefore long integration times are difficult to achieve. Here we demonstrate an alternative approach to dual-comb spectroscopy using two phase modulator combs originating from a single continuous-wave laser capable of > 2 hours of coherent real-time averaging. The combs of > 250 teeth and 203 MHz spacing were generated by driving the phase modulators with step-recovery diodes, passive devices that provided low-phase-noise harmonics for efficient coupling into an enhancement cavity at picowatt optical powers. With this approach, we demonstrate the sensitivity to simultaneously monitor ambient levels of CO$_2$, CO, HDO, and H$_2$O at a maximum acquisition rate of 150 kHz. Robus...

  19. Generation of ultrastable microwaves via optical frequency division

    Science.gov (United States)

    Fortier, T. M.; Kirchner, M. S.; Quinlan, F.; Taylor, J.; Bergquist, J. C.; Rosenband, T.; Lemke, N.; Ludlow, A.; Jiang, Y.; Oates, C. W.; Diddams, S. A.

    2011-07-01

    There has been increased interest in the use and manipulation of optical fields to address the challenging problems that have traditionally been approached with microwave electronics. Some examples that benefit from the low transmission loss, agile modulation and large bandwidths accessible with coherent optical systems include signal distribution, arbitrary waveform generation and novel imaging. We extend these advantages to demonstrate a microwave generator based on a high-quality-factor (Q) optical resonator and a frequency comb functioning as an optical-to-microwave divider. This provides a 10 GHz electrical signal with fractional frequency instability of digital sampling systems, and can also be valuable for large baseline interferometry, precision spectroscopy and the realization of atomic time.

  20. Enabling Arbitrary Wavelength Optical Frequency Combs on Chip

    CERN Document Server

    Soltani, Mohammad; Maleki, Lute

    2015-01-01

    A necessary condition for generation of bright soliton Kerr frequency combs in microresonators is to achieve anomalous group velocity dispersion (GVD) for the resonator modes. This condition is hard to implement in visible as well as ultraviolet since the majority of optical materials are characterized with large normal GVD in these wavelength regions. We overcome this challenge by borrowing ideas from strongly dispersive coupled systems in solid state physics and optics. We show that photonic compound ring resonators can possess large anomalous GVD at any desirable wavelength, even if each individual resonator is characterized with normal GVD. Based on this concept we design a mode locked frequency comb with thin-film silicon nitride compound ring resonators in the vicinity of Rubidium D1 line (794.6nm) and propose to use this optical comb as a flywheel for chip-scale optical clocks.

  1. Distributed Raman optical amplification in phase coherent transfer of optical frequencies

    CERN Document Server

    Clivati, Cecilia; Calonico, Davide; Faralli, Stefano; Levi, Filippo; Mura, Alberto; Poli, Nicola

    2012-01-01

    We describe the application of Raman Optical-fiber Amplification (ROA) for the phase coherent transfer of optical frequencies in an optical fiber link. ROA uses the transmission fiber itself as a gain medium for bi-directional coherent amplification. In a test setup we evaluated the ROA in terms of on-off gain, signal-to-noise ratio, and phase noise added to the carrier. We transferred a laser frequency in a 200 km optical fiber link with an additional 16 dB fixed attenuator (equivalent to 275 km of fiber on a single span), and evaluated both co-propagating and counter-propagating amplification pump schemes, demonstrating nonlinear effects limiting the co-propagating pump configuration. The frequency at the remote end has a fractional frequency instability of 3e-19 over 1000 s with the optical fiber link noise compensation.

  2. One-way quantum computing in the optical frequency comb.

    Science.gov (United States)

    Menicucci, Nicolas C; Flammia, Steven T; Pfister, Olivier

    2008-09-26

    One-way quantum computing allows any quantum algorithm to be implemented easily using just measurements. The difficult part is creating the universal resource, a cluster state, on which the measurements are made. We propose a scalable method that uses a single, multimode optical parametric oscillator (OPO). The method is very efficient and generates a continuous-variable cluster state, universal for quantum computation, with quantum information encoded in the quadratures of the optical frequency comb of the OPO.

  3. Optical frequency comb interference profilometry using compressive sensing.

    Science.gov (United States)

    Pham, Quang Duc; Hayasaki, Yoshio

    2013-08-12

    We describe a new optical system using an ultra-stable mode-locked frequency comb femtosecond laser and compressive sensing to measure an object's surface profile. The ultra-stable frequency comb laser was used to precisely measure an object with a large depth, over a wide dynamic range. The compressive sensing technique was able to obtain the spatial information of the object with two single-pixel fast photo-receivers, with no mechanical scanning and fewer measurements than the number of sampling points. An optical experiment was performed to verify the advantages of the proposed method.

  4. Cavity-enhanced coherent light scattering from a quantum dot.

    Science.gov (United States)

    Bennett, Anthony J; Lee, James P; Ellis, David J P; Meany, Thomas; Murray, Eoin; Floether, Frederik F; Griffths, Jonathan P; Farrer, Ian; Ritchie, David A; Shields, Andrew J

    2016-04-01

    The generation of coherent and indistinguishable single photons is a critical step for photonic quantum technologies in information processing and metrology. A promising system is the resonant optical excitation of solid-state emitters embedded in wavelength-scale three-dimensional cavities. However, the challenge here is to reject the unwanted excitation to a level below the quantum signal. We demonstrate this using coherent photon scattering from a quantum dot in a micropillar. The cavity is shown to enhance the fraction of light that is resonantly scattered toward unity, generating antibunched indistinguishable photons that are 16 times narrower than the time-bandwidth limit, even when the transition is near saturation. Finally, deterministic excitation is used to create two-photon N00N states with which we make superresolving phase measurements in a photonic circuit. PMID:27152337

  5. Optically transparent frequency selective surfaces on flexible thin plastic substrates

    Science.gov (United States)

    Dewani, Aliya A.; O'Keefe, Steven G.; Thiel, David V.; Galehdar, Amir

    2015-02-01

    A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

  6. Optically transparent frequency selective surfaces on flexible thin plastic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Dewani, Aliya A., E-mail: a.ashraf@griffith.edu.au; O’Keefe, Steven G.; Thiel, David V.; Galehdar, Amir [School Of Electrical Engineering, Griffith University, Brisbane, 4111 (Australia)

    2015-02-15

    A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm), flexible transparent plastic substrate (relative permittivity 3.2). It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing) to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

  7. Frequency-noise measurements of optical frequency combs by multiple fringe-side discriminator.

    Science.gov (United States)

    Coluccelli, Nicola; Cassinerio, Marco; Gambetta, Alessio; Laporta, Paolo; Galzerano, Gianluca

    2015-01-01

    The frequency noise of an optical frequency comb is routinely measured through the hetherodyne beat of one comb tooth against a stable continuous-wave laser. After frequency-to-voltage conversion, the beatnote is sent to a spectrum analyzer to retrive the power spectral density of the frequency noise. Because narrow-linewidth continuous-wave lasers are available only at certain wavelengths, heterodyning the comb tooth can be challenging. We present a new technique for direct characterization of the frequency noise of an optical frequency comb, requiring no supplementary reference lasers and easily applicable in all spectral regions from the terahertz to the ultraviolet. The technique is based on the combination of a low finesse Fabry-Perot resonator and the so-called "fringe-side locking" method, usually adopted to characterize the spectral purity of single-frequency lasers, here generalized to optical frequency combs. The effectiveness of this technique is demonstrated with an Er-fiber comb source across the wavelength range from 1 to 2 μm. PMID:26548900

  8. Distributed Raman optical amplification in phase coherent transfer of optical frequencies

    OpenAIRE

    Clivati, Cecilia; Bolognini, Gabriele; Calonico, Davide; Faralli, Stefano; Levi, Filippo; Mura, Alberto; Poli, Nicola

    2012-01-01

    We describe the application of Raman Optical-fiber Amplification (ROA) for the phase coherent transfer of optical frequencies in an optical fiber link. ROA uses the transmission fiber itself as a gain medium for bi-directional coherent amplification. In a test setup we evaluated the ROA in terms of on-off gain, signal-to-noise ratio, and phase noise added to the carrier. We transferred a laser frequency in a 200 km optical fiber link with an additional 16 dB fixed attenuator (equivalent to 27...

  9. Tunable Resonant-Cavity-Enhanced Photodetector with Double High-Index-Contrast Grating Mirrors

    DEFF Research Database (Denmark)

    Learkthanakhachon, Supannee; Yvind, Kresten; Chung, Il-Sug

    2013-01-01

    In this paper, we propose a broadband-tunable resonant-cavity-enhanced photodetector (RCE-PD) structure with double high-index-contrast grating (HCG) mirrors and numerically investigate its characteristics. The detector is designed to operate at 1550-nm wavelength. The detector structure consists...

  10. Ultra-high Frequency Linear Fiber Optic Systems

    CERN Document Server

    Lau, Kam

    2011-01-01

    This book provides an in-depth treatment of both linear fiber-optic systems and their key enabling devices. It presents a concise but rigorous treatment of the theory and practice of analog (linear) fiber-optics links and systems that constitute the foundation of Hybrid Fiber Coax infrastructure in present-day CATV distribution and cable modem Internet access. Emerging applications in remote fiber-optic feed for free-space millimeter wave enterprise campus networks are also described. Issues such as dispersion and interferometric noise are treated quantitatively, and means for mitigating them are explained. This broad but concise text will thus be invaluable not only to students of fiber-optics communication but also to practicing engineers. To the second edition of this book important new aspects of linear fiber-optic transmission technologies are added, such as high level system architectural issues, algorithms for deriving the optimal frequency assignment, directly modulated or externally modulated laser t...

  11. Kerr optical frequency combs: theory, applications and perspectives

    Science.gov (United States)

    Chembo, Yanne K.

    2016-06-01

    The optical frequency comb technology is one of the most important breakthrough in photonics in recent years. This concept has revolutionized the science of ultra-stable lightwave and microwave signal generation. These combs were originally generated using ultrafast mode-locked lasers, but in the past decade, a simple and elegant alternativewas proposed,which consisted in pumping an ultra-high-Q optical resonator with Kerr nonlinearity using a continuous-wave laser. When optimal conditions are met, the intracavity pump photons are redistributed via four-wave mixing to the neighboring cavity modes, thereby creating the so-called Kerr optical frequency comb. Beyond being energy-efficient, conceptually simple, and structurally robust, Kerr comb generators are very compact devices (millimetric down to micrometric size) which can be integrated on a chip. They are, therefore, considered as very promising candidates to replace femtosecond mode-locked lasers for the generation of broadband and coherent optical frequency combs in the spectral domain, or equivalently, narrow optical pulses in the temporal domain. These combs are, moreover, expected to provide breakthroughs in many technological areas, such as integrated photonics, metrology, optical telecommunications, and aerospace engineering. The purpose of this review article is to present a comprehensive survey of the topic of Kerr optical frequency combs.We provide an overview of the main theoretical and experimental results that have been obtained so far. We also highlight the potential of Kerr combs for current or prospective applications, and discuss as well some of the open challenges that are to be met at the fundamental and applied level.

  12. Optical frequency upconversion technique for transmission of wireless MIMO-type signals over optical fiber.

    Science.gov (United States)

    Shaddad, R Q; Mohammad, A B; Al-Gailani, S A; Al-Hetar, A M

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

  13. Squeezing Alters Frequency Tuning of WGM Optical Resonator

    Science.gov (United States)

    Mohageg, Makan; Maleki, Lute

    2010-01-01

    Mechanical squeezing has been found to alter the frequency tuning of a whispering-gallery-mode (WGM) optical resonator that has an elliptical shape and is made of lithium niobate. It may be possible to exploit this effect to design reconfigurable optical filters for optical communications and for scientific experiments involving quantum electrodynamics. Some background information is prerequisite to a meaningful description of the squeezing-induced alteration of frequency tuning: The spectrum of a WGM resonator is represented by a comblike plot of intensity versus frequency. Each peak of the comblike plot corresponds to an electromagnetic mode represented by an integer mode number, and the modes are grouped into sets represented by integer mode indices. Because lithium niobate is an electro-optically active material, the WGM resonator can be tuned (that is, the resonance frequencies can be shifted) by applying a suitable bias potential. The frequency shift of each mode is quantified by a tuning rate defined as the ratio between the frequency shift and the applied potential. In the absence of squeezing, all modes exhibit the same tuning rate. This concludes the background information. It has been demonstrated experimentally that when the resonator is squeezed along part of either of its two principal axes, tuning rates differ among the groups of modes represented by different indices (see figure). The differences in tuning rates could be utilized to configure the resonance spectrum to obtain a desired effect; for example, through a combination of squeezing and electrical biasing, two resonances represented by different mode indices could be set at a specified frequency difference something that could not be done through electrical biasing alone.

  14. Method of shifting and fixing optical frequency of an optical resonator, and optical resonator made by same

    Science.gov (United States)

    Savchenkov, Anatoliy A. (Inventor); Strekalov, Dmitry V. (Inventor); Maleki, Lute (Inventor); Matsko, Andrey B. (Inventor); Iltchenko, Vladimir S. (Inventor); Martin, Jan M. (Inventor)

    2010-01-01

    A method of shifting and fixing an optical frequency of an optical resonator to a desired optical frequency, and an optical resonator made by such a method are provided. The method includes providing an optical resonator having a surface and a refractive index, and obtaining a coating composition having a predetermined concentration of a substance and having a refractive index that is substantially similar to the refractive index of the optical resonator. The coating composition inherently possesses a thickness when it is applied as a coating. The method further includes determining a coating ratio for the surface of the optical resonator and applying the coating composition onto a portion of the surface of the optical resonator based upon the determined coating ratio.

  15. Optimal light harvesting structures at optical and infrared frequencies

    CERN Document Server

    Villate-Guío, F; García-Vidal, F J; Martín-Moreno, L; de León-Pérez, F

    2012-01-01

    One-dimensional light harvesting structures with a realistic geometry nano-patterned on an opaque metallic film are optimized to render high transmission efficiencies at optical and infrared frequencies. Simple design rules are developed for the particular case of a slit-groove array with a given number of grooves that are symmetrically distributed with respect to a central slit. These rules take advantage of the hybridization of Fabry-Perot modes in the slit and surface modes of the corrugated metal surface. Same design rules apply for optical and infrared frequencies. The parameter space of the groove array is also examined with a conjugate gradient optimization algorithm that used as a seed the geometries optimized following physical intuition. Both uniform and nonuniform groove arrays are considered. The largest transmission enhancement, with respect to a uniform array, is obtained for a chirped groove profile. Such enhancement is a function of the wavelength. It decreases from 39% in the optical part of ...

  16. Dual-frequency Brillouin fiber laser for optical generation of tunable low-noise radio frequency/microwave frequency.

    Science.gov (United States)

    Geng, Jihong; Staines, Sean; Jiang, Shibin

    2008-01-01

    We demonstrate a new approach, i.e., a cw dual-frequency Brillouin fiber laser pumped by two independent single-frequency Er-doped fiber lasers, for the generation of tunable low-noise rf/microwave optical signals. Its inherent features of both linewidth narrowing effect in a Brillouin fiber cavity and common mode noise cancellation between two laser modes sharing a common cavity allow us to achieve high frequency stability without using a supercavity. Beat frequency of the dual-frequency Brillouin fiber laser can be tuned from tens of megahertz up to 100 GHz by thermally tuning the wavelengths of the two pump lasers with tuning sensitivity of approximately 1.4 GHz/ degrees C. Allan variance measurements show the beat signals have the hertz-level frequency stability.

  17. Revealing Carrier-Envelope Phase through Frequency Mixing and Interference in Frequency Resolved Optical Gating

    CERN Document Server

    Snedden, Edward W; Jamison, Steven P

    2015-01-01

    We demonstrate that full temporal characterisation of few-cycle electromagnetic pulses, including retrieval of the carrier envelope phase (CEP), can be directly obtained from Frequency Resolved Optical Gating (FROG) techniques in which the interference between non-linear frequency mixing processes is resolved. We derive a framework for this scheme, defined Real Domain-FROG (ReD-FROG), as applied to the cases of interference between sum and difference frequency components and between fundamental and sum/difference frequency components. A successful numerical demonstration of ReD-FROG as applied to the case of a self-referenced measurement is provided. A proof-of-principle experiment is performed in which the CEP of a single-cycle THz pulse is accurately obtained and demonstrates the possibility for THz detection beyond the bandwidth limitations of electro-optic sampling.

  18. Electro-optical microwave signal processor for high-frequency wideband frequency channelization

    Science.gov (United States)

    Dawber, William N.; Webster, Ken

    1998-08-01

    An electro-optic microwave signal processor for activity monitoring in an electronic warfare receiver, offering wideband operation, parallel output in real time and 100 percent probability of intercept is presented, along with results from a prototype system. Requirements on electronic warfare receiver system are demanding, because they have to defect and identify potential threats across a large frequency bandwidth and in the high pulse density expected of the battlefield environment. A technique of processing signals across a wide bandwidth is to use a channelizer in the receiver front-end, in order to produce a number of narrow band outputs that can be individually processed. In the presented signal processor, received microwave signals ar unconverted onto an optical carrier using an electro- optic modulator and then spatially separated into a series of spots. The position and intensity of the spots is determined by the received signal(s) frequency and strength. Finally a photodiode array can be used for fast parallel data readout. Thus the signal processor output is fully channelized according to frequency. A prototype signal processor has been constructed, which can process microwave frequencies from 500MHz to 8GHz. A standard telecommunications electro-optic intensity modulator with a 3dB bandwidth of approximately 2.5GHz provides frequency upconversion. Readout is achieved using either a near IR camera or a 16 element linear photodiode array.

  19. Optical Feedback Characteristics in He-Ne Dual Frequency Lasers

    Institute of Scientific and Technical Information of China (English)

    MAO Wei; ZHANG Shu-Lian; ZHANG Lian-Qing; ZHU Jun; LI Yan

    2006-01-01

    @@ Optical feedback characteristics in He-Ne dual frequency lasers are studied systematically in different feedback power ratios with a variable attenuator. Feedback power ratios vary from 0.010 up to 0.998. Five distinct regimes of self-interference effects are found and defined as regimes Ⅰ, Ⅱ, Ⅲ,Ⅳ and V. Accordingly, five optical feedback levels have been put forward in He-Ne dual frequency lasers. Strong mode competitions are observed in regimes Ⅲ and Ⅳ. In regime Ⅴ, multiple feedback effects are investigated. The basic theoretical analysis is also presented.Our reults can advance the research ofself-mixing interferometer and displacement sensor of He-Ne orthogonally polarized dual frequency lasers.

  20. Micro--structured crystalline resonators for optical frequency comb generation

    CERN Document Server

    Grudinin, Ivan S

    2014-01-01

    Optical frequency combs have recently been demonstrated in micro--resonators through nonlinear Kerr processes. Investigations in the past few years provided better understanding of micro--combs and showed that spectral span and mode locking are governed by cavity spectrum and dispersion. While various cavities provide unique advantages, dispersion engineering has been reported only for planar waveguides. In this Letter, we report a resonator design that combines dispersion control, mode crossing free spectrum, and ultra--high quality factor. We experimentally show that as the dispersion of a MgF2 resonator is flattened, the comb span increases reaching 700 nm with as low as 60 mW pump power at 1560 nm wavelength, corresponding to nearly 2000 lines separated by 46 GHz. The new resonator design may enable efficient low repetition rate coherent octave spanning frequency combs without the need for external broadening, ideal for applications in optical frequency synthesis, metrology, spectroscopy, and communicatio...

  1. Intense harmonics generation with customized photon frequency and optical vortex

    Science.gov (United States)

    Zhang, Xiaomei; Shen, Baifei; Shi, Yin; Zhang, Lingang; Ji, Liangliang; Wang, Xiaofeng; Xu, Zhizhan; Tajima, Toshiki

    2016-08-01

    An optical vortex with orbital angular momentum (OAM) enriches the light and matter interaction process, and helps reveal unexpected information in relativistic nonlinear optics. A scheme is proposed for the first time to explore the origin of photons in the generated harmonics, and produce relativistic intense harmonics with expected frequency and an optical vortex. When two counter-propagating Laguerre-Gaussian laser pulses impinge on a solid thin foil and interact with each other, the contribution of each input pulse in producing harmonics can be distinguished with the help of angular momentum conservation of photons, which is almost impossible for harmonic generation without an optical vortex. The generation of tunable, intense vortex harmonics with different photon topological charge is predicted based on the theoretical analysis and three-dimensional particle-in-cell simulations. Inheriting the properties of OAM and harmonics, the obtained intense vortex beam can be applied in a wide range of fields, including atom or molecule control and manipulation.

  2. Investigation of a slot nanoantenna in optical frequency range

    Science.gov (United States)

    Dinesh kumar, V.; Asakawa, Kiyoshi

    2009-11-01

    Following the analogy of radio frequency slot antenna and its complementary dipole, we propose the implementation of a slot nanoantenna (SNA) in the optical frequency range. Using finite-difference time-domain (FDTD) method, we investigate the electromagnetic (EM) properties of a SNA formed in a thin gold film and compare the results with the properties of a gold dipole nanoantenna (DNA) of the same dimension as the slot. It is found that the response of the SNA is very similar to the DNA, like their counterparts in the radio frequency (RF) range. The SNA can enhance the near field intensity of incident field which strongly depends on its feedgap dimension. The resonance of the SNA is influenced by its slot length; for the increasing slot length, resonant frequency decreases whereas the sharpness of resonance increases. Besides, the resonance of the SNA is found sensitive to the thickness of metal film, when the latter is smaller than the skin depth. The effect of polarization of incident field on the EM response of the SNA was examined; the field enhancement is optimum when polarization is parallel to the feedgap. Finally, we calculate the radiation patterns of the DNA and SNA and compare them with those of the RF dipole antenna. The radiation pattern of the SNA is found to be independent of its slot length when excited at resonant frequency. To the best of our knowledge, this is the first study on a slot antenna in the optical frequency.

  3. Comparing a mercury optical lattice clock with microwave and optical frequency standards

    CERN Document Server

    Tyumenev, R; Bilicki, S; Bookjans, E; Targat, R Le; Lodewyck, J; Nicolodi, D; Coq, Y Le; Abgrall, M; Guéna, J; De Sarlo, L; Bize, S

    2016-01-01

    In this paper we report the evaluation of an optical lattice clock based on neutral mercury down to a relative uncertainty of $1.7\\times 10^{-16}$. Comparing this characterized frequency standard to a Cs atomic fountain we determine the absolute frequency of the $^1S_0 \\rightarrow \\phantom{}^3P_0$ transition of $^{199}$Hg as $\

  4. Generation of frequency-chirped optical pulses with felix

    Energy Technology Data Exchange (ETDEWEB)

    Knippels, G.M.H.; Meer, A.F.G. van der; Mols, R.F.X.A.M. [FOM-Institute for Plasma Physics, Nieuwegein (Netherlands)] [and others

    1995-12-31

    Frequency-chirped optical pulses have been produced in the picosecond regime by varying the energy of the electron beam on a microsecond time scale. These pulses were then compressed close to their bandwidth limit by an external pulse compressor. The amount of chirp can be controlled by varying the sweep rate on the electron beam energy and by cavity desynchronisation. To examine the generated chirp we used the following diagnostics: a pulse compressor, a crossed beam autocorrelator, a multichannel electron spectrometer and multichannel optical spectrometer. The compressor is build entirely using reflective optics to permit broad band operation. The autocorrelator is currently operating from 6 {mu}m to 30 {mu}m with one single crystal. It has been used to measure pulses as short as 500 fs. All diagnostics are evacuated to prevent pulse shape distortion or pulse lengthening caused by absorption in ambient water vapour. Pulse length measurements and optical spectra will be presented for different electron beam sweep rates, showing the presence of a frequency chirp. Results on the compression of the optical pulses to their bandwidth limit are given for different electron sweep rates. More experimental results showing the dependence of the amount of chirp on cavity desynchronisation will be presented.

  5. Optical frequency divider with division uncertainty at the 10^(-21) level

    CERN Document Server

    Yao, Yuan; Yu, Hongfu; Bi, Zhiyi; Ma, Longsheng

    2016-01-01

    Optical clocks with unprecedented accuracy of 10^(-18) will lead to innovations in many research areas. All the applications of optical clocks rely on the ability of precisely converting the frequency from one optical clock to another, or particularly to the frequencies in the fiber telecom band for long-distance transmission. Here, we report a low-noise, high precision optical frequency divider. It can realize accurate optical frequency conversion as well as enable precise measurement of optical frequency ratios. By comparing against the frequency ratio between the fundamental and the second harmonic of a 1064 nm laser rather than a second similar system, the optical frequency divider is demonstrated to have a frequency division instability of 6e-19 at 1 s and a fractional frequency division uncertainty of 1.4e-21, nearly three orders of magnitude better than the most accurate optical clocks. It allows optical clocks to be accessible to many precision measurement applications.

  6. Optical sum-frequency generation in whispering gallery mode resonators

    CERN Document Server

    Strekalov, Dmitry V; Huang, Yu-Ping; Kumar, Prem

    2013-01-01

    We demonstrate sum-frequency generation in a nonlinear whispering gallery mode resonator between a telecom wavelength and the Rb D2 line, achieved through natural phase matching. Due to the strong optical field confinement and ultra high Q of the cavity, we achieve a 1000-fold enhancement in the conversion efficiency compared to existing waveguide-based devices. The experimental data are in agreement with the nonlinear dynamics and phase matching theory in the spherical geometry employed. The experimental and theoretical results point to a new platform to manipulate the color and quantum states of light waves toward applications such as atomic memory based quantum networking and logic operations with optical signals.

  7. Frequency translation of light waves by propagation around an optical ring circuit containing a frequency shifter: I. Experiment.

    Science.gov (United States)

    Shimizu, K; Horiguchi, T; Koyamada, Y

    1993-11-20

    A technique for the external frequency translation of light waves is reported. The technique permits the stepwise sweeping of an optical frequency over a wide range with high linearity with respect to time. The frequency translator is composed of an optical pulse modulator and an optical ring circuit containing an acousto-optic frequency shifter and an optical amplifier. The pulse launched into the ring circuit undergoes a constant frequency shift for each circulation around the circuit and the frequency can be translated to a considerable degree from that of the original input pulse. We report a stepwise frequency translation over approximately 68 GHz for a 1.5-µm light wave with a strictly constant frequency-sweep rate and an approximately constant intensity.

  8. Design and simulation of an integrated optical ring-resonator based frequency discriminator for analog optical links

    NARCIS (Netherlands)

    Timens, R.B.; Marpaung, D.A.I.; Roeloffzen, C.G.H.; Etten, van W.

    2008-01-01

    The performance of a conventional intensity modulation direct detection analog optical links is limited by the high noise power associated with large optical carrier power. This optical carrier can be suppressed by using optical frequency modulation in conjunction with a frequency discriminator. In

  9. Effect of soil temperature on optical frequency transfer through unidirectional dense-wavelength-divisionmultiplexing fiber-optic links

    NARCIS (Netherlands)

    Pinkert, T.J.; Böll, O.; Willmann, Lorenz; Jansen, G.S.M.; Dijck, E.A.; Groeneveld, B.G.H.M.; Smets, R.; Bosveld, F.C.; Ubachs, W.; Jungmann, K.; Eikema, K.S.E.; Koelemeij, J.C.J.

    2015-01-01

    Results of optical frequency transfer over a carrier-grade dense-wavelength-division-multiplexing (DWDM) optical fiber network are presented. The relation between soil temperature changes on a buried optical fiber and frequency changes of an optical carrier through the fiber is modeled. Soil tempera

  10. Stabilization of an optical frequency comb to an external cavity

    OpenAIRE

    Rydberg, Olof

    2014-01-01

    The subject of this master's thesis is stabilizing a frequency comb laser to an external cavity using a couple of servo controllers. The aim of the project was to build a pair of servo controllers, replacing parts of the existing commercial and proprietary solution already in use. The system under control is an optical frequency comb, which is locked to an external cavity and is used for trace gas detection and spectroscopy. The comb is a broadband light source and needs to be locked to the e...

  11. Relativistic Corrections for Time and Frequency Transfer in Optical Fibres

    CERN Document Server

    Geršl, J; Wolf, P

    2016-01-01

    We derive relativistic corrections for one-way and two-way time and frequency transfer over optical fibres neglecting no terms that exceed 1 ps in time and $10^{-18}$ in fractional frequency, and estimate their magnitude in typical fibre links. We also provide estimates of the uncertainties in the evaluation of the relativistic corrections due to imperfect knowledge of parameters like the coordinates of the fibre and stations, Earth rotation, or thermal effects of the fibre index and length. The links between Teddington(UK) and Paris(F) as well as Braunschweig(D) and Paris(F), that are currently under construction, are studied as specific examples.

  12. Transferring the stability of iodine-stabilized diode laser at 634 nm to radio frequency by an optical frequency comb

    Institute of Scientific and Technical Information of China (English)

    Lin Yi; Xianghui Qi; Wenlan Chen; Dawei Zhou; Tong Zhou; Xiaoji Zhou; Xuzong Chen

    2009-01-01

    An optical frequency comb phase-locked on an iodine frequency stabilized diode laser at 634 nm is con structed to transfer the accuracy and stability from the optical domain to the radio frequency domain. An external-cavity diode laser is frequency-stabilized on the Doppler-free absorption signals of the hyperfine transition R(80)8-4 using the third-harmonic detection technique. The instability of the ultra-stable op tical oscillator is determined to be 7 x 10-12 by a cesium atomic clock via the optical frequency comb's mass frequency dividing technique.

  13. Cavity-enhanced laser cooling of solid-state materials in a standing-wave cavity

    Institute of Scientific and Technical Information of China (English)

    Youhua Jia; Biao Zhong; Jianping Yin

    2008-01-01

    We propose a new method to cool the Yba+-doped ZBLANP glass in a standing-wave cavity. There are two advantages of this cavity-enhanced technique: the pumping power is greatly enhanced and the absorption of the cooling material is greatly increased. We introduce the basic principle of the cavity-enhanced laser cooling and discuss the cooling effect of a solid-state material in a cavity. From the theoretical study, it is found that the laser cooling effect is strongly dependent on the reflectivity of the cavity mirrors, the length of the solid material, the surface scattering of the material, and so on. Some optimal parameters for efficient laser cooling are obtained.

  14. Strong optical feedback in birefringent dual frequency laser

    Institute of Scientific and Technical Information of China (English)

    Mao Wei; Zhang Shu-Lian

    2006-01-01

    Strong optical feedback in a birefringent dual frequency He-Ne laser with a high reflectivity feedback mirror has been investigated for the first time. The output characteristics of two orthogonally polarized modes are demonstrated in two different optical feedback cases: one is for both modes being fed back and the other is for only one of the modes being fed back. Strong mode competition can be observed between the two modes with strong optical feedback. And when one mode's intensity is near its maximum, the other mode is nearly extinguished. When both modes are fed back into the laser cavity, the mode competition is stronger than when only one mode is fed back. The difference in initial intensity between the two orthogonally polarized modes plays an important role in the mode competition, which has been experimentally and theoretically demonstrated.

  15. Sensitivity in frequency dependent angular rotation of optical vortices.

    Science.gov (United States)

    Rumala, Yisa S

    2016-03-10

    This paper presents robust strategies to enhance the rotation sensitivity (and resolution) of a coherent superposition of optical vortices emerging from a single spiral phase plate (SPP) device when light's optical frequency (or wavelength) going into the SPP device is varied. The paper discusses the generation and measurement of ultrasmall rotation. Factors that affect the ability to perform precision rotation measurements include the linewidth and stability of the input light source, the number of photon counts making position rotation measurements on the CCD detector, SPP reflectivity, the length of SPP device, and the angular modulation frequency of the intensity pattern due to a coherent superposition of optical vortices in a single SPP device. This paper also discusses parameters to obtain a high-sensitivity single shot measurement and multiple measurements. Furthermore, it presents what I believe is a new scaling showing the enhancement in sensitivity (and resolution) in the standard quantum limit and Heisenberg limit. With experimentally realizable parameters, there is an enhancement of rotation sensitivity by at least one order of magnitude compared to previous rotation measurements with optical vortices. Understanding robust strategies to enhance the rotation sensitivity in an SPP device is important to metrology in general and for building compact SPP sensors such as gyroscopes, molecular sensors, and thermal sensors. PMID:26974798

  16. Compressive sensing of sparse radio frequency signals using optical mixing.

    Science.gov (United States)

    Valley, George C; Sefler, George A; Shaw, T Justin

    2012-11-15

    We demonstrate an optical mixing system for measuring properties of sparse radio frequency (RF) signals using compressive sensing (CS). Two types of sparse RF signals are investigated: (1) a signal that consists of a few 0.4 ns pulses in a 26.8 ns window and (2) a signal that consists of a few sinusoids at different frequencies. The RF is modulated onto the intensity of a repetitively pulsed, wavelength-chirped optical field, and time-wavelength-space mapping is used to map the optical field onto a 118-pixel, one-dimensional spatial light modulator (SLM). The SLM pixels are programmed with a pseudo-random bit sequence (PRBS) to form one row of the CS measurement matrix, and the optical throughput is integrated with a photodiode to obtain one value of the CS measurement vector. Then the PRBS is changed to form the second row of the mixing matrix and a second value of the measurement vector is obtained. This process is performed 118 times so that we can vary the dimensions of the CS measurement matrix from 1×118 to 118×118 (square). We use the penalized ℓ(1) norm method with stopping parameter λ (also called basis pursuit denoising) to recover pulsed or sinusoidal RF signals as a function of the small dimension of the measurement matrix and stopping parameter. For a square matrix, we also find that penalized ℓ(1) norm recovery performs better than conventional recovery using matrix inversion. PMID:23164876

  17. Frequency-time coherence for all-optical sampling without optical pulse source

    Science.gov (United States)

    Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

    2016-09-01

    Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift.

  18. Frequency-time coherence for all-optical sampling without optical pulse source

    Science.gov (United States)

    Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

    2016-01-01

    Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift. PMID:27687495

  19. High-Performance Optical Frequency References for Space

    Science.gov (United States)

    Schuldt, Thilo; Döringshoff, Klaus; Milke, Alexander; Sanjuan, Josep; Gohlke, Martin; Kovalchuk, Evgeny V.; Gürlebeck, Norman; Peters, Achim; Braxmaier, Claus

    2016-06-01

    A variety of future space missions rely on the availability of high-performance optical clocks with applications in fundamental physics, geoscience, Earth observation and navigation and ranging. Examples are the gravitational wave detector eLISA (evolved Laser Interferometer Space Antenna), the Earth gravity mission NGGM (Next Generation Gravity Mission) and missions, dedicated to tests of Special Relativity, e.g. by performing a Kennedy- Thorndike experiment testing the boost dependence of the speed of light. In this context we developed optical frequency references based on Doppler-free spectroscopy of molecular iodine; compactness and mechanical and thermal stability are main design criteria. With a setup on engineering model (EM) level we demonstrated a frequency stability of about 2·10-14 at an integration time of 1 s and below 6·10-15 at integration times between 100s and 1000s, determined from a beat-note measurement with a cavity stabilized laser where a linear drift was removed from the data. A cavity-based frequency reference with focus on improved long-term frequency stability is currently under development. A specific sixfold thermal shield design based on analytical methods and numerical calculations is presented.

  20. Optically transparent frequency selective surfaces on flexible thin plastic substrates

    Directory of Open Access Journals (Sweden)

    Aliya A. Dewani

    2015-02-01

    Full Text Available A novel 2D simple low cost frequency selective surface was screen printed on thin (0.21 mm, flexible transparent plastic substrate (relative permittivity 3.2. It was designed, fabricated and tested in the frequency range 10-20 GHz. The plane wave transmission and reflection coefficients agreed with numerical modelling. The effective permittivity and thickness of the backing sheet has a significant effect on the frequency characteristics. The stop band frequency reduced from 15GHz (no backing to 12.5GHz with polycarbonate. The plastic substrate thickness beyond 1.8mm has minimal effect on the resonant frequency. While the inner element spacing controls the stop-band frequency, the substrate thickness controls the bandwidth. The screen printing technique provided a simple, low cost FSS fabrication method to produce flexible, conformal, optically transparent and bio-degradable FSS structures which can find their use in electromagnetic shielding and filtering applications in radomes, reflector antennas, beam splitters and polarizers.

  1. Optical Frequency Comb Spectroscopy of Rare Earth Atoms

    Science.gov (United States)

    Swiatlowski, Jerlyn; Palm, Christopher; Joshi, Trinity; Montcrieffe, Caitlin; Jackson Kimball, Derek

    2013-05-01

    We discuss progress in our experimental program to employ optical-frequency-comb-based spectroscopy to understand the complex spectra of rare-earth atoms. We plan to carry out systematic measurements of atomic transitions in rare-earth atoms to elucidate the energy level structure and term assignment and determine presently unknown atomic state parameters. This spectroscopic information is important in view of the increasing interest in rare-earth atoms for atomic frequency standards, in astrophysical investigations of chemically peculiar stars, and in tests of fundamental physics (tests of parity and time-reversal invariance, searches for time variation of fundamental constants, etc.). We are presently studying the use of hollow cathode lamps as atomic sources for two-photon frequency comb spectroscopy. Supported by the National Science Foundation under grant PHY-0958749.

  2. A Cs-Based Optical Frequency Measurement Using Cross-Linked Optical and Microwave Oscillators

    CERN Document Server

    Tamm, Chr; Lipphardt, B; Gerginov, V; Nemitz, N; Kazda, M; Weyers, S; Peik, E

    2013-01-01

    We describe a measurement of the frequency of the 2S1/2(F = 0) - 2D3/2(F' = 2) transition of 171Yb+ at the wavelength 436 nm (frequency 688 THz), using a single Yb+ ion confined in a Paul trap and two caesium fountains as references. In one of the fountains, the frequency of the microwave oscillator that interrogates the caesium atoms is stabilized by the laser that excites the Yb+ reference transition with a linewidth in the hertz range. The stability is transferred to the microwave oscillator with the use of a fiber laser based optical frequency comb generator that also provides the frequency conversion for the absolute frequency measurement. The frequency comb generator is configured as a transfer oscillator so that fluctuations of the pulse repetition rate and of the carrier offset frequency do not degrade the stability of the frequency conversion. The phase noise level of the generated ultrastable microwave signal is comparable to that of a cryogenic sapphire oscillator. For fountain operation with optic...

  3. Fractional frequency instability in the 10{sup -14} range with a thermal beam optical frequency reference

    Energy Technology Data Exchange (ETDEWEB)

    McFerran, John J.; Luiten, Andre N. [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley 6009, W.A. (Australia)

    2010-02-15

    We demonstrate a means of increasing the signal-to-noise ratio in a Ramsey-Borde interferometer with spatially separated oscillatory fields on a thermal atomic beam. The {sup 1}S{sub 0}{r_reversible}{sup 3}P{sub 1} intercombination line in neutral {sup 40}Ca is used as a frequency discriminator, with an extended cavity diode laser at 423 nm probing the ground state population after a Ramsey-Borde sequence of 657 nm light-field interactions with the atoms. Evaluation of the instability of the Ca frequency reference is carried out by comparison with (i) a hydrogen-maser and (ii) a cryogenic sapphire oscillator. In the latter case the Ca reference exhibits a square-root {Lambda} variance of 9.2x10{sup -14} at 1 s and 2.0x10{sup -14} at 64 s. This is an order-of-magnitude improvement for optical beam frequency references, to our knowledge. The shot noise of the readout fluorescence produces a limiting square-root {Lambda} variance of 7x10{sup -14}/{radical}({tau}), highlighting the potential for improvement. This work demonstrates the feasibility of a portable frequency reference in the optical domain with 10{sup -14} range frequency instability.

  4. A diode laser spectrometer at 634 nm and absolute frequency measurements using optical frequency comb

    Institute of Scientific and Technical Information of China (English)

    Yi Lin; Yuan Jie; Qi Xiang-Hui; Chen Wen-Lan; Zhou Da-Wei; Zhou Tong; Zhou Xiao-Ji; Chen Xu-Zong

    2009-01-01

    This paper reports that two identical external-cavity-diode-laser(ECDL)based spectrometers are constructed at 634 nm referencing on the hyperfine B-X transition a(80)8-4 of 127I2.The lasers are stabilized on the Doppler-free absorption signals using the third-harmonic detection technique.The instability of the stabilized laser is measured to be 2.8×10-12(after 1000 s)by counting the beat note between the two lasers.The absolute optical frequency of the transition is,for the first time,determined to be 472851936189.5 kHz by using an optical frequency comb referenced on the microwave caesium atomic clock.The uncertainty of the measurement is less than 4.9 kHz.

  5. Frequency comparison of optical lattice clocks beyond the Dick limit

    Science.gov (United States)

    Takamoto, Masao; Takano, Tetsushi; Katori, Hidetoshi

    2011-05-01

    The supreme accuracy of atomic clocks relies on the universality of atomic transition frequencies. The stability of a clock, meanwhile, measures how quickly the clock's statistical uncertainties are reduced. The ultimate measure of stability is provided by the quantum projection noise, which improves as 1/√N by measuring N uncorrelated atoms. Quantum projection noise limited stabilities have been demonstrated in caesium clocks and in single-ion optical clocks, where the quantum noise overwhelms the Dick effect attributed to local oscillator noise. Here, we demonstrate a synchronous frequency comparison of two optical lattice clocks using 87Sr and 88Sr atoms, respectively, for which the Allan standard deviation reached 1 × 10-17 in an averaging time of 1,600 s by cancelling out the Dick effect to approach the quantum projection noise limit. The scheme demonstrates the advantage of using a large number (N ~ 1,000) of atoms in optical clocks and paves the way to investigating the inherent uncertainties of clocks and relativistic geodesy on a timescale of tens of minutes.

  6. Cavity-Enhanced Gas Analyzer for In-Situ Sampling of Biogenic Gases and Their Isotopes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project concerns the novel application of cavity-enhanced absorption spectroscopy to quantify biogenic gases (CH4,...

  7. Invited Article: A compact optically coherent fiber frequency comb.

    Science.gov (United States)

    Sinclair, L C; Deschênes, J-D; Sonderhouse, L; Swann, W C; Khader, I H; Baumann, E; Newbury, N R; Coddington, I

    2015-08-01

    We describe the design, fabrication, and performance of a self-referenced, optically coherent frequency comb. The system robustness is derived from a combination of an optics package based on polarization-maintaining fiber, saturable absorbers for mode-locking, high signal-to-noise ratio (SNR) detection of the control signals, and digital feedback control for frequency stabilization. The output is phase-coherent over a 1-2 μm octave-spanning spectrum with a pulse repetition rate of ∼200 MHz and a residual pulse-to-pulse timing jitter <3 fs well within the requirements of most frequency-comb applications. Digital control enables phase coherent operation for over 90 h, critical for phase-sensitive applications such as timekeeping. We show that this phase-slip free operation follows the fundamental limit set by the SNR of the control signals. Performance metrics from three nearly identical combs are presented. This laptop-sized comb should enable a wide-range of applications beyond the laboratory.

  8. DWDM Fiber-Wireless Access System with Centralized Optical Frequency Comb-based RF Carrier Generation

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Beltrán, Marta; Sánchez, José;

    2013-01-01

    We propose and experimentally demonstrate an optical wireless DWDM system at 60 GHz with optical incoherent heterodyne up-conversion using an optical frequency comb. Multiple users with wireline and wireless services are simultaneously supported....

  9. Frequency-time coherence for all-optical sampling without optical pulse source

    CERN Document Server

    Preussler, Stefan; Schneider, Thomas

    2016-01-01

    Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave, allowing simple integration in appropriate platforms, such as Silicon Photonics. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift.

  10. Nonlinear optics at low powers: new mechanism of on-chip optical frequency comb generation

    CERN Document Server

    Rogov, Andrei

    2016-01-01

    Nonlinear optical effects provide a natural way of light manipulation and interaction, and form the foundation of applied photonics -- from high-speed signal processing and telecommunication, to ultra-high bandwidth interconnects and information processing. However, relatively weak nonlinear response at optical frequencies calls for operation at high optical powers, or boosting efficiency of nonlinear parametric processes by enhancing local field intensity with high quality-factor resonators near cavity resonance, resulting in reduced operational bandwidth and increased loss due to multi-photon absorption. Here, we present an alternative to this conventional approach, with strong nonlinear optical effects at substantially lower local intensities, based on period-doubling bifurcations near nonlinear cavity anti-resonance, and apply it to low-power optical comb generation in a silicon chip.

  11. Optical frequency comb based multi-band microwave frequency conversion for satellite applications.

    Science.gov (United States)

    Yang, Xinwu; Xu, Kun; Yin, Jie; Dai, Yitang; Yin, Feifei; Li, Jianqiang; Lu, Hua; Liu, Tao; Ji, Yuefeng

    2014-01-13

    Based on optical frequency combs (OFC), we propose an efficient and flexible multi-band frequency conversion scheme for satellite repeater applications. The underlying principle is to mix dual coherent OFCs with one of which carrying the input signal. By optically channelizing the mixed OFCs, the converted signal in different bands can be obtained in different channels. Alternatively, the scheme can be configured to generate multi-band local oscillators (LO) for widely distribution. Moreover, the scheme realizes simultaneous inter- and intra-band frequency conversion just in a single structure and needs only three frequency-fixed microwave sources. We carry out a proof of concept experiment in which multiple LOs with 2 GHz, 10 GHz, 18 GHz, and 26 GHz are generated. A C-band signal of 6.1 GHz input to the proposed scheme is successfully converted to 4.1 GHz (C band), 3.9 GHz (C band) and 11.9 GHz (X band), etc. Compared with the back-to-back (B2B) case measured at 0 dBm input power, the proposed scheme shows a 9.3% error vector magnitude (EVM) degradation at each output channel. Furthermore, all channels satisfy the EVM limit in a very wide input power range.

  12. Incoherent Optical Frequency Domain Reflectometry for Distributed Thermal Sensing

    DEFF Research Database (Denmark)

    Karamehmedovic, Emir

    2006-01-01

    increasing frequency, after which the inverse Fourier transform is applied to the signal from the backscattered light. This technique is compared with the more conventional optical time domain reflectometry, where a short pulse is sent through the fibre, and the location of the scattering section...... developed and implemented in Matlab. The computer model is calibrated and tested, and describes the entire system with high precision. Noise analysis and digital processing of the detected signal are discussed as well. An equation describing the standard deviation of the measured temperature is derived...... resolution of order 1m is strived to be achieved. These demands are attempted to be reached by employing a low-loss telecom-grade transmission single-mode fibre or an alternative fibre as the sensing fibre, and a pump laser operating in the low loss region of silica. An analysis of the optical module...

  13. Spectrally balanced detection for optical frequency domain imaging.

    Science.gov (United States)

    Chen, Yueli; de Bruin, Daniel M; Kerbage, Charles; de Boer, Johannes F

    2007-12-10

    In optical frequency domain imaging (OFDI) or swept-source optical coherence tomography, balanced detection is required to suppress relative intensity noise (RIN). A regular implementation of balanced detection by combining reference and sample arm signal in a 50/50 coupler and detecting the differential output with a balanced receiver is however, not perfect. Since the splitting ratio of the 50/50 coupler is wavelength dependent, RIN is not optimally canceled at the edges of the wavelength sweep. The splitting ratio has a nearly linear shift of 0.4% per nanometer. This brings as much as +/-12% deviation at the margins of wavelength-swept range centered at 1060nm. We demonstrate a RIN suppression of 33dB by spectrally corrected balanced detection, 11dB more that regular balanced detection. PMID:19550929

  14. Distributed dynamic strain measurement using optical frequency-domain reflectometry.

    Science.gov (United States)

    Zhou, Da-Peng; Chen, Liang; Bao, Xiaoyi

    2016-08-20

    Distributed dynamic strain measurement based on optical frequency-domain reflectometry is proposed. The technique makes use of the wide scanning range of a tunable laser source in a short sweeping time, and subdivides the overall spectrum into narrower frequency windows. The advantage of subdividing the laser spectral range is to improve the measurement uncertainty induced by the laser wavelength difference between repeated scans. The noise-limited dynamic strain resolution is investigated experimentally, indicating that a minimum detectable strain is less than 200 nε for a spatial resolution of 20 cm. By measuring the subdivided spectral shifts in the time sequence along the sensing fiber, the dynamic strain can be properly quantified over a 30 m measurement range for a highest sampling rate of up to 50 Hz. PMID:27556996

  15. Near-Zero-Refractive-Index Structure at Optical Frequencies

    Directory of Open Access Journals (Sweden)

    Hassan S. Ashour

    2013-01-01

    Full Text Available We have used a new class of left-handed materials, which uses 3D nanospheres distributed in loops in the dielectric host material. These 3D nanospheres loops give rise to negative effective permeability and permeability at Terahertz (optical frequencies. The modal dispersion relation for Terahertz TE surface waves has been derived for a slab waveguide constructed from a dielectric material slab sandwiched between two thick layers of Terahertz left-handed material (LHM. The modal dispersion relation and the power flow were numerically solved for a given set of parameters: dielectric slab thickness, the operating frequency, mode order, and the power flow and extinction in the structure. The real part of the effective refractive index exhibits near-zero values, with small extinction coefficient values. Besides that, the power flow in the dielectric core increased with slab thickness increase and the power attenuation decreased with thickness increase.

  16. Fibre optics wavemeters calibration using a self-referenced optical frequency comb

    Science.gov (United States)

    Galindo-Santos, J.; Velasco, A. V.; Corredera, P.

    2015-01-01

    Self-referenced optical frequency combs enable the measurement of optical frequencies with a very high accuracy, achieving uncertainties close to the atomic clock used as reference (CSIC and its application to the calibration of two wavemeters in the 1.5 μm optical communication window. Calibration uncertainties down to 12 MHz and 59 MHz were obtained, respectively, for each of the devices. Furthermore, the long-term behaviour of the higher resolution wavemeter was studied during a 750 h period of sustained operation, exhibiting a dispersion in the measurements of 7.72 MHz. Temperature dependence of the device was analysed, enabling to further reduce dispersion down to a 2.15 MHz range, with no significant temporal deviations.

  17. Evolutions of perturbations with special frequencies in lossless optical fibers

    Institute of Scientific and Technical Information of China (English)

    Xianqiong Zhong(钟先琼); Jianguo Chen(陈建国); Guoying Feng(冯国英); Dayi Li(李大义); Song Gao(高松)

    2004-01-01

    Expressing the perturbation optical field in terms of module and phase, using the linearized nonlinear Schrodinger equation governing the evolution of perturbations, we have deduced the analytical expressions of the modules, phases, and gain coefficients of the perturbations with zero or cut-off frequency, and studied the evolutions of the two perturbations travelling along lossless optical fibers in the negative dispersion regime. The results indicate that the phase of the perturbation with zero (or cut-off) frequency increases (or decreases) with the propagation distance monotonously and tends to its asymptotic value nπ + π/2 (or nπ) eventually. The evolution rates of the phases are closely related to the initial phase values. Although the asymptotic values of the field gain coefficients of the above mentioned two perturbations are equal to zero, and the increasing fashion of the modules is different from the familiar exponential type, it still suggests that the perturbations have a divergent nature when the propagation distance goes to infinity,indicating that the two kinds of perturbations can both lead to instability.

  18. Modeling and Simulation of a Resonant-Cavity-Enhanced InGaAs/GaAs Quantum Dot Photodetector

    Directory of Open Access Journals (Sweden)

    W. W. Wang

    2015-01-01

    Full Text Available We simulated and analyzed a resonant-cavity-enhancedd InGaAs/GaAs quantum dot n-i-n photodiode using Crosslight Apsys package. The resonant cavity has a distributed Bragg reflector (DBR at one side. Comparing with the conventional photodetectors, the resonant-cavity-enhanced photodiode (RCE-PD showed higher detection efficiency, faster response speed, and better wavelength selectivity and spatial orientation selectivity. Our simulation results also showed that when an AlAs layer is inserted into the device structure as a blocking layer, ultralow dark current can be achieved, with dark current densities 0.0034 A/cm at 0 V and 0.026 A/cm at a reverse bias of 2 V. We discussed the mechanism producing the photocurrent at various reverse bias. A high quantum efficiency of 87.9% was achieved at resonant wavelength of 1030 nm with a FWHM of about 3 nm. We also simulated InAs QD RCE-PD to compare with InGaAs QD. At last, the photocapacitance characteristic of the model has been discussed under different frequencies.

  19. BPSK optical mm-wave signal generation by septupling frequency via a single optical phase modulator

    Science.gov (United States)

    Wu, Peng; Ma, Jianxin

    2016-09-01

    In this paper, we have proposed a novel and simple scheme to generate the BPSK optical millimeter wave (MMW) signal with frequency septupling by using an optical phase modulator (PM) and a wavelength selective switch (WSS). In this scheme, the PM is driven by a radio frequency (RF) BPSK signal at the optimized modulation index of 4.89 to assure the 4th and 3rd-order sidebands have equal amplitudes. An wavelength selective switch (WSS) is used to abstract the -4th and +3rd-order sidebands from the spectrum generated by RF BPSK signal modulating the lightwave to form the BPSK optical MMW signal with frequency septupling the driving RF signal. In these two tones, only the +3rd-order sideband bears the BPSK signal while the -4th-order sideband is unmodulated since the phase information is canceled by the even times multiplication of the phase of BPSK signal. The MMW signal can avoid the pulse walk-off effect and the amplitude fading effect caused by the fiber chromatic dispersion. By adjusting the modulation index to assure the two tones have equal amplitude, the generated optical MMW signal has the maximal opto-electrical conversion efficiency and good transmission performance.

  20. Automatic analysis of ciliary beat frequency using optical flow

    Science.gov (United States)

    Figl, Michael; Lechner, Manuel; Werther, Tobias; Horak, Fritz; Hummel, Johann; Birkfellner, Wolfgang

    2012-02-01

    Ciliary beat frequency (CBF) can be a useful parameter for diagnosis of several diseases, as e.g. primary ciliary dyskinesia. (PCD). CBF computation is usually done using manual evaluation of high speed video sequences, a tedious, observer dependent, and not very accurate procedure. We used the OpenCV's pyramidal implementation of the Lukas-Kanade algorithm for optical flow computation and applied this to certain objects to follow the movements. The objects were chosen by their contrast applying the corner detection by Shi and Tomasi. Discrimination between background/noise and cilia by a frequency histogram allowed to compute the CBF. Frequency analysis was done using the Fourier transform in matlab. The correct number of Fourier summands was found by the slope in an approximation curve. The method showed to be usable to distinguish between healthy and diseased samples. However there remain difficulties in automatically identifying the cilia, and also in finding enough high contrast cilia in the image. Furthermore the some of the higher contrast cilia are lost (and sometimes found) by the method, an easy way to distinguish the correct sub-path of a point's path have yet to be found in the case where the slope methods doesn't work.

  1. High-frequency signal generation using 1550 nm VCSEL subject to two-frequency optical injection

    Science.gov (United States)

    Consoli, Antonio; Quirce, Ana; Valle, Angel; Esquivias, Ignacio; Pesquera, Luis; García Tijero, Jose Manuel

    2013-03-01

    We experimentally investigate high-frequency microwave signal generation using a 1550 nm single-mode VCSEL subject to two-frequency optical injection. We first consider a situation in which the injected signals come from two similar VCSELs. The polarization of the injected light is parallel to that of the injected VCSEL. We obtain that the VCSEL can be locked to one of the injected signals, but the observed microwave signal is originated by beating at the photodetector. In a second situation we consider injected signals that come from two external cavity tunable lasers with a significant increase of the injected power with respect to the VCSEL-by-VCSEL injection case. The polarization of the injected light is orthogonal to that of the free-running slave VCSEL. We show that in this case it is possible to generate a microwave signal inside the VCSEL cavity.

  2. Cavity-enhanced AlGaAs/GaAs resonant tunneling photodetectors for telecommunication wavelength light detection at 1.3 μm

    Science.gov (United States)

    Pfenning, Andreas; Hartmann, Fabian; Langer, Fabian; Kamp, Martin; Höfling, Sven; Worschech, Lukas

    2015-09-01

    We demonstrate a cavity-enhanced photodetector at the telecommunication wavelength of λ = 1.3 μm based on a resonant tunneling diode (RTD). The cavity-enhanced RTD photodetector consists of three integral parts: First, a Ga0.89In0.11N0.04As0.96 absorption layer that can be grown lattice-matched on GaAs and which is light-active in the near infrared spectral region due to its reduced bandgap energy. Second, an Al0.6Ga0.4As/GaAs double barrier resonant tunneling structure (RTS) that serves as high gain internal amplifier of weak electric signals caused by photogenerated electron-hole pairs within the GaInNAs absorption layer. Third, an optical distributed Bragg reflector (DBR) cavity consisting of five top and seven bottom alternating GaAs/AlAs mirror pairs, which provides an enhanced quantum efficiency at the resonance wavelength. The samples were grown by molecular beam epitaxy. Electro-optical properties of the RTDs were studied at room temperature. From the reflection-spectrum the optical resonance at λ = 1.29 μm was extracted. The current-voltage characteristics were studied in the dark and under illumination and a wellpronounced photo-response was found and is attributed to accumulation of photogenerated holes in the vicinity of the RTS. The maximum photocurrent was found at the optical resonance of 1.29 μm. At resonance, a sensitivity of S = 3.97 × 104 A/W was observed. From the sensitivity, a noise equivalent power of NEP = 1.18 × 10-16 W/Hz1/2, and a specific detectivity of D∗ ≅ 6.74 × 1012 cm Hz1/2/W were calculated. For a single absorbed photon a photocurrent of ISP = 50 pA was determined.

  3. Measuring absolute frequencies beyond the GPS limit via long-haul optical frequency dissemination.

    Science.gov (United States)

    Clivati, Cecilia; Cappellini, Giacomo; Livi, Lorenzo F; Poggiali, Francesco; de Cumis, Mario Siciliani; Mancini, Marco; Pagano, Guido; Frittelli, Matteo; Mura, Alberto; Costanzo, Giovanni A; Levi, Filippo; Calonico, Davide; Fallani, Leonardo; Catani, Jacopo; Inguscio, Massimo

    2016-05-30

    Global Positioning System (GPS) dissemination of frequency standards is ubiquitous at present, providing the most widespread time and frequency reference for the majority of industrial and research applications worldwide. On the other hand, the ultimate limits of the GPS presently curb further advances in high-precision, scientific and industrial applications relying on this dissemination scheme. Here, we demonstrate that these limits can be reliably overcome even in laboratories without a local atomic clock by replacing the GPS with a 642-km-long optical fiber link to a remote primary caesium frequency standard. Through this configuration we stably address the 1S0-3P0 clock transition in an ultracold gas of 173Yb, with a precision that exceeds the possibilities of a GPS-based measurement, dismissing the need for a local clock infrastructure to perform beyond-GPS high-precision tasks. We also report an improvement of two orders of magnitude in the accuracy on the transition frequency reported in literature. PMID:27410109

  4. Measuring absolute frequencies beyond the GPS limit via long-haul optical frequency dissemination

    CERN Document Server

    Clivati, C; Livi, L; Poggiali, F; de Cumis, M Siciliani; Mancini, M; Pagano, G; Frittelli, M; Mura, A; Costanzo, G A; Levi, F; Calonico, D; Fallani, L; Catani, J; Inguscio, M

    2015-01-01

    Global Positioning System (GPS) dissemination of frequency standards is ubiquitous at present, providing the most widespread time and frequency reference for the majority of industrial and research applications worldwide. On the other hand, the ultimate limits of the GPS presently curb further advances in high-precision, scientific and industrial applications relying on this dissemination scheme. Here, we demonstrate that these limits can be reliably overcome even in laboratories without a local atomic clock by replacing the GPS with a 642-km-long optical fiber link to a remote primary caesium frequency standard. Through this configuration we stably address the $^1$S$_0$---$^3$P$_0$ clock transition in an ultracold gas of $^{173}$Yb, with a precision that exceeds the possibilities of a GPS-based measurement, dismissing the need for a local clock infrastructure to perform high-precision tasks beyond GPS limit. We also report an improvement of two orders of magnitude in the accuracy on the transition frequency ...

  5. Measuring absolute frequencies beyond the GPS limit via long-haul optical frequency dissemination.

    Science.gov (United States)

    Clivati, Cecilia; Cappellini, Giacomo; Livi, Lorenzo F; Poggiali, Francesco; de Cumis, Mario Siciliani; Mancini, Marco; Pagano, Guido; Frittelli, Matteo; Mura, Alberto; Costanzo, Giovanni A; Levi, Filippo; Calonico, Davide; Fallani, Leonardo; Catani, Jacopo; Inguscio, Massimo

    2016-05-30

    Global Positioning System (GPS) dissemination of frequency standards is ubiquitous at present, providing the most widespread time and frequency reference for the majority of industrial and research applications worldwide. On the other hand, the ultimate limits of the GPS presently curb further advances in high-precision, scientific and industrial applications relying on this dissemination scheme. Here, we demonstrate that these limits can be reliably overcome even in laboratories without a local atomic clock by replacing the GPS with a 642-km-long optical fiber link to a remote primary caesium frequency standard. Through this configuration we stably address the 1S0-3P0 clock transition in an ultracold gas of 173Yb, with a precision that exceeds the possibilities of a GPS-based measurement, dismissing the need for a local clock infrastructure to perform beyond-GPS high-precision tasks. We also report an improvement of two orders of magnitude in the accuracy on the transition frequency reported in literature.

  6. Optical frequency domain reflectometry: principles and applications in fiber optic sensing

    Science.gov (United States)

    Kreger, Stephen T.; Rahim, Nur Aida Abdul; Garg, Naman; Klute, Sandra M.; Metrey, Daniel R.; Beaty, Noah; Jeans, James W.; Gamber, Robert

    2016-05-01

    Optical Frequency Domain Reflectometry (OFDR) is the basis of an emerging high-definition distributed fiber optic sensing (HD-FOS) technique that provides an unprecedented combination of resolution and sensitivity. OFDR employs swept laser interferometry to produce strain or temperature vs. sensor length with fiber Bragg gratings (FBGs) or Rayleigh scatter as the source signal. We look at the influence of HD-FOS on design and test of new, lighter weight, stronger and more fuel efficient vehicles. Examples include defect detection, model verification and structural health monitoring of composites, and temperature distribution monitoring of battery packs and inverters in hybrid and electric powertrains.

  7. Remoted all optical instantaneous frequency measurement system using nonlinear mixing in highly nonlinear optical fiber.

    Science.gov (United States)

    Bui, Lam Anh; Mitchell, Arnan

    2013-04-01

    A novel remoted instantaneous frequency measurement system using all optical mixing is demonstrated. This system copies an input intensity modulated optical carrier using four wave mixing, delays this copy and then mixes it with the original signal, to produce an output idler tone. The intensity of this output can be used to determine the RF frequency of the input signal. This system is inherently broadband and can be easily scaled beyond 40 GHz while maintaining a DC output which greatly simplifies receiving electronics. The remoted configuration isolates the sensitive and expensive receiver hardware from the signal sources and importantly allows the system to be added to existing microwave photonic implementations without modification of the transmission module. PMID:23571944

  8. Coherence analysis of optical frequency-modulated continuous-wave interference.

    Science.gov (United States)

    Zheng, Jesse

    2006-06-01

    I analyze the coherence of optical frequency-modulated continuous-wave (FMCW) interference. With a simple model modified from the classical coherence theory, I successfully derive the relationships among the frequency bandwidth, coherence length, and coherence time of the practical optical source, and the contrast of the beat signal in optical FMCW interference. PMID:16724123

  9. Time-Delay Interferometry with optical frequency comb

    CERN Document Server

    Tinto, Massimo

    2015-01-01

    Heterodyne laser phase measurements in a space-based gravitational wave interferometer are degraded by the phase fluctuations of the onboard clocks, resulting in unacceptable sensitivity performance levels of the interferometric data. In order to calibrate out the clock phase noises it has been previously suggested that additional inter-spacecraft phase measurements must be performed by modulating the laser beams. This technique, however, considerably increases system complexity and probability of subsystem failure. With the advent of self-referenced optical frequency combs, it is possible to generate the heterodyne microwave signal that is coherently referenced to the onboard laser. We show in this case that the microwave noise can be cancelled directly by applying modified second-generation Time-Delay Interferometric combinations to the heterodyne phase measurements. This approach avoids use of modulated laser beams as well as the need of additional ultra-stable oscillator clocks.

  10. Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS – applicability and corrections

    Directory of Open Access Journals (Sweden)

    D. Pöhler

    2008-12-01

    Full Text Available Atmospheric trace gas measurements by cavity assisted long-path absorption spectroscopy are an emerging technology. An interesting approach is the combination of CEAS with broad band light sources, the broad-band CEAS (BB-CEAS. BB-CEAS lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light path by the trace gas absorption, since cavity losses due to absorption by gases reduce the quality (Q of the cavity. In fact, at wavelength, where the quality of the BB-CEAS cavity is dominated by the trace gas absorption (esp. at very high mirror reflectivity, the light path will vary inversely with the trace gas concentration and the strength of the band will become nearly independent of the trace gas concentration c in the cavity, rendering the CEAS Method useless for trace gas measurements. Only in the limiting case where the mirror reflectivity determines Q at all wavelength, the strength of the band as seen by the BB-CEAS instrument becomes proportional to the concentration c. We investigate these relationships in detail and present methods to correct for the cases between the two above extremes, which are of course the important ones in practice.

  11. Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) – applicability and corrections

    OpenAIRE

    U. Platt; J. Meinen; D. Pöhler; T. Leisner

    2008-01-01

    Atmospheric trace gas measurements by cavity assisted long-path absorption spectroscopy are an emerging technology. An interesting approach is the combination of CEAS with broadband light sources, the broadband CEAS (BB-CEAS). BB-CEAS lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light pa...

  12. Chemical Sensing Using Infrared Cavity Enhanced Spectroscopy: Short Wave Infrared Cavity Ring Down Spectroscopy (SWIR CRDS) Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Richard M.; Harper, Warren W.; Aker, Pam M.; Thompson, Jason S.; Stewart, Timothy L.

    2003-10-01

    The principal goal of Pacific Northwest National Laboratory's (PNNL's) Remote Spectroscopy Project is to explore and develop the science and technology behind point and stand off infrared (IR) spectroscopic chemical sensors that are needed for detecting weapons proliferation activity and countering terrorism. Missions addressed include detecting chemical, biological, and nuclear weapons and their production; counter terrorism measures that involve screening luggage, personnel, and shipping containers for explosives, firearms, narcotics, chemical weapons and/or their residues; and mapping of contaminated areas. The science and technology developed in this program is dual use in that it additionally supports progress in a diverse set of agendas that include chemical weapons defense programs, air operations activities, emissions monitoring, law enforcement, and medical diagnostics. Sensors for these missions require extremely low limits of detection because many of the targeted signature species are either present in low concentrations or have extremely low vapor pressures. The sensors also need to be highly selective as the environments that they will be operated in will contain a variety of interferent species and false positive detection is not an option. PNNL has been working on developing a class of sensors that draw vapor into optical cavities and use laser-based spectroscopy to identify and quantify the vapor chemical content. The cavity enhanced spectroscopies (CES) afford extreme sensitivity, excellent selectivity, noise immunity, and rapid, real-time, in-situ chemical characterization. PNNL's CES program is currently focused on developing two types of sensors. The first one, which is based on cavity ring down spectroscopy (CRDS), uses short wave infrared (SWIR) lasers to interrogate species. The second sensor, which is based on noise immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE OHMS), uses long wave infrared (LWIR

  13. Using a high finesse optical resonator to provide a long light path for differential optical absorption spectroscopy: CE-DOAS

    OpenAIRE

    J. Meinen; J. Thieser; U. Platt; T. Leisner

    2008-01-01

    Cavity enhanced methods in absorption spectroscopy have seen a considerable increase in popularity during the past decade. Especially Cavity Enhanced Absorption Spectroscopy (CEAS) established itself in atmospheric trace gas detection by providing tens of kilometers of effective light path length using a cavity as short as 1 m. In this paper we report on the construction and testing of a compact and power efficient light emitting diode based broadband Cavity Enhanced Differential Optical Abso...

  14. All Optical Stabilization of a Soliton Frequency Comb in a Crystalline Microresonator

    CERN Document Server

    Jost, J D; Herr, T; Lecaplain, C; Brasch, V; Pfeiffer, M H P; Kippenberg, T J

    2015-01-01

    Microresonator based optical frequency combs (MFC) have demonstrated promise in extending the capabilities of optical frequency combs. Here we demonstrate all optical stabilization of a low noise temporal soliton based MFC in a crystalline resonator via a new technique to control the repetition rate. This is accomplished by thermally heating the microresonator with an additional probe laser coupled to an auxiliary optical resonator mode. The offset frequency is controlled by stabilization of the pump laser frequency to a reference optical frequency comb. We analyze the stabilization by performing an out of loop comparison and measure the overlapping Allan deviation. This all optical stabilization technique can prove useful as a low added noise actuator for self-referenced microresonator frequency combs.

  15. Cavity enhanced detection methods for probing the dynamics of spin correlated radical pairs in solution

    Science.gov (United States)

    Neil, Simon R. T.; Maeda, Kiminori; Henbest, Kevin B.; Goez, Martin; Hemmens, Robert; Timmel, Christiane R.; Mackenzie, Stuart R.

    2010-04-01

    Cavity enhanced absorption spectroscopy (CEAS) combined with phase-sensitive detection is employed to study the effects of static magnetic fields on radical recombination reactions. The chemical system comprises the photochemically generated thionine semiquinone radical and a 1,4-diazabicyclo[2.2.2]octane (DABCO) cationic radical in a micellar solution of sodium dodecyl sulphate. Data obtained using the modulated CEAS technique, describing the magnetic field effect (MFE) on reaction yields, are shown to be superior to those obtained using conventional transient absorption (TA) flash photolysis methods typically employed for these measurements. The high sensitivity afforded by modulated CEAS detection is discussed in terms of the new possibilities it offers such as the measurement of magnetic field effects in real biological systems which have hitherto been largely beyond the detection capabilities of existing techniques.

  16. Diagnosis of Multiple Gases Separated from Transformer Oil Using Cavity-Enhanced Raman Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Yun; XIA Yu-Xing; HUANG Ju-Ming; ZHAN Li

    2008-01-01

    The Raman signal of gas molecules is very weak due to its small scattering cross section. Here, a near-confocal cavity-enhanced Raman detection system is demonstrated. In the cavity, a high power light of 9 W is achieved by using a cw 200mW 532nm laser, which greatly enhances the detection sensitivity of gas species. A photomultiplier tube connected to a spectrometer is used as the detection system. The Raman spectra of the mixed gases separated from transformer oil has been observed. The relationship of absolute Raman intensity and gas pressure is also obtained. To our knowledge, this is the first Raman system to detect the gases separated from transformer oil.

  17. Frequency-Shifted Interferometry — A Versatile Fiber-Optic Sensing Technique

    OpenAIRE

    Fei Ye; Yiwei Zhang; Bing Qi; Li Qian

    2014-01-01

    Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI). This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applicati...

  18. Radio-frequency transparent demodulation for broadband hybrid wireless-optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Sambaraju, Rakesh; Alemany, Ruben;

    2010-01-01

    A novel demodulation technique which is transparent to radio-frequency (RF) carrier frequency is presented and experimentally demonstrated for multigigabit wireless signals. The presented demodulation technique employs optical single-sideband filtering, coherent detection, and baseband digital...

  19. Frequency translation of light waves by propagation around an optical ring circuit containing a frequency shifter: II. Theoretical analysis.

    Science.gov (United States)

    Shimizu, K; Horiguchi, T; Koyamada, Y

    1994-05-20

    Theoretical aspects of the frequency-translation ring circuit are considered through numerical simulations. We analyze the signal and noise propagation around an optical ring circuit that contains a frequency shifter, an erbium-doped fiber amplifier and a bandpass filter (BPF). The relations between the frequency-translation limit and some important parameters such as the BPF bandwidth and the polarization state are clarified. Numerical results for the frequency-translation limit are compared with reported experiments and a frequency translation of more than 100 GHz is predicted.

  20. Continued analysis of optical frequency-modulated continuous-wave interference.

    Science.gov (United States)

    Zheng, Jesse

    2005-02-10

    I continue to analyze systematically the theory of optical frequency-modulated continuous-wave (FMCW) interference. Two special cases, multiple-beam optical FMCW interference and multiple-wavelength optical FMCW interference, are discussed in detail. Multiple-beam optical FMCW interference generates a signal with multiple frequencies because of mutual interference among the waves. Multiple-wavelength optical FMCW interference produces a signal whose amplitude is modulated by a synthetic wave. The applications of both types of optical FMCW interference are also discussed. PMID:15751857

  1. Chromium:forsterite laser frequency comb stabilization and development of portable frequency references inside a hollow optical fiber

    Science.gov (United States)

    Thapa, Rajesh

    We have made significant accomplishments in the development of portable frequency standard inside hollow optical fibers. Such standards will improve portable optical frequency references available to the telecommunications industry. Our approach relies on the development of a stabilized Cr:forsterite laser to generate the frequency comb in the near-IR region. This laser is self referenced and locked to a CW laser which in turn is stabilized to a sub-Doppler feature of a molecular transition. The molecular transition is realized using a hollow core fiber filled with acetylene gas. We finally measured the absolute frequency of these molecular transitions to characterize the references. In this thesis, the major ideas, techniques and experimental results for the development and absolute frequency measurement of the portable frequency references are presented. A prism-based Cr:forsterite frequency comb is stabilized. We have effectively used the prism modulation along with power modulation inside the cavity in order to actively stabilize the frequency comb. We have also studied the carrier-envelope-offset frequency (f0) dynamics of the laser and its effect on laser stabilization. A reduction of f0 linewidth from ˜2 MHz to ˜20 kHz has also been observed. Both our in-loop and out-of-loop measurements of the comb stability showed that the comb is stable within a part in 1011 at 1-s gate time and is currently limited by our reference signal. In order to develop this portable frequency standard, saturated absorption spectroscopy is performed on the acetylene v1 + v3 band near 1532 nm inside different kinds of hollow optical fibers. The observed linewidths are a factor 2 narrower in the 20 mum fiber as compared to 10 mum fiber, and vary from 20-40 MHz depending on pressure and power. The 70 mum kagome fiber shows a further reduction in linewidth to less than 10 MHz. In order to seal the gas inside the hollow optical fiber, we have also developed a technique of splicing the

  2. Electronically reconfigurable bandpass microwave photonic filter using a windowed optical frequency comb

    Science.gov (United States)

    Deng, Hong; Fu, Songnian; Tang, Ming; Liu, Deming

    2015-03-01

    A center frequency-tunable multi-tap bandpass microwave photonic filter (MPF) is proposed and experimentally demonstrated, with reconfigurable capability by electronic control. A Mach-Zehnder modulator-based optical frequency comb (OFC) is used as an optical source, and its output is optically shaped before introducing a time delay by 70 km single-mode fiber (SMF) transmission. After an optical-to-electronic conversion, the frequency response in terms of central frequency and passband bandwidth can be electronically reconfigurable by varying either the input microwave frequency of the OFC or the waveshaper configuration without modification of the optical configuration. The experimental results show that more than a 35 dB out-of-band rejection ratio and at least a 3 GHz continuously tuning range of passband center frequency without any DC response can be successfully achieved.

  3. Acousto-Optic Devices For Use In Radio Frequency Target Simulators

    Science.gov (United States)

    Kirchner, Ernst K.

    1980-01-01

    Acousto-optic devices have been analyzed and developed for use as modulators, filters and correlators, and in spectrum analyzers. The ability of the acousto-optic unit to amplitude-modulate, frequency-modulate, and deflect laser beams, makes them suitable for these applications. The various signal processing and control functions provided by the acousto-optic devices are optimized by controlling the ratio of divergence angles of the optical beam and the acoustic beam in the acousto-optic interaction region. Another application of acousto-optic devices is to simulate moving targets to test fuzing altimeters and active missile control systems. The frequency modulation, amplitude modulation, and deflection properties of acousto-optic components are all utilized in a single acousto-optic unit to provide the variable range and Doppler simulation. Development of a suitable acousto-optic component for this simulation application is described, as is a description of a simulator employing this acousto-optic device.

  4. Design-oriented analytic model of phase and frequency modulated optical links

    Science.gov (United States)

    Monsurrò, Pietro; Saitto, Antonio; Tommasino, Pasquale; Trifiletti, Alessandro; Vannucci, Antonello; Cimmino, Rosario F.

    2016-07-01

    An analytic design-oriented model of phase and frequency modulated microwave optical links has been developed. The models are suitable for design of broadband high dynamic range optical links for antenna remoting and optical beamforming, where noise and linearity of the subsystems are a concern Digital filter design techniques have been applied to the design of optical filters working as frequency discriminator, that are the bottleneck in terms of linearity for these systems. The models of frequency modulated, phase modulated, and coherent I/Q link have been used to compare performance of the different architectures in terms of linearity and SFDR.

  5. Optical NRZ-to-RZ format conversion based on frequency chirp linearization and spectrum slicing

    Science.gov (United States)

    Wang, Dong; Huo, Li; Chen, Xin; Jiang, Xiangyu; Lou, Caiyun

    2015-12-01

    A flexible optical NRZ-to-RZ format converter based on a time lens followed by optical filtering is proposed and demonstrated experimentally. After frequency chirp linearization, 9-tone ultra-flat optical frequency comb of 25-GHz frequency spacing within 1 dB power variation is obtained. By changing the shape of the following optical band-pass filter, 3.4-ps Nyquist-shaped RZ signal and 3.7-ps Gaussian-shaped RZ signal are both achieved. The sensitivity improvements at a bit error rate of 10-9 are 3.3 dB and 1.7 dB, respectively.

  6. Recent developments in fiber-based optical frequency comb and its applications

    International Nuclear Information System (INIS)

    Fiber-based optical frequency combs, characterized by compact configuration and outstanding optical properties, have been developed into state-of-the-art precision instruments which are no longer used just for optical frequency metrology, but for a number of applications, including optical clocks, attosecond science, exoplanet searches, medical diagnostics, physicochemical processes control and advanced manufacturing. This short perspective presents some of the milestones and highlights in the evolution of fiber-based optical frequency combs and the technical revolution that are brought by them for a wide range of applications. Along the way, both the challenges and opportunities in the future development of the fiber-based optical frequency comb technology have been described as well. (review article)

  7. Recent developments in fiber-based optical frequency comb and its applications

    Science.gov (United States)

    Xia, Wei; Chen, Xuzong

    2016-04-01

    Fiber-based optical frequency combs, characterized by compact configuration and outstanding optical properties, have been developed into state-of-the-art precision instruments which are no longer used just for optical frequency metrology, but for a number of applications, including optical clocks, attosecond science, exoplanet searches, medical diagnostics, physicochemical processes control and advanced manufacturing. This short perspective presents some of the milestones and highlights in the evolution of fiber-based optical frequency combs and the technical revolution that are brought by them for a wide range of applications. Along the way, both the challenges and opportunities in the future development of the fiber-based optical frequency comb technology have been described as well.

  8. Technical Note: Using a high finesse optical resonator to provide a long light path for differential optical absorption spectroscopy: CE-DOAS

    OpenAIRE

    J. Meinen; J. Thieser; U. Platt; T. Leisner

    2010-01-01

    Cavity enhanced methods in absorption spectroscopy have seen a considerable increase in popularity during the past decade. Especially Cavity Enhanced Absorption Spectroscopy (CEAS) established itself in atmospheric trace gas detection by providing tens of kilometers of effective light path length using a cavity as short as 1 m. In this paper we report on the construction and testing of a compact and power efficient light emitting diode based broadband Cavity Enhanced Differential Optical Abso...

  9. Achieving High-Frequency Optical Control of Synaptic Transmission

    Science.gov (United States)

    Jackman, Skyler L.; Beneduce, Brandon M.; Drew, Iain R.

    2014-01-01

    The optogenetic tool channelrhodopsin-2 (ChR2) is widely used to excite neurons to study neural circuits. Previous optogenetic studies of synapses suggest that light-evoked synaptic responses often exhibit artificial synaptic depression, which has been attributed to either the inability of ChR2 to reliably fire presynaptic axons or to ChR2 elevating the probability of release by depolarizing presynaptic boutons. Here, we compare light-evoked and electrically evoked synaptic responses for high-frequency stimulation at three synapses in the mouse brain. At synapses from Purkinje cells to deep cerebellar nuclei neurons (PC→DCN), light- and electrically evoked synaptic currents were remarkably similar for ChR2 expressed transgenically or with adeno-associated virus (AAV) expression vectors. For hippocampal CA3→CA1 synapses, AAV expression vectors of serotype 1, 5, and 8 led to light-evoked synaptic currents that depressed much more than electrically evoked currents, even though ChR2 could fire axons reliably at up to 50 Hz. The disparity between optical and electrical stimulation was eliminated when ChR2 was expressed transgenically or with AAV9. For cerebellar granule cell to stellate cell (grc→SC) synapses, AAV1 also led to artificial synaptic depression and AAV9 provided superior performance. Artificial synaptic depression also occurred when stimulating over presynaptic boutons, rather than axons, at CA3→CA1 synapses, but not at PC→DCN synapses. These findings indicate that ChR2 expression methods and light stimulation techniques influence synaptic responses in a neuron-specific manner. They also identify pitfalls associated with using ChR2 to study synapses and suggest an approach that allows optogenetics to be applied in a manner that helps to avoid potential complications. PMID:24872574

  10. On geometrical scaling of split-ring and double-bar resonators at optical frequencies

    OpenAIRE

    Tretyakov, Sergei

    2006-01-01

    In this paper we consider the resonant frequency of split-ring resonators and double-bar resonators used to create artificial magnetic response at terahertz and optical frequencies. It is known that geometrical scaling of the resonant frequency of split rings breaks down at high frequencies (in the visible) due to electromagnetic properties of metals at those frequencies. Here we will discuss this phenomenon in terms of equivalent inductance and capacitance of the ring, derive an approximate ...

  11. Influence of low optical frequencies on actuation dynamics of microelectromechanical systems via Casimir forces

    NARCIS (Netherlands)

    Sedighi Ghozotkhar, Mehdi; Palasantzas, Georgios

    2015-01-01

    The role of the Casimir force on the analysis of microactuators is strongly influenced by the optical properties of interacting materials. Bifurcation and phase portrait analysis were used to compare the sensitivity of actuators when the optical properties at low optical frequencies were modeled usi

  12. Polarization-dependent loss characterization method based on optical frequency beat.

    Science.gov (United States)

    Ferreira da Silva, T; Nobre, C S; Temporão, G P

    2016-03-10

    Characterization of the polarization-dependent loss (PDL) of optical components is fundamental for the reliable operation of fiber-optic communication systems. Here we present a method for determining the PDL of optical devices based on optical frequency beating and spectral analysis. Depending on the beat note between components of two orthogonally polarized probe signals modulated at different frequencies, the PDL value and its axis can be determined from a single sweep of an optical spectrum analyzer. Our proposal represents an alternative high-speed option for PDL characterization. PMID:26974770

  13. High precision absolute distance measurement with the fiber femtosecond optical frequency comb

    Science.gov (United States)

    Guo, Jiashuai; Wu, Tengfei; Liang, Zhiguo; Wang, Yu; Han, Jibo

    2016-01-01

    The absolute distance measurement was experimentally demonstrated by using the fiber femtosecond optical frequency comb in air. The technique is based on the measurement of cross correlation between reference and measurement optical pulses. This method can achieve accuracy better than the commercial laser interferometer. It is attained sub-micrometer resolution in large scale measurement by using the fiber femtosecond optical frequency comb. It will be benefit for future laser lidar and satellite formation flying mission.

  14. Frequency stability measurement of a transfer-cavity-stabilized diode laser by using an optical frequency comb

    Science.gov (United States)

    Uetake, S.; Matsubara, K.; Ito, H.; Hayasaka, K.; Hosokawa, M.

    2009-10-01

    We report results of frequency stability measurements of an extended cavity diode laser (ECDL) whose frequency is stabilized by a non-evacuated scanning transfer cavity. The transfer cavity is locked to a commercial frequency stabilized helium-neon laser. Frequency stability is measured by use of an optical frequency comb. The environmental perturbations (variations of temperature, air pressure, and humidity) are also simultaneously measured. The observed frequency drift of the ECDL is well explained by environmental perturbations. An atmospheric pressure variation, which is difficult to control with a non-evacuated cavity, is mainly affected to the frequency stability. Thus we put the cavity into a simple O-ring sealed (non-evacuated) tube. With this simple O-ring sealed tube, the frequency drift is reduced by a factor of 3, and the Allan variance reaches a value of 2.4×10-10, corresponds to the frequency stability of 83 kHz, at the average time of 3000 s. Since the actual frequency drift is well estimated by simultaneous measurement of the ambient temperature, pressure, and humidity, a feed-forward compensation of frequency drifts is also feasible in order to achieve a higher frequency stability with a simple non-evacuated transfer cavity.

  15. Electro-mechanically induced GHz rate optical frequency modulation in silicon

    CERN Document Server

    Tallur, Siddharth

    2012-01-01

    We present a monolithic silicon acousto-optic frequency modulator (AOFM) operating at 1.09GHz. Direct spectroscopy of the modulated laser power shows asymmetric sidebands which indicate coincident amplitude modulation and frequency modulation. Employing mechanical levers to enhance displacement of the optical resonator resulted in greater than 67X improvement in the opto-mechanical frequency modulation factor over earlier reported numbers for silicon nanobeams.

  16. Aspects of the Application of Cavity Enhanced Spectroscopy to Nitrogen Oxides Detection

    Directory of Open Access Journals (Sweden)

    Zbigniew Bielecki

    2013-06-01

    Full Text Available This article presents design issues of high-sensitive laser absorption spectroscopy systems for nitrogen oxides (NOx detection. Examples of our systems and their investigation results are also described. The constructed systems use one of the most sensitive methods, cavity enhanced absorption spectroscopy (CEAS. They operate at different wavelength ranges using a blue—violet laser diode (410 nm as well as quantum cascade lasers (5.27 µm and 4.53 µm. Each of them is configured as a one or two channel measurement device using, e.g., time division multiplexing and averaging. During the testing procedure, the main performance features such as detection limits and measurements uncertainties have been determined. The obtained results are 1 ppb NO2, 75 ppb NO and 45 ppb N2O. For all systems, the uncertainty of concentration measurements does not exceed a value of 13%. Some experiments with explosives are also discussed. A setup equipped with a concentrator of explosives vapours was used. The detection method is based either on the reaction of the sensors to the nitrogen oxides directly emitted by the explosives or on the reaction to the nitrogen oxides produced during thermal decomposition of explosive vapours. For TNT, PETN, RDX and HMX a detection limit better than 1 ng has been achieved.

  17. Near infrared cavity enhanced absorption spectra of atmospherically relevant ether-1, 4-Dioxane

    Science.gov (United States)

    Chandran, Satheesh; Varma, Ravi

    2016-01-01

    1, 4-Dioxane (DX) is a commonly found ether in industrially polluted atmosphere. The near infrared absorption spectra of this compound has been recorded in the region 5900-8230 cm- 1 with a resolution of 0.08 cm- 1 using a novel Fourier transform incoherent broadband cavity-enhanced absorption spectrometer (FT-IBBCEAS). All recorded spectra were found to contain regions that are only weakly perturbed. The possible combinations of fundamental modes and their overtone bands corresponding to selected regions in the measured spectra are tabulated. Two interesting spectral regions were identified as 5900-6400 cm- 1 and 8100-8230 cm- 1. No significant spectral interference due to presence of water vapor was observed suggesting the suitability of these spectral signatures for spectroscopic in situ detection of DX. The technique employed here is much more sensitive than standard Fourier transform spectrometer measurements on account of long effective path length achieved. Hence significant enhancement of weaker absorption lines above the noise level was observed as demonstrated by comparison with an available measurement from database.

  18. Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

    CERN Document Server

    Tadesse, Semere Ayalew

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we demonstrate microwave frequency surface acoustic wave transducers co-integrated with nanophotonic resonators on piezoelectric aluminum nitride substrates. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength is achieved. The phase and modal matching conditions in this scheme are investigated for efficient modulation. The new acousto-optic platform can lead to novel optical devices based on nonlinear Brillouin processes and provides a direct...

  19. Generation of platicons and frequency combs in optical microresonators with normal GVD by modulated pump

    CERN Document Server

    Lobanov, Valery E; Gorodetsky, Michael L

    2015-01-01

    We demonstrate that flat-topped dissipative solitonic pulses, platicons, and corresponding frequency combs can be excited in optical microresonators with normal group velocity dispersion using either amplitude modulation of the pump or bichromatic pump. Soft excitation may occur in particular frequency range if modulation depth is large enough and modulation frequency is close to the free spectral range of the microresonator.

  20. Ultrahigh precision synchronization of optical and microwave frequency sources

    Science.gov (United States)

    Kalaydzhyan, A.; Peng, M. Y.; Kartner, F. X.

    2016-08-01

    In this paper we demonstrate that balanced optical-microwave phase detectors (BOMPD) are able to provide a robust long-term optical-RF synchronization with subfemtosecond residual timing drift over 24 hours in laboratory conditions without active temperature control of optical and electronic paths. Moreover, 10.833 GHz Sapphire-loaded cavity oscillator (SLCO) was successfully disciplined by 216.66 MHz laser oscillator using the BOMPD which resulted in a sub-femtosecond RMS jitter integrated from 1 Hz to 1 MHz.

  1. Influence of low optical frequencies on actuation dynamics of microelectromechanical systems via Casimir forces

    Science.gov (United States)

    Sedighi, Mehdi; Palasantzas, George

    2015-04-01

    The role of the Casimir force on the analysis of microactuators is strongly influenced by the optical properties of interacting materials. Bifurcation and phase portrait analysis were used to compare the sensitivity of actuators when the optical properties at low optical frequencies were modeled using the Drude and Plasma models. Indeed, for metallic systems, which have strong Casimir attraction, the details of the modeling of the low optical frequency regime can be dramatic, leading to predictions of either stable motion or stiction instability. However, this difference is strongly minimized for weakly conductive systems as are the doped insulators making actuation modeling more certain to predict.

  2. Cylindrical PVF2 film based fiber optic phase modulator - Phase shift nonlinearity and frequency response

    Science.gov (United States)

    Sudarshanam, V. S.; Claus, Richard O.

    1993-03-01

    A new cylindrical coil configuration for polyvinylidene flouride (PVF2) film based fiber optic phase modulator is studied for the frequency response and nonlinearity of phase shift at the resonance frequency. This configuration, hitherto unapproached for PVF2 film modulators, offers resonance at well defined, controllable and higher frequencies than possible for the flat-strip configuration. Two versions of this configuration are presented that differ strongly in both the resonance frequency and the phase shift nonlinearity coefficient.

  3. Ultra-high Frequency Linear Fiber Optic Systems

    CERN Document Server

    Lau, Kam Y

    2009-01-01

    Designed for a one-semester course on fiber-optics systems and communication links, this book provides a concise but rigorous treatment of the theory and practice of analog (linear) fiber-optics links and systems that constitute the foundation of Hybrid Fiber Coax infrastructure in present-day CATV distribution and cable modem Internet access. Emerging applications in remote fiber-optic feed for free-space millimeter wave enterprise campus networks are also described. Issues such as dispersion and interferometric noise are treated quantitatively, and means for mitigating them are explained. This broad but concise text will thus be invaluable not only to students of fiber-optics communication but also to practicing engineers.

  4. Using mechanics to convert between microwave and optical frequencies

    Science.gov (United States)

    Vainsencher, A.; Satzinger, K. J.; Peairs, G. A.; Cleland, A. N.

    2016-03-01

    We demonstrate unique piezoelectric optomechanical devices able to coherently transfer microwave electrical signals to modulated optical signals, and vice versa, transferring modulated optical signals to microwave electrical signals. This coherent bilateral transfer, demonstrated most recently in a single device design, holds promise for the eventual demonstration of coherent transfer in the quantum domain. The basis of design for the devices with which this was accomplished is an optomechanical crystal that supports co-located optical and mechanical resonant modes, coupled to one other via moving boundary (index of refraction) modulation, either induced by motion from energy in the mechanical mode, or by optical pressure due to energy in the optical mode. The basis for coupling microwave mechanical motion to microwave electrical signals is via the use of a piezoelectric material for the entire device, where transduction itself is accomplished using metal transducers remote from the optomechanical structure. This remote design minimizes the lossy interaction of any optical signals with the metal electrode structures, but introduces the need to couple the electromechanical transducer to the optomechanical transducer via itinerant phonons, which presents a new challenge.

  5. A simple model of suppressing stimulated Brillouin scattering in optical fiber with frequency-modulated laser

    International Nuclear Information System (INIS)

    A simple model is developed to study the mechanism of stimulated Brillouin scattering (SBS) suppression with frequency-modulated laser in optical fiber. By taking into account the laser frequency distribution along the fiber induced by frequency modulation, the average effective Brillouin gain is calculated to determine the SBS threshold. Experimental results show agreement with the numerical analysis. The application for SBS suppression in interferometric fiber sensing system is also discussed in this paper. The results show that the maximum input power can be increased effectively by frequency modulation method. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  6. Observation of Fundamental Thermal Noise in Optical Fibers down to Infrasonic Frequencies

    CERN Document Server

    Dong, Jing; Li, Tang; Liu, Liang

    2015-01-01

    The intrinsic thermal noise in optical fibers is the ultimate limit of fiber-based systems. However, at infrasonic frequencies, the spectral behavior of the intrinsic thermal noise remains unclear so far. We present the measurements of the fundamental thermal noise in optical fibers obtained using a balanced fiber Michelson interferometer. When an ultra-stable laser is used as the laser source and other noise sources are carefully controlled, the 1/f spectral density of thermal noise is observed down to infrasonic frequencies and the measured magnitude is consistent with the theoretical predictions at the frequencies from 0.2 Hz to 20 kHz. Moreover, as observed in the experiment, the level of 1/f thermal noise is reduced by changing the coating of optical fibers. Therefore, a possible way to reduce the thermal noise in optical fibers at low Fourier frequencies is indicated. Finally, the inconsistency between the experimental data on thermomechanical noise and existing theory is discussed.

  7. Experimental generation of frequency-tunable entangled optical beams with continuous variables

    Institute of Scientific and Technical Information of China (English)

    Zhihui Yan; Yana Shang; Xiaojun Jia; Changde Xie

    2011-01-01

    Frequency tunable continuous variable (CV) entangled optical beams are experimentally demonstrated from a non-degenerate optical parametric oscillator working above the threshold. The measured correlation variances of amplitude and phase quadratures are 3.2 and 1.5 dB, respectively, below the corresponding shot noise level (SNL) in the tuning range of 580 GHz (2.25 nm). The frequency tuning is realized by simply controlling the temperature of the nonlinear crystal.%@@ Frequency tunable continuous variable (CV) entangled optical beams are experimentally demonstrated from a non-degenerate optical parametric oscillator working above the threshold.The measured correlation variances of amplitude and phase quadratures are 3.2 and 1.5 dB, respectively, below the corresponding shot noise level (SNL) in the tuning range of 580 GHz (2.25 nm).The frequency tuning is realized by simply controlling the temperature of the nonlinear crystal.

  8. Optical parametric amplification and oscillation assisted by low-frequency stimulated emission

    CERN Document Server

    Longhi, Stefano

    2016-01-01

    Optical parametric amplification/oscillation provide a powerful tool for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency {\\it down-conversion} process, and thus it can not be realized for signal waves at a frequency $\\omega_3$ {\\it higher} than the frequency of the pump wave $\\omega_1$. In this work we suggest a route toward the realization of {\\it up-conversion} optical parametric amplification and oscillation, i.e. amplification of the signal wave by a coherent pump wave of lower frequency, assisted by stimulated emission of the auxiliary idler wave. When the signal field is resonated in an optical cavity, parametric oscillation is obtained. Design parameters for the observation of up-conversion optical parametric oscillation at $\\lambda_3=465$ nm are given for a periodically-poled lithium-niobate (PPLN) crystal doped with Nd$^{3+}$ ions.

  9. Manufacture of Free-Form Optical Surfaces with Limited Mid-Spatial Frequency Error Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Our proposed innovation is a robust manufacturing process for free-form optical surfaces with limited mid-spatial frequency (MSF) irregularity error. NASA and many...

  10. Optical frequency comb generation from aluminum nitride micro-ring resonator

    OpenAIRE

    Jung, Hojoong; Xiong, Chi; Fong, King Y.; Zhang, Xufeng; Hong X. Tang

    2013-01-01

    Aluminum nitride is an appealing nonlinear optical material for on-chip wavelength conversion. Here we report optical frequency comb generation from high quality factor aluminum nitride micro-ring resonators integrated on silicon substrates. By engineering the waveguide structure to achieve near-zero dispersion at telecommunication wavelengths and optimizing the phase matching for four-wave mixing, frequency combs are generated with a single wavelength continuous-wave pump laser. The Kerr coe...

  11. Frequency unlimited optical delay lines based on slow and fast light in SOAs

    DEFF Research Database (Denmark)

    Berger, Perrine; Bourderionnet, Jérôme; Pu, Minhao;

    2011-01-01

    We experimentally demonstrate that up-converted coherent population oscillations (CPO) in SOA open the possibility to conceive integrated optical tunable delay lines beyond the carrier lifetime limit, up to THz frequencies.......We experimentally demonstrate that up-converted coherent population oscillations (CPO) in SOA open the possibility to conceive integrated optical tunable delay lines beyond the carrier lifetime limit, up to THz frequencies....

  12. Optical Orthogonal Frequency Division Systems with Direct Detection Receivers

    OpenAIRE

    Pérez Rosas, Juan Miguel

    2013-01-01

    Estudio y optimización de parámetros en sistemas de transmisión por fibra óptica usando modulación OFDM y detección directa. [ANGLÈS] The new generation of Pasive Optical Networks (PONs) to cover the last-mile to the user, is today a hot topic of research. Stringent performance requirements are both capacity and reach; these, together with reduced cost lead to consideration of a new paradigm. In this context, Optical OFDM (O-OFDM) is regarded as a promising candidate. From the many archite...

  13. Self-Phasematched Nonlinear Optics in Integrated Semiconductor Microcavities

    CERN Document Server

    Hayat, Alex

    2007-01-01

    A novel concept of self-phasematched optical frequency conversion in dispersive dielectric microcavities is studied theoretically and experimentally. We develop a time-dependent model, incorporating the dispersion into the structure of the spatial cavity modes and translating the phasematching requirement into the optimization of a nonlinear cavity mode overlap. We design and fabricate integrated double-resonance semiconductor microcavities for self-phasematched second harmonic generation. The measured efficiency exhibits a significant maximum near the cavity resonance due to the intra-cavity enhancement of the input power and the dispersion-induced wavelength detuning effect on the mode overlap, in good agreement with our theoretical predictions.

  14. Flight-Like Optical Reference Cavity for GRACE Follow-On Laser Frequency Stabilization

    Science.gov (United States)

    Folkner, W. M.; deVine, G.; Klipstein, W. M.; McKenzie, K.; Spero, R.; Thompson, R.; Yu, N.; Stephens, M.; Leitch, J.; Pierce, R.; Shaddock, D.; Lam, T.

    2011-01-01

    We describe a prototype optical cavity and associated optics that has been developed to provide a stable frequency reference for a future space-based laser ranging system. This instrument is being considered for inclusion as a technology demonstration on the recently announced GRACE follow-on mission, which will monitor variations in the Earth's gravity field.

  15. Gaussian-shaped Optical Frequency Comb Generation for Microwave Photonic Filtering

    CERN Document Server

    Wu, Rui; Hamidi, Ehsan; Supradeepa, V R; Song, Min Hyup; Leaird, Daniel E; Weiner, Andrew M

    2011-01-01

    Using only electro-optic modulators, we generate a 41-line 10-GHz Gaussian-shaped optical frequency comb. We use this comb to demonstrate apodized microwave photonic filters with greater than 43-dB sidelobe suppression without the need for a pulse shaper.

  16. A long-term frequency-stabilized erbium-fiber-laser-based optical frequency comb with an intra-cavity electro-optic modulator

    CERN Document Server

    Zhang, Y; Zhao, W; Meng, S; Fan, S; Zhang, L; Guo, G; Zhang, S; Jiang, H

    2014-01-01

    We demonstrate a home-made optical frequency comb based on an erbium-doped-fiber femtosecond laser with a ring cavity. The repetition rate of the laser is about 209 MHz determined by optical length of the laser cavity. By controlling an intra-cavity electro-optic modulator and a Piezo-transducer, the repetition rate can be stabilized with megahertz bandwidth in a range of 3 kilohertz, enabling long-term repetition rate phase-locking. The in-loop frequency instability of the repetition rate, limited by measurement system, is 1.3E-13 at 1 second integration time and inversely proportional to integration time for short terms. Using a common path f-2f interferometer, the carrier envelope offset (CEO) frequency of the frequency comb is obtained with a signal-to-noise ratio of 40 dB for 3 megahertz resolution spectrum. Stabilized CEO frequency exhibits a deviation of 0.6 milihertz at 1 second integration time.

  17. Single-frequency and tunable operation of a continuous intracavity-frequency-doubled singly resonant optical parametric oscillator.

    Science.gov (United States)

    My, Thu-Hien; Drag, Cyril; Bretenaker, Fabien

    2008-07-01

    A widely tunable continuous intracavity-frequency-doubled singly resonant optical parametric oscillator based on MgO-doped periodically poled stoichiometric lithium tantalate crystal is described. The idler radiation resonating in the cavity is frequency doubled by an intracavity BBO crystal. Pumped in the green, this system can provide up to 485 mW of single-frequency orange radiation. The system is continuously temperature tunable between 1170 and 1355 nm for the idler, 876 and 975 nm for the signal, and between 585 and 678 nm for the doubled idler. The free-running power and frequency stability of the system have been observed to be better than those for a single-mode dye laser.

  18. Single-frequency and tunable operation of a continuous intracavity-frequency-doubled singly resonant optical parametric oscillator.

    Science.gov (United States)

    My, Thu-Hien; Drag, Cyril; Bretenaker, Fabien

    2008-07-01

    A widely tunable continuous intracavity-frequency-doubled singly resonant optical parametric oscillator based on MgO-doped periodically poled stoichiometric lithium tantalate crystal is described. The idler radiation resonating in the cavity is frequency doubled by an intracavity BBO crystal. Pumped in the green, this system can provide up to 485 mW of single-frequency orange radiation. The system is continuously temperature tunable between 1170 and 1355 nm for the idler, 876 and 975 nm for the signal, and between 585 and 678 nm for the doubled idler. The free-running power and frequency stability of the system have been observed to be better than those for a single-mode dye laser. PMID:18594663

  19. Probe-controlled soliton frequency shift in the regime of optical event horizon

    DEFF Research Database (Denmark)

    Gu, Jie; Guo, Hairun; Wang, Shaofei;

    2015-01-01

    In optical analogy of the event horizon, temporal pulse collision and mutual interactions are mainly between an intense solitary wave (soliton) and a dispersive probe wave. In such a regime, here we numerically investigate the probe-controlled soliton frequency shift as well as the soliton self...... in contrast to optical fibers or cubic nonlinear media, which could contribute to the community with a simple and flexible method to experimental implementations (C) 2015 Optical Society of America...

  20. Coherent, multi-heterodyne spectroscopy using stabilized optical frequency combs

    CERN Document Server

    Coddington, Ian; Newbury, Nathan R

    2007-01-01

    The broadband, coherent nature of narrow-linewidth fiber frequency combs is exploited to measure the full complex spectrum of a molecular gas through multi-heterodyne spectroscopy. We measure the absorption and phase shift experienced by each of 155,000 individual frequency comb lines, spaced by 100 MHz and spanning from 1495 nm to 1620 nm, after passing through a hydrogen cyanide gas. The measured phase spectrum agrees with Kramers-Kronig transformation of the absorption spectrum. This technique can provide a full complex spectrum rapidly, over wide bandwidths, and with hertz-level accuracy.

  1. Nonlinear Optical Frequency Conversion for Lasers in Space

    OpenAIRE

    Potreck, Arne

    2014-01-01

    A frequency conversion unit, based on two BiBO crystals in a crystal holder suitable for a future space mission, is presented within this work. Conversion efficiency at second harmonic generation followed by sum frequency generation was realized to be as high as 48±2 %, converting the fundamental radiation in the infrared at a wavelength of 1064 nm to a radiation in the ultraviolet at a wavelength of 355 nm. The realized conversion efficiency overcomes studies conducted in the past and fulfil...

  2. Broadband Continuous-Wave Multi-Harmonic Optical Comb Based on a Frequency Division-by-Three Optical Parametric Oscillator

    Directory of Open Access Journals (Sweden)

    Yen-Yin Lin

    2014-11-01

    Full Text Available We report a multi-watt broadband continuous-wave multi-harmonic optical comb based on a frequency division-by-three singly-resonant optical parametric oscillator. This cw optical comb is frequency-stabilized with the help of a beat signal derived from the signal and frequency-doubled idler waves. The measured frequency fluctuation in one standard deviation is ~437 kHz. This is comparable to the linewidth of the pump laser which is a master-oscillator seeded Yb:doped fiber amplifier at ~1064 nm. The measured powers of the fundamental wave and the harmonic waves up to the 6th harmonic wave are 1.64 W, 0.77 W, 3.9 W, 0.78 W, 0.17 W, and 0.11 W, respectively. The total spectral width covered by this multi-harmonic comb is ~470 THz. When properly phased, this multi-harmonic optical comb can be expected to produce by Fourier synthesis a light source consisting of periodic optical field waveforms that have an envelope full-width at half-maximum of 1.59 fs in each period.

  3. Quartz optical filter for wavelength selection of frequency-doubled laser based on optical rotatory dispersion effect

    Institute of Scientific and Technical Information of China (English)

    Shan Zhang; Fuquan Wu; Wendi Wu; Haifeng Wang

    2007-01-01

    Based on the optical rotatory dispersion effect, an optical filter for selecting the second harmonic of a frequency-doubled laser is constructed from quartz in combination with polarizers. The operating principle is analyzed by matrix formulation, and the result indicates that the second harmonic of a frequency-doubled laser will be obtained when the rotation angle has a difference of (2n + 1)π/2 (n = 0, 1, 2, 3,… ) between the two polarizations of the second-harmonic laser and the fundamental laser. The spectrum of the output laser is taken by the AQ-6315A spectrometer, and the experimental results are in good agreement with the theoretical results.

  4. Using Multiple Input Multiple Output as Hybrid Free Space Optics/Radio Frequency Links

    Directory of Open Access Journals (Sweden)

    M. Tatarko

    2013-06-01

    Full Text Available This paper describes overview and definitions about Multiple Input Multiple Output (MIMO formats which can be used in hybrid Free Space Optics/Radio Frequency (FSO/RF links. Free space optical links allow obtain high speed data transmission without optical fibers. This type of communication is dependent on weather properties and line of sight is needed. This fact has negative influence on infrared beams which are being use for transmission. Radio frequency links have different restrictions in compare with FSO links. Both links can complement each other. Availability can increase with using hybrid FSO/RF links as MIMO systems.

  5. Two-Photon Spectroscopy in Rb for an Optical Frequency Standard

    Science.gov (United States)

    Martin, Kyle; Phelps, Gretchen; Lemke, Nathan; Blakley, Daniel; Erickson, Christopher; Burke, John; Applied Technology Associates Team; Space Dynamics Laboratory Team; Air Force Research Laboratory Team

    2016-05-01

    The Air Force Research Laboratory is pursuing optical atomic clocks for navigation and timing applications. Optical clocks are of particular interest owing to their very high oscillation frequencies. We present an optical rubidium atomic frequency standard (O-RAFS), based upon a two-photon transition at 778 nm, that utilizes readily available commercial off-the-shelf components. Compared to existing GPS clocks, O-RAFS offers reduced short-term instability (7 ×10-13 /√{ τ}), improved manufacturability, and competitive size, weight, and power, making it an attractive candidate for future space operation.

  6. Stability limits of an optical frequency standard based on free Ca atoms

    CERN Document Server

    Sherman, J A

    2011-01-01

    We have quantified a short term instability budget for an optical frequency standard based on cold, freely expanding calcium atoms. Such systems are the subject of renewed interest due to their high frequency stability and relative technical simplicity compared to trapped atom optical clocks. By filtering the clock laser light at 657 nm through a high finesse cavity, we observe a slight reduction in the optical Dick effect caused by aliased local oscillator noise. The ultimately limiting technical noise is measured using a technique that does not rely on a second clock or fs-comb.

  7. Digital Square-Wave Frequency Modulated Microwave Sources for a Miniature Optically Pumped Cesium Beam Clock

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; ZHU Chengjin; LIU Ge; WANG Fengzhi; WANG Yiqiu; YANG Donghai

    2001-01-01

    Three different digital frequencymodulated microwave sources have been designed andapplied to our miniature optically pumped cesiumbeam clock.The main features and their influenceon clock accuracy have been experimentally tested.Itis proved that a digital square-wave frequency modu-lated microwave source using a microprocessor con-trolled direct-digital frequency synthesizer (DDFS)for our miniature optically pumped cesium beamclock works well,the frequency short term stability2 × 10 11/x r and the long term stability 3.5 x 10-13 forone day sample time have been obtained.

  8. A New Pumping-Probing Scheme for the Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    陈景标; 朱程锦; 王凤芝; 杨东海

    2001-01-01

    A new pumping-probing scheme for the optically pumped cesium beam frequency standard has been experimentally tested in our laboratory. The stability of the optically pumped cesium beam frequency standard was measured by comparing its 10 MHz output with an HP5071A commercial cesium atomic clock. The result shows that the frequency stability for the 1 s and 30000s sample times are 1.2 × 10-11 and 3.7 × 10-13, respectively. It was proved that the new pumping scheme works well.

  9. Computer simulation of the collision frequency of two particles in optical tweezers

    Institute of Scientific and Technical Information of China (English)

    Xu Sheng-Hua; Li Yin-Mei; Lou Li-Ren; Sun Zhi-Wei

    2005-01-01

    Optical tweezers have been successfully used in the study of colloid science. In most applications people are concerned with the behaviour of a single particle held in the optical tweezers. Recently, the ability of the optical tweezers to simultaneously hold two particles has been used to determine the stability ratio of colloidal dispersion. This new development stimulates the efforts to explore the characteristics of a two-particle system in the optical tweezers.An infinite spherical potential well has been used to estimate the collision frequency for two particles in the optical trap based on a Monte Carlo simulation. In this article, a more reasonable harmonic potential, commonly accepted for the optical tweezers, is adopted in a Monte Carlo simulation of the collision frequency. The effect of hydrodynamic interaction of particles in the trap is also considered. The simulation results based on this improved model show quantitatively that the collision frequency drops down sharply at first and then decreases slowly as the distance between the two particles increases. The simulation also shows how the collision frequency is related to the stiffness of the optical tweezers.

  10. A stabilized 18 GHz chip-scale optical frequency comb at 2.8x10-16 relative inaccuracy

    OpenAIRE

    Huang, S.-W.; Yang, J.; Yu, M.; McGuyer, B. H.; Kwong, D. -L.; Zelevinsky, T.; Wong, C. W.

    2015-01-01

    Optical frequency combs, coherent light sources that connect optical frequencies with microwave oscillations, have become the enabling tool for precision spectroscopy, optical clockwork and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but four-wave-mixing in high-Q resonators have emerged as alternative platforms. Here we report the generation and full stabilization of CMOS-compatible optical frequency combs. The spira...

  11. Photonic chip-based optical frequency comb using soliton Cherenkov radiation.

    Science.gov (United States)

    Brasch, V; Geiselmann, M; Herr, T; Lihachev, G; Pfeiffer, M H P; Gorodetsky, M L; Kippenberg, T J

    2016-01-22

    Optical solitons are propagating pulses of light that retain their shape because nonlinearity and dispersion balance each other. In the presence of higher-order dispersion, optical solitons can emit dispersive waves via the process of soliton Cherenkov radiation. This process underlies supercontinuum generation and is of critical importance in frequency metrology. Using a continuous wave-pumped, dispersion-engineered, integrated silicon nitride microresonator, we generated continuously circulating temporal dissipative Kerr solitons. The presence of higher-order dispersion led to the emission of red-shifted soliton Cherenkov radiation. The output corresponds to a fully coherent optical frequency comb that spans two-thirds of an octave and whose phase we were able to stabilize to the sub-Hertz level. By preserving coherence over a broad spectral bandwidth, our device offers the opportunity to develop compact on-chip frequency combs for frequency metrology or spectroscopy. PMID:26721682

  12. Multiple frequency optical mixer and demultiplexer and apparatus for remote sensing

    Science.gov (United States)

    Chen, Jeffrey R. (Inventor)

    2010-01-01

    A pulsed laser system includes a modulator module configured to provide pulsed electrical signals and a plurality of solid-state seed sources coupled to the modulator module and configured to operate, responsive to the pulsed electrical signals, in a pulse mode. Each of the plurality of solid-state seed sources is tuned to a different frequency channel separated from any adjacent frequency channel by a frequency offset. The pulsed laser system also includes a combiner that combines outputs from each of the solid state seed sources into a single optical path and an optical doubler and demultiplexer coupled to the single optical path and providing each doubled seed frequency on a separate output path.

  13. Integrated optical frequency shifter in silicon-organic hybrid (SOH) technology.

    Science.gov (United States)

    Lauermann, M; Weimann, C; Knopf, A; Heni, W; Palmer, R; Koeber, S; Elder, D L; Bogaerts, W; Leuthold, J; Dalton, L R; Rembe, C; Freude, W; Koos, C

    2016-05-30

    We demonstrate for the first time a waveguide-based frequency shifter on the silicon photonic platform using single-sideband modulation. The device is based on silicon-organic hybrid (SOH) electro-optic modulators, which combine conventional silicon-on-insulator waveguides with highly efficient electro-optic cladding materials. Using small-signal modulation, we demonstrate frequency shifts of up to 10 GHz. We further show large-signal modulation with optimized waveforms, enabling a conversion efficiency of -5.8 dB while suppressing spurious side-modes by more than 23 dB. In contrast to conventional acousto-optic frequency shifters, our devices lend themselves to large-scale integration on silicon substrates, while enabling frequency shifts that are several orders of magnitude larger than those demonstrated with all-silicon serrodyne devices. PMID:27410095

  14. Cascaded multiplexed optical link on a telecommunication network for frequency dissemination.

    Science.gov (United States)

    Lopez, Olivier; Haboucha, Adil; Kéfélian, Fabien; Jiang, Haifeng; Chanteau, Bruno; Roncin, Vincent; Chardonnet, Christian; Amy-Klein, Anne; Santarelli, Giorgio

    2010-08-01

    We demonstrate a cascaded optical link for ultrastable frequency dissemination comprised of two compensated links of 150 km and a repeater station. Each link includes 114 km of Internet fiber simultaneously carrying data traffic through a dense wavelength division multiplexing technology, and passes through two routing centers of the telecommunication network. The optical reference signal is inserted in and extracted from the communication network using bidirectional optical add-drop multiplexers. The repeater station operates autonomously ensuring noise compensation on the two links and the ultra-stable signal optical regeneration. The compensated link shows a fractional frequency instability of 3 x 10(-15) at one second measurement time and 5 x 10(-20) at 20 hours. This work paves the way to a wide dissemination of ultra-stable optical clock signals between distant laboratories via the Internet network.

  15. Cascaded multiplexed optical link on a telecommunication network for frequency dissemination

    CERN Document Server

    Lopez, Olivier; Kéfélian, Fabien; Jiang, Haifeng; Chanteau, Bruno; Roncin, Vincent; Chardonnet, Christian; Amy-Klein, Anne; Santarelli, Georgio

    2010-01-01

    We demonstrate a cascaded optical link for ultrastable frequency dissemination comprised of two compensated links of 150 km and a repeater station. Each link includes 114 km of Internet fiber simultaneously carrying data traffic through a dense wavelength division multiplexing technology, and passes through two routing centers of the telecommunication network. The optical reference signal is inserted in and extracted from the communication network using bidirectional optical add-drop multiplexers. The repeater station operates autonomously ensuring noise compensation on the two links and the ultra-stable signal optical regeneration. The compensated link shows a fractional frequency instability of 3 \\times 10-15 at one second measurement time and 5 \\times 10-20 at 20 hours. This work paves the way to a wide dissemination of ultra-stable optical clock signals between distant laboratories via the Internet network.

  16. Manipulating the optical bistability at terahertz frequency in the Fabry-Perot cavity with graphene.

    Science.gov (United States)

    Jiang, Leyong; Guo, Jun; Wu, Leiming; Dai, Xiaoyu; Xiang, Yuanjiang

    2015-11-30

    We investigate theoretically the optical bistability from a Fabry-Perot cavity with graphene in the terahertz (THz) frequency. It is demonstrated that the optical bistablility in this cavity can be realized due to the electric field enhancement and the giant third-order nonlinear conductivity of graphene. The optical bistable behavior is strongly dependent on the transmission amplitude of the mirror and the position of the graphene in the cavity. It is especially important that the hysterical behaviors of the transmitted light rely on the optical conductivity of graphene, making the Fabry-Perot cavity to be a good candidate for dynamic tunable optical bistable device in the THz frequencies, owing to the possibility of high tunability of graphene conductivity by means of external electrostatic or magnetostatic field.

  17. Frequency-Shifted Interferometry — A Versatile Fiber-Optic Sensing Technique

    Directory of Open Access Journals (Sweden)

    Fei Ye

    2014-06-01

    Full Text Available Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI. This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applications in fiber length and dispersion measurement, locating weak reflections along a fiber link, fiber-optic sensor multiplexing, and high-sensitivity cavity ring-down measurement. Detailed analysis of FSI system parameters is also presented.

  18. Low Frequency Error Analysis and Calibration for High-Resolution Optical Satellite's Uncontrolled Geometric Positioning

    Science.gov (United States)

    Wang, Mi; Fang, Chengcheng; Yang, Bo; Cheng, Yufeng

    2016-06-01

    The low frequency error is a key factor which has affected uncontrolled geometry processing accuracy of the high-resolution optical image. To guarantee the geometric quality of imagery, this paper presents an on-orbit calibration method for the low frequency error based on geometric calibration field. Firstly, we introduce the overall flow of low frequency error on-orbit analysis and calibration, which includes optical axis angle variation detection of star sensor, relative calibration among star sensors, multi-star sensor information fusion, low frequency error model construction and verification. Secondly, we use optical axis angle change detection method to analyze the law of low frequency error variation. Thirdly, we respectively use the method of relative calibration and information fusion among star sensors to realize the datum unity and high precision attitude output. Finally, we realize the low frequency error model construction and optimal estimation of model parameters based on DEM/DOM of geometric calibration field. To evaluate the performance of the proposed calibration method, a certain type satellite's real data is used. Test results demonstrate that the calibration model in this paper can well describe the law of the low frequency error variation. The uncontrolled geometric positioning accuracy of the high-resolution optical image in the WGS-84 Coordinate Systems is obviously improved after the step-wise calibration.

  19. Testing Time and Frequency Fiber-Optic Link Transfer by Hardware Emulation of Acoustic-Band Optical Noise

    Directory of Open Access Journals (Sweden)

    Lipiński Marcin

    2016-06-01

    Full Text Available The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

  20. Nonlinear modification of the laser noise power spectrum induced by a frequency-shifted optical feedback

    CERN Document Server

    Lacot, Eric; Girardeau, Vadim; Hugon, Olivier; Jacquin, Olivier

    2016-01-01

    In this article, we study the non-linear coupling between the stationary (i.e. the beating modulation signal) and transient (i.e. the laser quantum noise) dynamics of a laser subjected to frequency shifted optical feedback. We show how the noise power spectrum and more specifically the relaxation oscillation frequency of the laser are modified under different optical feedback condition. Specifically we study the influence of (i) the amount of light returning to the laser cavity and (ii) the initial detuning between the frequency shift and intrinsic relaxation frequency. The present work shows how the relaxation frequency is related to the strength of the beating signal and the shape of the noise power spectrum gives an image of the Transfer Modulation Function (i.e. of the amplification gain) of the nonlinear-laser dynamics.The theoretical predictions, confirmed by numerical resolutions, are in good agreements with the experimental data.

  1. Absolute frequency synthesis of pulsed coherent light waves through phase-modulation active optical feedback.

    Science.gov (United States)

    Shimizu, K; Horiguchi, T; Koyamada, Y

    1996-11-15

    A novel method for the broadband absolute frequency synthesis of pulsed coherent lightwaves is demonstrated. It is based on pulse recirculation around an active optical feedback ring containing a delay-line fiber, an external phase modulator, an acousto-optic frequency shifter (AOFS), and a high-finesse Fabry-Perot étalon. The modulation frequency F(M) and the frequency shift F(AO) that are due to AOFS are designed so that their sum or difference equals the free-spectral range of the étalon and F(AO) is set at larger than the half-width at full maximum of its resonant peaks. If one of the peak frequencies is tuned to the frequency of the initial pulse, the frequency of the recirculating pulse jumps to the next peak for each round trip. In the experiment the absolute frequency is synthesized over a frequency span of 700 GHz around the initial stabilized frequency of the master laser.

  2. Development of femtosecond optical frequency comb laser tracker

    Science.gov (United States)

    Yang, Ju-qing; Zhou, Wei-hu; Dong, Deng-feng; Zhang, Zi-li; Lao, Da-bao; Ji, Rong-yi; Wang, Da-yong

    2016-01-01

    A new type femtosecond laser tracker is one high precision measurement instrument with urgent need in science research region and industrial manufacture field. This paper focuses on the operational principle and the structure development of the femtosecond laser tracer, and the method of error compensation as well. The system modules were studied and constructed. The femtosecond frequency comb module was firstly analyzed and developed. The femtosecond laser frequency comb performed perfectly high precise distance measurement for laser tracker. The experimental result showed that the stability of repetition rate reached 3.0×10-12@1s and the stability of carrier envelop offset reached 1.0×10-10@1s. The initial experiment showed that measurement error was less than 1ppm. Later the error compensation module was introduced, and the optoelectronic aiming and tracking control module was built. The actual test result showed that the stability of miss distance was better than 2.0 μm, the tracking speed could reach 2m/s.

  3. Effect of soil temperature on one-way optical frequency transfer through dense-wavelength-division-multiplexing fibre links

    CERN Document Server

    Pinkert, T J; Jansen, G S M; Dijck, E A; Groeneveld, B G H M; Smets, R; Bosveld, F C; Ubachs, W; Jungmann, K; Eikema, K S E; Koelemeij, J C J

    2014-01-01

    Results of optical frequency transfer over a carrier-grade dense-wavelength-division-multiplexing (DWDM) optical fibre network are presented. The relation between soil temperature changes on a buried optical fibre and frequency changes of an optical carrier through the fibre is modelled. Soil temperatures, measured at various depths by the Royal Netherlands Meteorology Institute (KNMI) are compared with observed frequency variations through this model. A comparison of a nine-day record of optical frequency measurements through the 2 x 298 km fibre link with soil temperature data shows qualitative agreement. A soil temperature model is used to predict the link stability over longer periods (days-months-years). We show that one-way optical frequency dissemination is sufficiently stable to distribute and compare e.g. rubidium frequency standards over standard DWDM optical fibre networks.

  4. Nonlinear-optical frequency-doubling metareflector: pulsed regime

    Science.gov (United States)

    Popov, A. K.; Myslivets, S. A.

    2016-01-01

    The properties of backward-wave second-harmonic metareflector operating in pulse regime are investigated. It is made of metamaterial which enables phase matching of contra-propagating fundamental and second-harmonic waves. References are given to the works that prove such a possibility. Physical principles underlying differences in the proposed and standard settings as well as between continuous-wave and pulsed regimes are discussed. Pulsed regime is more practicable and has a broader scope of applications. A set of partial differential equations which describe such a reflector with the account for losses are solved numerically. It is shown that unlike second-harmonic generation in standard settings, contra-propagating pulse of second harmonic may become much longer than the incident fundamental one and the difference grows with decrease in the input pulse length as compared to thickness of the metaslab. The revealed properties are important for applications and may manifest themselves beyond the optical wavelength range.

  5. Frequency Comparison of [Formula: see text] Ion Optical Clocks at PTB and NPL via GPS PPP.

    Science.gov (United States)

    Leute, J; Huntemann, N; Lipphardt, B; Tamm, Christian; Nisbet-Jones, P B R; King, S A; Godun, R M; Jones, J M; Margolis, H S; Whibberley, P B; Wallin, A; Merimaa, M; Gill, P; Peik, E

    2016-07-01

    We used precise point positioning, a well-established GPS carrier-phase frequency transfer method to perform a direct remote comparison of two optical frequency standards based on single laser-cooled [Formula: see text] ions operated at the National Physical Laboratory (NPL), U.K. and the Physikalisch-Technische Bundesanstalt (PTB), Germany. At both institutes, an active hydrogen maser serves as a flywheel oscillator which is connected to a GPS receiver as an external frequency reference and compared simultaneously to a realization of the unperturbed frequency of the (2)S1/2(F=0)-(2)D3/2(F=2) electric quadrupole transition in [Formula: see text] via an optical femtosecond frequency comb. To profit from long coherent GPS-link measurements, we extrapolate the fractional frequency difference over the various data gaps in the optical clock to maser comparisons which introduces maser noise to the frequency comparison but improves the uncertainty from the GPS-link instability. We determined the total statistical uncertainty consisting of the GPS-link uncertainty and the extrapolation uncertainties for several extrapolation schemes. Using the extrapolation scheme with the smallest combined uncertainty, we find a fractional frequency difference [Formula: see text] of -1.3×10(-15) with a combined uncertainty of 1.2×10(-15) for a total measurement time of 67 h. This result is consistent with an agreement of the frequencies realized by both optical clocks and with recent absolute frequency measurements against caesium fountain clocks within the corresponding uncertainties.

  6. Second-harmonic frequency-resolved optical gating covering two and a half optical octaves using a single spectrometer

    Science.gov (United States)

    Marceau, C.; Thomas, S.; Kassimi, Y.; Gingras, G.; Witzel, B.

    2015-05-01

    We report the measurement of laser pulse shapes covering the range 580-3250 nm using second-harmonic generation frequency-resolved optical gating equipped with a single inexpensive visible-NIR miniature spectrometer and a single pair of homemade broadband beam splitters. Our experimental scheme exploits frequency up-conversion by BBO crystals and appropriate corrections for dispersion, beam splitter filtering and phase-matching efficiency. The signal and idler waves from a commercial optical parametric amplifier pumped by a Ti:Sapphire laser (26 fs, 1 kHz) have been characterized as well as their second harmonic. The pulse shapes out of a commercial difference frequency generation module mixing signal and idler have also been measured up to 3250 nm. The resulting pulses range from 20 to 120 fs, and their chirp characteristics are also exposed. Our approach is demonstrated over most of the doubling crystal transparency range.

  7. Bromine Explosions In Smog Chamber Experiments: A comparison of Cavity-Enhanced (CE) and White-cell DOAS

    Science.gov (United States)

    Buxmann, J.; Hoch, D. J.; Sihler, H.; Pöhler, D.; Platt, U.; Bleicher, S.; Balzer, N.; Zetzsch, C.

    2011-12-01

    Reactive halogen species (RHS), such as Cl, Br or BrO, can significantly influence chemical processes in the troposphere, including the destruction of ozone, change in the chemical balance of hydrogen radicals (OH, HO2), increased deposition of toxic compounds (like mercury) with potential consequences for the global climate. Previous studies have shown that salt lakes can be significant sources for gaseous RHS. Environmental conditions such as salt composition, relative humidity (RH), pH, and temperature (T) can strongly influence reactive bromine levels, but are difficult to quantify in the field. Therefore, we conducted laboratory experiments by exposing NaCl salt containing 0.33% (by weight) NaBr to simulated sunlight in a Teflon smog-chamber under various conditions of RH and ozone concentrations. BrO levels were observed by a Differential-Optical-Absorption-Spectrometer (DOAS) in combination with a multi-reflection cell (White-cell). The concentrations of OH- and Cl- radicals were quantified by the radical clock method. We present the first direct observation of BrO from the "Bromine Explosion" (auto catalytic release of reactive bromine from salt surfaces - key to ozone destruction) in the laboratory above a simulated salt pan. The maximum BrO mixing ratio of 6419±71 ppt at 60% RH was observed to be one order of magnitude higher than at 37% RH and 2% RH. The release of RHS from the salt pan is possibly controlled by the thickness of the quasi liquid layer, covering the reactive surface of the halide crystals, as the layer thickness strongly depends on RH. Furthermore, a new cavity enhanced DOAS (CE-DOAS) instrument was designed and successfully used in chamber experiments. For the first time, such an instrument uses a spectral interval in the UV - wavelength range (325-365 nm) to identify BrO. We show a comparison of the CE-DOAS and White-cell DOAS instrument in a series of experiments, where e.g. a peak BrO mixing ratio up to 380 ppt within the first

  8. Tailoring alphabetical metamaterials in optical frequency: plasmonic coupling, dispersion, and sensing.

    Science.gov (United States)

    Zhang, Jun; Cao, Cuong; Xu, Xinlong; Liow, Chihao; Li, Shuzhou; Tan, Pingheng; Xiong, Qihua

    2014-04-22

    Tailoring optical properties of artificial metamaterials, whose optical properties go beyond the limitations of conventional and naturally occurring materials, is of importance in fundamental research and has led to many important applications such as security imaging, invisible cloak, negative refraction, ultrasensitive sensing, and transformable and switchable optics. Herein, by precisely controlling the size, symmetry, and topology of alphabetical metamaterials with U, S, Y, H, U-bar, and V shapes, we have obtained highly tunable optical response covering visible-to-infrared (vis-NIR) optical frequency. In addition, we show a detailed study on the physical origin of resonance modes, plasmonic coupling, the dispersion of resonance modes, and the possibility of negative refraction. We have found that all the electronic and magnetic modes follow the dispersion of surface plasmon polaritons; thus, essentially they are electronic- and magnetic-surface-plasmon-polaritons-like (ESPP-like and MSPP-like) modes resulted from diffraction coupling between localized surface plasmon and freely propagating light. On the basis of the fill factor and formula of magnetism permeability, we predict that the alphabetical metamaterials should show the negative refraction capability in visible optical frequency. Furthermore, we have demonstrated the specific ultrasensitive surface enhanced Raman spectroscopy (SERS) sensing of monolayer molecules and femtomolar food contaminants by tuning their resonance to match the laser wavelength, or by tuning the laser wavelength to match the plasmon resonance of metamaterials. Our tunable alphabetical metamaterials provide a generic platform to study the electromagnetic properties of metamaterials and explore the novel applications in optical frequency.

  9. Tuning of Detection Wavelength in a Resonant-Cavity-Enhanced Quantum-Dot-Embedded Photodiode by Changing Detection Angle

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hao; ZHU Hui; ZHENG Hou-Zhi; XU Ping; PENG Hong-Ling; TAN Ping-Heng; YANG Fu-Hua; NI Hai-Qiao; ZENG Yu-Xin; GAN Hua-Dong

    2005-01-01

    @@ We have Fabricated a resonant-cavity-enhanced photodiode (RCE-PD) with InGaAs quantum dots (QDs) as an active medium. This sort of QD-embedded RCE-PD is capable of a peak external quantum efficiency of 32%and responsivity of 0.27 A/W at 1.058 μm with a full width at half maximum (FWHM) of 5nm. Angle-resolved photocurrent response eventually proves that with the detection angle changing from 0° to 60°, the peak-current wavelength shifts towards the short wavelength side by 37nm, while the quantum efficiency remains larger than 15%.

  10. Highly stable piezoelectrically tunable optical cavities

    CERN Document Server

    Möhle, Katharina; Döringshoff, Klaus; Nagel, Moritz; Peters, Achim

    2013-01-01

    We have implemented highly stable and tunable frequency references using optical high finesse cavities which incorporate a piezo actuator. As piezo material we used ceramic PZT, crystalline quartz, or PZN-PT single crystals. Lasers locked to these cavities show a relative frequency stability better than 1 x 10^{-14}, which is most likely not limited by the piezo actuators. The piezo cavities can be electrically tuned over more than one free spectral range (> 1.5 GHz) with only a minor decrease in frequency stability. Furthermore, we present a novel cavity design, where the piezo actuator is prestressed between the cavity spacer components. This design features a hermetically sealable intra cavity volume suitable for, e.g., cavity enhanced spectroscopy.

  11. Antenna-load interactions at optical frequencies: impedance matching to quantum systems.

    Science.gov (United States)

    Olmon, R L; Raschke, M B

    2012-11-01

    The goal of antenna design at optical frequencies is to deliver optical electromagnetic energy to loads in the form of, e.g., atoms, molecules or nanostructures, or to enhance the radiative emission from such structures, or both. A true optical antenna would, on a qualitatively new level, control the light-matter interaction on the nanoscale for controlled optical signal transduction, radiative decay engineering, quantum coherent control, and super-resolution microscopy, and provide unprecedented sensitivity in spectroscopy. Resonant metallic structures have successfully been designed to approach these goals. They are called optical antennas in analogy to radiofrequency (RF) antennas due to their capability to collect and control electromagnetic fields at optical frequencies. However, in contrast to the RF, where exact design rules for antennas, waveguides, and antenna-load matching in terms of their impedances are well established, substantial physical differences limit the simple extension of the RF concepts into the optical regime. Key distinctions include, for one, intrinsic material resonances including quantum state excitations (metals, metal oxides, semiconductor homo- and heterostructures) and extrinsic resonances (surface plasmon/phonon polaritons) at optical frequencies. Second, in the absence of discrete inductors, capacitors, and resistors, new design strategies must be developed to impedance match the antenna to the load, ultimately in the form of a vibrational, electronic, or spin excitation on the quantum level. Third, there is as yet a lack of standard performance metrics for characterizing, comparing and quantifying optical antenna performance. Therefore, optical antenna development is currently challenged at all the levels of design, fabrication, and characterization. Here we generalize the ideal antenna-load interaction at optical frequencies, characterized by three main steps: (i) far-field reception of a propagating mode exciting an antenna

  12. An aircraft based three channel broadband cavity enhanced absorption spectrometer for simultaneous measurements of NO3, N2O5 and NO2

    Directory of Open Access Journals (Sweden)

    R. Nightingale

    2011-06-01

    Full Text Available A three channel broadband cavity enhanced absorption spectroscopy (BBCEAS instrument has been developed for airborne measurements of atmospheric trace gases involved in night-time oxidation chemistry and air quality. The instrument was deployed on board the Facility for Airborne Atmospheric Measurements BAe 146-301 atmospheric research aircraft during the Role of Nighttime Chemistry in Controlling the Oxidising Capacity of the Atmosphere (RONOCO measurement campaigns between December 2009 and January 2011. In its present configuration (i.e. specifications of the cavity optics and spectrometers the instrument is designed to measure NO3, N2O5 (by detection of NO3 after thermal dissociation of N2O5, H2O and NO2 by characterising the wavelength dependent optical attenuation within ambient samples by molecular absorption around 662 nm (NO3 and H2O and 445 nm (NO2. This paper reports novel advancements in BBCEAS instrumentation including a refined method for performing BBCEAS mirror reflectivity calibrations using measurements of the phase delay introduced by the optical cavities to amplitude modulated radiation. Furthermore, a new methodology is introduced for fitting the strong but unresolved transitions of water vapour, which is required for accurate retrieval of water absorption features from the 662 nm absorption band used to measure NO3 concentrations. The paper also details the first example of airborne measurements of NO3, N2O5 and NO2 over Europe from a flight over the North Sea and Thames Estuary on the night of the 20 July 2010, one of the most polluted days of the RONOCO summertime flying period. As part of this analysis, the performance of the BBCEAS instrument is assessed by comparing airborne NO2 measurements to those reported concurrently by a photolytic chemiluminescence based detector.

  13. Optical frequency-domain chromatic dispersion measurement method for higher-order modes in an optical fiber.

    Science.gov (United States)

    Ahn, Tae-Jung; Jung, Yongmin; Oh, Kyunghwan; Kim, Dug Young

    2005-12-12

    We propose a new chromatic dispersion measurement method for the higher-order modes of an optical fiber using optical frequency modulated continuous-wave (FMCW) interferometry. An optical fiber which supports few excited modes was prepared for our experiments. Three different guiding modes of the fiber were identified by using far-field spatial beam profile measurements and confirmed with numerical mode analysis. By using the principle of a conventional FMWC interferometry with a tunable external cavity laser, we have demonstrated that the chromatic dispersion of a few-mode optical fiber can be obtained directly and quantitatively as well as qualitatively. We have also compared our measurement results with those of conventional modulation phase-shift method. PMID:19503215

  14. Radio frequency phototube and optical clock: High resolution, high rate and highly stable single photon timing technique

    Energy Technology Data Exchange (ETDEWEB)

    Margaryan, Amur

    2011-10-01

    A new timing technique for single photons based on the radio frequency phototube and optical clock or femtosecond optical frequency comb generator is proposed. The technique has a 20 ps resolution for single photons, is capable of operating with MHz frequencies and achieving 10 fs instability level.

  15. Performance analysis on quality of optical frequency comb generated by the recirculating frequency shifter based on linear IQ modulator

    Science.gov (United States)

    Sun, Lu; Li, Jianping; Lin, Jiachuan; Xi, Lixia; Tang, Xianfeng; Zhang, Xiaoguang

    2015-11-01

    An optical frequency comb generator using a modified single-sideband recirculating frequency shifter scheme adopting a linear IQ modulator as the kernel device (SSB-RFS-LIQM) is proposed. The optical comb lines generated by the proposed scheme possess good features such as extreme flatness and high optical signal-to-noise ratio (OSNR), compared to the quality we can obtain when we use a conventional IQ modulator in the SSB-RFS structure (called SSB-RFS-CIQM scheme). The mechanism of how the SSB-RFS-LIQM works is carefully analyzed with analytical and numerical methods. With the capability of strong suppression of high-order crosstalk and less demand of the gain of erbium-doped fiber amplifiers (and hence less amplified spontaneous noise induced) in the loop, 5.5 dB OSNR improvement can be achieved when 100 extreme flat comb lines are generated using the SSB-RFS-LIQM scheme compared to using the SSB-RFS-CIQM scheme.

  16. Dual-pump Kerr Micro-cavity Optical Frequency Comb with varying FSR spacing

    Science.gov (United States)

    Wang, Weiqiang; Chu, Sai T.; Little, Brent E.; Pasquazi, Alessia; Wang, Yishan; Wang, Leiran; Zhang, Wenfu; Wang, Lei; Hu, Xiaohong; Wang, Guoxi; Hu, Hui; Su, Yulong; Li, Feitao; Liu, Yuanshan; Zhao, Wei

    2016-01-01

    In this paper, we demonstrate a novel dual-pump approach to generate robust optical frequency comb with varying free spectral range (FSR) spacing in a CMOS-compatible high-Q micro-ring resonator (MRR). The frequency spacing of the comb can be tuned by an integer number FSR of the MRR freely in our dual-pump scheme. The dual pumps are self-oscillated in the laser cavity loop and their wavelengths can be tuned flexibly by programming the tunable filter embedded in the cavity. By tuning the pump wavelength, broadband OFC with the bandwidth of >180 nm and the frequency-spacing varying from 6 to 46-fold FSRs is realized at a low pump power. This approach could find potential and practical applications in many areas, such as optical metrology, optical communication, and signal processing systems, for its excellent flexibility and robustness. PMID:27338250

  17. Optical Synthesis of Terahertz and Millimeter-Wave Frequencies with Discrete Mode Diode Lasers

    CERN Document Server

    O'Brien, Stephen; Bitauld, David; Brandonisio, Nicola; Amann, Andreas; Phelan, Richard; Kelly, Brian; O'Gorman, James

    2010-01-01

    It is shown that optical synthesis of terahertz and millimeter-wave frequencies can be achieved using two-mode and mode-locked discrete mode diode lasers. These edge-emitting devices incorporate a spatially varying refractive index profile which is designed according to the spectral output desired of the laser. We first demonstrate a device which supports two primary modes simultaneously with high spectral purity. In this case sinusoidal modulation of the optical intensity at terahertz frequencies can be obtained. Cross saturation of the material gain in quantum well lasers prevents simultaneous lasing of two modes with spacings in the millimeter-wave region. We show finally that by mode-locking of devices that are designed to support a minimal set of four primary modes, we obtain a sinusoidal modulation of the optical intensity in this frequency region.

  18. Photonic chip based optical frequency comb using soliton induced Cherenkov radiation

    CERN Document Server

    Brasch, Victor; Geiselmann, Michael; Lihachev, Grigoriy; Pfeiffer, Martin H P; Gorodetsky, Michael L; Kippenberg, Tobias J

    2014-01-01

    By continuous wave pumping of a dispersion engineered, planar silicon nitride microresonator, continuously circulating, sub-30fs short temporal dissipative solitons are generated, that correspond to pulses of 6 optical cycles and constitute a coherent optical frequency comb in the spectral domain. Emission of soliton induced Cherenkov radiation caused by higher order dispersion broadens the spectral bandwidth to 2/3 of an octave, sufficient for self referencing, in excellent agreement with recent theoretical predictions and the broadest coherent microresonator frequency comb generated to date. The ability to preserve coherence over a broad spectral bandwidth using soliton induced Cherenkov radiation marks a critical milestone in the development of planar optical frequency combs, enabling on one hand application in e.g. coherent communications, broadband dual comb spectroscopy and Raman spectral imaging, while on the other hand significantly relaxing dispersion requirements for broadband microresonator frequen...

  19. Photonic generation of linearly chirped millimeter wave based on comb-spacing tunable optical frequency comb

    Science.gov (United States)

    Xia, Zongyang; Xie, Weilin; Sun, Dongning; Shi, Hongxiao; Dong, Yi; Hu, Weisheng

    2013-12-01

    We demonstrated a photonic approach to generate a phase-continuous frequency-linear-chirped millimeter-wave (mm-wave) signal with high linearity based on continuous-wave phase modulated optical frequency comb and cascaded interleavers. Through linearly sweeping the frequency of the radio frequency (RF) driving signal, high-order frequency-linear-chirped optical comb lines are generated and then extracted by the cascaded interleavers. By beating the filtered high-order comb lines, center frequency and chirp range multiplied linear-chirp microwave signals are generated. Frequency doubled and quadrupled linear-chirp mm-wave signals of range 48.6 to 52.6 GHz and 97.2 to 105.2 GHz at chirp rates of 133.33 and 266.67 GHz/s are demonstrated with the ±1st and ±2nd optical comb lines, respectively, while the RF driving signal is of chirp range 24.3 to 26.3 GHz and chirp time 30 ms.

  20. Optical fiber strain sensor using fiber resonator based on frequency comb Vernier spectroscopy

    DEFF Research Database (Denmark)

    Zhang, Liang; Lu, Ping; Chen, Li;

    2012-01-01

    A novel (to our best knowledge) optical fiber strain sensor using a fiber ring resonator based on frequency comb Vernier spectroscopy is proposed and demonstrated. A passively mode-locked optical fiber laser is employed to generate a phased-locked frequency comb. Strain applied to the optical fiber...... of the fiber ring resonator can be measured with the transmission spectrum. A good linearity is obtained between displacement and the inverse of wavelength spacing with an R2 of 0.9989, and high sensitivities better than 40  pm/με within the range of 0 to 10  με are achieved. The sensitivity can...... be proportionally improved by increasing the length of the optical fiber ring resonator....

  1. WDM-CAP-PON integration with VLLC system based on optical frequency comb

    Science.gov (United States)

    He, Jing; Dong, Huan; Deng, Rui; Shi, Jin; Chen, Lin

    2016-09-01

    In this paper, a wavelength division multiplexing carrier-less amplitude phase modulation passive optical network (WDM-CAP-PON) integration with visible laser light communication (VLLC) system is proposed and experimentally demonstrated. To reduce the cost of WDM system, the optical frequency comb scheme using one Mach-Zehnder modulator (MZM) is utilized and five flat optical combs can be generated. Meanwhile, a blue laser diode (LD) as a VLLC optical source can provide high data rate and long transmission distance. Utilizing overlap frequency domain equalization (OFDE) and negative chirp of MZM, the system performance in both Q-factor and receiver sensitivity can be improved. After 20 km standard single mode fiber (SSMF) and 4.5 m free space transmission, the experimental results show that 10 Gb/s CAP signal can be achieved under 7% forward error correction (FEC) limit of 3 . 8 × 10-3.

  2. Comment on "Orientation dependence of the optical spectra in graphene at high frequencies"

    Science.gov (United States)

    Nguyen, Huy-Viet; Nguyen, V. Hung

    2016-09-01

    Zhang et al. [Phys. Rev. B 77, 241402(R) (2008), 10.1103/PhysRevB.77.241402] reported a theoretical study of the optical spectra of monolayer graphene employing the Kubo formula within a tight-binding model. Their calculations predicted that at high frequencies the optical conductivity of graphene becomes strongly anisotropic. In particular, at frequencies comparable to the energy separation of the upper and lower bands at the Γ point, the optical conductivity is strongly suppressed if the field polarization is along the zigzag direction whereas it is significantly high for the armchair one. We find that, unfortunately, this result is just a consequence of the incorrect determination of the current operator in k space. Here, we present a standard scheme to obtain this operator correctly. As a result, we show that the optical conductivity of monolayer graphene is indeed isotropic, which is consistent with the results of other (both theoretical and experimental) studies in the literature.

  3. Advances in optically pumped semiconductor lasers for blue emission under frequency doubling

    Science.gov (United States)

    Bai, Yanbo; Wisdom, Jeffrey; Charles, John; Hyland, Patrick; Scholz, Christian; Xu, Zuntu; Lin, Yong; Weiss, Eli; Chilla, Juan; Lepert, Arnaud

    2016-03-01

    Optically pumped semiconductor lasers (OPSL) offer the advantage of excellent beam quality, wavelength agility, and high power scaling capability. In this talk we will present our recent progress of high-power, 920nm OPSLs frequency doubled to 460nm for lightshow applications. Fundamental challenges and mitigations are revealed through electrical, optical, thermal, and mechanical modeling. Results also include beam quality enhancement in addressing the competition from diode lasers.

  4. Influence of Feedback Levels on Polarized Optical Feedback Characteristics in Zeeman-Birefringence Dual Frequency Lasers

    Institute of Scientific and Technical Information of China (English)

    MAO Wei; ZHANG Shu-Lian; ZHOU Lu-Fei; LIU Xiao-Yan; WANG Ming-Ming

    2007-01-01

    The influence of Feedback levels on the intensity and polarization properties of polarized optical feedback in a Zeeman-birefringence dual frequency laser is systematically investigated. By changing the feedback power ratio, different feedback levels are obtained. Three distinct regimes of polarized optical feedback effects are found and defined as regimes Ⅰ, Ⅱand Ⅲ. The feedback level boundaries among the regimes are acquired experimentally. The theoretical analysis is presented to be in good agreement with the experimental results.

  5. High-Speed Microscale Optical Tracking Using Digital Frequency-Domain Multiplexing

    OpenAIRE

    MacLachlan, Robert A.; Riviere, Cameron N.

    2009-01-01

    Position-sensitive detectors (PSDs), or lateral-effect photodiodes, are commonly used for high-speed, high-resolution optical position measurement. This paper describes the instrument design for multidimensional position and orientation measurement based on the simultaneous position measurement of multiple modulated sources using frequency-domain-multiplexed (FDM) PSDs. The important advantages of this optical configuration in comparison with laser/mirror combinations are that it has a large ...

  6. Optically pumped terahertz lasers with high pulse repetition frequency: theory and design

    Institute of Scientific and Technical Information of China (English)

    Yude Sun; Shiyou Fu; Jing Wang; Zhenghe Sun; Yanchao Zhang; Zhaoshuo Tian; Qi Wang

    2009-01-01

    Optically pumped terahertz (THz) lasers with high pulse repetition frequency are designed. Such a laser includes two parts: the optically pumping laser and the THz laser. The structures of the laser are described and analyzed. The rate equations for the pulsed THz laser are given. The kinetic process and laser pulse waveform for this kind of laser are numerically calculated based on the theory of rate equations. The theoretical results give a helpful guide to the research of such lasers.

  7. The optical frequency method of distance measurement with sub-nanometer resolution

    Science.gov (United States)

    Cip, Ondrej; Petru, Frantisek; Lazar, Josef

    2005-02-01

    We present design and experimental setup for direct transformation of the relative change of distances in measuring arm of the Michelson interferometer to relative changes of the resonant optical-frequency of Fabry-Perot (F.-P.) resonator. The method consists of a mechanical coupled moving system of the corner cube mirror of the interferometer measuring arm with one of the mirrors of F.-P. resonator. A piezoelectric transducer (PZT) with elongation 10 microns approximately drives that moving system. An external tunable laser source at 633 nm wavelength provides identification of one of the resonant optical frequency of F.-P. resonator by the frequency locking mechanism with synchronous detection technique in the servo loop feedback. Because the definition of the meter unit is based on iodine stabilized He-Ne laser, then the optical frequency of the locked tunable laser is frequency compared with He-Ne-I2 laser by the heterodyne optical mixing. A fast high-resolution counter counts the resultant radio-frequency signal as a product of the optical mixing. Measured frequency values and values of interference phase acquired by the interferometer are simultaneously sampled step by step for each elongation position of PZT element. We used that experimental setup for the testing process where a verification of scale-linearity of Michelson interferometer with total resolution 0,3 nm is investigated. The experimental data achieved by F.-P. resonator during such a way shows the absolute uncertainty better than 0,08 nm for the relative distance change 1.5 microns. We verified the scale-linearity of Michelson interferometer to +/-1,0 nm limit.

  8. Optical frequency comb generation from aluminum nitride micro-ring resonator

    CERN Document Server

    Jung, Hojoong; Fong, King Y; Zhang, Xufeng; Tang, Hong X

    2013-01-01

    Aluminum nitride is an appealing nonlinear optical material for on-chip wavelength conversion. Here we report optical frequency comb generation from high quality factor aluminum nitride micro-ring resonators integrated on silicon substrates. By engineering the waveguide structure to achieve near-zero dispersion at telecommunication wavelengths and optimizing the phase matching for four-wave mixing, frequency combs are generated with a single wavelength continuous-wave pump laser. The Kerr coefficient (n2) of aluminum nitride is further extracted from our experimental results.

  9. Instability Parameters of Optical Oscillation Frequency in Plasma Central Discharge and Periphery Region

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhu-Wen; M.A.LIEBERMAN; Sungjin KIM

    2006-01-01

    @@ We have observed relaxation oscillations in a capacitive discharge in Ar gas, connected to a peripheral ground chamber. The plasma oscillations observed from time-varying optical emission from the main discharge chamber show, for example, a high frequency (75.37kHz) relaxation oscillation, at 100mTorr and 8 W absorbed power,and a low frequency (2.72 Hz) relaxation oscillation, 100mTorr and 325 W absorbed power. Time-varying optical emission intensity and plasma density are also detected with a Langmuir probe. The theoretical result agrees well with experiments.

  10. Multifrequency Magneto-optic Bragg Diffraction and Radio Frequency Signal Parallel Processing

    Institute of Scientific and Technical Information of China (English)

    SHANG Dan; WU Bao-jian; QIU Kun

    2008-01-01

    Magneto-optic(MO) coupling of guided optical waves with microwave magnetostatic waves(MSWs) simultaneously excited by multiple radio frequency(RF) signals can lead to multifrequency diffraction effects and then parallel processing of RF signals can be realized by using of the characteristics that diffraction efficiencies(Des) are approximately in direct proportion to RF signals intensities and diffraction angles are related to frequencies of the corresponding RF signals within linear MO interaction region. In this paper, studied is the multifrequency MO Bragg diffraction in first-order MO interaction approximation, and obtained was the approximate analytical expression for principle diffraction efficiency(PDE). Also, put forward was a parallel imaging method of relative intensity of RF signals based on single-frequency diffraction. By calculation and analysis, it is shown that the relative error is not more than 0.3 dB for the case of three RF signals within the frequency space of 60 MHz.

  11. Generation of tunable few optical-cycle pulses by visible-to-infrared frequency conversion

    Science.gov (United States)

    Darginavičius, J.; Tamošauskas, G.; Piskarskas, A.; Valiulis, G.; Dubietis, A.

    2012-07-01

    We demonstrate a simple method for infrared few optical-cycle pulse generation, which is based on collinear visible-to-infrared frequency conversion and involves difference-frequency generation and subsequent two-step optical parametric amplification. The numerical simulations and experiments using BBO crystals show an efficient frequency down conversion of visible ˜20 fs pulses from a commercial blue-pumped noncollinear optical parametric amplifier yielding 1.2-2.4 μm tunable sub-100 μJ pulses with duration of 3 to 5 optical-cycles. The proposed method could be readily extended to generate few optical-cycle pulses in the mid-infrared spectral range (up to 5.5 μm) using, e.g., LiIO3 and LiNbO3 crystals, as demonstrated by the numerical simulations. In these crystals, even shorter, two-optical-cycle mid-infrared pulses could be obtained at particular wavelengths where group velocity matching between the signal and idler waves is achieved.

  12. Radio frequency and microwave plasma for optical thin film deposition

    International Nuclear Information System (INIS)

    For the next generation of fusion lasers reflecting mirrors with laser damage thresholds of at least 40 J/cm2 for 10 ns laser pulses at 1.064 μm are needed. Up to now, no deposition technique has been developed to produce such mirrors. Best R ampersand D-values realized today are around 30 J/cm2 for e-beam evaporated mirrors. R ampersand D on conventional e-beam coating processes over the last 10 years has come up with marginal improvements in laser damage thresholds only. However, new technologies, like PICVD developed for the fabrication of ultra-low loss fiber preforms, seem to offer the potential to solve this problem. It is well known that fused silica produced by CVD processes can have laser damage thresholds as high as 80 J/cm2. However, the thickness of a single deposited film is in the μm-range for most of the CVD processes used for preform manufacturing; since interference optics need films in theλ/4n range the use of preform-fabrication processes for the purpose of interference mirror fabrication is limited to a few plasma based CVD technologies, namely PCVD. Especially PICVD is a very powerful technology to fabricate thin film multilayers for interference mirrors, because this technique is able to produce films down to monolayer thickness with nearly perfect stoichiometry and morphology. In first and preliminary experiments the usual deposition in a circular tube at high temperatures has been used for simplicity. However, to produce large area high quality laser mirrors this principle know-how has to be transferred from circular to planar geometry. Experiments showed, that there may be some limitations with respect to the homogeneity of a planar deposition using microwave excitation for the plasma. Therefore experiments have been performed in parallel with both RF and microwave excitation for comparison. In the following we will restrict ourselves to the description and discussions of the planar processes

  13. High-resolution absolute frequency referenced fiber optic sensor for quasi-static strain sensing

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Timothy T.-Y.; Chow, Jong H.; Shaddock, Daniel A.; Littler, Ian C. M.; Gagliardi, Gianluca; Gray, Malcolm B.; McClelland, David E.

    2010-07-20

    We present a quasi-static fiber optic strain sensing system capable of resolving signals below nanostrain from 20 mHz. A telecom-grade distributed feedback CW diode laser is locked to a fiber Fabry-Perot sensor, transferring the detected signals onto the laser. An H{sup 13}C{sup 14}N absorption line is then used as a frequency reference to extract accurate low-frequency strain signals from the locked system.

  14. Waveguide-type optical passive ring resonator gyro using frequency modulation spectroscopy technique

    Science.gov (United States)

    Liang, Ning; Lijun, Guo; Mei, Kong; Tuoyuan, Chen

    2014-12-01

    This paper reports the experimental results of silica on a silicon ring resonator in a resonator micro optic gyroscope based on the frequency modulation spectroscopy technique by our research group. The ring resonator is composed of a 4 cm diameter silica waveguide. By testing at λ = 1550 nm, the FSR, FWHM and the depth of resonance are 3122 MHz, 103.07 MHz and 0.8 respectively. By using a polarization controller, the resonance curve under the TM mode can be inhibited. The depth of resonance increased from 0.8 to 0.8913, namely the finesse increase from 30.33 to 33.05. In the experiments, there is an acoustic-optical frequency shifter (AOFS) in each light loop. We lock the lasing frequency at the resonance frequency of the silica waveguide ring resonator for the counterclockwise lightwave; the frequency difference between the driving frequencies of the two AOFS is equivalent to the Sagnac frequency difference caused by gyro rotation. Thus, the gyro output is observed. The slope of the linear fit is about 0.330 mV/(°/s) based on the -900 to 900 kHz equivalent frequency and the gyro dynamic range is ±2.0 × 103 rad/s.

  15. Frequency doubled telecom fiber laser for a cold atom interferometer using optical lattices

    CERN Document Server

    Theron, Fabien; Dieu, Emily; Zahzam, Nassim; Cadoret, Malo; Zahzam, Nassim; Bresson, Alexandre

    2016-01-01

    A compact and robust laser system, based on a frequency-doubled telecom laser, providing all the lasers needed for a rubidium cold atom interferometer using optical lattices is presented. Thanks to an optical switch at 1.5 \\mu m and a dual-wavelength second harmonic generation system, only one laser amplifier is needed for all the laser system. Our system delivers at 780 nm a power of 900 mW with a detuning of 110 GHz for the optical lattice and a power of 650 mW with an adjustable detuning between 0 and -1 GHz for the laser cooling, the detection and the Raman transitions.

  16. Frequency comparison of ${}^{171}$Yb${}^+$ ion optical clocks at PTB and NPL via GPS PPP

    CERN Document Server

    Leute, J; Lipphardt, B; Tamm, Chr; Nisbet-Jones, P B R; King, S A; Godun, R M; Jones, J M; Margolis, H S; Whibberley, P B; Wallin, A; Merimaa, M; Gill, P; Peik, E

    2015-01-01

    We used Precise Point Positioning, a well-established GPS carrier-phase frequency transfer method to perform a direct remote comparison of two optical frequency standards based on single laser-cooled $^{171}$Yb$^+$ ions operated at NPL, UK and PTB, Germany. At both institutes an active hydrogen maser serves as a flywheel oscillator; it is connected to a GPS receiver as an external frequency reference and compared simultaneously to a realization of the unperturbed frequency of the ${{}^2S_{1/2}(F=0)-{}^2D_{3/2}(F=2)}$ electric quadrupole transition in ${}^{171}$Yb${}^+$ via an optical femtosecond frequency comb. To profit from long coherent GPS link measurements we extrapolate over the various data gaps in the optical clock to maser comparisons which introduces maser noise to the frequency comparison but improves the uncertainty from the GPS link. We determined the total statistical uncertainty consisting of the GPS link uncertainty and the extrapolation uncertainties for several extrapolation schemes. Using t...

  17. Two-Way Optical Frequency Comparisons Over 100km Telecommunication Network Fibers

    CERN Document Server

    Bercy, Anthony; Lopez, Olivier; Chardonnet, Christian; Pottie, Paul-Eric; Amy-Klein, Anne

    2014-01-01

    By using two-way frequency transfer, we demonstrate ultra-high resolution comparison of optical frequencies over a telecommunication fiber link of 100 km operating simultaneously digital data transfer. We first propose and experiment a bi-directional scheme using a single fiber. We show that the relative stability at 1 s integration time is 7 10^18 and scales down to 5 10^21. The same level of performance is reached when an optical link is implemented with an active compensation of the fiber noise. We also implement a real-time two-way frequency comparison over a uni-directional telecommunication network using a pair of parallel fibers. The relative frequency stability is 10^15 at 1 s integration time and reaches 2 10^17 at 40 000 s. The fractional uncertainty of the frequency comparisons was evaluated for the best case to 2 10^20. These results open the way to accurate and high resolution frequency comparison of optical clocks over intercontinental fiber networks.

  18. Radio frequency controlled synthetic wavelength sweep for absolute distance measurement by optical interferometry

    International Nuclear Information System (INIS)

    We present a new technique applied to the variable optical synthetic wavelength generation in optical interferometry. It consists of a chain of optical injection locking among three lasers: first a distributed-feedback laser is used as a master to injection lock an intensity-modulated laser that is directly modulated around 15 GHz by a radio frequency generator on a sideband. A second distributed-feedback laser is injection locked on another sideband of the intensity-modulated laser. The variable synthetic wavelength for absolute distance measurement is simply generated by sweeping the radio frequency over a range of several hundred megahertz, which corresponds to the locking range of the two slave lasers. In this condition, the uncertainty of the variable synthetic wavelength is equivalent to the radio frequency uncertainty. This latter has a relative accuracy of 10-7 or better, resulting in a resolution of ±25 μm for distances exceeding tens of meters. The radio frequency generator produces a linear frequency sweep of 1 ms duration (i.e., exactly equal to one absolute distance measurement acquisition time), with frequency steps of about 1 MHz. Finally, results of absolute distance measurements for ranges up to 10 m are presented

  19. Radio frequency controlled synthetic wavelength sweep for absolute distance measurement by optical interferometry.

    Science.gov (United States)

    Le Floch, Sébastien; Salvadé, Yves; Mitouassiwou, Rostand; Favre, Patrick

    2008-06-01

    We present a new technique applied to the variable optical synthetic wavelength generation in optical interferometry. It consists of a chain of optical injection locking among three lasers: first a distributed-feedback laser is used as a master to injection lock an intensity-modulated laser that is directly modulated around 15 GHz by a radio frequency generator on a sideband. A second distributed-feedback laser is injection locked on another sideband of the intensity-modulated laser. The variable synthetic wavelength for absolute distance measurement is simply generated by sweeping the radio frequency over a range of several hundred megahertz, which corresponds to the locking range of the two slave lasers. In this condition, the uncertainty of the variable synthetic wavelength is equivalent to the radio frequency uncertainty. This latter has a relative accuracy of 10(-7) or better, resulting in a resolution of +/-25 microm for distances exceeding tens of meters. The radio frequency generator produces a linear frequency sweep of 1 ms duration (i.e., exactly equal to one absolute distance measurement acquisition time), with frequency steps of about 1 MHz. Finally, results of absolute distance measurements for ranges up to 10 m are presented. PMID:18516123

  20. Multi-band local microwave signal generation based on an optical frequency comb generator

    Science.gov (United States)

    Wang, Wen Ting; Liu, Jian Guo; Sun, Wen Hui; Chen, Wei; Zhu, Ning Hua

    2015-03-01

    We propose and experimental demonstrate a new method to generate multi-band local microwave signals based on an optical frequency comb generator (OFCG) by applying an optical sideband injection locking technique and an optical heterodyning technique. The generated microwave signal can cover multi bands from S band to Ka band. A tunable multiband microwave signal spanning from 5 GHz to 40 GHz can be generated by the beating between the optical carrier and injection locked modulation sidebands in a photodetector without an optical filter. The wavelength of the slave laser can be continuously and near-linearly adjusted by proper changing its bias current. By tuning the bias current of the slave laser, the wavelength of that is matched to one of the modulation sidebands of the OFCG. The performance of the arrangement in terms of the tunability and stability of the generated microwave signal is also studied.

  1. Multiple source frequency-modulated continuous-wave optical reflectometry: theory and experiment.

    Science.gov (United States)

    Vasilyev, Arseny; Satyan, Naresh; Xu, Shengbo; Rakuljic, George; Yariv, Amnon

    2010-04-01

    We propose and demonstrate a novel approach to increase the effective bandwidth of a frequency-modulated continuous-wave (FMCW) ranging system. This is achieved by algorithmically stitching together the swept spectra of separate laser sources. The result is an improvement in the range resolution proportional to the increase in the swept-frequency range. An analysis of this system as well as the outline of the stitching algorithm are presented. Using three distinct swept-frequency optical waveforms, we experimentally demonstrate a threefold improvement in the range resolution of a three-sweep approach over the conventional FMCW method. PMID:20357879

  2. Kilohertz-resolution spectroscopy of cold atoms with an optical frequency comb

    CERN Document Server

    Fortier, T M; Stalnaker, J E; Ortega, D; Diddams, S A; Oates, C W; Hollberg, L

    2006-01-01

    We have performed sub-Doppler spectroscopy on the narrow intercombination line of cold calcium atoms using the amplified output of a femtosecond laser frequency comb. Injection locking of a 657-nm diode laser with a femtosecond comb allows for two regimes of amplification, one in which many lines of the comb are amplified, and one where a single line is predominantly amplified. The output of the laser in both regimes was used to perform kilohertz-level spectroscopy. This experiment demonstrates the potential for high-resolution absolute-frequency spectroscopy over the entire spectrum of the frequency comb output using a single high-finesse optical reference cavity.

  3. Kilohertz-resolution spectroscopy of cold atoms with an optical frequency comb.

    Science.gov (United States)

    Fortier, T M; Coq, Y Le; Stalnaker, J E; Ortega, D; Diddams, S A; Oates, C W; Hollberg, L

    2006-10-20

    We have performed sub-Doppler spectroscopy on the narrow intercombination line of cold calcium atoms using the amplified output of a femtosecond laser frequency comb. Injection locking of a 657-nm diode laser with a femtosecond comb allows for two regimes of amplification, one in which many lines of the comb are amplified, and one where a single line is predominantly amplified. The output of the laser in both regimes was used to perform kilohertz-level spectroscopy. This experiment demonstrates the potential for high-resolution absolute-frequency spectroscopy over the entire spectrum of the frequency comb output using a single high-finesse optical reference cavity. PMID:17155398

  4. Generation of Optical Millimeter Wave Using Two Cascaded Polarization Modulators Based on Frequency Octupling Without Filtering

    Science.gov (United States)

    Yang, Yang; Ma, Jianxin; Zhang, Ruijiao; Xin, Xiangjun; Zhang, Junyi

    2015-11-01

    An approach to generate an optical millimeter wave is introduced with frequency octupling using two cascaded polarization modulators followed by polarizers, respectively. By adjusting the modulation indexes of polarization modulators, only the ±4th-order sidebands are generated with a pure spectrum. Since no filter is needed, the proposed technique can be used to generate a frequency-tunable millimeter wave with a large frequency-tunable range. To prove the feasibility of the proposed approach, a simulation is conducted to generate an 80-GHz millimeter wave, and then its transmission performance is checked.

  5. Gated frequency-resolved optical imaging with an optical parametric amplifier for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, S.M.; Bliss, D.E.

    1997-02-01

    Implementation of optical imagery in a diffuse inhomogeneous medium such as biological tissue requires an understanding of photon migration and multiple scattering processes which act to randomize pathlength and degrade image quality. The nature of transmitted light from soft tissue ranges from the quasi-coherent properties of the minimally scattered component to the random incoherent light of the diffuse component. Recent experimental approaches have emphasized dynamic path-sensitive imaging measurements with either ultrashort laser pulses (ballistic photons) or amplitude modulated laser light launched into tissue (photon density waves) to increase image resolution and transmissive penetration depth. Ballistic imaging seeks to compensate for these {open_quotes}fog-like{close_quotes} effects by temporally isolating the weak early-arriving image-bearing component from the diffusely scattered background using a subpicosecond optical gate superimposed on the transmitted photon time-of-flight distribution. The authors have developed a broadly wavelength tunable (470 nm -2.4 {mu}m), ultrashort amplifying optical gate for transillumination spectral imaging based on optical parametric amplification in a nonlinear crystal. The time-gated image amplification process exhibits low noise and high sensitivity, with gains greater than 104 achievable for low light levels. We report preliminary benchmark experiments in which this system was used to reconstruct, spectrally upcovert, and enhance near-infrared two-dimensional images with feature sizes of 65 {mu}m/mm{sup 2} in background optical attenuations exceeding 10{sup 12}. Phase images of test objects exhibiting both absorptive contrast and diffuse scatter were acquired using a self-referencing Shack-Hartmann wavefront sensor in combination with short-pulse quasi-ballistic gating. The sensor employed a lenslet array based on binary optics technology and was sensitive to optical path distortions approaching {lambda}/100.

  6. Centralized optical-frequency-comb-based RF carrier generator for DWDM fiber-wireless access systems

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Beltran, Marta; Sanchez, Jose;

    2014-01-01

    In this paper, we report on a gigabit capacity fiber-wireless system that enables smooth integration between high-speed wireless networks and dense wavelength-division-multiplexing (DWDM) access networks. By employing a centralized optical frequency comb, both the wireline and the wireless services...

  7. Return-map for low-frequency fluctuations in semiconductor lasers with optical feedback

    DEFF Research Database (Denmark)

    Mørk, Jesper; Sabbatier, H.; Sørensen, Mads Peter;

    1999-01-01

    We show that the phenomenon of low-frequency fluctuations (LFF) , commonly observed in semiconductor lasers with optical feedback, can be explained by a simple return-map, implying a tremendous simplification in the description of the slow time-scale dynamics of the system. Experimentally observed...

  8. Velocity Distribution of Effective Atoms in a Small Optically Pumped Cesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; WANG Fengzhi; YANG Donghai; WANG YiQiu

    2001-01-01

    In this paper, the velocity distribution of effective atoms in a small optically pumped cesium beam frequency standard has been achieved from the Fourier transforms of the experimentally recorded Ramsey patterns. The result fits well with the theoretical calculation. The second order Doppler shift correction of the small cesium atomic clock is obtained from the velocity distribution of effective atoms.

  9. Optimization of Ta2O5 optical thin film deposited by radio frequency magnetron sputtering.

    Science.gov (United States)

    Shakoury, R; Willey, Ronald R

    2016-07-10

    Radio frequency magnetron sputtering has been used here to find the parameters at which to deposit Ta2O5 optical thin films with negligible absorption in the visible spectrum. The design of experiment methodology was employed to minimize the number of experiments needed to find the optimal results. Two independent approaches were used to determine the index of refraction n and k values.

  10. Bistability and low-frequency fluctuations in semiconductor lasers with optical feedback: a theoretical analysis

    DEFF Research Database (Denmark)

    Mørk, Jesper; Tromborg, Bjarne; Christiansen, Peter Leth

    1988-01-01

    Near-threshold operation of a semiconductor laser exposed to moderate optical feedback may lead to low-frequency fluctuations. In the same region, a kink is observed in the light-current characteristic. Here it is demonstrated that these nonlinear phenomena are predicted by a noise driven multimo...

  11. Laser Frequency Stabilization and Control through Offset Sideband Locking to Optical Cavities

    Science.gov (United States)

    Thorpe, James I.; Livas, J.; Numata, K.

    2008-01-01

    We describe a class of techniques whereby a laser frequency can be stabilized to a fixed optical cavity resonance with an adjustable offset, providing a wide tuning range for the central frequency. These techniques require only minor modifications to the standard Pound-Drever-Hall locking techniques and have the advantage of not altering the intrinsic stability of the frequency reference. In a laboratory investigation the sideband techniques were found to perform equally well as the standard, non-tunable Pound-Drever-Hall technique, each providing more than four decades of frequency noise suppression over the free-running noise. An application of a tunable system as a pre-stabilization stage in a phase-lock loop is also presented with the combined system achieving a frequency noise suppression of nearly twelve orders of magnitude.

  12. Enhanced hybrid asymmetrically clipped orthogonal frequency division multiplexing for optical wireless communications

    Science.gov (United States)

    Guan, Rui; Huang, Nuo; Wang, Jin-Yuan; Wang, Houyu; Chen, Ming

    2016-05-01

    This paper presents an enhanced hybrid asymmetrically clipped optical orthogonal frequency division multiplexing (EHACO-OFDM) scheme, which benefits from the simultaneous transmission of ACO-OFDM, pulse-amplitude-modulated discrete multitone modulation, and direct-current-biased optical orthogonal frequency division multiplexing (DCO-OFDM). Since the entire available bandwidth is utilized for data modulation, this scheme can achieve higher spectral efficiency than HACO-OFDM and ACO-OFDM. Moreover, as a smaller DC bias is introduced in our scheme, it is more power efficient than asymmetrically clipped DC-biased optical OFDM (ADO-OFDM) and DCO-OFDM. A modified receiver is also designed for this system, taking advantage of an iterative algorithm and a pairwise averaging. It has been shown by simulation that our three-path simultaneous transmission scheme can surpass the existing mixed OFDM-based schemes at high data rates. In addition, compared with the noniterative receiver, the modified receiver exhibits significant gains.

  13. Method for determiantion of the frequency-contrast characteristics of electronic-optic systems

    Science.gov (United States)

    Mardirossian, Garo; Zhekov, Zhivko

    The frequency-contrast characteristics is an important criterion to judge the quality of electronic-optic systems, which boast an increasing application in space research, astronomy, martial art etc. The paper provides a brief description of the methods for determining the frequency-contrast characteristics of optic systems, developed at the Space Research Institute of the Bulgarian Academy of Science. The suggested methods have been used to develop a couple of electronic-optic systems participated in the designed ground-based and aerospace scientific-research equipment. Based on the obtained practical results, the conclusion was made that the methods provide to obtain sufficiently precise data, which coincide well with the results, obtained when using other methods.

  14. A photo-driven dual-frequency addressable optical device of banana-shaped molecules

    Energy Technology Data Exchange (ETDEWEB)

    Krishna Prasad, S., E-mail: skpras@gmail.com; Lakshmi Madhuri, P.; Hiremath, Uma S.; Yelamaggad, C. V. [Centre for Soft Matter Research, Jalahalli, Bangalore 560 013 (India)

    2014-03-17

    We propose a photonic switch employing a blend of host banana-shaped liquid crystalline molecules and guest photoisomerizable calamitic molecules. The material exhibits a change in the sign of the dielectric anisotropy switching from positive to negative, at a certain crossover frequency of the probing field. The consequent change in electric torque can be used to alter the orientation of the molecules between surface-determined and field-driven optical states resulting in a large change in the optical transmission characteristics. Here, we demonstrate the realization of this feature by an unpolarized UV beam, the first of its kind for banana-shaped molecules. The underlying principle of photoisomerization eliminates the need for a second driving frequency. The device also acts as a reversible conductance switch with an order of magnitude increase of conductivity brought about by light. Possible usage of this for optically driven display devices and image storage applications is suggested.

  15. Optical Heterodyne Investigation of the Microwave Frequency Acoustic Properties of Liquids.

    Science.gov (United States)

    Bonney, Rob

    An optical heterodyne interferometer with a state -of-the-art microwave frequency acoustic transducer was used to measure the acoustic properties of liquids and solutions at frequencies up to 1.5 GHz. Heterodyne detection with a strong optical local oscillator was used to detect a weak optical signal beam produced by Bragg deflection from an acoustic wave coupled into a liquid sample. The acoustic transducer had a frequency range of 0.2-1.5 GHz. Several liquid mixtures were measured for the first time, including aqueous dimethyl sulfoxide, and ethyl acetate in carbon disulphide. In some cases, previously unknown dispersions were characterized. A thermodynamic model (valid in the low frequency limit) involving the heat of mixing was used successfully to predict the variation of velocity with composition of liquid mixtures. With this model as a guide, an attempt was made to identify a liquid mixture which would make a superior medium for the acoustic microscope. The search produced results which supported theoretical predictions, but no superior medium was found. Solutions of biomolecules were also investigated due to interest in possible resonant acoustic modes in DNA. No dispersions or resonances were found in solutions of polyglycines, and results for DNA solutions were inconclusive. Applications of this work include general studies in liquid acoustics at very high frequencies, acoustic studies of DNA solutions, and characterization of media for such technological applications as acoustic microscopy or phase conjugation using stimulated Brillouin scattering.

  16. All-optical central-frequency-programmable and bandwidth-tailorable radar.

    Science.gov (United States)

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-01

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution. PMID:26795596

  17. All-optical central-frequency-programmable and bandwidth-tailorable radar

    Science.gov (United States)

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-01

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution.

  18. Ultralow-phase-noise millimetre-wave signal generator assisted with an electro-optics-modulator-based optical frequency comb

    Science.gov (United States)

    Ishizawa, A.; Nishikawa, T.; Goto, T.; Hitachi, K.; Sogawa, T.; Gotoh, H.

    2016-01-01

    Low-noise millimetre-wave signals are valuable for digital sampling systems, arbitrary waveform generation for ultra-wideband communications, and coherent radar systems. However, the phase noise of widely used conventional signal generators (SGs) will increase as the millimetre-wave frequency increases. Our goal has been to improve commercially available SGs so that they provide a low-phase-noise millimetre-wave signal with assistance from an electro-optics-modulator-based optical frequency comb (EOM-OFC). Here, we show that the phase noise can be greatly reduced by bridging the vast frequency difference between the gigahertz and terahertz ranges with an EOM-OFC. The EOM-OFC serves as a liaison that magnifies the phase noise of the SG. With the EOM-OFC used as a phase noise “booster” for a millimetre-wave signal, the phase noise of widely used SGs can be reduced at an arbitrary frequency f (6 ≦ f ≦ 72 GHz). PMID:27185040

  19. Ultralow-phase-noise millimetre-wave signal generator assisted with an electro-optics-modulator-based optical frequency comb

    Science.gov (United States)

    Ishizawa, A.; Nishikawa, T.; Goto, T.; Hitachi, K.; Sogawa, T.; Gotoh, H.

    2016-05-01

    Low-noise millimetre-wave signals are valuable for digital sampling systems, arbitrary waveform generation for ultra-wideband communications, and coherent radar systems. However, the phase noise of widely used conventional signal generators (SGs) will increase as the millimetre-wave frequency increases. Our goal has been to improve commercially available SGs so that they provide a low-phase-noise millimetre-wave signal with assistance from an electro-optics-modulator-based optical frequency comb (EOM-OFC). Here, we show that the phase noise can be greatly reduced by bridging the vast frequency difference between the gigahertz and terahertz ranges with an EOM-OFC. The EOM-OFC serves as a liaison that magnifies the phase noise of the SG. With the EOM-OFC used as a phase noise “booster” for a millimetre-wave signal, the phase noise of widely used SGs can be reduced at an arbitrary frequency f (6 ≦ f ≦ 72 GHz).

  20. Ultrabroadband phased-array radio frequency (RF) receivers based on optical techniques

    Science.gov (United States)

    Overmiller, Brock M.; Schuetz, Christopher A.; Schneider, Garrett; Murakowski, Janusz; Prather, Dennis W.

    2014-03-01

    Military operations require the ability to locate and identify electronic emissions in the battlefield environment. However, recent developments in radio detection and ranging (RADAR) and communications technology are making it harder to effectively identify such emissions. Phased array systems aid in discriminating emitters in the scene by virtue of their relatively high-gain beam steering and nulling capabilities. For the purpose of locating emitters, we present an approach realize a broadband receiver based on optical processing techniques applied to the response of detectors in conformal antenna arrays. This approach utilizes photonic techniques that enable us to capture, route, and process the incoming signals. Optical modulators convert the incoming signals up to and exceeding 110 GHz with appreciable conversion efficiency and route these signals via fiber optics to a central processing location. This central processor consists of a closed loop phase control system which compensates for phase fluctuations induced on the fibers due to thermal or acoustic vibrations as well as an optical heterodyne approach for signal conversion down to baseband. Our optical heterodyne approach uses injection-locked paired optical sources to perform heterodyne downconversion/frequency identification of the detected emission. Preliminary geolocation and frequency identification testing of electronic emissions has been performed demonstrating the capabilities of our RF receiver.

  1. High-frequency chaotic dynamics enabled by optical phase-conjugation

    Science.gov (United States)

    Mercier, Émeric; Wolfersberger, Delphine; Sciamanna, Marc

    2016-01-01

    Wideband chaos is of interest for applications such as random number generation or encrypted communications, which typically use optical feedback in a semiconductor laser. Here, we show that replacing conventional optical feedback with phase-conjugate feedback improves the chaos bandwidth. In the range of achievable phase-conjugate mirror reflectivities, the bandwidth increase reaches 27% when compared with feedback from a conventional mirror. Experimental measurements of the time-resolved frequency dynamics on nanosecond time-scales show that the bandwidth enhancement is related to the onset of self-pulsing solutions at harmonics of the external-cavity frequency. In the observed regime, the system follows a chaotic itinerancy among these destabilized high-frequency external-cavity modes. The recorded features are unique to phase-conjugate feedback and distinguish it from the long-standing problem of time-delayed feedback dynamics.

  2. Ultra-Narrow Bandwidth Optical Resonators for Integrated Low Frequency Noise Lasers

    Science.gov (United States)

    Spencer, Daryl T.

    The development of narrowband resonators has far reaching applications in integrated optics. As a precise reference of wavelength, filters can be used in sensors, metrology, nonlinear optics, microwave photonics, and laser stabilization. In this work, we develop record high quality factor (Q) Si 3N4 waveguide resonators, and utilize them to stabilize a heterogeneously integrated Si/III V laser. To increase the Q factor of waveguide resonators, particular attention is given to loss mechanisms. Propagation loss of filtering is performed with Si resonant mirrors in the laser cavity. A 30 million Q factor Si3N4 resonator is used with electrical feedback to reduce close in noise and frequency walk off. The laser shows high frequency noise levels of 60x103 Hz2/Hz corresponding to 160 kHz linewidth, and the low frequency noise is suppressed 33 dB to 103 Hz2/Hz with the PDH system.

  3. Continuously tunable wavelength output from an Er-doped fiber femtosecond optical frequency comb with single-point frequency-doubling technique

    Science.gov (United States)

    Liu, H.; Cao, S. Y.; Meng, F.; Lin, B. K.; Fang, Z. J.

    2015-07-01

    Femtosecond optical frequency combs (FOFCs) with wavelengths covering the visible range have potential applications in the absolute frequency measurement of iodine-stabilized lasers and optical clock lasers. In this paper, an Er-FOFC with a tunable wavelength output from 689 to 813 nm based on the single-point frequency-doubling technique is demonstrated. Meanwhile, a beat frequency signal between the Er-FOFC and a tested laser at 729 nm with a signal-to-noise ratio of 30 dB at a resolution bandwidth of 100 kHz is obtained.

  4. Cavity-enhanced second harmonic generation via nonlinear-overlap optimization

    CERN Document Server

    Lin, Zin; Loncar, Marko; Johnson, Steven G; Rodriguez, Alejandro W

    2015-01-01

    We describe an approach based on topology optimization that enables automatic discovery of wavelength-scale photonic structures for achieving high-efficiency second-harmonic generation (SHG). A key distinction from previous formulation and designs that seek to maximize Purcell factors at individual frequencies is that our method not only aims to achieve frequency matching (across an entire octave) and large radiative lifetimes, but also optimizes the equally important nonlinear--coupling figure of merit $\\bar{\\beta}$, involving a complicated spatial overlap-integral between modes. We apply this method to the particular problem of optimizing micropost and grating-slab cavities (one-dimensional multilayered structures) and demonstrate that a variety of material platforms can support modes with the requisite frequencies, large lifetimes $Q \\gtrsim 10^3$, small modal volumes $\\sim (\\lambda/n)^3$, and extremely large $\\bar{\\beta} \\gtrsim 10^{-2}$, orders of magnitude larger than the state of the art.

  5. High frequency electro-optic measurement of strained silicon racetrack resonators

    Science.gov (United States)

    Borghi, Massimo; Mancinelli, Mattia; Merget, Florian; Witzens, Jeremy; Bernard, Martino; Ghulinyan, Mher; Pucker, Georg; Pavesi, Lorenzo

    2016-05-01

    In this paper, we report on time resolved electro-optic measurements in strained silicon resonators. Strain is induced by applying a mechanical deformation to the device. It is demonstrated that the linear electro-optic effect vanishes when the applied voltage modulation varies much faster than the free carrier lifetime, and that this occurs independently on the level of the applied stress. This demonstrates that, at frequencies which lie below the free carrier recombination rate, the electro-optic modulation is caused by plasma carrier dispersion. After normalizing out free carrier effects, it is found an upper limit of (8 +/- 3) pm/V to the value of the strain induced χ(2)eff, zzz tensor component. This is an order of magnitude lower than the previously reported values for static electro-optic measurements.

  6. Imaging system of wavelet optics described by the Gaussian linear frequency-modulated complex wavelet

    Science.gov (United States)

    Tan, Liying; Ma, Jing; Wang, Guangming

    2005-12-01

    The image formation and the point-spread function of an optical system are analyzed by use of the wavelet basis function. The image described by a wavelet is no longer an indivisible whole image. It is, rather, a complex image consisting of many wavelet subimages, which come from the changes of different parameters (scale) a and c, and parameters b and d show the positions of wavelet subimages under different scales. A Gaussian frequency-modulated complex-valued wavelet function is introduced to express the point-spread function of an optical system and used to describe the image formation. The analysis, in allusion to the situation of illumination with a monochromatic plain light wave, shows that using the theory of wavelet optics to describe the image formation of an optical system is feasible.

  7. Bi-directional conversion between microwave and optical frequencies in a piezoelectric optomechanical device

    Science.gov (United States)

    Vainsencher, Amit; Satzinger, K. J.; Peairs, G. A.; Cleland, A. N.

    2016-07-01

    We describe the principles of design, fabrication, and operation of a piezoelectric optomechanical crystal with which we demonstrate bi-directional conversion of energy between microwave and optical frequencies. The optomechanical crystal has an optical mode at 1523 nm co-located with a mechanical breathing mode at 3.8 GHz, with a measured optomechanical coupling strength gom/2π of 115 kHz. The breathing mode is driven and detected by curved interdigitated transducers that couple to a Lamb mode in suspended membranes on either end of the optomechanical crystal, allowing the external piezoelectric modulation of the optical signal as well as the converse, the detection of microwave electrical signals generated by a modulated optical signal. We compare measurements to theory where appropriate.

  8. A broadband cavity-enhanced spectrometer for measuring the extinction of aerosols at blue and near-UV wavelengths

    Science.gov (United States)

    Venables, Dean; Fullam, Donovan; Hoa Le, Phuoc; Chen, Jun; Böge, Olaf; Herrmann, Hartmut

    2016-04-01

    We describe a new broadband cavity-enhanced absorption spectrometer for sensitive extinction measurements of aerosols. The instrument is distinguished by its broad and continuous spectral coverage from the near-UV to blue wavelengths (ca. 320 to 450 nm). The short wavelength region has been little explored compared to visible wavelengths, but is important because (1) brown carbon (BrC) absorbs strongly in this wavelength region, and (2) absorption of near-UV radiation in the atmosphere alters the photolysis rate of the key atmospheric species O3, NO2, and HONO, with implications for air quality and atmospheric oxidation capacity. The instrument performance and the effect of a switchable in-line filter are characterised. Early results using the instrument in the TROPOS atmospheric simulation chamber are presented. These experiments include studies of secondary organic aerosol formation (SOA), and biomass burning experiments of rice and wheat straw, followed by experiments simulating particle aging under daytime and nighttime conditions.

  9. Multi-carrier transmission for hybrid radio frequency with optical wireless communications

    Science.gov (United States)

    Wang, Gang; Chen, Genshe; Shen, Dan; Pham, Khanh; Blasch, Erik; Nguyen, Tien M.

    2015-05-01

    Radio frequency (RF) wireless communication is reaching its capacity to support large data rate transmissions due to hardware constraints (e.g., silicon processes), software strategies (e.g., information theory), and consumer desire for timely large file exchanges (e.g., big data and mobile cloud computing). A high transmission rate performance must keep pace with the generated huge volumes of data for real-time processing. Integrated RF and optical wireless communications (RF/OWC) could be the next generation transmission technology to satisfy both the increased data rate exchange and the communications constraints. However, with the promising benefits of RF/OWC, challenges remain to fully develop hybrid RF with wireless optical communications such as uniform waveform design for information transmission and detection. In this paper, an orthogonal frequency division multiplexing (OFDM) transmission scheme, which widely employed in RF communications, is developed for optical communications. The traditional high peak-to-average power ratio (PAPR) in OFDM is reduced to improve system performance. The proposed multi-carrier waveform is evaluated with a frequency-selective fading channel. The results demonstrate that bit error rate (BER) performance of our proposed optical OFDM transmission technique outperforms the traditional OWC on-off keying (OOK) transmission scheme.

  10. A study of ultra-stable optical clocks, frequency sources and standards for space applications

    International Nuclear Information System (INIS)

    Optical or laser-based communication systems are expected to supplement microwave based systems for satellite-to-satellite and spacecraft-to-satellite communications early in the next millennium. Optical systems can carry far more traffic than microwave and address the need to increase communication bandwidths to meet the demands of commerce and the entertainment industry. There is already significant research and commercial interest in this area (now driven particularly by the multi-media and Internet services delivery sector) and there is a strong need to establish which are the best choices of optical sources to develop for space based optical communications. In addition to communication requirements there are strong arguments for developing ultra-stable optical frequency sources and detectors in space for at least two other purposes. At present the microwave radiation that is used for communications is also used for other purposes, for example navigation or tracking, and 'space science' experiments. With the switch from the microwave to the optical for communications it may well be convenient to switch to the optical for these and other functions. This study has examined the potential stable laser requirements for a range of space applications. An interim report was presented in the form of a conference paper summarising our initial findings (see Appendix 5). This final report gives our conclusions in more detail and recommends areas for further study

  11. Optical two-way time and frequency transfer over free space

    CERN Document Server

    Giorgetta, Fabrizio R; Sinclair, Laura C; Baumann, Esther; Coddington, Ian; Newbury, Nathan R

    2012-01-01

    The transfer of high-quality time-frequency signals between remote locations underpins a broad range of applications including precision navigation and timing, the new field of clock-based geodesy, long-baseline interferometry, coherent radar arrays, tests of general relativity and fundamental constants, and the future redefinition of the second [1-7]. However, present microwave-based time-frequency transfer [8-10] is inadequate for state-of-the-art optical clocks and oscillators [1,11-15] that have femtosecond-level timing jitter and accuracies below 1E-17; as such, commensurate optically-based transfer methods are needed. While fiber-based optical links have proven suitable [16,17], they are limited to comparisons between fixed sites connected by a specialized bidirectional fiber link. With the exception of tests of the fundamental constants, most applications instead require more flexible connections between remote and possibly portable optical clocks and oscillators. Here we demonstrate optical time-frequ...

  12. Frequency ratios of optical lattice clocks at the 17th decimal place

    Science.gov (United States)

    Katori, Hidetoshi

    2016-05-01

    Optical lattice clocks benefit from a low quantum-projection noise by simultaneously interrogating a large number of atoms, which are trapped in an optical lattice tuned to the ``magic wavelength'' to largely cancel out light shift perturbation in the clock transition. About a thousand atoms enable the clocks to achieve 10-18 instability in a few hours of operation, allowing intensive investigation and control of systematic uncertainties. As optical lattice clocks have reached inaccuracies approaching 10-18, it is now the uncertainty of the SI second (~ 10-16) itself that restricts the measurement of the absolute frequencies of such optical clocks. Direct comparisons of optical clocks are, therefore, the only way to investigate and utilize their superb performance beyond the SI second. In this presentation, we report on frequency comparisons of optical lattice clocks with neutral strontium (87 Sr), ytterbium (171 Yb) and mercury (199 Hg) atoms. By referencing cryogenic Sr clocks, we determine frequency ratios, νYb/νSr and νHg/νSr, of a cryogenic Yb clock and a Hg clock with uncertainty at the mid 10-17 level. Such ratios provide an access to search for temporal variation of the fundamental constants. We also present remote comparisons between cryogenic Sr clocks located at RIKEN and the University of Tokyo over a 30-km-long phase-stabilized fiber link. The gravitational red shift Δν /ν0 ~ 1.1× 10-18 Δh cm-1 reads out the height difference of Δh ~ 15 m between the two clocks with uncertainty of 5 cm, which demonstrates a step towards relativistic geodesy. ERATO, JST.

  13. Spatial-Resolution Improvement in Optical Frequency Domain Reflectometry System Based on Tunable Linear Fiber Laser

    Energy Technology Data Exchange (ETDEWEB)

    Li Guoyu; Li Yan [Institute of Information Engineering, Handan College, Handan, 056005 (China); Zhao Peng, E-mail: guoyu_li@yahoo.cn [School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China)

    2011-02-01

    In optical frequency domain reflectometry (OFDR) system, the spatial resolution is obtained by using the total frequency-sweep span of the tunable laser. However, in practice, the spatial resolution is severely limited by nonlinearity in the lightwave-frequency sweep of the tunable laser. A closed-loop PZT modulated DBR linear fiber laser is proposed to improve the spatial resolution of the OFDR system. Experimental results show that the spatial resolution of OFDR system has improved greatly. When the frequency sweep excursion is 66GHz and the fiber under test (FUT) is 7 m, the OFDR system has a spatial resolution of 1.5 m with open-loop PZT modulated laser. But the spatial resolution increases to 35 cm with closed-loop PZT modulated laser.

  14. Research on fiber-optic interferometric hydrophone array using frequency division multiplying technique

    Institute of Scientific and Technical Information of China (English)

    CAO Jianian; LI Xuyou; WANG Zhaoxia; LUO Jicheng; FU Lintai

    2001-01-01

    From the point of view of system design, a configuration of fiber-optic interferometric hydrophone array and its modulation and demodulation approach using frequency division multiplexing technique based on Phase Generated Carrier (PGC) is introduced. And the emphasis on demonstrating the relationship among the number of units N, the detectable signal amplitude D and the detectable frequency ωs through analyzing the frequency spectrum of the output signal of the J × K array and the key factor which restricts N, D, ωo for increasing are presented. The maximum phase shift and the law of its variation according to frequency are specially analyzed. The results induced from some relative theory were verified by experiments.

  15. Improvement spatial resolution of frequency modulated continuous wave laser ranging system by splicing equal optical frequency interval sampled signal

    Science.gov (United States)

    Shi, Guang; Zhang, Fumin; Qu, Xinghua

    2015-02-01

    A dual interferometry FMCW laser ranging system is presented. The auxiliary interferometer for generating the clock pulses at equally spaced optical frequencies is incorporated into the main interferometer to simplify the system configuration and to compensate the tuning linearity of the laser source. The need of widely tunable laser limits the practical application of the FMCW laser ranging for precision industrial measurement. Splicing sampled signal method is proposed to break though the tuning range of the laser source limitation against the special resolution. In the experiments, 50 μm range resolution at 8.7 m is demonstrated, and this resolution is maintained over the entire measuring range. The measuring range depending on the power and coherence length of the source can reach more than 20 m. The system structure is simple, and the requirement on the tuning range of laser source is reduced in this system.

  16. Design of Transparent Anodes for Resonant Cavity Enhanced Light Harvesting in Organic Solar Cells

    KAUST Repository

    Sergeant, Nicholas P.

    2012-01-03

    The use of an ITO-free MoO 3/Ag/MoO 3 anode to control the photon harvesting in PCDTBT:PC 70BM solar cells is proposed. At first sight, the fact that these anodes possess reduced far-field transmission compared to ITO may seem to be a disadvantage. But, despite this, we show that by carefully tuning the resonant optical cavity we can enhance the external quantum efficiency close to the band edge of PCDTBT, resulting in high photocurrent and power conversion efficiency on par with ITO. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. New resonant cavity-enhanced absorber structures for mid-infrared detector application

    OpenAIRE

    Zohar, Moshe; Auslender, Mark; Faraone, Lorenzo; Hava, Shlomo

    2012-01-01

    A new dielectric Fabry-Perot cavity was designed for a resonant enhancing optical absorption by a thin absorber layer embedded into the cavity. In this cavity, the front mirror is a subwavelength grating with $\\sim 100$% retroreflection. For a HgCdTe absorber in a matching cavity of the new type, the design is shown to meet the combined challenges of increasing the absorbing efficiency of the entire device up to $\\sim 100$% and reducing its size and overall complexity, compared to a conventio...

  18. Direct stress optic coefficients for YTZP ceramic and PTFE at GHz frequencies.

    Science.gov (United States)

    Schemmel, Peter; Diederich, Gilles; Moore, Andrew J

    2016-04-18

    We report the first measurement of the direct stress optic coefficient for yttria-partially stabilized zirconia (YTZP) ceramic, using illumination between 260 and 380 GHz with applied stresses up to 27 MPa. YTZP exhibited a linear change in refractive index as a function of stress across the entire applied stress domain. A direct stress optic coefficient was also measured for polytetrafluoroethylene (PTFE). PTFE showed viscoelastic behavior at stress values above 4.5 MPa. These results open the way for quantitative sub-surface stress measurements in structural ceramics and ceramic coating systems at GHz and THz frequencies. PMID:27137250

  19. Second harmonic 423-nm laser generated by BIBO crystal for calcium optical frequency standard

    Institute of Scientific and Technical Information of China (English)

    Zhenhui Chen; Bo Lu; Zhixue Xu; Wei Zhuang; Chuang Yu; Deshui Yu; Kaikai Huang; Xuzong Chen; Jinbiao Chen

    2008-01-01

    Calcium is one prospective element for the modern optical frequency standard.The 423-nm transition line of calcium atoms has been widely used in laser slowing and laser cooling, the precise spectrum measurement, and the magnetic optical trapping (MOT).However, there is no any available commercial diode laser working at this wavelength.We built a 423-nm laser based on extra bow-tie cavity and by using a Brewster cut uncoated BIBO (BiB3O6) crystal, which worked at room temperature, with conversion efficiency of 3.75%, and a potential up to 20%.

  20. Rigorous intensity and phase-shift manipulation in optical frequency conversion

    Science.gov (United States)

    Yang, Bo; Yue, Yang-Yang; Lu, Rong-Er; Hong, Xu-Hao; Zhang, Chao; Qin, Yi-Qiang; Zhu, Yong-Yuan

    2016-06-01

    A simple method is employed to investigate the nonlinear frequency conversion in optical superlattices (OSL) with pump depletion. Four rigorous phase-matching conditions for different purposes are obtained directly from the nonlinear coupled equations, and the resulting OSL domain structures are generally aperiodic rather than periodic. With this method, not only the intensity but also the phase-shift of the harmonic waves can be manipulated at will. The second-harmonic generation of Gaussian beam is further investigated. This work may provide a guidance for the practical applications of designing nonlinear optical devices with high conversion efficiency.

  1. Control of polarization signal distortion by frequency domain phase conjugation in optical fiber systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Optical frequency domain phase conjugation(FDPC) is based on phase conjuga-tion of spectrum of an input signal.It is equivalent to the phase conjugation and the time reversal of the temporal envelope of an input signal.The use of FDPC to con-trol polarization signal distortion in birefringent optical fiber systems is proposed.Evolution of polarization signals in the system using midway FDPC is analyzed theoretically and simulated numerically.It is shown that the distortion of polariza-tion signals can be controlled effectively by FDPC.The impairments due to disper-sion and nonlinear effects can be suppressed simultaneously.

  2. Control of polarization signal distortion by frequency domain phase conjusation in optical fiber systems

    Institute of Scientific and Technical Information of China (English)

    BU Yang; WANG XiangZhao

    2008-01-01

    Optical frequency domain phase conjugation (FDPC) is based on phase conjugation of spectrum of an input signal. It is equivalent to the phase conjugation and the time reversal of the temporal envelope of an input signal. The use of FDPC to con-trol polarization signal distortion in birefringent optical fiber systems is proposed. Evolution of polarization signals in the system using midway FDPC is analyzed theoretically and simulated numerically. It is shown that the distortion of polariza-tion signals can be controlled effectively by FDPC. The impairments due to disper-sion and nonlinear effects can be suppressed simultaneously.

  3. Multi-band radio over fiber system with all-optical halfwave rectification, transmission and frequency down-conversion

    DEFF Research Database (Denmark)

    Prince, Kamau; Tafur Monroy, Idelfonso

    2011-01-01

    We introduce a novel application of all-optical half-wave rectification in the transportation and delivery of multi-frequency radio-over fiber signals. System evaluation was performed of transmission over various optical fiber types and all-optical envelope detection was implemented to achieve...

  4. Optical pulse compression reflectometry based on single-sideband modulator driven by electrical frequency-modulated pulse

    Science.gov (United States)

    Zou, Weiwen; Yu, Lei; Yang, Shuo; Chen, Jianping

    2016-05-01

    We propose a novel scheme to generate a linear frequency-modulated optical pulse with high extinction ratio based on an electrical frequency-modulated pulse and optical single-sideband modulator. This scheme is proved to improve the stability and accuracy of optical pulse compression reflectometry (OPCR). In the experiment, a high spatial resolution of 10 cm and a long measurement range of 10.8 km using a laser source with 2-km coherence length are demonstrated.

  5. A broadband chip-scale optical frequency synthesizer at 2.7 × 10−16 relative uncertainty

    OpenAIRE

    Huang, Shu-Wei; Yang, Jinghui; Yu, Mingbin; McGuyer, Bart H.; Kwong, Dim-Lee; Zelevinsky, Tanya; Wong, Chee Wei

    2016-01-01

    Optical frequency combs—coherent light sources that connect optical frequencies with microwave oscillations—have become the enabling tool for precision spectroscopy, optical clockwork, and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but Kerr nonlinear dynamics in high-Q solid-state microresonators has recently demonstrated promising features as alternative platforms. The advance not only fosters studies of chip-scale ...

  6. Eavesdropping time and frequency: phase noise cancellation along a time-varying path, such as an optical fiber

    CERN Document Server

    Grosche, Gesine

    2013-01-01

    Single-mode optical fiber is a highly efficient connecting medium, used not only for optical telecommunications but also for the dissemination of ultra-stable frequencies or timing signals. In 1994, Ma, Jungner, Ye and Hall described a measurement and control system to deliver the same optical frequency at two places, namely the two ends of a fiber, by eliminating the "fiber-induced phase-noise modulation, which corrupts high-precision frequency-based applications". We present a simple detection and control scheme to deliver the same optical frequency at many places anywhere along a transmission path, or in its vicinity, with a relative instability of 1 part in $10^{19}$. The same idea applies to radio frequency and timing signals. This considerably simplifies future efforts to make precise timing/frequency signals available to many users, as required in some large scale science experiments.

  7. Parallel fiber amplifiers with carrier–envelope drift control for coherent combination of optical frequency combs

    International Nuclear Information System (INIS)

    We demonstrated an active feed-forward method for compensating the relative phase drifts of fiber optical amplifiers. The frequency drifts of relative phase noise were well controlled in a variation range from ± 15 Hz of free-running, to approximately ± 1.5 Hz between the amplifier input and output. Coherent combination of two femtosecond fiber chirped-pulse amplifiers seeded by a Ti:S comb oscillator was achieved, which would benefit frequency comb combination to achieve high accuracy and high power. (paper)

  8. Low-frequency fluctuation in multimode semiconductor laser subject to optical feedback

    Institute of Scientific and Technical Information of China (English)

    Xu Zhang; Huiying Ye; Zhaoxin Song

    2008-01-01

    Dynamics of a semiconductor laser subject to moderate optical feedback operating in the low-frequency fluctuation regime is numerically investigated.Multimode Lang-Kobayashi(LK)equations show that the low-frequency intensity dropout including the total intensity and sub-modes intensity is accompanied by sudden dropout simultaneously,which is in good agreement with experimental observation.The power fluctuation is quite annoying in practical applications,therefore it becomes important to study the mechanism of power fluctuation.It is also shown that many factors,such as spontaneous emission noise and feedback parameter,may influence power fluctuation larger than previously expected.

  9. Characterization of Ultrafast Laser Pulses using a Low-dispersion Frequency Resolved Optical Grating Spectrometer

    Science.gov (United States)

    Whitelock, Hope; Bishop, Michael; Khosravi, Soroush; Obaid, Razib; Berrah, Nora

    2016-05-01

    A low dispersion frequency-resolved optical gating (FROG) spectrometer was designed to characterize ultrashort (recombines the pulses in a birefringent medium. The instrument detects a wavelength-sensitive change in polarization of the weak probe pulse in the presence of the stronger pump pulse inside the birefringent medium. Scanning the time delay between the two pulses and acquiring spectra allows for characterization of the frequency and time content of ultrafast laser pulses, that is needed for interpretation of experimental results obtained from these ultrafast laser systems. Funded by the DoE-BES, Grant No. DE-SC0012376.

  10. High frequency anodising of aluminium–TiO2 surface composites: Anodising behaviour and optical appearance

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Bordo, Kirill; Jensen, Flemming;

    2015-01-01

    High frequency anodising of Al–TiO2 surface composites using pulse reverse pulse technique was investigated with an aim to understand the effect of the anodising parameters on the optical appearance, microstructure, hardness and growth rate of the anodic layer. Friction stir processing was employed......, which measures the total and diffuse reflectance from the surface. The change in optical reflectance spectra from the anodised layer was correlated to the applied anodising parameters and microstructure of the anodic layer as well as the Al–TiO2 substrate. Change in hardness of the anodised layer...... was also measured as a function of various anodising parameters. Anodic film growth, hardness, and total reflectance of the surface were found to be highly dependent on the anodising frequency and the anodic cycle potential. Longer exposure times to the anodising electrolyte at lower growth rates resulted...

  11. Scaling laws of the cavity enhancement for NV centers in diamond

    CERN Document Server

    Kaupp, Hanno; Chang, Huan-Cheng; Reichel, Jakob; Hänsch, Theodor W; Hunger, David

    2013-01-01

    We employ a fiber-based optical microcavity with high Finesse to study the enhancement of fluorescence emission of NV centers in nanodiamonds. Harnessing the full tunability and open access of the resonator, we explicitly demonstrate the scaling laws of the Purcell enhancement by varying both the mode volume and the quality factor over a large range. While changes in the emission lifetime remain small in the regime of a broadband emitter, we observe an ideal Purcell factor of up to 450. Our results show a way for the realization of wavelength-tunable, narrow-band single-photon sources and demonstrate a system that has the potential to reach the strong coupling regime.

  12. Silicon photonic crystal cavity enhanced second-harmonic generation from monolayer WSe2

    CERN Document Server

    Fryett, Taylor K; Zheng, Jiajiu; Liu, Chang-Hua; Xu, Xiaodong; Majumdar, Arka

    2016-01-01

    Nano-resonator integrated with two-dimensional materials (e.g. transition metal dichalcogenides) have recently emerged as a promising nano-optoelectronic platform. Here we demonstrate resonatorenhanced second-harmonic generation (SHG) in tungsten diselenide using a silicon photonic crystal cavity. By pumping the device with the ultrafast laser pulses near the cavity mode at the telecommunication wavelength, we observe a near visible SHG with a narrow linewidth and near unity linear polarization, originated from the coupling of the pump photon to the cavity mode. The observed SHG is enhanced by factor of ~200 compared to a bare monolayer on silicon. Our results imply the efficacy of cavity integrated monolayer materials for nonlinear optics and the potential of building a silicon-compatible second-order nonlinear integrated photonic platform.

  13. Envelope time reversal of optical pulses following frequency conversion with accelerating quasi-phase-matching

    CERN Document Server

    Yachini, Michal; Bahabad, Alon

    2016-01-01

    It is shown theoretically that the use of accelerating spatiotemporal quasi-phase-matching (QPM) modulation patterns in media with parametric optical interactions makes it possible to generate a time-reversed replica of the pump pulse envelope in a frequency converted signal. The conversion is dependent on the group-velocity mismatch between the fundamental and up-converted harmonics, and controlled by the acceleration rate (chirp) of the QPM phase pattern. Analytical results are corroborated by numerical simulations.

  14. NONLINEAR OPTICAL FREQUENCY CONVERTER OF LASER RADIATION ON THE LBO TYPE I CRYSTALS

    OpenAIRE

    N. V. Kondratyuk; D. A. Goman; A. L. Protasenya

    2014-01-01

    Describes nonlinear optical frequency converter of laser radiation based on the two LBO type I crystals allowing to receive pulses of radiation at three wavelengths of 1064 nm, 532 nm and 355 nm with an adjustable pulse energy. For fine adjustment of the output pulse energy used two dual phase plates that change the orientation of the plane of polarization of the two waves in cascade third harmonic generation. Measured the efficiency of the generation of harmonics of the intensity of radiatio...

  15. Selective engineering of cavity resonance for frequency matching in optical parametric processes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xiyuan; Rogers, Steven [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Jiang, Wei C. [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Lin, Qiang, E-mail: qiang.lin@rochester.edu [Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627 (United States)

    2014-10-13

    We propose to selectively engineer a single cavity resonance to achieve frequency matching for optical parametric processes in high-Q microresonators. For this purpose, we demonstrate an approach, selective mode splitting (SMS), to precisely shift a targeted cavity resonance, while leaving other cavity modes intact. We apply SMS to achieve efficient parametric generation via four-wave mixing in high-Q silicon microresonators. The proposed approach is of great potential for broad applications in integrated nonlinear photonics.

  16. Selective observation of starch in a water plant using optical sum frequency microscopy

    OpenAIRE

    Miyauchi, Yoshihiro; Sano, Haruyuki; Mizutani, Goro

    2006-01-01

    The photosynthesis, transfer, and storage of starch are the most important biogenic processes occurring in plants. In order to observe the colorless and transparent starch granules in a plant, a chemical pretreatment such as staining of the starch is currently required, which seriously damages the tissue cells in the plant. In this study, it is demonstrated that non-destructive chemical analysis of starch granules in a plant can be performed by using optical second harmonic and sum frequenc...

  17. Selective engineering of cavity resonance for frequency matching in optical parametric processes

    CERN Document Server

    Lu, Xiyuan; Jiang, Wei C; Lin, Qiang

    2014-01-01

    We propose to selectively engineer a single cavity resonance to achieve frequency matching for optical parametric processes in high-Q microresonators. For this purpose, we demonstrate an approach, selective mode splitting (SMS), to precisely shift a targeted cavity resonance, while leaving other cavity modes intact. We apply SMS to achieve efficient parametric generation via four-wave mixing in high-Q silicon microresonators. The proposed approach is of great potential for broad applications in integrated nonlinear photonics.

  18. Control of the soliton self-frequency shift dynamics using topographic optical fibers.

    Science.gov (United States)

    Bendahmane, A; Vanvincq, O; Mussot, A; Kudlinski, A

    2013-09-01

    We demonstrate that the dynamics of the soliton self-frequency shift can be accurately controlled by using tapered optical fibers with optimized longitudinal profile shape (that we term topographic fibers). The tapering profiles tailored for a targeted soliton spectral trajectory through dispersion and nonlinearity management are determined by an inverse algorithm. This control is demonstrated experimentally with topographic photonic crystal fibers fabricated directly on a drawing tower.

  19. Mathematical models of intraresonant frequency transformations in nonlinear optics and their numerical realization

    Energy Technology Data Exchange (ETDEWEB)

    Dovgii, B.P. [Kiev State Univ. (Ukraine)

    1994-06-05

    A system of m{sub o} + 2m{sub 1}, quasilinear equations of Schroedinger type is studied in a cylindrical region; homogeneous boundary conditions are imposed on the lateral surface of the cylinder. We present mathematical models which describe the intraresonant frequency, transformation (interaction of the waves) in nonlinear optics. An iteration method for their approximation is developed, and questions of its correctness are investigated. 11 refs.

  20. Laser frequency locking with 46 GHz offset using an electro-optic modulator for magneto-optical trapping of francium atoms

    CERN Document Server

    Harada, K; Ezure, S; Kato, K; Hayamizu, T; Kawamura, H; Inoue, T; Arikawa, H; Ishikawa, T; Aoki, T; Uchiyama, A; Sakamoto, K; Ito, S; Itoh, M; Ando, S; Hatakeyama, A; Hatanaka, K; Imai, K; Murakami, T; Nataraj, H S; Shimizu, Y; Sato, T; Wakasa, T; Yoshida, H P; Sakemi, Y

    2016-01-01

    We demonstrated a frequency offset locking between two laser sources using a waveguide-type electro-optic modulator (EOM) with 10th-order sidebands for magneto-optical trapping of Fr atoms. The frequency locking error signal was successfully obtained by performing delayed self-homodyne detection of the beat signal between the repumping frequency and the 10th-order sideband component of the trapping light. Sweeping the trapping-light and repumping-light frequencies with keeping its frequency difference of 46 GHz was confirmed over 1 GHz by monitoring the Doppler absorption profile of I2. This technique enables us to search for a resonance frequency of magneto-optical trapping of Fr.

  1. Astronomical optical frequency comb generation and test in a fiber-fed MUSE spectrograph

    Science.gov (United States)

    Chavez Boggio, J. M.; Fremberg, T.; Moralejo, B.; Rutowska, M.; Hernandez, E.; Zajnulina, M.; Kelz, A.; Bodenmüller, D.; Sandin, C.; Wysmolek, M.; Sayinc, H.; Neumann, J.; Haynes, R.; Roth, M. M.

    2014-07-01

    We here report on recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam and present preliminary test results using the fiber-fed Multi Unit Spectroscopic Explorer (MUSE) spectrograph. The frequency comb is generated by propagating two free-running lasers at 1554.3 and 1558.9 nm through two dispersionoptimized nonlinear fibers. The generated comb is centered at 1590 nm and comprises more than one hundred lines with an optical-signal-to-noise ratio larger than 30 dB. A nonlinear crystal is used to frequency double the whole comb spectrum, which is efficiently converted into the 800 nm spectral band. We evaluate first the wavelength stability using an optical spectrum analyzer with 0.02 nm resolution and wavelength grid of 0.01 nm. After confirming the stability within 0.01 nm, we compare the spectra of the astro-comb and the Ne and Hg calibration lamps: the astro-comb exhibits a much larger number of lines than lamp calibration sources. A series of preliminary tests using a fiber-fed MUSE spectrograph are subsequently carried out with the main goal of assessing the equidistancy of the comb lines. Using a P3d data reduction software we determine the centroid and the width of each comb line (for each of the 400 fibers feeding the spectrograph): equidistancy is confirmed with an absolute accuracy of 0.4 pm.

  2. Dual optical frequency comb architecture with capabilities from visible to mid-infrared.

    Science.gov (United States)

    Jerez, Borja; Martín-Mateos, Pedro; Prior, Estefanía; de Dios, Cristina; Acedo, Pablo

    2016-06-27

    In this paper, a new approach to dual comb generation based on well-known optical techniques (Gain-Switching and Optical Injection Locking) is presented. The architecture can be implemented using virtually every kind of continuous-wave semiconductor laser source (DFB, VCSEL, QCL) and without the necessity of electro-optic modulators. This way, a frequency-agile and adaptive dual-comb architecture is provided with potential implementation capabilities from mid-infrared to near ultraviolet. With a RF comb comprising around 70 teeth, the system is validated in the 1.5 μm region measuring the absorption feature of H13CN at 1538.523 nm with a minimum integration time of 10 μs. PMID:27410649

  3. Coherent coupling between radio frequency, optical, and acoustic waves in piezo-optomechanical circuits

    CERN Document Server

    Balram, Krishna C; Song, Jin Dong; Srinivasan, Kartik

    2015-01-01

    The interaction of optical and mechanical modes in nanoscale optomechanical systems has been widely studied for applications ranging from sensing to quantum information science. Here, we develop a platform for cavity optomechanical circuits in which localized and interacting 1550 nm photons and 2.4 GHz phonons are combined with photonic and phononic waveguides. Working in GaAs facilitates manipulation of the localized mechanical mode either with a radio frequency field through the piezo-electric effect, or optically through the strong photoelastic effect. We use this to demonstrate a novel acoustic wave interference effect, analogous to coherent population trapping in atomic systems, in which the coherent mechanical motion induced by the electrical drive can be completely cancelled out by the optically-driven motion. The ability to manipulate cavity optomechanical systems with equal facility through either photonic or phononic channels enables new device and system architectures for signal transduction betwee...

  4. Radiation effects on optical frequency domain reflectometry fiber-based sensor.

    Science.gov (United States)

    Rizzolo, S; Marin, E; Cannas, M; Boukenter, A; Ouerdane, Y; Périsse, J; Macé, J-R; Bauer, S; Marcandella, C; Paillet, P; Girard, S

    2015-10-15

    We investigate the radiation effects on germanosilicate optical fiber acting as the sensing element of optical frequency domain reflectometry devices. Thanks to a new setup permitting to control temperature during irradiation, we evaluate the changes induced by 10 keV x rays on their Rayleigh response up to 1 MGy in a temperature range from -40°C up to 75°C. Irradiation at fixed temperature points out that its measure is reliable during both irradiation and the recovery process. Mixed temperature and radiation measurements show that changing irradiation temperature leads to an error in distributed measurements that depends on the calibration procedure. These results demonstrate that Rayleigh-based optical fiber sensors are very promising for integration in harsh environments. PMID:26469566

  5. Optical feedback characteristics in a dual-frequency laser during laser cavity tuning

    Institute of Scientific and Technical Information of China (English)

    Liu Gang; Zhang Shu-Lian; Li Yan; Zhu Jun

    2005-01-01

    The optical feedback characteristics in a Zeeman-birefringence dual-frequency laser are studied during the laser cavity tuning in three different kinds of optical feedback conditions: (i) only //-light is fed back; (ii) only (┴)-light is fed back; (iii) both lights are fed back. A compact displacement sensor is designed using the experimental result that there is a nearly 90 degrees phase delay between the two lights' cosine optical feedback signals when both lights are fed back into the laser cavity. The priority order that the two lights' intensity curves appear can be used for direction discrimination. The resolution of the displacement sensor is at least 79 nm, and the sensor can discriminate the target's moving direction easily.

  6. Time-Frequency (Wigner Analysis of Linear and Nonlinear Pulse Propagation in Optical Fibers

    Directory of Open Access Journals (Sweden)

    José Azaña

    2005-06-01

    Full Text Available Time-frequency analysis, and, in particular, Wigner analysis, is applied to the study of picosecond pulse propagation through optical fibers in both the linear and nonlinear regimes. The effects of first- and second-order group velocity dispersion (GVD and self-phase modulation (SPM are first analyzed separately. The phenomena resulting from the interplay between GVD and SPM in fibers (e.g., soliton formation or optical wave breaking are also investigated in detail. Wigner analysis is demonstrated to be an extremely powerful tool for investigating pulse propagation dynamics in nonlinear dispersive systems (e.g., optical fibers, providing a clearer and deeper insight into the physical phenomena that determine the behavior of these systems.

  7. Generation of optical frequency combs in a fiber-ring/microresonator laser system.

    Science.gov (United States)

    Guo, Changlei; Che, Kaijun; Xu, Huiying; Zhang, Pan; Tang, Deyu; Ren, Changyan; Luo, Zhengqian; Cai, Zhiping

    2016-06-01

    We propose and experimentally demonstrate a simple scheme for generating optical frequency combs (OFCs) in a fiber-ring/microresonator laser system. The ultrahigh Q whispering gallery mode microresonator is employed both as a mode reflection mirror to generate erbium lasing and as a Kerr-nonlinearity initiator that introduces optical parametric oscillation signals to form OFCs. By controlling the coupling position between the fiber taper and microresonator, optimizing the fiber polarization, as well as the pump power from a 974 nm laser diode (LD), versatile OFCs can be tuned out from single-wavelength states. The OFCs have single, multiple, or combined free spectral ranges. In addition, a Raman-gain-assisted OFC is also observed with a bandwidth of ∼230  nm. This LD-pumped and multifunctional laser system could find applications in precision spectroscopy, biochemical sensing, and optical fiber communication systems. PMID:27244418

  8. Colloidal superlattices for unnaturally high-index metamaterials at broadband optical frequencies

    CERN Document Server

    Lee, Seungwoo

    2015-01-01

    The recent advance in the assembly of metallic nanoparticles (NPs) has enabled sophisticated engineering of unprecedented light-matter interaction at the optical domain. In this work, I expand the design flexibility of NP optical metamaterial to push the upper limit of accessible refractive index to the unnaturally high regime. The precise control over the geometrical parameters of NP superlattice monolayer conferred the dramatic increase in electric resonance and related effective permittivity far beyond the naturally accessible regime. Simultaneously, effective permeability, another key factor to achieving high refractive index, was effectively suppressed by reducing the thickness of NPs. By establishing this design rule, I have achieved unnaturally high refractive index (15.7 at the electric resonance and 7.3 at the quasi-static limit) at broadband optical frequencies (100 THz ~ 300 THz). I also combined this NP metamaterial with graphene to electrically control the high refractive index over the broad opt...

  9. Influence of optical feedback on laser frequency spectrum and threshold conditions

    DEFF Research Database (Denmark)

    Osmundsen, Jens Henrik; Gade, Niels

    1983-01-01

    The steady state behavior of the external cavity operated laser has been analyzed, taking into account multiple reflections. The effect of optical feedback is included in the phase- and gain-conditions by a factor which is shown to have a simple geometrical representation. From this representation...... it is easily seen how the laser frequency spectrum and the threshold gain depend on external parameters such as distance to the reflection point and the amount of optical feedback. Furthermore, by inserting a variable attenuator in the external cavity and measuring the threshold current versus transmittance we...... have simultaneously determined the photon lifetime and the absolute amount of optical feedback. For the laser considered we found the photon lifetimetau_{p} = 1.55ps....

  10. Frequency-resolved optical gating measurement of ultrashort pulses by using single nanowire

    Science.gov (United States)

    Yu, Jiaxin; Liao, Feng; Gu, Fuxing; Zeng, Heping

    2016-09-01

    The use of ultrashort pulses for fundamental studies and applications has been increasing rapidly in the past decades. Along with the development of ultrashort lasers, exploring new pulse diagnositic approaches with higher signal-to-noise ratio have attracted great scientific and technological interests. In this work, we demonstrate a simple technique of ultrashort pulses characterization with a single semiconductor nanowire. By performing a frequency-resolved optical gating method with a ZnO nanowire coupled to tapered optical microfibers, the phase and amplitude of a pulse series are extracted. The generated signals from the transverse frequency conversion process can be spatially distinguished from the input, so the signal-to-noise ratio is improved and permits lower energy pulses to be identified. Besides, since the nanometer scale of the nonlinear medium provides relaxed phase-matching constraints, a measurement of 300-nm-wide supercontinuum pulses is achieved. This system is highly compatible with standard optical fiber systems, and shows a great potential for applications such as on-chip optical communication.

  11. Frequency-resolved optical gating measurement of ultrashort pulses by using single nanowire

    Science.gov (United States)

    Yu, Jiaxin; Liao, Feng; Gu, Fuxing; Zeng, Heping

    2016-01-01

    The use of ultrashort pulses for fundamental studies and applications has been increasing rapidly in the past decades. Along with the development of ultrashort lasers, exploring new pulse diagnositic approaches with higher signal-to-noise ratio have attracted great scientific and technological interests. In this work, we demonstrate a simple technique of ultrashort pulses characterization with a single semiconductor nanowire. By performing a frequency-resolved optical gating method with a ZnO nanowire coupled to tapered optical microfibers, the phase and amplitude of a pulse series are extracted. The generated signals from the transverse frequency conversion process can be spatially distinguished from the input, so the signal-to-noise ratio is improved and permits lower energy pulses to be identified. Besides, since the nanometer scale of the nonlinear medium provides relaxed phase-matching constraints, a measurement of 300-nm-wide supercontinuum pulses is achieved. This system is highly compatible with standard optical fiber systems, and shows a great potential for applications such as on-chip optical communication. PMID:27609521

  12. Long-distance remote comparison of ultrastable optical frequencies with 10(-15) instability in fractions of a second.

    Science.gov (United States)

    Pape, A; Terra, O; Friebe, J; Riedmann, M; Wübbena, T; Rasel, E M; Predehl, K; Legero, T; Lipphardt, B; Schnatz, H; Grosche, G

    2010-09-27

    We demonstrate a fully optical, long-distance remote comparison of independent ultrastable optical frequencies reaching a short term stability that is superior to any reported remote comparison of optical frequencies. We use two ultrastable lasers, which are separated by a geographical distance of more than 50 km, and compare them via a 73 km long phase-stabilized fiber in a commercial telecommunication network. The remote characterization spans more than one optical octave and reaches a fractional frequency instability between the independent ultrastable laser systems of 3 x 10 (-15) in 0.1 s. The achieved performance at 100 ms represents an improvement by one order of magnitude to any previously reported remote comparison of optical frequencies and enables future remote dissemination of the stability of 100 mHz linewidth lasers within seconds.

  13. Frequency and time domain analysis of an external cavity laser with strong filtered optical feedback

    DEFF Research Database (Denmark)

    Detoma, Enrico; Tromborg, Bjarne; Montrosset, Ivo

    The stability properties of an external cavity laser with strong grating-filtered optical feedback to an anti-reflection coated facet are studied with a general frequency domain model. The model takes into account non-linear effects like four wave mixing and gain compression. A small-signal analy...... copression in the lasing mode. An integral equation for the electrical field is derived from the frequency domain model and used for time domain simulations of large-signal behavior.......The stability properties of an external cavity laser with strong grating-filtered optical feedback to an anti-reflection coated facet are studied with a general frequency domain model. The model takes into account non-linear effects like four wave mixing and gain compression. A small......-signal analysis in the frequency domain allows a calculation of the range of operation without mode hopping around the grating reflectivity peak. This region should be as large as possible for proper operation of the tunable laser source. The analysis shows this stabilizing effect of mode coupling and gain...

  14. Brillouin amplification in phase coherent transfer of optical frequencies over 480 km fiber

    CERN Document Server

    Terra, O; Schnatz, H

    2010-01-01

    We describe the use of fiber Brillouin amplification (FBA) for the coherent transmission of optical frequencies over a 480 km long optical fiber link. FBA uses the transmission fiber itself for efficient, bi-directional coherent amplification of weak signals with pump powers around 30 mW. In a test setup we measured the gain and the achievable signal-to-noise ratio (SNR) of FBA and compared it to that of the widely used uni-directional Erbium doped fiber amplifiers (EDFA) and to our recently built bi-directional EDFA. We measured also the phase noise introduced by the FBA and used a new and simple technique to stabilize the frequency of the FBA pump laser. We then transferred a stabilized laser frequency over a wide area network with a total fiber length of 480 km using only one intermediate FBA station. After compensating the noise induced by the fiber, the frequency is delivered to the user end with an uncertainty below 2x10-18 and an instability sigma(tau) = 2x10-14/(tau/second).

  15. Effects of laser frequency drift in phase-sensitive optical time-domain reflectometry fiber sensors

    CERN Document Server

    Zhirnov, Andrey; Stepanov, Konstantin; Nesterov, Evgeny; Karasik, Valery; Svelto, Cesare; Pnev, Alexey

    2016-01-01

    The present work studies the influence of laser frequency drifts on operating of phase-sensitive optical time-domain reflectometry ($\\Phi$-OTDR) fiber sensors. A mathematical model and numerical simulations are employed to highlight the influence of frequency drifts of light sources on two characteristic scales: large-time (minutes) and short-time (milliseconds) frequency drifts. Numerical simulation results are compared with predictions given by the fluctuation ratio coefficient (FRC), and they are in a qualitative agreement. In addition to qualitative criteria for light sources given by the FRC, quantitive requirements for optimal light sources for $\\Phi$-OTDR sensors are obtained. Numerical simulation results are verified by comparison with experimental data for three significantly different types of light source.

  16. Quantum Correlations, Entanglement, and Squeezed States of Light in Kerr Optical Frequency Combs

    CERN Document Server

    Chembo, Yanne K

    2014-01-01

    The dynamical behavior of Kerr optical frequency combs is very well understood today from the perspective of the semi-classical approximation. In this article, we provide a theoretical understanding of the phenomena of quantum correlations, multimode entanglement and squeezed states of light that can occur in these frequency combs when quantum noise is accounted for. We prove that for all stationary spatio-temporal patterns, the side-modes that are symmetrical relatively to the central (pumped) mode in the frequency domain display quantum correlations that can lead to squeezed states of light under some optimal conditions that are analytically determined. We show that these quantum correlations can persist regardless the dynamical state of the system (rolls or solitons), regardless of the spectral extension of the comb (number sidemodes), and regardless of the dispersion regime (normal or anomalous). We study with particular emphasis the two principal architectures for Kerr comb generation, namely the add-thr...

  17. A broadband chip-scale optical frequency synthesizer at 2.7 × 10(-16) relative uncertainty.

    Science.gov (United States)

    Huang, Shu-Wei; Yang, Jinghui; Yu, Mingbin; McGuyer, Bart H; Kwong, Dim-Lee; Zelevinsky, Tanya; Wong, Chee Wei

    2016-04-01

    Optical frequency combs-coherent light sources that connect optical frequencies with microwave oscillations-have become the enabling tool for precision spectroscopy, optical clockwork, and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but Kerr nonlinear dynamics in high-Q solid-state microresonators has recently demonstrated promising features as alternative platforms. The advance not only fosters studies of chip-scale frequency metrology but also extends the realm of optical frequency combs. We report the full stabilization of chip-scale optical frequency combs. The microcomb's two degrees of freedom, one of the comb lines and the native 18-GHz comb spacing, are simultaneously phase-locked to known optical and microwave references. Active comb spacing stabilization improves long-term stability by six orders of magnitude, reaching a record instrument-limited residual instability of [Formula: see text]. Comparing 46 nitride frequency comb lines with a fiber laser frequency comb, we demonstrate the unprecedented microcomb tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7 × 10(-16), heralding novel solid-state applications in precision spectroscopy, coherent communications, and astronomical spectrography.

  18. A broadband chip-scale optical frequency synthesizer at 2.7 × 10(-16) relative uncertainty.

    Science.gov (United States)

    Huang, Shu-Wei; Yang, Jinghui; Yu, Mingbin; McGuyer, Bart H; Kwong, Dim-Lee; Zelevinsky, Tanya; Wong, Chee Wei

    2016-04-01

    Optical frequency combs-coherent light sources that connect optical frequencies with microwave oscillations-have become the enabling tool for precision spectroscopy, optical clockwork, and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but Kerr nonlinear dynamics in high-Q solid-state microresonators has recently demonstrated promising features as alternative platforms. The advance not only fosters studies of chip-scale frequency metrology but also extends the realm of optical frequency combs. We report the full stabilization of chip-scale optical frequency combs. The microcomb's two degrees of freedom, one of the comb lines and the native 18-GHz comb spacing, are simultaneously phase-locked to known optical and microwave references. Active comb spacing stabilization improves long-term stability by six orders of magnitude, reaching a record instrument-limited residual instability of [Formula: see text]. Comparing 46 nitride frequency comb lines with a fiber laser frequency comb, we demonstrate the unprecedented microcomb tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7 × 10(-16), heralding novel solid-state applications in precision spectroscopy, coherent communications, and astronomical spectrography. PMID:27152341

  19. A broadband chip-scale optical frequency synthesizer at 2.7 × 10−16 relative uncertainty

    Science.gov (United States)

    Huang, Shu-Wei; Yang, Jinghui; Yu, Mingbin; McGuyer, Bart H.; Kwong, Dim-Lee; Zelevinsky, Tanya; Wong, Chee Wei

    2016-01-01

    Optical frequency combs—coherent light sources that connect optical frequencies with microwave oscillations—have become the enabling tool for precision spectroscopy, optical clockwork, and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but Kerr nonlinear dynamics in high-Q solid-state microresonators has recently demonstrated promising features as alternative platforms. The advance not only fosters studies of chip-scale frequency metrology but also extends the realm of optical frequency combs. We report the full stabilization of chip-scale optical frequency combs. The microcomb’s two degrees of freedom, one of the comb lines and the native 18-GHz comb spacing, are simultaneously phase-locked to known optical and microwave references. Active comb spacing stabilization improves long-term stability by six orders of magnitude, reaching a record instrument-limited residual instability of 3.6mHz/τ. Comparing 46 nitride frequency comb lines with a fiber laser frequency comb, we demonstrate the unprecedented microcomb tooth-to-tooth relative frequency uncertainty down to 50 mHz and 2.7 × 10−16, heralding novel solid-state applications in precision spectroscopy, coherent communications, and astronomical spectrography. PMID:27152341

  20. Raman Self-Frequency Shift of Dissipative Kerr Solitons in an Optical Microresonator.

    Science.gov (United States)

    Karpov, Maxim; Guo, Hairun; Kordts, Arne; Brasch, Victor; Pfeiffer, Martin H P; Zervas, Michail; Geiselmann, Michael; Kippenberg, Tobias J

    2016-03-11

    The formation of temporal dissipative Kerr solitons in microresonators driven by a continuous-wave laser enables the generation of coherent, broadband, and spectrally smooth optical frequency combs as well as femtosecond pulse sources with compact form factors. Here we report the observation of a Raman-induced soliton self-frequency shift for a microresonator dissipative Kerr soliton also referred to as the frequency-locked Raman soliton. In amorphous silicon nitride microresonator-based single soliton states the Raman effect manifests itself by a spectrum that is sech^{2} in shape and whose center is spectrally redshifted from the continuous wave pump laser. The shift is theoretically described by the first-order shock term of the material's Raman response, and we infer a Raman shock time of ∼20  fs for amorphous silicon nitride. Moreover, we observe that the Raman-induced frequency shift can lead to a cancellation or overcompensation of the soliton recoil caused by the formation of a coherent dispersive wave. The observations are in agreement with numerical simulations based on the Lugiato-Lefever equation with a Raman shock term. Our results contribute to the understanding of Kerr frequency combs in the soliton regime, enable one to substantially improve the accuracy of modeling, and are relevant to the understanding of the fundamental timing jitter of microresonator solitons.

  1. Raman Self-Frequency Shift of Dissipative Kerr Solitons in an Optical Microresonator.

    Science.gov (United States)

    Karpov, Maxim; Guo, Hairun; Kordts, Arne; Brasch, Victor; Pfeiffer, Martin H P; Zervas, Michail; Geiselmann, Michael; Kippenberg, Tobias J

    2016-03-11

    The formation of temporal dissipative Kerr solitons in microresonators driven by a continuous-wave laser enables the generation of coherent, broadband, and spectrally smooth optical frequency combs as well as femtosecond pulse sources with compact form factors. Here we report the observation of a Raman-induced soliton self-frequency shift for a microresonator dissipative Kerr soliton also referred to as the frequency-locked Raman soliton. In amorphous silicon nitride microresonator-based single soliton states the Raman effect manifests itself by a spectrum that is sech^{2} in shape and whose center is spectrally redshifted from the continuous wave pump laser. The shift is theoretically described by the first-order shock term of the material's Raman response, and we infer a Raman shock time of ∼20  fs for amorphous silicon nitride. Moreover, we observe that the Raman-induced frequency shift can lead to a cancellation or overcompensation of the soliton recoil caused by the formation of a coherent dispersive wave. The observations are in agreement with numerical simulations based on the Lugiato-Lefever equation with a Raman shock term. Our results contribute to the understanding of Kerr frequency combs in the soliton regime, enable one to substantially improve the accuracy of modeling, and are relevant to the understanding of the fundamental timing jitter of microresonator solitons. PMID:27015482

  2. Coordinated optical and radar observations of ionospheric pumping for a frequency pass through the second electron gyroharmonic at HAARP

    OpenAIRE

    Kosch, Mike J.; Pedersen, T.; Mishin, E.; Oyama, S.; Hughes, J; Senior, Andrew; Watkins, B.; Bristow, B.

    2007-01-01

    On 4 February 2005, the High-frequency Active Auroral Research Program (HAARP) facility was operated in O and X mode while pointing into the magnetic zenith to produce artificial optical emissions in the ionospheric F layer. The pump frequency was set to 2.85 MHz to ensure passing through the second electron gyroharmonic of the decaying ionosphere. Optical recordings at 557.7 and 630 nm were performed simultaneously with the side-viewing high frequency (HF) and colocated ultra high frequency ...

  3. Frequency ratios of Sr, Yb and Hg based optical lattice clocks and their applications

    CERN Document Server

    Takamoto, Masao; Das, Manoj; Nemitz, Nils; Ohkubo, Takuya; Yamanaka, Kazuhiro; Ohmae, Noriaki; Takano, Tetsushi; Akatsuka, Tomoya; Yamaguchi, Atsushi; Katori, Hidetoshi

    2015-01-01

    This article describes the recent progress of optical lattice clocks with neutral strontium ($^{87}$Sr), ytterbium ($^{171}$Yb) and mercury ($^{199}$Hg) atoms. In particular, we present frequency comparison between the clocks locally via an optical frequency comb and between two Sr clocks at remote sites using a phase-stabilized fibre link. We first review cryogenic Sr optical lattice clocks that reduce the room-temperature blackbody radiation shift by two orders of magnitude and serve as a reference in the following clock comparisons. Similar physical properties of Sr and Yb atoms, such as transition wavelengths and vapour pressure, have allowed our development of a compatible clock for both species. A cryogenic Yb clock is evaluated by referencing a Sr clock. We also report on a Hg clock, which shows one order of magnitude less sensitivity to blackbody radiation, while its large nuclear charge makes the clock sensitive to the variation of fine-structure constant. Connecting all three types of clocks by an o...

  4. Frequency-domain nonlinear optics in two-dimensionally patterned quasi-phase-matching media.

    Science.gov (United States)

    Phillips, C R; Mayer, B W; Gallmann, L; Keller, U

    2016-07-11

    Advances in the amplification and manipulation of ultrashort laser pulses have led to revolutions in several areas. Examples include chirped pulse amplification for generating high peak-power lasers, power-scalable amplification techniques, pulse shaping via modulation of spatially-dispersed laser pulses, and efficient frequency-mixing in quasi-phase-matched nonlinear crystals to access new spectral regions. In this work, we introduce and demonstrate a new platform for nonlinear optics which has the potential to combine these separate functionalities (pulse amplification, frequency transfer, and pulse shaping) into a single monolithic device that is bandwidth- and power-scalable. The approach is based on two-dimensional (2D) patterning of quasi-phase-matching (QPM) gratings combined with optical parametric interactions involving spatially dispersed laser pulses. Our proof of principle experiment demonstrates this technique via mid-infrared optical parametric chirped pulse amplification of few-cycle pulses. Additionally, we present a detailed theoretical and numerical analysis of such 2D-QPM devices and how they can be designed. PMID:27410862

  5. Frequency-domain analysis of computer-controlled optical surfacing processes

    Institute of Scientific and Technical Information of China (English)

    ZHOU Lin; DAI YiFan; XIE XuHui; LI ShengYi

    2009-01-01

    Mid-high spatial frequency errors are often induced on optical surfaces polished by computer-controlled optical surfacing (CCOS) processes. In order to efficiently remove these errors, which would degrade the performances of optical systems, the ability of a CCOS process to correct the errors have been investigated based on the convolution integral model in view of the availability of material removal. To quantify the ability, some conceptions, such as figure correcting ability and material removal availability (MRA), have been proposed. The research result reveals that the MRA of the CCOS process to correct a single spatial frequency error is determined by its tool removal function (TRF), and it equals the normalized amplitude spectrum of the Fourier transform of its TRF. Finally, three sine surfaces were etched using ion beam figuring (IBF), which is a typical CCOS process. The experimental results have verified the theoretical analysis. The employed method and the conclusions of this work provide a useful mathematical basis to analyze and optimize CCOS processes.

  6. Laser system for Doppler cooling of ytterbium ion in an optical frequency standard

    Energy Technology Data Exchange (ETDEWEB)

    Chepurov, S V; Lugovoy, A A; Kuznetsov, S N [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2014-06-30

    A laser system for Doppler cooling of ytterbium ion on the {sup 2}S{sub 1/2} → {sup 2}P{sub 1/2} transition in a single-ion optical frequency standard is developed. The second harmonic of a semiconductor laser with a wavelength of 739 nm is used for cooling. The laser frequency is doubled in a nonlinear BiBO crystal embedded in a ring resonator, which also serves as a reference for laser frequency stabilisation. Second-harmonic power of ∼100 μW is generated at a wavelength of 369.5 nm. Diode laser radiation is modulated by an electro-optic modulator at 14.75 GHz to generate a sideband exciting the {sup 2}S{sub 1/2} (F = 0) → {sup 2}P{sub 1/2} (F = 1) hyperfine component of the cooling transition that is not excited by resonant cooling light. The sideband relative intensity of a few percent proved to be sufficient to reduce the ion dwelling time in the {sup 2}S{sub 1/2} (F = 0) state to less than 10{sup -4} s and increase the cooling efficiency. (extreme light fields and their applications)

  7. Measurement of optical-beat frequency in a photoconductive terahertz-wave generator using microwave higher harmonics

    Science.gov (United States)

    Murasawa, Kengo; Sato, Koki; Hidaka, Takehiko

    2011-05-01

    A new method for measuring optical-beat frequencies in the terahertz (THz) region using microwave higher harmonics is presented. A microwave signal was applied to the antenna gap of a photoconductive (PC) device emitting a continuous electromagnetic wave at about 1 THz by the photomixing technique. The microwave higher harmonics with THz frequencies are generated in the PC device owing to the nonlinearity of the biased photoconductance, which is briefly described in this article. Thirteen nearly periodic peaks in the photocurrent were observed when the microwave was swept from 16 to 20 GHz at a power of -48 dBm. The nearly periodic peaks are generated by the homodyne detection of the optical beat with the microwave higher harmonics when the frequency of the harmonics coincides with the optical-beat frequency. Each peak frequency and its peak width were determined by fitting a Gaussian function, and the order of microwave harmonics was determined using a coarse (i.e., lower resolution) measurement of the optical-beat frequency. By applying the Kalman algorithm to the peak frequencies of the higher harmonics and their standard deviations, the optical-beat frequency near 1 THz was estimated to be 1029.81 GHz with the standard deviation of 0.82 GHz. The proposed method is applicable to a conventional THz-wave generator with a photomixer.

  8. Ultrahigh-frequency microwave phase shifts mediated by ultrafast dynamics in quantum-dot semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2010-01-01

    We present a novel scheme to achieve tunable microwave phase shifts at frequencies exceeding 100 GHz based on wavelength conversion induced by high-speed cross-gain modulation in quantum-dot semiconductor optical amplifiers....

  9. Absolute frequency measurement of an SF6 two-photon line using a femtosecond optical comb and sum-frequency generation

    CERN Document Server

    Amy-Klein, A; Guinet, M; Daussy, C; López, O; Shelkovnikov, A; Chardonnet, C; Amy-Klein, Anne; Goncharov, Andrei; Guinet, Mickael; Daussy, Christophe; Lopez, Olivier; Shelkovnikov, Alexander; Chardonnet, Christian

    2005-01-01

    We demonstrate a new simple technique to measure IR frequencies near 30 THz using a femtosecond (fs) laser optical comb and sum-frequency generation. The optical frequency is directly compared to the distance between two modes of the fs laser, and the resulting beat note is used to control this distance which depends only on the repetition rate fr of the fs laser. The absolute frequency of a CO2 laser stabilized onto an SF6 two-photon line has been measured for the first time. This line is an attractive alternative to the usual saturated absorption OsO4 resonances used for the stabilization of CO2 lasers. First results demonstrate a fractional Allan deviation of 3.10-14 at 1 s.

  10. High-frequency electro-optic measurement of strained silicon racetrack resonators.

    Science.gov (United States)

    Borghi, M; Mancinelli, M; Merget, F; Witzens, J; Bernard, M; Ghulinyan, M; Pucker, G; Pavesi, L

    2015-11-15

    The observation of the electro-optic effect in strained silicon waveguides has been considered a direct manifestation of an induced χ(2) nonlinearity in the material. In this work, we perform high-frequency measurements on strained silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes, independent of the applied strain, when the applied voltage varies much faster than the carrier effective lifetime and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free-carrier effects, our results set an upper limit of (8±3) pm/V to the induced high-speed effective χeff,zzz(2) tensor element at an applied stress of -0.5 GPa. This upper limit is about 1 order of magnitude lower than previously reported values for static electro-optic measurements. PMID:26565856

  11. High frequency electro-optic measurement of strained silicon racetrack resonators

    CERN Document Server

    Borghi, M; Merget, F; Witzens, J; Bernard, M; Ghulinyan, M; Pucker, G; Pavesi, L

    2015-01-01

    The observation of the electro-optic effect in strained silicon waveguides has been considered as a direct manifestation of an induced $\\chi^{(2)}$ non-linearity in the material. In this work, we perform high frequency measurements on strained silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes independently of the applied strain when the applied voltage varies much faster than the carrier effective lifetime, and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free carrier effects, our results set an upper limit of $8\\,pm/V$ to the induced high-speed $\\chi^{(2)}_{eff,zzz}$ tensor element at an applied stress of $-0.5\\,GPa$. This upper limit is about one order of magnitude lower than the previously reported values for static electro-optic measurements.

  12. Optical tomography with the discontinuous Galerkin formulation of the radiative transfer equation in frequency domain

    International Nuclear Information System (INIS)

    Optical tomography is an inverse method of probing semi-transparent media with the help of light sources. The reconstruction of the optical properties usually employs finite volumes or continuous finite elements formulations of light transport as a forward model for the predictions. In a previous study, we have introduced a generalization of the inversion approach with finite elements formulations by using an integral form of the objective function. The novelty is that the surfaces of the detectors are taken into account in the reconstruction and compatibility is obtained for all finite element formulations. This present paper illustrates this new approach by developing a Discontinuous Galerkin formulation as a forward model for an optical tomography application in the frequency domain framework. Numerical tests are performed to gauge the accuracy of the method in recovering optical properties distribution with a gradient-based algorithm where the adjoint method is used to fastly compute the objective function gradient. It is seen that the reconstruction is accurate and can be affected by noise on the measurements as expected. Filtering of the gradient at each iteration of the reconstruction is used to cope with the ill-posed nature of the inverse problem and to improves the quality and accuracy of the reconstruction.

  13. Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic

    OpenAIRE

    Kosch, M. J.; Pedersen, T.; Hughes, J; Marshall, R.; Gerken, E.; Senior, A.; D. Sentman; M. McCarrick; Djuth, F.T.

    2005-01-01

    International audience High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The H...

  14. Frequency modulated few-cycle optical pulse trains induced controllable ultrafast coherent population oscillations in three-level atomic systems

    OpenAIRE

    Kumar, Parvendra; Sarma, Amarendra K.

    2012-01-01

    We report a study on the ultrafast coherent population oscillations (UCPO) in two level atoms induced by the frequency modulated few-cycle optical pulse train. The phenomenon of UCPO is investigated by numerically solving the optical Bloch equations beyond the rotating wave approximation. We demonstrate that the quantum state of the atoms and the frequency of UCPO may be controlled by controlling the number of pulses in the pulse trains and the pulse repetition time respectively. Moreover, th...

  15. Application of Electron-Shelving Detection via 423 nm Transition in Calcium-Beam Optical Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    HUANG Kai-Kai; ZHANG Jian-Wei; YU De-Shui; CHEN Zhen-Hui; ZHUAN Wei; CHEN Jing-Biao

    2006-01-01

    A new scheme of small compact optical frequency standard based on thermal calcium beam with application of 423 nm shelving detection and sharp-angle velocity selection detection is proposed. Combining these presented techniques, we conclude that a small compact optical frequency standard based on thermal calcium beam will outperform the commercial caesium-beam microwave clock, like the 5071 Cs clock (from HP to Agilent, now Symmetricom company), both in accuracy and stability.

  16. High sensitivity resonance frequency measurements of individualmicro-cantilevers using fiber optical interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Duden, Thomas; Radmilovic, Velimir

    2009-03-04

    We describe a setup for the resonance frequency measurement of individual microcantilevers. The setup displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The high sensitivity to specimen vibrations is achieved by the combination of optical Fabry-Perot interferometry and narrow band RF detection. Wave fronts reflected on the specimen and on the fiber tip end face interfere, thus no reference plane on the specimen is needed, as demonstrated with the example of freestanding silicon nitride micro-cantilevers. The resulting system is integrated in a DB-235 dual beam FIB system, thereby allowing the measurement of micro-cantilever responses during observation in SEM mode. The FIB was used to modify the optical fiber tip. At this point of our RF system development, the microcantilevers used to characterize the detector were not modified in situ.

  17. Indoor location estimation with optical-based orthogonal frequency division multiplexing communications

    Science.gov (United States)

    Aminikashani, Mohammadreza; Gu, Wenjun; Kavehrad, Mohsen

    2016-05-01

    Visible light communication (VLC) using light-emitting diodes has been gaining increasing attention in recent years as it is appealing for a wide range of applications such as indoor positioning. Orthogonal frequency division multiplexing (OFDM) has been applied to indoor wireless optical communications in order to mitigate the effect of multipath distortion of the optical channel as well as increasing the data rate. An OFDM VLC system is proposed, which can be utilized for both communications and indoor positioning. A positioning algorithm based on power attenuation is used to estimate the receiver coordinates. We further calculate the positioning errors in all the locations of a room and compare them with those using single-carrier modulation schemes, i.e., on-off keying modulation. We demonstrate that our proposed OFDM positioning system outperforms by 74% its conventional counterpart. Finally, we investigate the impact of different system parameters on the positioning accuracy of the proposed OFDM VLC system.

  18. Performance of low-cost commercial fiber-optic transceivers for reference frequency distribution

    Science.gov (United States)

    Dragonette, Richard; Suter, Joseph J.

    1993-01-01

    Precision time and frequency reference signals were effectively disseminated using high-quality intricate fiber-optic distribution systems. The quality of signals distributed by such systems is excellent, but the cost of these systems makes them unavailable to many potential users. A study of signal quality maintained using inexpensive commercial transmitter/receiver pairs is undertaken. Seven different transmitter/receiver pairs obtained from four different manufacturers were thoroughly tested using a 5 MHz sinusoid derived from a precision, temperature controlled, crystal-controlled oscillator. The electrical signal output from each fiber-optic receiver was tested for spectral purity, single-sideband phase noise, and AM noise, and the results are tabulated and discussed without identification of the manufacturer or the equipment model number.

  19. New developments in frequency domain optical tomography. Part I: Forward model and gradient computation

    International Nuclear Information System (INIS)

    This two part study introduces new developments in frequency domain optical tomography to take into account the collimated source direction in the computation of both the forward and the adjoint models. The solution method is based on the least square finite element method associated to the discrete ordinates method where no empirical stabilization is needed. In this first part of the study, the solution method of the forward model is highlighted with an easy handling of complex boundary condition through a penalization method. Gradient computation from an adjoint method is developed rigorously in a continuous manner through a lagrangian formalism for the deduction of the adjoint equation and the gradient of the objective function. The proposed formulation can be easily generalized to stationary and time domain optical tomography by keeping the same expressions.

  20. Optical sum-frequency generation in a whispering-gallery-mode resonator

    International Nuclear Information System (INIS)

    We demonstrate sum-frequency generation between a telecom wavelength and the Rb D2 line, achieved through natural phase matching in a nonlinear whispering gallery mode resonator. Due to the strong optical field confinement and ultra high Q of the cavity, the process saturates already at sub-mW pump peak power, at least two orders of magnitude lower than in existing waveguide-based devices. The experimental data are in agreement with the nonlinear dynamics and phase matching theory based on spherical geometry. Our experimental and theoretical results point toward a new platform for manipulating the color and quantum states of light waves for applications such as atomic memory based quantum networking and logic operations with optical signals. (paper)

  1. Optical Frequency Optimization of a High Intensity Laser Power Beaming System Utilizing VMJ Photovoltaic Cells

    Science.gov (United States)

    Raible, Daniel E.; Dinca, Dragos; Nayfeh, Taysir H.

    2012-01-01

    An effective form of wireless power transmission (WPT) has been developed to enable extended mission durations, increased coverage and added capabilities for both space and terrestrial applications that may benefit from optically delivered electrical energy. The high intensity laser power beaming (HILPB) system enables long range optical 'refueling" of electric platforms such as micro unmanned aerial vehicles (MUAV), airships, robotic exploration missions and spacecraft platforms. To further advance the HILPB technology, the focus of this investigation is to determine the optimal laser wavelength to be used with the HILPB receiver, which utilizes vertical multi-junction (VMJ) photovoltaic cells. Frequency optimization of the laser system is necessary in order to maximize the conversion efficiency at continuous high intensities, and thus increase the delivered power density of the HILPB system. Initial spectral characterizations of the device performed at the NASA Glenn Research Center (GRC) indicate the approximate range of peak optical-to-electrical conversion efficiencies, but these data sets represent transient conditions under lower levels of illumination. Extending these results to high levels of steady state illumination, with attention given to the compatibility of available commercial off-the-shelf semiconductor laser sources and atmospheric transmission constraints is the primary focus of this paper. Experimental hardware results utilizing high power continuous wave (CW) semiconductor lasers at four different operational frequencies near the indicated band gap of the photovoltaic VMJ cells are presented and discussed. In addition, the highest receiver power density achieved to date is demonstrated using a single photovoltaic VMJ cell, which provided an exceptionally high electrical output of 13.6 W/sq cm at an optical-to-electrical conversion efficiency of 24 percent. These results are very promising and scalable, as a potential 1.0 sq m HILPB receiver of

  2. NONLINEAR OPTICAL FREQUENCY CONVERTER OF LASER RADIATION ON THE LBO TYPE I CRYSTALS

    Directory of Open Access Journals (Sweden)

    N. V. Kondratyuk

    2014-01-01

    Full Text Available Describes nonlinear optical frequency converter of laser radiation based on the two LBO type I crystals allowing to receive pulses of radiation at three wavelengths of 1064 nm, 532 nm and 355 nm with an adjustable pulse energy. For fine adjustment of the output pulse energy used two dual phase plates that change the orientation of the plane of polarization of the two waves in cascade third harmonic generation. Measured the efficiency of the generation of harmonics of the intensity of radiation at 1064 nm.

  3. Resonance Frequency of Optical Microbubble Resonators: Direct Measurements and Mitigation of Fluctuations

    Science.gov (United States)

    Cosci, Alessandro; Berneschi, Simone; Giannetti, Ambra; Farnesi, Daniele; Cosi, Franco; Baldini, Francesco; Nunzi Conti, Gualtiero; Soria, Silvia; Barucci, Andrea; Righini, Giancarlo; Pelli, Stefano

    2016-01-01

    This work shows the improvements in the sensing capabilities and precision of an Optical Microbubble Resonator due to the introduction of an encaging poly(methyl methacrylate) (PMMA) box. A frequency fluctuation parameter σ was defined as a score of resonance stability and was evaluated in the presence and absence of the encaging system and in the case of air- or water-filling of the cavity. Furthermore, the noise interference introduced by the peristaltic and the syringe pumping system was studied. The measurements showed a reduction of σ in the presence of the encaging PMMA box and when the syringe pump was used as flowing system. PMID:27589761

  4. Frequency-Domain Chromatic Dispersion Equalization Using Overlap-Add Methods in Coherent Optical System

    CERN Document Server

    Xu, Tianhua; Popov, Sergei; Forzati, Marco; Martensson, Jonas; Mussolin, Marco; Li, Jie; Wang, Ke; Zhang, Yimo; Friberg, Ari T

    2016-01-01

    The frequency domain equalizers (FDEs) employing two types of overlap-add zero-padding (OLA-ZP) methods are applied to compensate the chromatic dispersion in a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent optical transmission system. Simulation results demonstrate that the OLA-ZP methods can achieve the same acceptable performance as the overlap-save method. The required minimum overlap (or zero-padding) in the FDE is derived, and the optimum fast Fourier transform length to minimize the computational complexity is also analyzed.

  5. Transformation optics: a time- and frequency-domain analysis of electron-energy loss spectroscopy

    CERN Document Server

    Kraft, Matthias; Pendry, J B

    2016-01-01

    Electron energy loss spectroscopy (EELS) and Cathodoluminescence (CL) play a pivotal role in many of the cutting edge experiments in plasmonics. EELS and CL experiments are usually supported by numerical simulations, which, whilst accurate, may not provide as much physical insight as analytical calculations do. Fully analytical solutions to EELS and CL systems in plasmonics are rare and difficult to obtain. This paper aims to narrow this gap by introducing a new method based on Transformation optics that allows to calculate the quasi-static frequency and time-domain response of plasmonic particles under electron beam excitation.

  6. Carrier-envelope offset frequency stabilization in a femtosecond optical parametric oscillator without nonlinear interferometry.

    Science.gov (United States)

    Balskus, Karolis; Fleming, Melissa; McCracken, Richard A; Zhang, Zhaowei; Reid, Derryck T

    2016-03-01

    By exploiting the correlation between changes in the wavelength and the carrier-envelope offset frequency (f(CEO)) of the signal pulses in a synchronously pumped optical parametric oscillator, we show that f(CEO) can be stabilized indefinitely to a few megahertz in a 333 MHz repetition-rate system. Based on a position-sensitive photodiode, the technique is easily implemented, requires no nonlinear interferometry, has a wide capture range, and is compatible with feed-forward techniques that can enable f(CEO) stabilization at loop bandwidths far exceeding those currently available to OPO combs. PMID:26974092

  7. Frequency domain optical tomography using a conjugate gradient method without line search

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Keol [Departement des Sciences Appliquees, Universite du Quebec a Chicoutimi, 555 Boulevard de l' Universite, P4-3240, Chicoutimi, Quebec, G7H 2B1 (Canada); Charette, Andre [Departement des Sciences Appliquees, Universite du Quebec a Chicoutimi, 555 Boulevard de l' Universite, P4-3240, Chicoutimi, Quebec, G7H 2B1 (Canada)]. E-mail: andre_charette@uqac.ca

    2007-03-15

    A conjugate gradient method without line search (CGMWLS) is presented. This method is used to retrieve the local maps of absorption and scattering coefficients inside the tissue-like test medium, with the synthetic data. The forward problem is solved with a discrete-ordinates finite-difference method based on the frequency domain formulation of radiative transfer equation. The inversion results demonstrate that the CGMWLS can retrieve simultaneously the spatial distributions of optical properties inside the medium within a reasonable accuracy, by reducing cross-talk between absorption and scattering coefficients.

  8. High resolution kilometric range optical telemetry in air by radio frequency phase measurement

    Science.gov (United States)

    Guillory, Joffray; Šmíd, Radek; García-Márquez, Jorge; Truong, Daniel; Alexandre, Christophe; Wallerand, Jean-Pierre

    2016-07-01

    We have developed an optical Absolute Distance Meter (ADM) based on the measurement of the phase accumulated by a Radio Frequency wave during its propagation in the air by a laser beam. In this article, the ADM principle will be described and the main results will be presented. In particular, we will emphasize how the choice of an appropriate photodetector can significantly improve the telemeter performances by minimizing the amplitude to phase conversion. Our prototype, tested in the field, has proven its efficiency with a resolution better than 15 μm for a measurement time of 10 ms and distances up to 1.2 km.

  9. Optical coherence tomography and low-frequency mechanics: A moderated discussion

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, Dennis M. [Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts (United States); Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts (United States); Ruggero, Mario A. [Knowles Hearing Center, Northwestern University, Evanston, Illinois (United States)

    2015-12-31

    The following is an edited transcript of a recorded discussion session on the topics of “Optical Coherence Tomography” and “Low-Frequency Mechanics”. The discussion, moderated by the authors, took place at the 12{sup th} International Workshop on the Mechanics of Hearing held at Cape Sounio, Greece, in June 2014. All participants knew that the session was being recorded. In view of both the spontaneous nature of the discussion and the editing, however, this transcript may not represent the considered or final views of the participants, and may not represent a consensus of experts in the field. The reader is advised to consult additional independent publications.

  10. Digital pilot aided carrier frequency offset estimation for coherent optical transmission systems.

    Science.gov (United States)

    Zhao, Donghe; Xi, Lixia; Tang, Xianfeng; Zhang, Wenbo; Qiao, Yaojun; Zhang, Xiaoguang

    2015-09-21

    We present a digital pilot aided carrier frequency offset estimation (FOE) method for coherent optical transmission systems. Unlike the conventional pilot tone insertion scheme, the pilot of the proposed method is generated in a digital manner and can serve as a good FOE indicator. Aided by this kind of digital pilot, the FOE is implemented by determining the location of the digital pilot in the spectrum. Theoretical analysis and numerical simulations show that the proposed method has the advantages in wide range, high accuracy, modulation formats independent, no need to remove the modulation, and high tolerance to the residual chromatic dispersion (CD) and polarization mode dispersion (PMD).

  11. All-Optical Frequency Modulated High Pressure MEMS Sensor for Remote and Distributed Sensing

    DEFF Research Database (Denmark)

    Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

    2011-01-01

    We present the design, fabrication and characterization of a new all-optical frequency modulated pressure sensor. Using the tangential strain in a circular membrane, a waveguide with an integrated nanoscale Bragg grating is strained longitudinally proportional to the applied pressure causing...... a shift in the Bragg wavelength. The simple and robust design combined with the small chip area of 1 × 1.8 mm2 makes the sensor ideally suited for remote and distributed sensing in harsh environments and where miniaturized sensors are required. The sensor is designed for high pressure applications up...

  12. Nonlinear optical frequency conversion with KTP and BiBO crystals for lasers in space

    OpenAIRE

    Potreck, Arne; Schröder, Helmut; Lammers, Melanie; Tzeremes, Georgios; Riede, Wolfgang

    2014-01-01

    Within ESA’s ADM-Aeolus and EarthCARE missions Doppler-wind Lidar systems will be operated in the Earth’s orbit to measure global wind profiles. The active instrument will be based on a Nd:YAG laser, frequency tripled by nonlinear optical crystals. Different crystals are therefore to compare and qualify in regard of their space acceptability. A dedicated set-up to measure the maximum conversion efficiencies and its stability during longterm operation for KTP crystals (SHG) and BiBO crystals (...

  13. Detection of radio frequency magnetic fields using nonlinear magneto-optical rotation

    CERN Document Server

    Ledbetter, M P; Budker, D; Pustelny, S; Rochester, S M; Yashchuk, V V

    2006-01-01

    We describe a room-temperature alkali-metal atomic magnetometer for detection of small, high frequency magnetic fields. The magnetometer operates by detecting optical rotation due to the precession of an aligned ground state in the presence of a small oscillating magnetic field. The resonance frequency of the magnetometer can be adjusted to any desired value by tuning the bias magnetic field. We demonstrate a sensitivity of $100\\thinspace{\\rm pG/\\sqrt{Hz}\\thinspace(RMS)}$ in a 3.5 cm diameter, paraffin coated cell. Based on detection at the photon shot-noise limit, we project a sensitivity of $20\\thinspace{\\rm pG/\\sqrt{Hz}\\thinspace(RMS)}$.

  14. Tunable High-Frequency Gravitational-Wave Detection with optically-levitated sensors

    CERN Document Server

    Arvanitaki, Asimina

    2012-01-01

    We propose a tunable resonant sensor to detect gravitational waves in the frequency range of 30 - 300 kHz using optically trapped and cooled dielectric microspheres or micro-discs. The technique we describe can exceed the sensitivity of laser-based gravitational wave observatories in this frequency range by 1 - 3 orders of magnitude, using an instrument of only a few percent of their size. Such a device extends the search volume for 100 kHz gravitational wave sources by more than 10^6, and could detect monochromatic gravitational radiation from the annihilation of QCD axions in the cloud they form around stellar mass black holes within our galaxy due to the superradiance effect.

  15. Study on high coupling efficiency Er-doped fiber laser for femtosecond optical frequency comb

    Science.gov (United States)

    Pang, Lihui; Liu, Wenjun; Han, Hainian; Wei, Zhiyi

    2016-09-01

    The femtosecond laser is crucial to the operation of the femtosecond optical frequency comb. In this paper, a passively mode-locked erbium-doped fiber laser is presented with 91.4 fs pulse width and 100.8 MHz repetition rate, making use of the nonlinear polarized evolution effect. Using a 976 nm pump laser diode, the average output power is 16 mW from the coupler and 27 mW from the polarization beam splitter at the pump power of 700 mW. The proposed fiber laser can offer excellent temporal purity in generated pulses with high power, and provide a robust source for fiber-based frequency combs and supercontinuum generation well suited for industrial applications.

  16. Negative frequencies get real: a missing puzzle piece in nonlinear optics

    CERN Document Server

    Conforti, Matteo; Faccio, Daniele; Biancalana, Fabio

    2013-01-01

    Motivated by recent experimental results, we demonstrate that the ubiquitous pulse propagation equation based on a single generalized nonlinear Schroedinger equation is incomplete and inadequate to explain the formation of the so called negative resonant radiation emitted by optical solitons. The origin of this deficiency is due to the absence of a peculiar nonlinear coupling between the positive and negative frequency components of the ultrashort pulse spectrum during propagation, a feature that the slowly-varying envelope approximation is unable to capture. We therefore introduce a conceptually new model, based on the envelope of the analytic signal, that takes into account the full spectral dynamics of all frequency components, is prone to analytical treatment and retains the simulation efficiency of the nonlinear Schroedinger equation. We use our new equation to derive from first principles the phase-matching condition of the negative resonant radiation observed in previous experiments.

  17. Low-frequency, self-sustained oscillations in inductively coupled plasmas used for optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Coffer, J.; Encalada, N.; Huang, M.; Camparo, J. [Physical Sciences Laboratories, The Aerospace Corporation 2310, E. El Segundo Blvd., El Segundo, California 90245 (United States)

    2014-10-28

    We have investigated very low frequency, on the order of one hertz, self-pulsing in alkali-metal inductively-coupled plasmas (i.e., rf-discharge lamps). This self-pulsing has the potential to significantly vary signal-to-noise ratios and (via the ac-Stark shift) resonant frequencies in optically pumped atomic clocks and magnetometers (e.g., the atomic clocks now flying on GPS and Galileo global navigation system satellites). The phenomenon arises from a nonlinear interaction between the atomic physics of radiation trapping and the plasma's electrical nature. To explain the effect, we have developed an evaporation/condensation theory (EC theory) of the self-pulsing phenomenon.

  18. Distributed vibration sensing with time-resolved optical frequency-domain reflectometry.

    Science.gov (United States)

    Zhou, Da-Peng; Qin, Zengguang; Li, Wenhai; Chen, Liang; Bao, Xiaoyi

    2012-06-01

    The distributed vibration or dynamic strain information can be obtained using time-resolved optical frequency-domain reflectometry. Time-domain information is resolved by measuring Rayleigh backscatter spectrum in different wavelength ranges which fall in successive time sequence due to the linear wavelength sweep of the tunable laser source with a constant sweeping rate. The local Rayleigh backscatter spectrum shift of the vibrated state with respect to that of the non-vibrated state in time sequence can be used to determine dynamic strain information at a specific position along the fiber length. Standard single-mode fibers can be used as sensing head, while the measurable frequency range of 0-32 Hz with the spatial resolution of 10 cm can be achieved up to the total length of 17 m. PMID:22714342

  19. A time/frequency quantum analysis of the light generated by synchronously pumped optical parametric oscillators

    CERN Document Server

    Jiang, Shifeng; Fabre, Claude; 10.1088/1367-2630/14/4/043006

    2012-01-01

    We present in this paper a general model for determining the quantum properties of the light generated by a synchronously pumped optical parametric oscillator (SPOPO) operating below threshold. This model considers time and frequency on an equal footing, which allows us to find new quantum properties, related for example to the carrier envelope offset (CEO) phase, and to consider situations that are close to real experiments. We show that, in addition to multimode squeezing in the so-called 'supermodes', the system exhibits quadrature entanglement between frequency combs of opposite CEO phases. We have also determined the quantum properties of the individual pulses and their quantum correlations with the neighboring pulses. Finally, we determine the quantum Cramer-Rao limit for an ultra-short time delay measurement using a given number of pulses generated by the SPOPO.

  20. Artificial optical emissions at HAARP for pump frequencies near the third and second electron gyro-harmonic

    Directory of Open Access Journals (Sweden)

    M. J. Kosch

    2005-07-01

    Full Text Available High-power high-frequency radio waves beamed into the ionosphere cause plasma turbulence, which can accelerate electrons. These electrons collide with the F-layer neutral oxygen causing artificial optical emissions identical to natural aurora. Pumping at electron gyro-harmonic frequencies has special significance as many phenomena change their character. In particular, artificial optical emissions become strongly reduced for the third and higher gyro-harmonics. The High frequency Active Auroral Research Program (HAARP facility is unique in that it can select a frequency near the second gyro-harmonic. On 25 February 2004, HAARP was operated near the third and passed through the second gyro-harmonic for the first time in a weakening ionosphere. Two novel observations are: firstly, a strong enhancement of the artificial optical emission intensity near the second gyro-harmonic, which is opposite to higher gyro-harmonics; secondly, the optical enhancement maximum occurs for frequencies just above the second gyro-harmonic. We provide the first experimental evidence for these effects, which have been predicted theoretically. In addition, irregular optical structures were created when the pump frequency was above the ionospheric critical frequency.

    Keywords. Active experiments – Auroral ionosphere – Wave-particle interactions

  1. Full investigation of the resonant frequency servo loop for resonator fiber-optic gyro.

    Science.gov (United States)

    Ma, Huilian; Lu, Xiao; Yao, Linzhi; Yu, Xuhui; Jin, Zhonghe

    2012-07-20

    Resonator fiber-optic gyro (RFOG) is a high-accuracy inertial rotation sensor based on the Sagnac effect. A high-accuracy resonant frequency servo loop is indispensable for a high-performance RFOG. It is composed of a frequency discriminator, a loop filter, and a laser actuator. Influences of the loop parameters are fully developed. Optimized loop parameters are obtained by considering the noise reduction and wide dynamic performance of the RFOG. As a result, with the integration time of 10 s, the accuracy of the resonant frequency loop is increased to 0.02 Hz (1σ). It is equivalent to a rotation rate of 0.067°/h, which is close to the shot noise limit for the RFOG, while a minimum rotation of ±0.05°/s has been carried out simultaneously. These are the best results reported to date, to the best of our knowledge, for an RFOG using the miniature semiconductor laser that benefits from the optimization of the resonant frequency servo-loop parameters.

  2. Temporal characterization of FEL micropulses as function of cavity length detuning using frequency-resolved optical gating

    Energy Technology Data Exchange (ETDEWEB)

    Richman, B.A. [Stanford Univ., CA (United States); DeLong, K.W.; Trebino, R. [Sandia National Lab., Livermore, CA (United States)

    1995-12-31

    Results of frequency resolved optical gating (FROG) measurements on the Stanford mid-IR FEL system show the effect of FEL cavity length detuning on the micropulse temporal structure. The FROG technique enables the acquisition of complete and uniquely invertible amplitude and phase temporal dependence of optical pulses. Unambiguous phase and amplitude profiles are recovered from the data. The optical pulses are nearly transform limited, and the pulse length increases with cavity length detuning.

  3. Effects of initial frequency chirp on the linear propagation characteristics of the exponential optical pulse

    Institute of Scientific and Technical Information of China (English)

    Zheng Hong-Jun; Liu Shan-Liang

    2006-01-01

    In this paper, the linear propagation characteristics of the exponential optical pulse with initial linear and nonlinear frequency chirp are numerically studied in a single mode fibre for β2< 0. It can be found that the temporal full width at half maximum and time-bandwidth product of exponential pulse monotonically increase with the increase of propagation distance and decrease with the increase of linear chirp C for C < 0.5, go through an initial decreasing stage near ζ = 1, then increase with the increase of propagation distance and linear chirp C for C ≥ 0.5. The broadening of pulses with negative chirp is faster than that with positive chirp. The exponential pulse with linear chirp gradually evolves into a near-Gaussian pulse. The effect of nonlinear chirp on waveform of the pulse is much greater than that of linear chirp. The temporal waveform breaking of exponential pulse with nonlinear chirp is first observed in linear propagation. Furthermore, the expressions of the spectral width and time-bandwidth product of the exponential optical pulse with the frequency chirp are given by use of the numerical analysis method.

  4. Polyimide-etalon all-optical ultrasound transducer for high frequency applications

    Science.gov (United States)

    Sheaff, Clay; Ashkenazi, Shai

    2014-03-01

    We have enhanced our design for an all-optical high frequency ultrasound transducer consisting of a UV-absorbing polyimide film integrated into an etalon receiver operating in the NIR range. A dielectric stack having high NIR reflectivity and high UV transmittance was chosen as the first mirror for increased sensitivity and the allowance of polyimide as the etalon medium. A 13 ns, 0.7 μJ optical pulse at 355 nm and a continuous-wave NIR laser were focused onto the structure with a spot diameter of 120 and 35 μm, respectively. In receive mode the etalon had a noise-equivalent pressure of 4.1 kPa over a bandwidth of 5 - 50 MHz (0.61 Pa/√Hz ). The device generated a pressure of 270 kPa at a depth of 200 μm, and the -3 dB bandwidth of the emission extended from 27 to 60 MHz. In transmit/receive mode, the pulse-echo had a center frequency of 35 MHz with a -6 dB bandwidth of 49 MHz (140 %). Lastly, wire targets were imaged by scanning the UV spot to create a synthetic aperture of transmitters centered upon a single receiver.

  5. Multipoint joint time and frequency dissemination in delay-stabilized fiber optic links.

    Science.gov (United States)

    Śliwczyński, Ł; Krehlik, P

    2015-03-01

    This paper presents the system for dissemination of both the RF frequency (e.g., 5, 10, or 100 MHz) and time (pulse per second) signals using an actively tapped fiber-optic link with electronic stabilization of the propagation delay. In principle several nodes for accessing the time/frequency signals may be added without the degradation of the dissemination in the main link. We are discussing the algorithm of determining the propagation delay from the local end of the link to the access node that is required for calibration of the time dissemination. Performed analysis shows that the uncertainty of the time calibration at the access node may in practice be dominated by the dependence of the propagation delay of the receivers on impinging optical powers and is only weakly affected by the distance between the local and access modules. The uncertainty is, however, still low, being only about two times higher compared with the calibration uncertainty of the main link. Experimental results performed on several spooled fibers show that the accuracy of described calibration procedures, expressed as a difference from the results of direct measurement, is not worse than 35 ps. PMID:25768810

  6. Ge Nanoislands Grown by Radio Frequency Magnetron Sputtering: Comprehensive Investigation of Surface Morphology and Optical Properties

    Directory of Open Access Journals (Sweden)

    Alireza Samavati

    2015-01-01

    Full Text Available The comprehensive investigation of the effect of growth parameters on structural and optical properties of Si-based single layer Ge nanoislands grown via Stranski-Krastanov mechanism employing radio frequency magnetron sputtering due to its high deposition rate, easy procedure, economical cost, and safety is carried out. The estimated width and height of Ge nanoislands produced by this technique are in the range of ∼8 to ∼30 and ∼2 to 8 nm, respectively. Varieties parameters are manipulated to optimize the surface morphology and structural and optical behavior of Ge nanoislands. The resulted nanoislands are analyzed using various analytical techniques including atomic force microscope, X-ray diffraction, energy dispersive X-ray spectroscopy, room temperature photoluminescence, and Raman spectroscopy. The optimum parameters for growing high quality samples having high number density and homogenous and small size distribution are found to be 400°C for substrate temperature, 300 sec for deposition time, 10 sccm for Ar flow, and 100 W for radio frequency power. The excellent features of the results suggest that our systematic investigation on the organized growth factors and their effects on surface parameters and photoluminescence emission energy may constitute a basis for the tunable growth of Ge nanoislands (100 nanoislands suitable in nanophotonics.

  7. High-Speed Microscale Optical Tracking Using Digital Frequency-Domain Multiplexing.

    Science.gov (United States)

    Maclachlan, Robert A; Riviere, Cameron N

    2009-06-01

    Position-sensitive detectors (PSDs), or lateral-effect photodiodes, are commonly used for high-speed, high-resolution optical position measurement. This paper describes the instrument design for multidimensional position and orientation measurement based on the simultaneous position measurement of multiple modulated sources using frequency-domain-multiplexed (FDM) PSDs. The important advantages of this optical configuration in comparison with laser/mirror combinations are that it has a large angular measurement range and allows the use of a probe that is small in comparison with the measurement volume. We review PSD characteristics and quantitative resolution limits, consider the lock-in amplifier measurement system as a communication link, discuss the application of FDM to PSDs, and make comparisons with time-domain techniques. We consider the phase-sensitive detector as a multirate DSP problem, explore parallels with Fourier spectral estimation and filter banks, discuss how to choose the modulation frequencies and sample rates that maximize channel isolation under design constraints, and describe efficient digital implementation. We also discuss hardware design considerations, sensor calibration, probe construction and calibration, and 3-D measurement by triangulation using two sensors. As an example, we characterize the resolution, speed, and accuracy of an instrument that measures the position and orientation of a 10 mm × 5 mm probe in 5 degrees of freedom (DOF) over a 30-mm cube with 4-μm peak-to-peak resolution at 1-kHz sampling.

  8. Cryogenic optical lattice clocks with a relative frequency difference of $1\\times 10^{-18}$

    CERN Document Server

    Ushijima, Ichiro; Das, Manoj; Ohkubo, Takuya; Katori, Hidetoshi

    2014-01-01

    Time and frequency are the most accurately measurable quantities, providing foundations for science and modern technologies. The accuracy relies on the SI (Syst\\'eme International) second that refers to Cs microwave clocks with fractional uncertainties at $10^{-16}$. Recent revolutionary progress of optical clocks aims to achieve $1\\times 10^{-18}$ uncertainty, which however has been hindered by long averaging-times or by systematic uncertainties. Here, we demonstrate optical lattice clocks with $^{87}$Sr atoms interrogated in a cryogenic environment to address the blackbody radiation-induced frequency-shift, which remains the primary source of clocks' uncertainties and has initiated vigorous theoretical and experimental investigations. The quantum-limited stability for $N \\sim 1,000$ atoms allows investigation of the uncertainties at $2\\times 10^{-18}$ in two hours of clock operation. After 11 measurements performed over a month, the two cryo-clocks agree to within $(-1.1\\pm 1.6)\\times 10^{-18}$. Besides its...

  9. High-Speed Microscale Optical Tracking Using Digital Frequency-Domain Multiplexing.

    Science.gov (United States)

    Maclachlan, Robert A; Riviere, Cameron N

    2009-06-01

    Position-sensitive detectors (PSDs), or lateral-effect photodiodes, are commonly used for high-speed, high-resolution optical position measurement. This paper describes the instrument design for multidimensional position and orientation measurement based on the simultaneous position measurement of multiple modulated sources using frequency-domain-multiplexed (FDM) PSDs. The important advantages of this optical configuration in comparison with laser/mirror combinations are that it has a large angular measurement range and allows the use of a probe that is small in comparison with the measurement volume. We review PSD characteristics and quantitative resolution limits, consider the lock-in amplifier measurement system as a communication link, discuss the application of FDM to PSDs, and make comparisons with time-domain techniques. We consider the phase-sensitive detector as a multirate DSP problem, explore parallels with Fourier spectral estimation and filter banks, discuss how to choose the modulation frequencies and sample rates that maximize channel isolation under design constraints, and describe efficient digital implementation. We also discuss hardware design considerations, sensor calibration, probe construction and calibration, and 3-D measurement by triangulation using two sensors. As an example, we characterize the resolution, speed, and accuracy of an instrument that measures the position and orientation of a 10 mm × 5 mm probe in 5 degrees of freedom (DOF) over a 30-mm cube with 4-μm peak-to-peak resolution at 1-kHz sampling. PMID:20428484

  10. Ultrastable optical frequency dissemination on a multi-access fibre network

    Science.gov (United States)

    Bercy, Anthony; Lopez, Olivier; Pottie, Paul-Eric; Amy-Klein, Anne

    2016-07-01

    We report a laboratory demonstration of the dissemination of an ultrastable optical frequency signal to two distant users simultaneously using a branching network. The ultrastable signal is extracted along a main fibre link; it is optically tracked by a narrow linewidth laser diode, which light is injected in a secondary link. The propagation noise of both links is actively compensated. We implement this scheme with two links of 50-km fibre spools, the extraction being set up at the mid-point of the main link. We show that the extracted signal at the end of the secondary link exhibits a fractional frequency instability of 1.4 × 10-15 at 1-s measurement time, almost equal to the 1.3 × 10-15 instability of the main link output end. The long-term instabilities are also very similar, at a level of 3-5 × 10-20 at 3 × 104-s integration time. We also show that the setting up of this extraction device, or of a simpler one, at the main link input, can test the proper functioning of the noise rejection on this main link. This work is a significant step towards a robust and flexible ultrastable network for multi-users dissemination.

  11. Ultra-stable optical frequency dissemination on a multi-access fibre network

    CERN Document Server

    Bercy, Anthony; Pottie, Paul-Eric; Amy-Klein, Anne

    2016-01-01

    We report the dissemination of an ultrastable optical frequency signal to two distant users simultaneously using a branching network. The ultrastable signal is extracted along a main fibre link; it is optically tracked with a narrow-linewidth laser diode, which light is injected in a secondary link. The propagation noise of both links is actively compensated. We implement this scheme with two links of 50-km fibre spools, the extraction being setup at the mid-point of the main link. We show that the extracted signal at the end of the secondary link exhibits fractional frequency instability of 1.4x10-15 at 1-s measurement time, almost equal to the 1.3x10-15 instability of the main link output end. The long-term instabilities are also very similar, at a level of 3-5x10-20 at 3x104-s integration time. We also show that the setting up of this extraction device, or a simpler one, at the main link input, can test the proper functioning of the noise rejection on this main link. This work is a significant step towards...

  12. Using a fourth-generation cavity enhanced spectrometer to isotopically investigate nitrous oxide emissions from biochar amended soils.

    Science.gov (United States)

    Grabenhofer, Jutta; Dercon, Gerd; Heiling, Maria; Mayr, Leo; Resch, Christian; Hood-Nowotny, Rebecca

    2016-04-01

    Research into the impacts of biochar on key processes in the nitrogen cycle is important to understand biochar's potential role in sustainable agriculture. There is conflicting evidence that biochar can reduce globally significant greenhouse gas emissions, especially N2O, one of the most important greenhouse gases in agriculture. However to date there is little information on the mechanisms involved. The source of N2O is dependent on the physical, chemical and biological status of the soil at a microbial scale and we need to understand how biochar influences it. Using the 15N2O gas flux method combined with gross rate measurements of nitrification and modelling, it should be possible to determine the parameters which drive N2O emissions and to evaluate the specific impact of biochar on these important N loss processes. To date the scope of isotopic studies on nitrous oxide emissions have been limited, due in part to technical and infrastructural access to complex and expensive mass spectrometry. With the advent of laser based systems these logistical and analytical constraints could be overcome and allow for a deeper and geographically more representative, understanding and assessment of the role of biochar in reducing nitrous oxide emissions from soil. In this study we have developed a simple method for investigated nitrous oxide emissions from soils amended with biochar, employing state of the art stable isotope techniques, using a fourth-generation cavity enhanced absorption technique a variant of conventional Cavity Ringdown Spectroscopy (CRDS) for measurement of isotopes of nitrous oxide. We will present methodologies used and results from these experiments, techniques that should path the way for a greater global understand nitrous oxide emissions from soils.

  13. Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser

    OpenAIRE

    Huang, Lin; Mills, Arthur K; Zhao, Yuan; Jones, David J.; Tang, Shuo

    2016-01-01

    We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 78...

  14. Semiconductor ring lasers with delayed optical feedback: low-frequency fluctuations

    Science.gov (United States)

    Van der Sande, Guy; Mashal, Lilia; Nguimdo, Romain Modeste; Cornelles-Soriano, Miguel C.; Danckaert, Jan; Verschaffelt, Guy

    2014-05-01

    Semiconductor lasers subject to external feedback are known to exhibit a wide variety of dynamical regimes desired for some applications such as chaos cryptography, random bit generation, and reservoir computing. Low-frequency fluctuations is one of the most frequently encountered regimes. It is characterized by a fast drop in laser intensity followed by a gradual recovery. The duration of this recovery process is irregular and of the order of hundred nanoseconds. The average time between dropouts is much larger than the laser system characteristic time-scales. Semiconductor ring lasers are currently the focus of a rapidly thriving research activity due to their unique feature of directional bistability. They can be employed in systems for all-optical switching, gating, wavelength-conversion functions, and all-optical memories. Semiconductor ring lasers do not require cleaved facets or gratings for optical feedback and are thus particularly suited for monolithic integration. We experimentally and numerically address the issue of low-frequency fluctuations considering a semiconductor ring laser in a feedback configuration where only one directional mode is re-injected into the same directional mode, a so-called single self-feedback. We have observed that the system is very sensitive to the feedback strength and the injection current. In particular, the power dropouts are more regular when the pump current is increased and become less frequent when the feedback strength is increased. In addition, we find two different recovery processes after the power dropouts of the low-frequency fluctuations. The recovery can either occur via pulses or in a stepwise manner. Since low-frequency fluctuations are not specific to semiconductor ring lasers, we expect these recovery processes to appear also in VCSELs and edge-emitting lasers under similar feedback conditions. The numerical simulations also capture these different behaviors, where the representation in the phase space of

  15. Frequency shifts in an optical lattice clock due to magnetic-dipole and electric-quadrupole transitions.

    Science.gov (United States)

    Taichenachev, A V; Yudin, V I; Ovsiannikov, V D; Pal'chikov, V G; Oates, C W

    2008-11-01

    We report a hitherto undiscovered frequency shift for forbidden J = 0-->J = 0 clock transitions excited in atoms confined to an optical lattice. These shifts result from magnetic-dipole and electric-quadrupole transitions, which have a spatial dependence in an optical lattice that differs from that of the stronger electric-dipole transitions. In combination with the residual translational motion of atoms in an optical lattice, this spatial mismatch leads to a frequency shift via differential energy level spacing in the lattice wells for ground state and excited state atoms. We estimate that this effect could lead to fractional frequency shifts as large as 10(-16), which might prevent lattice-based optical clocks from reaching their predicted performance levels. Moreover, these effects could shift the magic wavelength in lattice clocks in three dimensions by as much as 100 MHz, depending on the lattice configuration.

  16. Multi-service small-cell cloud wired/wireless access network based on tunable optical frequency comb

    Science.gov (United States)

    Xiang, Yu; Zhou, Kun; Yang, Liu; Pan, Lei; Liao, Zhen-wan; Zhang, Qiang

    2015-11-01

    In this paper, we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network (C-RAN) based on radio-over-fiber passive optical network (RoF-PON) system, which utilizes scalable multiple- frequency millimeter-wave (MF-MMW) generation based on tunable optical frequency comb (TOFC). In the baseband unit (BBU) pool, the generated optical comb lines are modulated into wired, RoF and WiFi/WiMAX signals, respectively. The multi-frequency RoF signals are generated by beating the optical comb line pairs in the small cell. The WiFi/WiMAX signals are demodulated after passing through the band pass filter (BPF) and band stop filter (BSF), respectively, whereas the wired signal can be received directly. The feasibility and scalability of the proposed multi-service wired/wireless integrated C-RAN are confirmed by the simulations.

  17. Optical characteristics for capacitively and inductively radio frequency discharge and post-discharge of helium

    Science.gov (United States)

    Tanışlı, Murat; Şahin, Neslihan

    2016-01-01

    The optical properties for radiofrequency (RF) post-discharge of pure helium (He) with two different methods as capacitively and inductively have been presented using the modified Boltzmann method in comparison. Optical emission spectroscopy (OES) is often used in the diagnosis of laboratory plasma, such as gas discharge plasma. OES is a very useful method for calculating of the electron temperature in the plasma and the determination of different atoms and molecules. In this study, OES is applied for characterizations of capacitively and inductively RF He plasma at pressures between 0.62 and 2.2 mbar for newly reactor type. Plasmas are generated with an RF power generator at a frequency of 13.56 MHz and output powers of 100, 160, and 200 W. Spectra have been evaluated in the range 200-1200 nm by an optical spectrometer. At low pressure, the main spectral features reported are the wavelengths of the atomic He transitions at 388.87 and 728.13 nm. The atomic emission intensities showed a maximum in inductive system when the pressure is about 0.62 mbar. OES of capacitive discharge and inductive discharge is compared in detail. The transition for 587.56 nm is shown to be increased in time.

  18. Asynchronous, all-optical signal processing based on the self-frequency shift of a gigahertz Raman soliton.

    Science.gov (United States)

    Kato, Masao; Fujiura, Kazuo; Kurihara, Takashi

    2005-03-10

    Ultrafast asynchronous all-optical signal processing is experimentally demonstrated. It is based on the intensity-dependent, self-frequency shift of a gigahertz Raman soliton. We demonstrate error-free, asynchronous, all-optical, bit-by-bit, self-signal recognition and demultiplexing from contended optical packets without use of an optical buffer, control pulse, or bit-phase synchronization. Fourfold, contended, 9.95-Gbit/s optical packets are transmitted through a conventional repeater span of 80 km and simultaneously demultiplexed to multiwavelength 9.95-Gbit/s optical packets with 0.5-dB processing sensitivity. Furthermore, we successfully accomplish demultiplexing from overlapping signals in contended optical packets with better than 3-dB recognition sensitivity. We confirm the capability of realizing a 3x cascade operation from bit-error-rate measurements.

  19. Observation of Rb Two-Photon Absorption Directly Excited by an Erbium-Fiber-Laser-Based Optical Frequency Comb via Spectral Control

    OpenAIRE

    Wu, Jiutao; Hou, Dong; Dai, Xiaoliang; Qin, Zhengyu; Zhang, Zhigang; Zhao, Jianye

    2013-01-01

    We demonstrated the observation of Rb two-photon absorption directly excided by an optical frequency comb at fiber communication bands. A chain of comb spectral control is elaborately implemented to increase the power of the second harmonic optical frequency comb generation and the two-photon transition strength. A two-photon transition spectrum is obtained with clearly resolved transition lines. It provides a potential approach to realize the optical frequency comb or optical clock at ~1.5{\\...

  20. Narrow linewidth laser system realized by linewidth transfer using a fiber-based frequency comb for the magneto-optical trapping of strontium.

    Science.gov (United States)

    Akamatsu, Daisuke; Nakajima, Yoshiaki; Inaba, Hajime; Hosaka, Kazumoto; Yasuda, Masami; Onae, Atsushi; Hong, Feng-Lei

    2012-07-01

    A narrow linewidth diode laser system at 689 nm is realized by phase-locking an extended cavity diode laser to one tooth of a narrow linewidth optical frequency comb. The optical frequency comb is phase-locked to a narrow linewidth laser at 1064 nm, which is frequency stabilized to a high-finesse optical cavity. We demonstrate the magneto-optical trapping of Sr using an intercombination transition with the developed laser system. PMID:22772290

  1. Fast Characterization of Dispersion and Dispersion Slope of Optical Fiber Links using Spectral Interferometry with Frequency Combs

    CERN Document Server

    Supradeepa, V R; Leaird, Daniel E; Weiner, Andrew M

    2009-01-01

    We demonstrate fast characterization (~1.4 microseconds) of both the dispersion and dispersion slope of long optical fiber links (~25 km) using dual quadrature spectral interferometry with an optical frequency comb. Compared to previous spectral interferometry experiments limited to fiber lengths of meters, the long coherence length and the periodic delay properties of frequency combs, coupled with fast data acquisition, enable spectral interferometric characterization of fibers longer by several orders of magnitude. We expect that our method will be useful to recently proposed lightwave techniques like coherent WDM and to coherent modulation formats by providing a real time monitoring capability for the link dispersion. Another area of application would be in stabilization of systems which perform frequency and timing distribution over long fiber links using stabilized optical frequency combs.

  2. Measurement of the Yb I $^1S_0 - ^1P_1$ transition frequency at 399 nm using an optical frequency comb

    CERN Document Server

    Kleinert, Michaela; Bergeson, Scott D

    2016-01-01

    We determine the frequency of the Yb I $^1S_0 - ^1P_1$ transition at 399 nm using an optical frequency comb. Although this transition was measured previously using an optical transfer cavity [D. Das et al., Phys. Rev. A 72, 032506 (2005)], recent work has uncovered significant errors in that method. We compare our result of 750 526 533.49 $\\pm$ 0.33 MHz for the Yb-174 isotope with those from the literature and discuss observed differences. We verify the correctness of our method by measuring the frequencies of well-known transitions in Rb and Cs, and by demonstrating proper control of systematic errors in both laser metrology and atomic spectroscopy. We also demonstrate the effect of quantum interference due to hyperfine structure in a divalent atomic system.

  3. Frequency measurement of THz waves by electro-optic sampling using Mach-Zehnder-modulator-based flat comb generator

    Science.gov (United States)

    Morohashi, Isao; Kirigaya, Mayu; Kaneko, Yuta; Katayama, Ikufumi; Sakamoto, Takahide; Sekine, Norihiko; Kasamatsu, Akifumi; Hosako, Iwao

    2016-02-01

    In the recent progress in terahertz (THz) devices, various kinds of source devices, such as resonant tunneling diodes, quantum cascade lasers and so forth, have been developed. Frequency measurement of THz radiations, which can operate in high speed and at room-temperature, is important for development of high-performance THz source devices. Recently, frequency measurement using optical combs are demonstrated by several groups. In these techniques, modelocked lasers (MLLs) are used for optical comb source, so that phase-locking techniques are required in order to stabilize the repetition frequency of the MLLs. On the other hand, a modulator-based optical comb generator has high accuracy and stability in the comb spacing, which is comparable to that of microwave signal driving the modulator. Thus it is suitable for frequency measurement of THz waves. In this paper, we demonstrated frequency measurement of THz waves using a Mach-Zehnder-modulator-based flat comb generator (MZ-FCG). The frequency measurement was carried out by an electro-optic (EO) sampling method, where an optical two-tone signal extracted from the optical comb generated by the MZ-FCG was used for the probe light. A 100 GHz signal generated by a W-band frequency multiplier and the probe beam collinearly traveled through an EO crystal, and beat signals between them were measured by a combination of a balanced photodetector and a spectrum analyzer. As a result, frequency measurement of the 100 GHz wave was successfully demonstrated, in which the linewidth of the beat signal was less than 1 Hz.

  4. Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry

    Science.gov (United States)

    2016-01-01

    Laser spectroscopy in the linear regime of radiation–matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

  5. Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry.

    Science.gov (United States)

    Gianfrani, Livio

    2016-03-28

    Laser spectroscopy in the linear regime of radiation-matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

  6. Direct comparison of two cold-atom-based optical frequency standards by using a femtosecond-laser comb.

    Science.gov (United States)

    Vogel, K R; Diddams, S A; Oates, C W; Curtis, E A; Rafac, R J; Itano, W M; Bergquist, J C; Fox, R W; Lee, W D; Wells, J S; Hollberg, L

    2001-01-15

    With a fiber-broadened, femtosecond-laser frequency comb, the 76-THz interval between two laser-cooled optical frequency standards was measured with a statistical uncertainty of 2x10(-13) in 5 s , to our knowledge the best short-term instability thus far reported for an optical frequency measurement. One standard is based on the calcium intercombination line at 657 nm, and the other, on the mercury ion electric-quadrupole transition at 282 nm. By linking this measurement to the known Ca frequency, we report a new frequency value for the Hg(+) clock transition with an improvement in accuracy of ~10(5) compared with its best previous measurement. PMID:18033520

  7. Low Power-Consumption and High Response Frequency Thermo-Optic Variable Optical Attenuators Based on Silicon-on-Insulator Materials

    Institute of Scientific and Technical Information of China (English)

    FANG Qing; CHEN Peng; XIN Hong-Li; WANG Chun-Xia; LI Fang; LIU Yu-Liang

    2005-01-01

    @@ A novel silicon-on-insulator thermo-optic variable optical attenuator with isolated grooves based on a multimode interference coupler principle is fabricated by the inductive coupled plasma etching technology. The maximum fibre-to-fibre insertion loss is lower than 2.2 dB, the dynamic attenuation range is from 0 to 30 dB in the wavelength range 1500-1600nm, and the maximum power consumption is only 140mW. The response frequency of the fabricated variable optical attenuator is about 30 kHz. Compared to the variable optical attenuator without isolated grooves, the maximum power consumption decreases more than 220mW, and the response frequency rises are more than 20kHz.

  8. Antireflection coating formed by plasma-enhanced chemical-vapor deposition for terahertz-frequency germanium optics

    Science.gov (United States)

    Hosako, Iwao

    2003-07-01

    A method of manufacturing optical coatings for germanium optics used at terahertz frequencies has been developed. The various optical coatings used at terahertz frequencies are difficult to manufacture conventionally because these coatings must be as thick as several tens of micrometers, which is far thicker than those used in the optical region. One way to overcome this problem is to form a silicon oxide layer through plasma-enhanced chemical-vapor deposition, with silane (SiH4) as a source gas. Using this method, I formed 21-μm-thick silicon oxide films as antireflection (AR) layers for germanium optics and obtained low reflection at 1.7 THz (wavelength, λ = 175 μm). This method is easily applied to large-aperture optics and micro-optics as well as to optics with a complex surface form. The AR coatings can also be formed for photoconductive detectors made from germanium doped with gallium at a low temperature (160 °C) this low temperature ensures that the doped impurities in the germanium do not diffuse. Fabrication of optical coatings upon substrates that have refractive indices of 3.84-11.7 may also be possible by control of the refractive indices of the deposited layers.

  9. Optical Frequency Mixing in Periodically-Patterned and in Quasi-Periodically-Patterned Nonlinear media

    International Nuclear Information System (INIS)

    Nonlinear frequency mixing processes, e.g. second harmonic generation, sum and difference frequency generation, etc., require matching of the phases of the interacting waves. The traditional method to achieve it is by selecting a specific angle of propagation in a birefringent nonlinear crystal. The main limitation of the birefringent phase matching method stems from the fact that for many interesting interactions, the phase matching condition cannot be satisfied in a specific crystal. This obstacle can be removed by the technique of quasi-phase-matching (QPM), where the nonlinear coefficient of the material is modulated at a fixed spatial frequency that equals the wave-vector phase mismatch between the interacting waves. An important development in recent years is the ability to periodically reverse the sign of the nonlinear coefficient in ferroelectric crystals by applying a high electric field through a periodic electrode. Some recent QPM interactions in periodically-poled KTP that were recently achieved at Tel-Aviv University include continuous-wave optical parametric oscillations, as well as generation of tunable mid-infrared radiation by difference frequency generation. Periodic patterning of the nonlinear coefficient enables to phase match only a single interaction. It would be advantageous to further extend the applications of this technique in order to simultaneously satisfy several interactions on a single crystal. This cannot be usually achieved in a periodic pattern, however more sophisticated quasi-periodic structures can be designed in this case. An interesting analogy can be drawn between artificially-made quasi-periodically-patterned nonlinear crystals and quasi-crystals found in nature, in rapidly-cooled metallic alloys

  10. A stabilized 18 GHz chip-scale optical frequency comb at 2.8x10-16 relative inaccuracy

    CERN Document Server

    Huang, S -W; Yu, M; McGuyer, B H; Kwong, D -L; Zelevinsky, T; Wong, C W

    2015-01-01

    Optical frequency combs, coherent light sources that connect optical frequencies with microwave oscillations, have become the enabling tool for precision spectroscopy, optical clockwork and attosecond physics over the past decades. Current benchmark systems are self-referenced femtosecond mode-locked lasers, but four-wave-mixing in high-Q resonators have emerged as alternative platforms. Here we report the generation and full stabilization of CMOS-compatible optical frequency combs. The spiral microcomb's two degrees-of-freedom, one of the comb line and the native 18 GHz comb spacing, are first simultaneously phase-locked to known optical and microwave references. Second, with pump power control, active comb spacing stabilization improves the long-term stability by six orders-of-magnitude, reaching an instrument-limited 3.6 mHz/sqrt(t) residual instability. Third, referencing thirty-three of the nitride frequency comb lines against a fiber comb, we demonstrate the comb tooth-to-tooth frequency relative inaccu...

  11. Optical frequency comb spectroscopy at 3-5.4 {\\mu}m with a doubly resonant optical parametric oscillator

    CERN Document Server

    Khodabakhsh, Amir; Rutkowski, Lucile; Johansson, Alexandra C; Lee, Kevin F; Jiang, Jie; Mohr, Christian; Fermann, Martin E; Foltynowicz, Aleksandra

    2016-01-01

    We present a versatile mid-infrared frequency comb spectroscopy system based on a doubly resonant optical parametric oscillator tunable in the 3-5.4 {\\mu}m range and two detection methods, a Fourier transform spectrometer (FTS) and a Vernier spectrometer. Using the FTS with a multipass cell we measure high-precision broadband absorption spectra of CH$_4$ and NO at ~3.3 {\\mu}m and ~5.2 {\\mu}m, respectively, and of atmospheric species (CH$_4$, CO, CO$_2$ and H$_2$O) in air in the signal and idler wavelength range. The figure of merit of the system is on the order of 10$^{-8}$ cm$^{-1}$ Hz$^{-1/2}$ per spectral element, and multiline fitting yields minimum detectable concentrations of 10-20 ppb Hz$^{-1/2}$ for CH$_4$, NO and CO. For the first time in the mid-infrared, we perform continuous-filtering Vernier spectroscopy using a low finesse enhancement cavity, a grating and a single detector, and measure the absorption spectrum of CH$_4$ and H$_2$O in ambient air at ~3.3 {\\mu}m.

  12. Real-time locating and speed measurement of fibre fuse using optical frequency-domain reflectometry

    Science.gov (United States)

    Jiang, Shoulin; Ma, Lin; Fan, Xinyu; Wang, Bin; He, Zuyuan

    2016-05-01

    We propose and experimentally demonstrate real-time locating and speed measurement of fibre fuse by analysing the Doppler shift of reflected light using optical frequency-domain reflectometry (OFDR). Our method can detect the start of a fibre fuse within 200 ms which is equivalent to a propagation distance of about 10 cm in standard single-mode fibre. We successfully measured instantaneous speed of propagating fibre fuses and observed their subtle fluctuation owing to the laser power instability. The resolution achieved for speed measurement in our demonstration is 1 × 10‑3 m/s. We studied the fibre fuse propagation speed dependence on the launched power in different fibres. Our method is promising for both real time fibre fuse monitoring and future studies on its propagation and termination.

  13. In Situ Frequency Measurement of Inidividual Nanostructures Using Fiber Optical Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Duden, Thomas; Duden, Thomas; Radmilovic, Velimir

    2008-07-01

    In this paper we describe a setup for the resonance frequency measurement of nanocantilevers, which displays both high spatial selectivity and sensitivity to specimen vibrations by utilizing a tapered uncoated fiber tip. The spatial selectivity is determined by the tip geometry, the high sensitivity to vibrations stems from interference of wave fronts reflected on the specimen and on the fiber tip itself. No reference plane on the specimen is needed, as demonstrated with the example of a freestanding silicon nitride cantilever. The resulting system is integrated in the DB-235 dual beam FIB system, thus allowing the measurement of sample responses in-situ, during observation in SEM mode. By combining optical interferometry and narrow band RF amplification and detection, we demonstrate an exceptional vibrational sensitivity at high spatial resolution.

  14. Ptychographic reconstruction algorithm for frequency resolved optical gating: super-resolution and supreme robustness

    CERN Document Server

    Sidorenko, Pavel; Avnat, Zohar; Cohen, Oren

    2016-01-01

    Frequency-resolved optical gating (FROG) is probably the most popular technique for complete characterization of ultrashort laser pulses. In FROG, a reconstruction algorithm retrieves the pulse from a measured spectrogram, yet current FROG reconstruction algorithms require and exhibit several restricting features that weaken FROG performances. For example, the delay step must correspond to the spectral bandwidth measured with large enough SNR a condition that limits the temporal resolution of the reconstructed pulse, obscures measurements of weak broadband pulses, and makes measurement of broadband mid-IR pulses hard and slow because the spectrograms become huge. We develop a new approach for FROG reconstruction, based on ptychography (a scanning coherent diffraction imaging technique), that removes many of the algorithmic restrictions. The ptychographic reconstruction algorithm is significantly faster and more robust to noise than current FROG algorithms, which are based on generalized projections (GP). We d...

  15. Second-harmonic mode coupling in microresonator-based optical frequency comb generation

    CERN Document Server

    Xue, Xiaoxiao; Xuan, Yi; Jaramillo-Villegas, Jose A; Wang, Pei-Hsun; Leaird, Daniel E; Erkintalo, Miro; Qi, Minghao; Weiner, Andrew M

    2016-01-01

    Microresonator-based optical frequency comb (microcomb) generation can potentially achieve ultra-compact volume and low power consumption for portable applications. The comb formation is a consequence of cascaded four-wave-mixing due to the third-order Kerr nonlinearity. Mode coupling can affect the comb self-starting and mode-locking behaviors, resulting in complex dynamics that is far from well understood. Understanding the mechanism of mode coupling in comb generation proves highly important to achieve stable and robust microcomb sources. Here, we report a nonlinear mode coupling mechanism in microresonators with simultaneous second- and third-order nonlinearities. The nonlinear dynamics governed by the third-order nonlinearity is altered by second-harmonic mode coupling. As a demonstration of this effect, second-harmonic assisted coherent comb generation is achieved in the normal dispersion region, where comb creation is prohibited in the absence of mode coupling. Since second-order nonlinearity has been ...

  16. Real-time locating and speed measurement of fibre fuse using optical frequency-domain reflectometry.

    Science.gov (United States)

    Jiang, Shoulin; Ma, Lin; Fan, Xinyu; Wang, Bin; He, Zuyuan

    2016-01-01

    We propose and experimentally demonstrate real-time locating and speed measurement of fibre fuse by analysing the Doppler shift of reflected light using optical frequency-domain reflectometry (OFDR). Our method can detect the start of a fibre fuse within 200 ms which is equivalent to a propagation distance of about 10 cm in standard single-mode fibre. We successfully measured instantaneous speed of propagating fibre fuses and observed their subtle fluctuation owing to the laser power instability. The resolution achieved for speed measurement in our demonstration is 1 × 10(-3) m/s. We studied the fibre fuse propagation speed dependence on the launched power in different fibres. Our method is promising for both real time fibre fuse monitoring and future studies on its propagation and termination. PMID:27146550

  17. Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Longfang [School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA 5005 (Australia); Department of Electrical and Electronic Engineering, The University of Bristol, Bristol, BS8 1TH (United Kingdom); López-García, Martin; Oulton, Ruth; Klemm, Maciej [Department of Electrical and Electronic Engineering, The University of Bristol, Bristol, BS8 1TH (United Kingdom); Withayachumnankul, Withawat; Fumeaux, Christophe, E-mail: christophe.fumeaux@adelaide.edu.au [School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA 5005 (Australia); Shah, Charan M.; Mitchell, Arnan; Bhaskaran, Madhu; Sriram, Sharath [Functional Materials and Microsystems Research Group, School of Electrical and Computer Engineering, RMIT University, Melbourne VIC 3001 (Australia)

    2014-11-10

    The capability of manipulating light at subwavelength scale has fostered the applications of flat metasurfaces in various fields. Compared to metallic structure, metasurfaces made of high permittivity low-loss dielectric resonators hold the promise of high efficiency by avoiding high conductive losses of metals at optical frequencies. This letter investigates the spectral and angular characteristics of a dielectric resonator metasurface composed of periodic sub-arrays of resonators with a linearly varying phase response. The far-field response of the metasurface can be decomposed into the response of a single grating element (sub-array) and the grating arrangement response. The analysis also reveals that coupling between resonators has a non-negligible impact on the angular response. Over a wide wavelength range, the simulated and measured angular characteristics of the metasurface provide a definite illustration of how different grating diffraction orders can be selectively suppressed or enhanced through antenna sub-array design.

  18. Tunable femtosecond laser in the visible range with an intracavity frequency-doubled optical parametric oscillator

    Science.gov (United States)

    Zhu, Jiang-Feng; Xu, Liang; Lin, Qing-Feng; Zhong, Xin; Han, Hai-Nian; Wei, Zhi-Yi

    2013-05-01

    We demonstrated experimentally a synchronously pumped intracavity frequency-doubled femtosecond optical parametric oscillator (OPO) using a periodically-poled lithium niobate (PPLN) as the nonlinear material in combination with a lithium triborate (LBO) as the doubling crystal. A Kerr-lens-mode-locked (KLM) Ti:sapphire oscillator at the wavelength of 790 nm was used as the pump source, which was capable of generating pulses with a duration as short as 117 fs. A tunable femtosecond laser covering the 624-672 nm range was realized by conveniently adjusting the OPO cavity length. A maximum average output power of 260 mW in the visible range was obtained at the pump power of 2.2 W, with a typical pulse duration of 205 fs assuming a sech2 pulse profile.

  19. Channel estimation for asymmetrically clipped optical orthogonal frequency division multiplexing communication system

    Science.gov (United States)

    Zhao, Hui; Li, Minghui; Wang, Ruyan; Wu, Dapeng

    2013-07-01

    The channel estimation problem for asymmetrically clipped optical orthogonal frequency division multiplexing wireless communication systems is investigated. In order to resolve the noise-sensitive problem of traditional least squares-based channel estimation method, a new channel estimation method which is based on superimposed training sequence and guarantees the linear minimum mean square error estimate is proposed. Cycle training sequence is added at variable power ratio to the information sequence at the transmitter prior to transmission. Then, statistical average method is employed to separate training and information sequences at the receiver. Simulation results show that the power ratio of training sequence needs to balance between the mean square error (MSE) of estimation and the error bit rate. Moreover, compared with the traditional least squares-based method, the proposed method has significantly improved the estimation performance under the condition of low signal-to-noise ratio, especially, when the MSE of the estimation reduces 1 to 2 orders.

  20. Optical Time-Frequency Packing: Principles, Design, Implementation, and Experimental Demonstration

    CERN Document Server

    Secondini, Marco; Fresi, Francesco; Meloni, Gianluca; Cavaliere, Fabio; Colavolpe, Giulio; Forestieri, Enrico; Potì, Luca; Sabella, Roberto; Prati, Giancarlo

    2014-01-01

    Time-frequency packing (TFP) transmission provides the highest achievable spectral efficiency with a constrained modulation format and detector complexity. In this work, the application of the TFP technique to fiber-optic systems is investigated and experimentally demonstrated. The main theoretical aspects, design guidelines, and implementation issues are discussed, focusing on those aspects which are peculiar to TFP systems. In particular, adaptive compensation of propagation impairments, matched filtering, and maximum a posteriori probability detection are obtained by a combination of a butterfly equalizer and four low-complexity parallel Bahl-Cocke-Jelinek-Raviv (BCJR) detectors. A novel algorithm that ensures adaptive equalization, channel estimation, and a proper distribution of tasks between the equalizer and BCJR detectors is proposed. A set of irregular low-density parity-check codes with different rates is designed to operate at low error rates and approach the spectral efficiency limit achievable by...

  1. A new Generation of Spectrometer Calibration Techniques based on Optical Frequency Combs

    CERN Document Server

    Schmidt, Piet O; Kimeswenger, Stefan

    2007-01-01

    Typical astronomical spectrographs have a resolution ranging between a few hundred to 200.000. Deconvolution and correlation techniques are being employed with a significance down to 1/1000 th of a pixel. HeAr and ThAr lamps are usually used for calibration in low and high resolution spectroscopy, respectively. Unfortunately, the emitted lines typically cover only a small fraction of the spectrometer's spectral range. Furthermore, their exact position depends strongly on environmental conditions. A problem is the strong intensity variation between different (intensity ratios {>300). In addition, the brightness of the lamps is insufficient to illuminate a spectrograph via an integrating sphere, which in turn is important to calibrate a long-slit spectrograph, as this is the only way to assure a uniform illumination of the spectrograph pupil. Laboratory precision laser spectroscopy has experienced a major advance with the development of optical frequency combs generated by pulsed femto-second lasers. These lase...

  2. Time-and-frequency domains approach to data processing in multiwavelength optical scatterometry of dielectric gratings

    KAUST Repository

    Granet, Gérard

    2013-01-01

    This paper focuses on scatterometry problems arising in lithography production of periodic gratings. Namely, the paper introduces a theoretical and numerical-modeling-oriented approach to scatterometry problems and discusses its capabilities. The approach allows for reliable detection of deviations in gratings\\' critical dimensions (CDs) during the manufacturing process. The core of the approach is the one-to-one correspondence between the electromagnetic (EM) characteristics and the geometric/material properties of gratings. The approach is based on highly accurate solutions of initial boundary-value problems describing EM waves\\' interaction on periodic gratings. The advantage of the approach is the ability to perform simultaneously and interactively both in frequency and time domains under conditions of possible resonant scattering of EM waves by infinite or finite gratings. This allows a detection of CDs for a wide range of gratings, and, thus is beneficial for the applied scatterometry. (C) 2013 Optical Society of America

  3. Diffusion optical spectroscopy of cancerous and normal prostate tissues in time-resolved and frequency domain

    Science.gov (United States)

    Zhou, Kenneth J.; Pu, Yang; Chen, Jun

    2014-03-01

    It is well-known that light transport can be well described using Maxwell's electromagnetic theory. In biological tissue, the scattering particles cause the interaction of scattered waves from neighboring particles. Since such interaction cannot be ignored, multiple scattering occurs. The theoretical solution of multiple scattering is complicated. A suitable description is that the wavelike behavior of light is ignored and the transport of an individual photon is considered to be absorbed or scattered. This is known as the Radiative Transfer Equation (RTE) theory. Analytical solutions to the RTE that explicitly describes photon migration can be obtained by introducing some proper approximations. One of the most popular models used in the field of tissue optics is the Diffusion Approximation (DA). In this study, we report on the results of our initial study of optical properties of ex vivo normal and cancerous prostate tissues and how tissue parameters affect the near infrared light transporting in the two types of tissues. The time-resolved transport of light is simulated as an impulse isotropic point source of energy within a homogeneous unbounded medium with different absorption and scattering properties of cancerous and normal prostate tissues. Light source is also modulated sinusoidally to yield a varied fluence rate in frequency domain at a distant observation point within the cancerous and normal prostate tissues. Due to difference of the absorption and scattering coefficients between cancerous and normal tissues, the expansion of light pulse, intensity, phase are found to be different.

  4. Reversibly Stretchable, Optically Transparent Radio-Frequency Antennas Based on Wavy Ag Nanowire Networks.

    Science.gov (United States)

    Kim, Byoung Soo; Shin, Keun-Young; Pyo, Jun Beom; Lee, Jonghwi; Son, Jeong Gon; Lee, Sang-Soo; Park, Jong Hyuk

    2016-02-01

    We report a facile approach for producing reversibly stretchable, optically transparent radio-frequency antennas based on wavy Ag nanowire (NW) networks. The wavy configuration of Ag NWs is obtained by floating the NW networks on the surface of water, followed by compression. Stretchable antennas are prepared by transferring the compressed NW networks onto elastomeric substrates. The resulting antennas show excellent performance under mechanical deformation due to the wavy configuration, which allows the release of stress applied to the NWs and an increase in the contact area between NWs. The antennas formed from the wavy NW networks exhibit a smaller return loss and a higher radiation efficiency when strained than the antennas formed from the straight NW networks, as well as an improved stability in cyclic deformation tests. Moreover, the wavy NW antennas require a relatively small quantity of NWs, which leads to low production costs and provides an optical transparency. These results demonstrate the potential of these wavy Ag NW antennas in applications of wireless communications for wearable systems.

  5. Frequency-swept coherently detected spectral amplitude code for flexible implicit optical label switching

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Cao; Fushen Chen; Zhigao Yang

    2011-01-01

    A new optical label switching system with coherently detected implicit spectral amplitude code(SAC)labels is proposed in this letter.The implicit SAC labels are recognized using a frequency-swept local light source oscillator.Intensity modulation payloads of 625 Mb/s and 1.25 Gb/s are considered.Label and pavload bit error rate(BER) performances are assessed and compared by simulations.The results reveal that,at a BER value of 10-9,-32.4dBm label received power can be obtained.In addition,8.3-dB optical signal-to-noise ratio(OSNR) is obtained when carrying a payload of 625 Mb/s.The label BER value hardly reaches 10-9 if the payload bit rate is at 1.25 Gb/s; however,a high payload bit rate only has little influence on received payload quality at a BER value of 10-9.Finally,a payload of 1.25 Gb/s could obtain-28.2 dBm received power and 9.5-dB OSNR.

  6. System design and image processing algorithms for frequency domain optical coherence tomography in the coronary arteries

    Science.gov (United States)

    Adler, Desmond C.; Xu, Chenyang; Petersen, Christopher; Schmitt, Joseph M.

    2010-02-01

    We report on the design of a frequency domain optical coherence tomography (FD-OCT) system, fiber optic imaging catheter, and image processing algorithms for in vivo clinical use in the human coronary arteries. This technology represents the third generation of commercially-available OCT system developed at LightLab Imaging Inc. over the last ten years, enabling three-dimensional (3D) intravascular imaging at unprecedented speeds and resolutions for a commercial system. The FD-OCT engine is designed around an exclusively licensed micro-cavity swept laser that was co-developed with AXSUN Technologies Ltd. The laser's unique combination of high sweep rates, broad tuning ranges, and narrow linewidth enable imaging at 50,000 axial lines/s with an axial resolution of lumen dimensions, stent malapposition, and neointimal thickness. This system has been used in over 2000 procedures since August 2007 at over 40 clinical sites, providing cardiologists with an advanced tool for 3D assessment of the coronary arteries.

  7. Suppression of optical beat interference-noise in orthogonal frequency division multiple access-passive optical network link using self-homodyne balanced detection

    Science.gov (United States)

    Won, Yong-Yuk; Jung, Sang-Min; Han, Sang-Kook

    2014-08-01

    A new technique, which reduces optical beat interference (OBI) noise in orthogonal frequency division multiple access-passive optical network (OFDMA-PON) links, is proposed. A self-homodyne balanced detection, which uses a single laser for the optical line terminal (OLT) as well as for the optical network unit (ONU), reduces OBI noise and also improves the signal to noise ratio (SNR) of the discrete multi-tone (DMT) signal. The proposed scheme is verified by transmitting quadrature phase shift keying (QPSK)-modulated DMT signal over a 20-km single mode fiber. The optical signal to noise ratio (OSNR), that is required for BER of 10-5, is reduced by 2 dB in the balanced detection compared with a single channel due to the cancellation of OBI noise in conjunction with the local laser.

  8. Stabilization and frequency control of a DFB laser with a tunable optical reflector integrated in a Silicon Photonics PIC

    CERN Document Server

    Hauck, Johannes; Romero-García, Sebastían; Müller, Juliana; Shen, Bin; Richter, Jens; Merget, Florian; Witzens, Jeremy

    2016-01-01

    We investigate the effect of tunable optical feedback on a commercial DFB laser edge coupled to a Silicon Photonics planar integrated circuit in which a tunable reflector has been implemented by means of a ring resonator based add-drop multiplexer. Controlled optical feedback allows for fine-tuning of the laser oscillation frequency. Under certain conditions it also allows suppression of bifurcation modes triggered by reflections occurring elsewhere on the chip. A semi-analytical model describing laser dynamics under combined optical feedback from the input facet of the edge coupler and from the tunable on-chip reflector fits the measurements. Compensation of detrimental effects from reflections induced elsewhere on a transceiver chip may allow moving isolators downstream in future communications systems, facilitating direct hybrid laser integration in Silicon Photonics chips, provided a suitable feedback signal for a control system can be identified. Moreover, the optical frequency tuning at lower feedback l...

  9. Magnetometric sensitivity optimization for nonlinear optical rotation with frequency-modulated light: rubidium D2 line

    CERN Document Server

    Kimball, D F Jackson; Guttikonda, Srikanth; Bahr, Eric J; Chan, Lok Fai

    2009-01-01

    Coherence between ground-state Zeeman sublevels of alkali atoms can survive thousands of collisions with paraffin-coated cell walls. The resulting long coherence times achieved in evacuated, paraffin-coated cells enable precise measurement of energy shifts of ground-state Zeeman sublevels. In the present work, nonlinear magneto-optical rotation with frequency-modulated light (FM NMOR) is used to measure ground-state Zeeman shifts for rubidium atoms contained in a paraffin-coated cell. The magnetometric sensitivity of FM NMOR for the rubidium D2 line is studied as a function of light power, detuning, frequency-modulation amplitude, and rubidium vapor density. For a 5-cm diameter cell at temperature 35 degrees C, the optimal shot-noise-projected magnetometric sensitivity is found to be ~ 2 x 10^{-11} G/Hz^{1/2} (corresponding to a sensitivity to Zeeman shifts of ~ 10 microHz/Hz^{1/2} or ~ 4 x 10^{-20} eV/Hz^{1/2}).

  10. Frequency-resolved optical gating for complete reconstruction of attosecond bursts : FROG CRAB

    International Nuclear Information System (INIS)

    Full text: We will show that when an atom is ionized by an XUV pulse in the presence of a low frequency laser field, this laser field acts as an ultrafast electron phase modulator on the electron wave-packet generated in the continuum. This phase modulator has a very large bandwidth and enables to transpose the most efficient techniques used for the temporal characterization of femtosecond pulses - such as SPIDER, FROG, or chronocyclic tomography - to attosecond fields, via continuum electron wave-packets replicas of these fields. We will then detail some of the attosecond metrology techniques derived from this general principle. We will especially insist on a recently proposed technique, FROG CRAB, which allows the complete temporal characterization of arbitrarily complex attosecond fields. FROG CRAB is direct transposition of Frequency-Resolved Optical Gating to attosecond electron wave-packets, using a femtosecond laser pulse as a phase gate. All the experimental tools for the implementation of CRAB are available. Besides its technical interest, CRAB establishes a direct connection between the main attosecond characterization techniques demonstrated experimentally so far, and considerably extends their scope, thus providing a general perspective on attosecond metrology. Refs. 2 (author)

  11. ELSTAB-Fiber-Optic Time and Frequency Distribution Technology: A General Characterization and Fundamental Limits.

    Science.gov (United States)

    Krehlik, Przemyslaw; Sliwczynski, Lukasz; Buczek, Lukasz; Kolodziej, Jacek; Lipinski, Marcin

    2016-07-01

    In this paper, we present an overview of the electronically stabilized (thus named ELSTAB) fiber-optic time and frequency (T&F) distribution system based on our idea of using variable electronic delay lines as compensating elements. Various extensions of the basic system, allowing building a long-haul, multiuser network are described. The fundamental limitations of the method arising from fiber chromatic dispersion and system dynamics are discussed. We briefly characterize the main hardware challenge of the system, which is the design of a pair of low-noise, precisely matched delay lines. Finally, we present experimental results with T&F distribution over up to 615 km of fiber, where we demonstrate frequency stability in the range of 1-7 ×10(-17) for 10(5) s averaging and time calibration with accuracy well below 50 ps. Also, practical implementation of the ELSTAB in the Polish T&F distribution network is shown. PMID:26599816

  12. Integrated wideband optical frequency combs with high stability and their application in microwave photonic filters

    Science.gov (United States)

    Sun, Wenhui; Wang, Sunlong; Zhong, Xin; Liu, Jianguo; Wang, Wenting; Tong, Youwan; Chen, Wei; Yuan, Haiqing; Yu, Lijuan; Zhu, Ninghua

    2016-08-01

    An integrated wideband optical frequency comb (OFC) based on a semiconductor quantum dot laser is realized with high stability. The OFC module is packaged in our lab. A circuit which is designed to provide a low-ripple current and control the temperature regards as a servo system to enhance the stability of the OFC. The frequency stability of the OFC is 2.7×10-9 (Allan Variance). The free spectral range (FSR) of the OFC is 40 GHz and the number of comb lines is up to 55. The flatness of the OFC over span of 4 nm can be limited to 0.5 dB. Negative coefficients microwave photonic filters with multiple taps are generated based on the proposed OFC. For the 10 taps microwave photonic filter, the pass-band at 8.74 GHz has a 3 dB bandwidth of 630 MHz with 16.58 dB side-lobe suppression. Compared with the published microwave photonic filters, the proposed system is more stable, of more compact structures, and of less power consumption.

  13. Frequency dispersion of the first hyperpolarizabilities of reference molecules for nonlinear optics

    Energy Technology Data Exchange (ETDEWEB)

    Wergifosse, Marc de; Champagne, Benoît [Laboratoire de Chimie Théorique, Unité de Chimie Physique Théorique et Structurale, Université de Namur, rue de Bruxelles, 61, B-5000 Namur (Belgium); Castet, Frédéric [Institut des Sciences Moléculaires (ISM, UMR 5255 CNRS), Université de Bordeaux, 351 Cours de la Libération, F-33405 Talence Cedex (France)

    2015-05-21

    The frequency dispersion of the hyper-Rayleigh scattering first hyperpolarizabilities (β{sub HRS}) of five reference molecules for nonlinear optics, namely, carbon tetrachloride, chloroform, dichloromethane, acetonitrile, and trichloroacetonitrile, is described using the coupled-cluster singles and doubles quadratic response function (CCSD-QRF) as well as approximate schemes. Comparisons to approximate schemes in which the frequency dispersion is evaluated as either a multiplicative or an additive correction to the static hyperpolarizability yield the following observations: (i) errors of the order of 10% or less are usually encountered when using the multiplicative scheme for photon energies far from the lowest dipole-allowed excitation energies, (ii) spurious cases cannot be excluded as evidenced by carbon tetrachloride where the multiplicative scheme predicts a decrease of β{sub HRS} in contradiction to the increase obtained using the CCSD-QRF method, and (iii) the additive scheme is at best as reliable as the multiplicative approximation. The two-state approximation presents the advantage of correcting the wrong behavior of the additive and multiplicative schemes for carbon tetrachloride, but it is not an improved solution for the other compounds, while the question of selecting the appropriate dominant excited state remains unanswered. Finally, a new β{sub xyz} value of 18.9 a.u. is proposed for carbon tetrachloride in gas phase at λ = 1064 nm, to be compared with the measured 16.9 ± 1.4 a.u. value due to Shelton.

  14. Blood optical properties at various glucose level values in THz frequency range

    Science.gov (United States)

    Gusev, S. I.; Borovkova, M. A.; Strepitov, M. A.; Khodzitsky, M. K.

    2015-07-01

    the patients. Most biomolecules have characteristic signature frequencies in the terahertz (THz) range, which can reveal their presence and determine the concentration. Therefore, this paper is intended to study the blood optical properties in the THz frequency range in order to determine THz radiation effect on blood. The main aim of this investigation is to determine the effect of blood glucose concentration on the blood optical properties. In the case if blood optical properties vary at different glucose concentrations having a proportional relationship between them, these results will confirm the possibility of development of non-invasive procedures for blood glucose level diagnostics.

  15. Quasiphasematched concurrent nonlinearities in periodically poled KTiOPO_4 for quantum computing over the optical frequency comb

    CERN Document Server

    Pysher, Matthew; Peng, Peng; Arie, Ady; Pfister, Olivier

    2009-01-01

    We report the successful design and experimental implementation of three coincident nonlinear interactions, namely ZZZ ("type-0''), ZYY (type-I), and YYZ/YZY (type-II) second harmonic generation of 780 nm light from a 1560 nm pump beam in a single, multigrating, periodically poled KTiOPO_4 crystal. The resulting nonlinear medium is the key component for making a scalable quantum computer over the optical frequency comb of a single optical parametric oscillator.

  16. On the performance of joint iterative detection and decoding in coherent optical channels with laser frequency fluctuations

    Science.gov (United States)

    Castrillón, Mario A.; Morero, Damián A.; Agazzi, Oscar E.; Hueda, Mario R.

    2015-08-01

    The joint iterative detection and decoding (JIDD) technique has been proposed by Barbieri et al. (2007) with the objective of compensating the time-varying phase noise and constant frequency offset experienced in satellite communication systems. The application of JIDD to optical coherent receivers in the presence of laser frequency fluctuations has not been reported in prior literature. Laser frequency fluctuations are caused by mechanical vibrations, power supply noise, and other mechanisms. They significantly degrade the performance of the carrier phase estimator in high-speed intradyne coherent optical receivers. This work investigates the performance of the JIDD algorithm in multi-gigabit optical coherent receivers. We present simulation results of bit error rate (BER) for non-differential polarization division multiplexing (PDM)-16QAM modulation in a 200 Gb/s coherent optical system that includes an LDPC code with 20% overhead and net coding gain of 11.3 dB at BER = 10-15. Our study shows that JIDD with a pilot rate ⩽ 5 % compensates for both laser phase noise and laser frequency fluctuation. Furthermore, since JIDD is used with non-differential modulation formats, we find that gains in excess of 1 dB can be achieved over existing solutions based on an explicit carrier phase estimator with differential modulation. The impact of the fiber nonlinearities in dense wavelength division multiplexing (DWDM) systems is also investigated. Our results demonstrate that JIDD is an excellent candidate for application in next generation high-speed optical coherent receivers.

  17. Two-way optical frequency comparisons at 5 ×10-21 relative stability over 100-km telecommunication network fibers

    Science.gov (United States)

    Bercy, Anthony; Stefani, Fabio; Lopez, Olivier; Chardonnet, Christian; Pottie, Paul-Eric; Amy-Klein, Anne

    2014-12-01

    By using two-way frequency transfer, we implement a real-time frequency comparison over a uni-directional telecommunication network of 100 km using a pair of parallel fibers with simultaneous digital data transfer. The relative frequency stability is 10-15 at 1-s integration time and reaches 2 ×10-17 at 40 000 s, three orders of magnitude below the one-way fiber instability. We also demonstrate ultrahigh-resolution comparison of optical frequencies with a bidirectional scheme using a single fiber. We show that the relative stability at 1-s integration time is 7 ×10-18 and scales down to 5 ×10-21 . The same level of performance is reached when an optical link is implemented with an active compensation of the fiber noise. The fractional uncertainty of the frequency comparisons was evaluated for the best case to 2 ×10-20 . These results open the way to accurate and high-resolution frequency comparison of optical clocks over intercontinental fiber networks.

  18. Tunable error-free optical frequency conversion of a 4ps optical short pulse over 25 nm by four-wave mixing in a polarisation-maintaining optical fibre

    Science.gov (United States)

    Morioka, T.; Kawanishi, S.; Saruwatari, M.

    1994-05-01

    Error-free, tunable optical frequency conversion of a transform-limited 4.0 ps optical pulse signalis demonstrated at 6.3 Gbit/s using four-wave mixing in a polarization-maintaining optical fibre. The process generates 4.0-4.6 ps pulses over a 25nm range with time-bandwidth products of 0.31-0.43 and conversion power penalties of less than 1.5 dB.

  19. Optical frequency comb-based local oscillator phase noise cancellation in time-delay-interferometer for gravitational wave detection

    Science.gov (United States)

    Yu, Nan

    Time-delay-interferometer (TDI) is well established as an effective technique to mitigate laser phase noises in laser interferometer gravitational wave detection (GWD). Just as important in the TDI scheme is the ability to suppress the rf local oscillator noise (LO) in the optical heterodyne measurements. We show that LO noises can be effectively and elegantly cancelled by employing optical frequency combs in which the rf signal phases are coherent with the optical phases. In addition, the deployment of optical combs eliminates the need for separate ultra-stable oscillators. This is a simpler and more reliable approach than the modulation scheme, and it can be applied to the most generalized TDI combinations. In this proposed effort, we will investigate the application of optical combs in TDI and demonstrate in a test bed simultaneous noise cancellations in both ranging lasers and rf LOs in a generalized TDI configuration.

  20. Cavity enhanced absorption spectroscopy for N2O detection at 2.86μm using a continuous tunable color center laser

    Institute of Scientific and Technical Information of China (English)

    Shaocheng Li(李少成); Qingxu Yu(于清旭); Maarten van Herpen; Sacco te Lintel Hekkert; Frans J. M. Harren

    2003-01-01

    The cavity enhanced absorption technique is applied to N2O detection around 2.86 μm using a continuouswave color center laser. A high-finesse triangular ring cavity is used in this technology. Transmission through the cavity is obtained by jittering the cavity-length with a piezo on one of the cavity mirrors.A minimum detectable absorption coefficient of 2 × 10-6 cm-1 is achieved with a mirror reflectivity of 99.24%, corresponding to a N2O detection limit of 600 parts per billion.

  1. Spatially-dense, multi-spectral, frequency-domain diffuse optical tomography of breast cancer

    Science.gov (United States)

    Ban, Han Yong

    Diffuse optical tomography (DOT) employs near-infrared light to image the concentration of chromophores and cell organelles in tissue and thereby providing access to functional parameters that can differentiate cancerous from normal tissues. This thesis describes research at the bench and in the clinic that explores and identifies the potential of DOT breast cancer imaging. The bench and clinic instrumentation differ but share important features: they utilize a very large, spatially dense, set of source-detector pairs (10 7) for imaging in the parallel-plate geometry. The bench experiments explored three-dimensional (3D) image resolution and fidelity as a function of numerous parameters and also ascertained the effects of a chest wall phantom. The chest wall is always present but is typically ignored in breast DOT. My experiments clarified chest wall influences and developed schemes to mitigate these effects. Mostly, these schemes involved selective data exclusion, but their efficacy also depended on reconstruction approach. Reconstruction algorithms based on analytic (fast) Fourier inversion and linear algebraic techniques were explored. The clinical experiments centered around a DOT instrument that I designed, constructed, and have begun to test (in-vitro and in-vivo). This instrumentation offers many features new to the field. Specifically, the imager employs spatially-dense, multi-spectral, frequency-domain data; it possesses the world's largest optical source-detector density yet reported, facilitated by highly-parallel CCD-based frequency-domain imaging based on gain-modulation heterodyne detection. The instrument thus measures both phase and amplitude of the diffusive light waves. Other features include both frontal and sagittal breast imaging capabilities, ancillary cameras for measurement of breast boundary profiles, real-time data normalization, and mechanical improvements for patient comfort. The instrument design and construction is my most significant

  2. Miniature fiber-optic multiphoton microscopy system using frequency-doubled femtosecond Er-doped fiber laser.

    Science.gov (United States)

    Huang, Lin; Mills, Arthur K; Zhao, Yuan; Jones, David J; Tang, Shuo

    2016-05-01

    We report on a miniature fiber-optic multiphoton microscopy (MPM) system based on a frequency-doubled femtosecond Er-doped fiber laser. The femtosecond pulses from the laser source are delivered to the miniature fiber-optic probe at 1.58 µm wavelength, where a standard single mode fiber is used for delivery without the need of free-space dispersion compensation components. The beam is frequency-doubled inside the probe by a periodically poled MgO:LiNbO3 crystal. Frequency-doubled pulses at 786 nm with a maximum power of 80 mW and a pulsewidth of 150 fs are obtained and applied to excite intrinsic signals from tissues. A MEMS scanner, a miniature objective, and a multimode collection fiber are further used to make the probe compact. The miniature fiber-optic MPM system is highly portable and robust. Ex vivo multiphoton imaging of mammalian skins demonstrates the capability of the system in imaging biological tissues. The results show that the miniature fiber-optic MPM system using frequency-doubled femtosecond fiber laser can potentially bring the MPM imaging for clinical applications. PMID:27231633

  3. Yellow nanosecond sum-frequency generating optical parametric oscillator using periodically poled LiNbO3

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Bruun-Larsen, M.; Balle-Petersen, O.;

    2008-01-01

    Nanosecond yellow light has been generated through simultaneously phase matched sum-frequency generation and optical parametric oscillation in a periodically poled LiNbO3 crystal. 300 mW of yellow light at a wavelength of 586 nm has been generated from 1.3 W of laser power from a Q-switched Yb...

  4. Analytic approach to the small-signal frequency response of saturated semiconductor optical amplifiers using multisection model

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An analytic solution derived by multisection model to the small-signal frequency response (SSFR) of wavelength conversion based on cross-gain modulation (XGM) in semiconductor optical amplifiers (SOAs) is presented. The result contains details that can affect the characteristics of SSFR significantly more than previous ones.

  5. Influence of nanoscale temperature rises on photoacoustic generation: discrimination between optical absorbers based on nonlinear photoacoustics at high frequency

    CERN Document Server

    Simandoux, Oliver; Gâteau, Jérôme; Bossy, Emmanuel

    2013-01-01

    In the thermoelastic regime, photoacoustic sensing of optical absorption relies on conversion from light to acoustic energy via the coefficient of thermal expansion \\beta. In this work, we confront confront experimental measurements to theoretical predictions of nonlinear photoacoustic generation based on the dynamic variation of \\beta(T) during the optical excitation of absorbers in aqueous solution. The photoacoustic generation from solutions of organic dye and gold nanospheres (with same optical densities), illuminated with 532 nm nanosecond pulses, was detected using a high frequency ultrasound transducer (center frequency 20 MHz). Photoacoustic emission was observed with gold nanospheres at low fluence (a few mJ/cm2) for an equilibrium temperature around 4{\\deg}C, where the linear photoacoustic effect in water vanishes, highlighting the nonlinear emission from the solution of nanospheres. Under the same condition, no emission was observed with the absorbing organic dye. At a fixed fluence of 5 mJ/cm2, th...

  6. Optical Properties of High-Frequency Radio Sources from the Australia Telescope 20 GHz (AT20G) Survey

    CERN Document Server

    Mahony, Elizabeth K; Croom, Scott M; Ekers, Ronald D; Bannister, Keith W; Chhetri, Rajan; Hancock, Paul J; Johnston, Helen M; Massardi, Marcella; Murphy, Tara

    2011-01-01

    Our current understanding of radio-loud AGN comes predominantly from studies at frequencies of 5 GHz and below. With the recent completion of the Australia Telescope 20 GHz (AT20G) survey, we can now gain insight into the high-frequency radio properties of AGN. This paper presents supplementary information on the AT20G sources in the form of optical counterparts and redshifts. Optical counterparts were identified using the SuperCOSMOS database and redshifts were found from either the 6dF Galaxy survey or the literature. We also report 144 new redshifts. For AT20G sources outside the Galactic plane, 78.5% have optical identifications and 30.9% have redshift information. The optical identification rate also increases with increasing flux density. Targets which had optical spectra available were examined to obtain a spectral classification. There appear to be two distinct AT20G populations; the high luminosity quasars that are generally associated with point-source optical counterparts and exhibit strong emissio...

  7. Tuneable dual-comb spectrometer based on commercial femtosecond lasers and reference cell for optical frequency calibration

    Science.gov (United States)

    Portuondo-Campa, E.; Bennès, J.; Balet, L.; Kundermann, S.; Merenda, F.; Boer, G.; Lecomte, S.

    2016-07-01

    Two commercial femtosecond laser sources have been used to implement a dual-comb spectrometer tuneable across a spectral range from 1.5 to 2.2 μm. The optical linewidth of the comb modes was characterized for different time scales in order to estimate the achievable spectral resolution for an optimal acquisition time. The transmission spectra of three different gas samples were recorded, demonstrating good agreement with reference data. Frequency axis calibration was provided via the parallel monitoring of a reference sample. This technique allows an accurate calibration of the frequency axis of the spectrometer, with no need for stabilization or optical referencing of the frequency combs. Our set-up represents a good compromise for a compact and versatile dual-comb spectrometer based on commercially available parts with possible applications in trace-gas monitoring, remote sensing and spectroscopy of short-lived processes.

  8. Identifying the role of the local density of optical states in frequency conversion of light in a microcavity

    CERN Document Server

    Yüce, Emre; Claudon, Julien; Gérard, Jean-Michel; Vos, Willem L

    2014-01-01

    We have reversibly switched the resonance of a GaAs-AlAs microcavity in the near-infrared near $\\lambda =1300$ nm within 300 fs by the electronic Kerr effect. We reveal by pump-probe spectroscopy a remarkable red shift or blue shift of the light confined inside the cavity for small pulse delays, depending on their temporal ordering. The color-converted light is efficiently generated in a broad frequency continuum that differs markedly from the instantaneous cavity resonance in terms of the central frequency and bandwidth. From observations on cavities with different quality factors, we identify the role of the local density of optical states (LDOS) available to the newly generated light frequencies. In particular, we distinguish the effect of the LDOS related to the cavity resonance itself, and the LDOS continuum that leaks in from the vacuum surrounding the cavity. Our new insights provide a unified picture for seemingly disparate results in traditional and nanophotonic nonlinear optics.

  9. Two-dimensional optical coherence vibration tomography for low-frequency vibration measurement and response-only modal analysis

    Science.gov (United States)

    Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun

    2016-10-01

    A high-speed camera-based two-dimensional optical coherence vibration tomography (2DOCVT) system with a subnanometre displacement resolution was developed and employed for low-frequency vibration measurement and modal analysis. Experimental results demonstrated the ability of low-frequency absolute displacement measurement of structural line vibrations without scanning. Three-dimensional (3D) surface displacement of a vibrating structure could also be obtained using the developed 2DOCVT by scanning the structure. The scanning 2DOCVT system acted like a 3D optical coherence vibration tomography system. The developed 2DOCVT system could capture structural modal parameters without vibration excitation input information, and therefore, it is a response-only method. The 2DOCVT could be recommended in the application of low-frequency vibration measurement and modal analysis of beam and plate structures, especially when the vibration amplitude is at nanometre or micrometre scale.

  10. Measurement of ciliary beat frequency using ultra-high resolution optical coherence tomography

    Science.gov (United States)

    Chen, Jason J.; Jing, Joseph C.; Su, Erica; Badger, Christopher; Coughlan, Carolyn A.; Chen, Zhongping; Wong, Brian J. F.

    2016-02-01

    Ciliated epithelial cells populate up to 80% of the surface area of the human airway and are responsible for mucociliary transport, which is the key protective mechanism that provides the first line of defense in the respiratory tract. Cilia beat in a rhythmic pattern and may be easily affected by allergens, pollutants, and pathogens, altering ciliary beat frequency (CBF) subsequently. Diseases including cystic fibrosis, chronic obstructive pulmonary disease, and primary ciliary dyskinesia may also decrease CBF. CBF is therefore a critical component of respiratory health. The current clinical method of measuring CBF is phase-contrast microscopy, which involves a tissue biopsy obtained via brushing of the nasal cavity. While this method is minimally invasive, the tissue sample must be oriented to display its profile view, making the visualization of a single layer of cilia challenging. In addition, the conventional method requires subjective analysis of CBF, e.g., manually counting by visual inspection. On the contrary, optical coherence tomography (OCT) has been used to study the retina in ophthalmology as well as vasculature in cardiology, and offers higher resolution than conventional computed tomography and magnetic resonance imaging. Based on this technology, our lab specifically developed an ultra-high resolution OCT system to image the microstructure of the ciliated epithelial cells. Doppler analysis was also performed to determine CBF. Lastly, we also developed a program that utilizes fast Fourier transform to determine CBF under phase-contrast microscopy, providing a more objective method compared to the current method.

  11. REVIEW ARTICLE: Optical frequency comb generation in gas-filled hollow core photonic crystal fibres

    Science.gov (United States)

    Couny, F.; Benabid, F.

    2009-10-01

    The efficiency of gas-based nonlinear processes is often limited by the diffraction of the pump laser as it propagates through the nonlinear medium. As a consequence, phenomena with strong nonlinear response requirements, such as high harmonic generation or Raman sideband generation, lack the required laser-matter interaction to fulfil their potential. Indeed, the conversion efficiency of these techniques is usually low and the experimental set-up cumbersome. The advent of hollow core photonic crystal fibre technology drafts new territories for nonlinear optics, and in particular offers new alternatives for sub-femtosecond pulse generation. The air-guiding fibre combines unprecedented laser confinement over long interaction lengths and, when filled with an adequate nonlinear gas, offers improved conversion efficiency and up to a million-fold reduction of the pump power threshold. This paper presents a review of the types of hollow core PCF available for nonlinear applications and the results obtained for efficient Raman conversion in H2-filled hollow core PCF that led to the observation of a multi-octave frequency comb spanning from ~325 to ~2300 nm using a single pump laser with relatively low power. The generated ultra-broad spectrum creates a simple route towards a compact source of attosecond pulses.

  12. Quantifying the statistical complexity of low-frequency fluctuations in semiconductor lasers with optical feedback

    International Nuclear Information System (INIS)

    Low-frequency fluctuations (LFFs) represent a dynamical instability that occurs in semiconductor lasers when they are operated near the lasing threshold and subject to moderate optical feedback. LFFs consist of sudden power dropouts followed by gradual, stepwise recoveries. We analyze experimental time series of intensity dropouts and quantify the complexity of the underlying dynamics employing two tools from information theory, namely, Shannon's entropy and the Martin, Plastino, and Rosso statistical complexity measure. These measures are computed using a method based on ordinal patterns, by which the relative length and ordering of consecutive interdropout intervals (i.e., the time intervals between consecutive intensity dropouts) are analyzed, disregarding the precise timing of the dropouts and the absolute durations of the interdropout intervals. We show that this methodology is suitable for quantifying subtle characteristics of the LFFs, and in particular the transition to fully developed chaos that takes place when the laser's pump current is increased. Our method shows that the statistical complexity of the laser does not increase continuously with the pump current, but levels off before reaching the coherence collapse regime. This behavior coincides with that of the first- and second-order correlations of the interdropout intervals, suggesting that these correlations, and not the chaotic behavior, are what determine the level of complexity of the laser's dynamics. These results hold for two different dynamical regimes, namely, sustained LFFs and coexistence between LFFs and steady-state emission.

  13. Nonlinear optical frequency conversion of an amplified Fourier Domain Mode Locked (FDML) laser.

    Science.gov (United States)

    Leonhardt, Rainer; Biedermann, Benjamin R; Wieser, Wolfgang; Huber, Robert

    2009-09-14

    We report on the highly efficient non-linear optical frequency conversion of the wavelength swept output from a Fourier Domain Mode Locked (FDML) laser. Different concepts for power scaling of FDML lasers by post-amplification with active fibers are presented. A two-stage post-amplification of an FDML laser with an amplification factor of 300 up to a peak power of 1.5 W is used to supply sufficient power levels for non-linear conversion. Using a single-mode dispersion shifted fiber (DSF), we convert this amplified output that covers the region between 1541 nm and 1545 nm to a wavelength range from 1572 nm to 1663 nm via modulation instability (MI). For this four wave mixing process we observe an efficiency of approximately 40%. The anti-Stokes signal between 1435 nm and 1516 nm was observed with lower conversion efficiency. In addition to shifting the wavelength, the effect of MI also enables a substantial increase in the wavelength sweep rate of the FDML laser by a factor of approximately 50 to 0.55 nm/ns. PMID:19770897

  14. The wave energy flux of high frequency diffracting beams in complex geometrical optics

    Science.gov (United States)

    Maj, Omar; Mariani, Alberto; Poli, Emanuele; Farina, Daniela

    2013-04-01

    We consider the construction of asymptotic solutions of Maxwell's equations for a diffracting wave beam in the high frequency limit and address the description of the wave energy flux transported by the beam. With this aim, the complex eikonal method is applied. That is a generalization of the standard geometrical optics method in which the phase function is assumed to be complex valued, with the non-negative imaginary part accounting for the finite width of the beam cross section. In this framework, we propose an argument which simplifies significantly the analysis of the transport equation for the wave field amplitude and allows us to derive the wave energy flux. The theoretical analysis is illustrated numerically for the case of electron cyclotron beams in tokamak plasmas by using the GRAY code [D. Farina, Fusion Sci. Technol. 52, 154 (2007)], which is based upon the complex eikonal theory. The results are compared to those of the paraxial beam tracing code TORBEAM [E. Poli et al., Comput. Phys. Commun. 136, 90 (2001)], which provides an independent calculation of the energy flow.

  15. The wave energy flux of high frequency diffracting beams in complex geometrical optics

    Energy Technology Data Exchange (ETDEWEB)

    Maj, Omar; Poli, Emanuele [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Mariani, Alberto [Istituto di Fisica del Plasma ' P. Caldirola,' Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, via R. Cozzi 53, I-20125 Milano (Italy); Universita degli Studi di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); Farina, Daniela [Istituto di Fisica del Plasma ' P. Caldirola,' Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, via R. Cozzi 53, I-20125 Milano (Italy)

    2013-04-15

    We consider the construction of asymptotic solutions of Maxwell's equations for a diffracting wave beam in the high frequency limit and address the description of the wave energy flux transported by the beam. With this aim, the complex eikonal method is applied. That is a generalization of the standard geometrical optics method in which the phase function is assumed to be complex valued, with the non-negative imaginary part accounting for the finite width of the beam cross section. In this framework, we propose an argument which simplifies significantly the analysis of the transport equation for the wave field amplitude and allows us to derive the wave energy flux. The theoretical analysis is illustrated numerically for the case of electron cyclotron beams in tokamak plasmas by using the GRAY code [D. Farina, Fusion Sci. Technol. 52, 154 (2007)], which is based upon the complex eikonal theory. The results are compared to those of the paraxial beam tracing code TORBEAM [E. Poli et al., Comput. Phys. Commun. 136, 90 (2001)], which provides an independent calculation of the energy flow.

  16. Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

    Science.gov (United States)

    Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

    2015-05-01

    194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

  17. Superresolved optical imaging through higher-order spatial frequency harmonic generation without beating the diffraction limit of light

    CERN Document Server

    Li, Zhixiang; Zhang, Guoquan

    2016-01-01

    We proposed a method to achieve superresolved optical imaging without beating the diffraction limit of light. This is achieved by magnifying the ideal optical image of the object through higher-order spatial frequency generation while keeping the size of the effective point spread function of the optical imaging system unchanged. A proof-of-principle experiment was demonstrated in a modified $4f$-imaging system, where the spatial frequency of a two-line source was doubled or tripled on the confocal Fourier plane of the $4f$-imaging system through a light pulse storage and retrieval process based on the electromagnetically induced transparency effect in a Pr$^{3+}$:$\\rm Y_2SiO_5$ crystal, and an originally unresolvable image of the two line sources in the conventional $4f$-imaging system became resolvable with the spatial frequency doubling or tripling. Our results offer an original way towards improving optical imaging resolution without beating the diffraction limit of light, which is totally different from ...

  18. All optical up-converted signal generation with high dispersion tolerance using frequency quadrupling technique for radio over fiber system

    Science.gov (United States)

    Gu, Yiying; Zhao, Jiayi; Hu, Jingjing; Kang, Zijian; Zhu, Wenwu; Fan, Feng; Han, Xiuyou; Zhao, Mingshan

    2016-05-01

    A novel all optical up-converted signal generation scheme with optical single-sideband (OSSB) technique for radio over fiber (RoF) application is presented and experimentally demonstrated using low-bandwidth devices. The OSSB signal is generated by one low-bandwidth intensity LiNbO3 Mach-Zehnder modulator (LN-MZM) under frequency quadrupling modulation scheme and one low-bandwidth LN-MZM under double sideband carrier suppressed modulation (DSB-CS) scheme. The proposed all OSSB generation scheme is capable of high tolerance of fiber chromatic dispersion induced power fading (DIPF) effect. Benefiting from this novel OSSB generation scheme, a 26 GHz radio frequency (RF) signal up-conversion is realized successfully when one sideband of the optical LO signal is reused as the optical carrier for intermediate frequency (IF) signal modulation. The received vector signal transmission over long distance single-mode fiber (SMF) shows negligible DIPF effect with the error vector magnitude (EVM) of 15.7% rms. In addition, a spurious free dynamic range (SFDR) of the OSSB up-converting system is measured up to 81 dB Hz2/3. The experiment results indicate that the proposed system may find potential applications in future wireless communication networks, especially in microcellular personal communication system (MPCS).

  19. Apparatus and method for qualitative and quantitative measurements of optical properties of turbid media using frequency-domain photon migration

    Science.gov (United States)

    Tromberg, Bruce J.; Tsay, Tsong T.; Berns, Michael W.; Svaasand, Lara O.; Haskell, Richard C.

    1995-01-01

    Optical measurements of turbid media, that is media characterized by multiple light scattering, is provided through an apparatus and method for exposing a sample to a modulated laser beam. The light beam is modulated at a fundamental frequency and at a plurality of integer harmonics thereof. Modulated light is returned from the sample and preferentially detected at cross frequencies at frequencies slightly higher than the fundamental frequency and at integer harmonics of the same. The received radiance at the beat or cross frequencies is compared against a reference signal to provide a measure of the phase lag of the radiance and modulation ratio relative to a reference beam. The phase and modulation amplitude are then provided as a frequency spectrum by an array processor to which a computer applies a complete curve fit in the case of highly scattering samples or a linear curve fit below a predetermined frequency in the case of highly absorptive samples. The curve fit in any case is determined by the absorption and scattering coefficients together with a concentration of the active substance in the sample. Therefore, the curve fitting to the frequency spectrum can be used both for qualitative and quantitative analysis of substances in the sample even though the sample is highly turbid.

  20. Design and realization of integrated optical frequency modulation discriminator for a high performance microwave photonic link

    NARCIS (Netherlands)

    Marpaung, D.A.I.; Roeloffzen, C.G.H.; Timens, R.B.; Leinse, A.; Hoekman, M.

    2010-01-01

    This paper reports the design, fabrication and the characterization of an integrated optical filter for an FM discriminator. The filter is based on optical ring resonator structures which are fully reconfigurable using thermo-optical tuning. The desired characteristic, which is a linear slope with z

  1. Observation of Rb Two-Photon Absorption Directly Excited by an Erbium-Fiber-Laser-Based Optical Frequency Comb via Spectral Control

    CERN Document Server

    Wu, Jiutao; Dai, Xiaoliang; Qin, Zhengyu; Zhang, Zhigang; Zhao, Jianye

    2013-01-01

    We demonstrated the observation of Rb two-photon absorption directly excided by an optical frequency comb at fiber communication bands. A chain of comb spectral control is elaborately implemented to increase the power of the second harmonic optical frequency comb generation and the two-photon transition strength. A two-photon transition spectrum is obtained with clearly resolved transition lines. It provides a potential approach to realize the optical frequency comb or optical clock at ~1.5{\\mu}m with high stability and accuracy.

  2. Ultrafast nonlinear-optical metrology of specialty fibers: parallel multimode fiber dispersion tracing by cross-correlation frequency-resolved optical gating

    International Nuclear Information System (INIS)

    An accurate fiber dispersion measurement is demonstrated for different types of solid- and hollow-core photonic-crystal fibers (PCFs) using cross-correlation frequency-resolved optical gating (XFROG) with ultrashort light pulses. In the multimode regime, the XFROG technique is shown to enable a simultaneous dispersion measurement for several modes in parallel, offering a powerful fiber characterization tool for ultrafast science and metrology

  3. Non-invasive optical monitoring of the newborn piglet brain using continuous-wave and frequency-domain spectroscopy

    International Nuclear Information System (INIS)

    We have used continuous-wave (CW) and frequency-domain spectroscopy to investigate the optical properties of the newborn piglet brain in vivo and non-invasively. Three anaesthetized, intubated, ventilated and instrumented newborn piglets were placed into a stereotaxic instrument for optimal experimental stability, reproducible probe-to-scalp optical contact and 3D adjustment of the optical probe. By measuring the absolute values of the brain absorption and reduced scattering coefficients at two wavelengths (758 and 830 nm), frequency-domain spectroscopy provided absolute readings (in contrast to the relative readings of CW spectroscopy) of cerebral haemoglobin concentration and saturation during experimentally induced perturbations in cerebral haemodynamics and oxygenation. Such perturbations included a modulation of the inspired oxygen concentration, transient brain asphyxia, carotid artery occlusion and terminal brain asphyxia. The baseline cerebral haemoglobin saturation and concentration, measured with frequency-domain spectroscopy, were about 60% and 42 μM respectively. The cerebral saturation values ranged from a minimum of 17% (during transient brain asphyxia) to a maximum of 80% (during recovery from transient brain asphyxia). To analyse the CW optical data, we have (a) derived a mathematical relationship between the cerebral optical properties and the differential pathlength factor and (b) introduced a method based on the spatial dependence of the detected intensity (dc slope method). The analysis of the cerebral optical signals associated with the arterial pulse and with respiration demonstrates that motion artefacts can significantly affect the intensity recorded from a single optode pair. Motion artefacts can be strongly reduced by combining data from multiple optodes to provide relative readings in the dc slope method. We also report significant biphasic changes (initial decrease and successive increase) in the reduced scattering coefficient measured

  4. Non-invasive optical monitoring of the newborn piglet brain using continuous-wave and frequency-domain spectroscopy

    Science.gov (United States)

    Fantini, Sergio; Hueber, Dennis; Franceschini, Maria Angela; Gratton, Enrico; Rosenfeld, Warren; Stubblefield, Phillip G.; Maulik, Dev; Stankovic, Miljan R.

    1999-06-01

    We have used continuous-wave (CW) and frequency-domain spectroscopy to investigate the optical properties of the newborn piglet brain in vivo and non-invasively. Three anaesthetized, intubated, ventilated and instrumented newborn piglets were placed into a stereotaxic instrument for optimal experimental stability, reproducible probe-to-scalp optical contact and 3D adjustment of the optical probe. By measuring the absolute values of the brain absorption and reduced scattering coefficients at two wavelengths (758 and 830 nm), frequency-domain spectroscopy provided absolute readings (in contrast to the relative readings of CW spectroscopy) of cerebral haemoglobin concentration and saturation during experimentally induced perturbations in cerebral haemodynamics and oxygenation. Such perturbations included a modulation of the inspired oxygen concentration, transient brain asphyxia, carotid artery occlusion and terminal brain asphyxia. The baseline cerebral haemoglobin saturation and concentration, measured with frequency-domain spectroscopy, were about 60% and 42 µM respectively. The cerebral saturation values ranged from a minimum of 17% (during transient brain asphyxia) to a maximum of 80% (during recovery from transient brain asphyxia). To analyse the CW optical data, we have (a) derived a mathematical relationship between the cerebral optical properties and the differential pathlength factor and (b) introduced a method based on the spatial dependence of the detected intensity (dc slope method). The analysis of the cerebral optical signals associated with the arterial pulse and with respiration demonstrates that motion artefacts can significantly affect the intensity recorded from a single optode pair. Motion artefacts can be strongly reduced by combining data from multiple optodes to provide relative readings in the dc slope method. We also report significant biphasic changes (initial decrease and successive increase) in the reduced scattering coefficient measured

  5. Clinical studies of frequency domain optical coherence tomography in the coronary arteries: the first 200 patients

    Science.gov (United States)

    Petersen, Christopher; Adler, Desmond; Schmitt, Joseph

    2010-02-01

    We report clinical study results of three-dimensional (3D) in vivo imaging of human coronary arteries using frequency domain optical coherence tomography (FD-OCT). At the time of this report, over 2000 patients in over 10 countries have been imaged using FD-OCT systems and disposable fiberoptic catheters developed by LightLab Imaging Inc. The first commercial versions of the systems were introduced in Europe in May 2009. The system operates at 50,000 axial lines/s, performing a 50 mm spiral pullback in 2.5 seconds with a rotational frame rate of 100 Hz. The commercial system employs a proprietary micro-cavity swept laser, allowing imaging of vessel diameters up to 10 mm. Data compiled from early studies indicate that FD-OCT is being used for post-intervention imaging of deployed coronary stents in over 40% of cases. High-resolution 3D imaging of stent geometry immediately following deployment enables detection of stent malapposition, which can increase the risk of thrombosis. Longer term follow-up imaging of stented vessels can detect thrombus formation, which can be treated pharmacologically, and excessive neointimal growth, which may require angioplasty or re-stenting. FD-OCT is also being used for pre-intervention imaging of stenotic lesions in about 60% of cases. Here FD-OCT is used to measure the minimum lumen area and to identify calcified deposits, side branches, or other vascular structures that could interfere with the stenting procedure. Overall, FD-OCT continues to be adopted at an increasing rate and has provided interventional cardiologists with a powerful tool for pre- and postintervention assessment of the coronary arteries.

  6. Collinear type II second-harmonic-generation frequency-resolved optical gating for use with high-numerical-aperture objectives

    Energy Technology Data Exchange (ETDEWEB)

    Fittinghoff, D.N. [Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093-0339 (United States); Squier, J.A. [Department of Electrical Engineering and Computer Science, University of California, San Diego, La Jolla, California 92093-0339 (United States); Barty, C.P. [Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093-0339 (United States); Sweetser, J.N.; Trebino, R. [Combustion Research, Sandia National Laboratories, Livermore, California 94551 (United States); Mueller, M. [BioCetrum Amsterdam, Institute for Molecular Cell Biology, Kruislaan 316, 1098 SM Amsterdam (The Netherlands)

    1998-07-01

    Ultrashort-pulse lasers are now commonly used for multiphoton microscopy, and optimizing the performance of such systems requires careful characterization of the pulses at the tight focus of the microscope objective. We solve this problem by use of a collinear geometry in frequency-resolved optical gating that uses type II second-harmonic generation and that allows the full N.A. of the microscope objective to be used. We then demonstrate the technique by measuring the intensity and the phase of a 22-fs pulse focused by a 20{times} , 0.4-N.A. air objective. {copyright} {ital 1998} {ital Optical Society of America}

  7. All-optical single-sideband frequency upconversion utilizing the XPM effect in an SOA-MZI.

    Science.gov (United States)

    Kim, Doo-Ho; Lee, Joo-Young; Choi, Hyung-June; Song, Jong-In

    2016-09-01

    An all-optical single sideband (OSSB) frequency upconverter based on the cross-phase modulation (XPM) effect is proposed and experimentally demonstrated to overcome the power fading problem caused by the chromatic dispersion of fiber in radio-over-fiber systems. The OSSB frequency upconverter consists of an arrayed waveguide grating (AWG) and a semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) and does not require an extra delay line used for phase noise compensation. The generated OSSB radio frequency (RF) signal transmitted over single-mode fibers up to 20 km shows a flat electrical RF power response as a function of the fiber length. The upconverted electrical RF signal at 48 GHz shows negligible degradation of the phase noise even without an extra delay line. The measured phase noise of the upconverted RF signal (48 GHz) is -74.72 dBc/Hz at an offset frequency of 10 kHz. The spurious free dynamic range (SFDR) measured by a two-tone test to estimate the linearity of the OSSB frequency upconverter is 72.5 dB·Hz2/3. PMID:27607637

  8. 非相干宽带腔增强吸收光谱技术应用于实际大气亚硝酸的测量%Incoherent broadband cavity enhanced absorption spectroscopy for measurements of atmospheric HONO

    Institute of Scientific and Technical Information of China (English)

    段俊; 秦敏; 方武; 凌六一; 胡仁志; 卢雪; 沈兰兰; 王丹; 谢品华

    2015-01-01

    介绍了基于紫外发光二极管光源的非相干宽带腔增强吸收光谱技术,并用于实际大气亚硝酸(HONO)和二氧化氮(NO2 )的同时测量. 分析了腔内气体的瑞利散射对测量的影响,测试了紫外发光二极管光源的稳定性,使用氦气和氮气的瑞利散射差异性标定了镜片反射率随波长的变化曲线,在HONO吸收峰(368.2 nm)处镜片反射率约为0.99965. 应用Allan方差统计方法确定出测量光谱最佳采集时间为320 s, 对应的HONO和NO2的探测限(1σ)分别为0.22 ppb和0.45 ppb. 使用非相干宽带腔增强吸收光谱测量装置对大气HONO和NO2进行了连续三日的实际观测, 将测量得到的HONO浓度变化与差分吸收光谱测量装置的测量结果进行对比,线性相关系数R2为0.917.%We report the development of an incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) based on an ultraviolet light emitting diode (UV-LED), and the IBBCEAS instrument is used for simultaneously measuring of the atmospheric HONO and NO2. The cavity-enhanced method is characterized by high sensitivity and spatial resolution. The incoherent broadband light is focused into a high-finesse optical cavity, two highly reflecting mirrors form the ends of the cavity, and the light is then trapped between the two highly reflecting mirrors, resulting in long photon residence time and long optical path length. The effects of the Rayleigh scattering of the gases in the cavity and stability of the UV-LED light source were discussed in this paper. The reflectivity of the highly reflecting mirror was calibrated by the difference of Rayleigh scattering of He and N2, and the optimum averaging time of the IBBCEAS instrument was confirmed to be 320 s by the Allan variance analysis. Detection limits (1σ) of 0.22 ppb for HONO and 0.45 ppb for NO2 were achieved with an optimum acquisition time of 320 s. In order to test the accuracy of measured results by the IBBCEAS instrument

  9. Single-Frequency High-Power Continuous-Wave Oscillation at 1003 nm of an Optically Pumped Semiconductor Laser

    CERN Document Server

    Jacquemet, M; Dion, J; Strassner, M; Lucas-Leclin, G; Georges, P; Sagnes, I; Garnache, A; Jacquemet, Mathieu; Domenech, Manuela; Dion, Julie; Strassner, Martin; Lucas-Leclin, Gaelle; Georges, Patrick; Sagnes, Isabelle; Garnache, Arnaud

    2006-01-01

    This work reports single-frequency laser oscillation at 1003.4 nm of an optically pumped external cavity semiconductor laser. By using a gain structure bonded onto a high conductivity substrate, we demonstrate both theoretically and experimentally the strong reduction of the thermal resistance of the active semiconductor medium, resulting in a high power laser emission. The spectro-temporal dynamics of the laser is also explained. Furthermore, an intracavity frequency-doubling crystal was used to obtain a stable single-mode generation of blue (501.5 nm) with an output power around 60 mW.

  10. Hilbert Transform based Quadrature Hybrid RF Photonic Coupler via a Micro-Resonator Optical Frequency Comb Source

    CERN Document Server

    Nguyen, Thach G; Chu, Sai T; Little, Brent E; Morandotti, Roberto; Mitchell, Arnan; Moss, David J

    2015-01-01

    We demonstrate a photonic RF Hilbert transformer for broadband microwave in-phase and quadrature-phase generation based on an integrated frequency optical comb, generated using a nonlinear microring resonator based on a CMOS compatible, high-index contrast, doped-silica glass platform. The high quality and large frequency spacing of the comb enables filters with up to 20 taps, allowing us to demonstrate a quadrature filter with more than a 5-octave (3 dB) bandwidth and an almost uniform phase response.

  11. Frequency stabilization of an optically pumped far-infrared laser to the harmonic of a microwave synthesizer.

    Science.gov (United States)

    Danylov, A A; Light, A R; Waldman, J; Erickson, N

    2015-12-10

    Measurements of the frequency stability of a far-infrared molecular laser have been made by mixing the harmonic of an ultrastable microwave source with a portion of the laser output signal in a terahertz (THz) Schottky diode balanced mixer. A 3 GHz difference-frequency signal was used in a frequency discriminator circuit to lock the laser to the microwave source. Comparisons of the short- and long-term laser frequency stability under free-running and locked conditions show a significant improvement with locking. Short-term frequency jitter was reduced by an order of magnitude, from approximately 40 to 4 kHz, and long-term drift was reduced by more than three orders of magnitude, from approximately 250 kHz to 80 Hz. The results, enabled by the efficient Schottky diode balanced mixer downconverter, demonstrate that ultrastable microwave-based frequency stabilization of THz optically pumped lasers (OPLs) will now be possible at frequencies extending well above 4.0 THz. PMID:26836876

  12. Space-frequency analysis with parallel computing in a phase-sensitive optical time-domain reflectometer distributed sensor.

    Science.gov (United States)

    Hui, Xiaonan; Ye, Taihang; Zheng, Shilie; Zhou, Jinhai; Chi, Hao; Jin, Xiaofeng; Zhang, Xianmin

    2014-10-01

    For a phase-sensitive optical time-domain reflectometer (ϕ-OTDR) distributed sensor system, space-frequency analysis can reduce the false alarm by analyzing the frequency distribution compared with the traditional difference value method. We propose a graphics processing unit (GPU)-based parallel computing method to perform multichannel fast Fourier transform (FFT) and realize the real-time space-frequency analysis. The experiment results show that the time taken by the multichannel FFT decreased considerably based on this GPU parallel computing. The method can be completed with a sensing fiber up to 16 km long and an entry-level GPU. Meanwhile, the GPU can reduce the computing load of the central processing unit from 70% down to less than 20%. We carried out an experiment on a two-point space-frequency analysis, and the results clearly and simultaneously show the vibration point locations and frequency components. The sensor system outputs the real-time space-frequency spectra continuously with a spatial resolution of 16.3 m and frequency resolution of 2.25 Hz.

  13. Propagation of Optical Pulses and Pulsed Beams in the Frequency Domain

    Institute of Scientific and Technical Information of China (English)

    林强; 王立刚

    2001-01-01

    The diffraction integral formulae in the temporal and spatial-temporal frequency domains are derived by using a Fourier transform and tensor analysis method. Based on these formulae, the abcd law in the temporal frequency domain and the tensor ABCD law in the four-dimensional spatial-temporal frequency domain are derived. An application example of the derived formulae is provided.

  14. Modulation Depth Based on Frequency-shift Characteristic of LiNbO3 Waveguide Electro-optic Intensity Modulator

    Institute of Scientific and Technical Information of China (English)

    Hui-juan ZHOU; Zhou MENG; Yi LIAO

    2010-01-01

    The modulation depth,defined according to practical mod-ulation results,which changes with the microwave power and its fre-quency,is significant for systems utilizing the frequency-shift charac-teristic of the LiNbO3 waveguide Electro-Optic Intensity Modulator (EOIM).By analyzing the impedance mismatch between the micro-wave source and the EOIM,the effective voltage applied to the RF port of the EOIM is deprived frcm the microwave power and its fre-quency.Associating with analyses of the phase velocity mismatch be-tween the microwave and the optical wave,the theoretical modulation depth has been obtained,which is verified by experimental results.We provide a method to choose the appropriate modulation depth to optimize the desired sideband through proper transmission bias far the system based an the frequency-shift characteristic of the EOIM.

  15. Single-Frequency High-Power Continuous-Wave Oscillation at 1003 nm of an Optically Pumped Semiconductor Laser

    OpenAIRE

    Jacquemet, Mathieu; Domenech, Manuela; Dion, Julie; Strassner, Martin; Lucas-Leclin, Gaëlle; Georges, Patrick; Sagnes, Isabelle; Garnache, Arnaud

    2006-01-01

    11 pages International audience This work reports single-frequency laser oscillation at 1003.4 nm of an optically pumped external cavity semiconductor laser. By using a gain structure bonded onto a high conductivity substrate, we demonstrate both theoretically and experimentally the strong reduction of the thermal resistance of the active semiconductor medium, resulting in a high power laser emission. The spectro-temporal dynamics of the laser is also explained. Furthermore, an intracav...

  16. Nonlinear magneto-optical rotation of frequency-modulated light resonant with a low-J transition

    CERN Document Server

    Malakyan, Y P; Budker, D; Kimball, D F; Yashchuk, V V; Malakyan, Yu. P.

    2003-01-01

    A low-light-power theory of nonlinear magneto-optical rotation of frequency-modulated light resonant with a J=1->J'=0 transition is presented. The theory is developed for a Doppler-free transition, and then modified to account for Doppler broadening and velocity mixing due to collisions. The results of the theory are shown to be in qualitative agreement with experimental data obtained for the rubidium D1 line.

  17. All-fiber wavelength swept ring laser based on Fabry-Perot filter for optical frequency domain imaging

    OpenAIRE

    Jun, Changsu; Villiger, Martin; Oh, Wang-Yuhl; Bouma, Brett E.

    2014-01-01

    Innovations in laser engineering have yielded several novel configurations for high repetition rate, broad sweep range, and long coherence length wavelength swept lasers. Although these lasers have enabled high performance frequency-domain optical coherence tomography, they are typically complicated and costly and many require access to proprietary materials or devices. Here, we demonstrate a simplified ring resonator configuration that is straightforward to construct from readily available m...

  18. Generation of high-energy self-phase-stabilized pulses by difference-frequency generation followed by optical parametric amplification.

    Science.gov (United States)

    Manzoni, C; Vozzi, C; Benedetti, E; Sansone, G; Stagira, S; Svelto, O; De Silvestri, S; Nisoli, M; Cerullo, G

    2006-04-01

    We produce ultrabroadband self-phase-stabilized near-IR pulses by a novel approach where a seed pulse, obtained by difference-frequency generation of a hollow-fiber broadened supercontinuum, is amplified by a two-stage optical parametric amplifier. Energies up to 20 microJ with a pulse spectrum extending from 1.2 to 1.6 microm are demonstrated, and a route for substantial energy scaling is indicated.

  19. Design and realization of integrated optical frequency modulation discriminator for a high performance microwave photonic link

    OpenAIRE

    Marpaung, D.A.I.; Roeloffzen, C. G. H.; Timens, R.B.; Leinse, A.; Hoekman, M.

    2010-01-01

    This paper reports the design, fabrication and the characterization of an integrated optical filter for an FM discriminator. The filter is based on optical ring resonator structures which are fully reconfigurable using thermo-optical tuning. The desired characteristic, which is a linear slope with zero in a particular region, is demonstrated. This characteristic is needed in a high performance microwave photonics link with increased spurious free dynamic range.

  20. Optical conductivity of warm dense matter in wide frequency range within quantum statistical and kinetic approach

    CERN Document Server

    Veysman, M; Winkel, M; Reinholz, H

    2016-01-01

    Fundamental properties of warm dense matter are described by the dielectric function, which gives access to the frequency-dependent electrical conductivity, absorption, emission and scattering of radiation, charged particles stopping and further macroscopic properties. Different approaches to the dielectric function and the related dynamical collision frequency are compared in a wide frequency range. The high-frequency limit describing inverse bremsstrahlung and the low-frequency limit of the dc conductivity are considered. Sum rules and Kramers-Kronig relation are checked for the generalized linear response theory and the standard approach following kinetic theory. The results are discussed in application to aluminum, xenon and argon plasmas.