WorldWideScience

Sample records for bandgap fiber amplifier

  1. Single-mode ytterbium-doped large-mode-area photonic bandgap rod fiber amplifier

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Scolari, Lara; Broeng, Jes

    2011-01-01

    Enabling Single-Mode (SM) operation in Large-Mode-Area (LMA) fiber amplifiers and lasers is critical, since a SM output ensures high beam quality and excellent pointing stability. In this paper, we demonstrate and test a new design approach for achieving SM LMA rod fibers by using a photonic...... bandgap structure. The structure allows resonant coupling of higher-order modes from the core and acts as a spatially Distributed Mode Filter (DMF). With this approach, we demonstrate passive SM performance in an only ~50cm long and straight ytterbium-doped rod fiber. The amplifier has a mode field...

  2. Fiber Amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten

    2017-01-01

    The chapter provides a discussion of optical fiber amplifiers and through three sections provides a detailed treatment of three types of optical fiber amplifiers, erbium doped fiber amplifiers (EDFA), Raman amplifiers, and parametric amplifiers. Each section comprises the fundamentals including...... the basic physics and relevant in-depth theoretical modeling, amplifiers characteristics and performance data as a function of specific operation parameters. Typical applications in fiber optic communication systems and the improvement achievable through the use of fiber amplifiers are illustrated....

  3. Highly efficient high power single-mode fiber amplifier utilizing the distributed mode filtering bandgap rod fiber

    DEFF Research Database (Denmark)

    Laurila, Marko; Alkeskjold, Thomas T.; Jørgensen, Mette Marie

    2012-01-01

    We report on an ytterbium doped single mode distributed mode filtering rod fiber in an amplifier configuration delivering high average output power, up to 292 watts, using a mode-locked 30ps source at 1032nm with good power conversion efficiency. We study the modal stability of the output beam...... at high average output power levels and demonstrate a 44% power improvement before the threshold-like onset of mode instabilities by operating the rod fiber in a leaky waveguide regime. We investigate the guiding dynamics of the rod fiber and explain the improved performance by thermally induced...

  4. Resonant filtered fiber amplifiers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Laurila, Marko; Olausson, Christina Bjarnal Thulin

    2013-01-01

    In this paper we present our recent result on utilizing resonant/bandgap fiber designs to achieve high performance ytterbium doped fiber amplifers for achieving diffraction limited beam quality in large mode area fibers, robust bending performance and gain shaping for long wavelength operation of...

  5. Liquid Crystal photonic Bandgap Fiber Devices

    DEFF Research Database (Denmark)

    Wei, Lei

    presents bandgaps. These bandgaps can be tuned by applying an electric field or by varying the temperature. Therefore, tunable all-in-fiber devices with controllable optical properties can be realized. This thesis focuses on the design, fabrication and development of com-pact LCPBG fiber devices. An on......In this Ph.D. thesis, an experimental investigation of liquid crystal photonic bandgap (LCPBG) fiber devices and applications is presented. Photonic crystal fibers (PCFs) consist of a cladding microstructure with periodic index variations and a core defined by a defect of the structure....... The presence of liquid crystals (LCs) in the air-holes of the PCF transforms the fiber from a total internal reflection (TIR) guiding type into a photonic bandgap (PBG) guiding type. The light is confined to the silica core by coherent scattering from the LC-filled air-holes and the transmission spectrum...

  6. Electrospun amplified fiber optics.

    Science.gov (United States)

    Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

    2015-03-11

    All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm(-1)). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics.

  7. Gaussian Filtering with Tapered Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Scolari, Lara; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2006-01-01

    We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm......We present a device based on a tapered Liquid Crystal Photonic Bandgap Fiber that allows active all-in-fiber filtering. The resulting Photonic Bandgap Fiber device provides a Gaussian filter covering the wavelength range 1200-1600 nm...

  8. Advances in photonic bandgap fiber functionality

    DEFF Research Database (Denmark)

    Lyngsøe, Jens Kristian

    In order to take advantage of the many intriguing optical properties of photonic bandgap fibers, there are some technological challenges that have to be addressed. Among other things this includes transmission loss and the fibers ability to maintain field polarization. The work presented in this ...

  9. Wide bandgap matrix switcher, amplifier and oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Sampayan, Stephen

    2016-08-16

    An electronic device comprising an optical gate, an electrical input an electrical output and a wide bandgap material positioned between the electrical input and the electrical output to control an amount of current flowing between the electrical input and the electrical output in response to a stimulus received at the optical gate can be used in wideband telecommunication applications in transmission of multi-channel signals.

  10. A 158 fs 5.3 nJ fiber-laser system at 1 mu m using photonic bandgap fibers for dispersion control and pulse compression

    DEFF Research Database (Denmark)

    Nielsen, C.K.; Jespersen, Kim Giessmann; Keiding, S.R.

    2006-01-01

    We demonstrate a 158 fs 5.3 nJ mode-locked laser system based on a fiber oscillator, fiber amplifier and fiber compressor. Dispersion compensation in the fiber oscillator was obtained with a solid-core photonic bandgap (SC-PBG) fiber spliced to standard fibers, and external compression is obtained...

  11. Liquid Crystals and Photonic Bandgap Fiber Components

    DEFF Research Database (Denmark)

    Weirich, Johannes; Wei, Lei; Scolari, Lara

    Liquid Crystal(LC)filled Photonic Crystal Fibers(PCFs) represent a promising platform for the design and the fabrication of tunable all-in fiber devices. Tunability is achieved by varying the refractive index of the LC thermally, optically or electrically. In this contribution we present important...... parts of the LC theory as well as an application of a LC infiltrated PCF subject to an external electrostatic field. The fiber is placed between two electrodes and the voltage is increased step by step leading to the reorientation of the LC in the fiber capillaries. This mechanism can be used to produce...... a swichable polarizer, and an on chip LC photonic bandgap fiber polarimeter is presented, which admits strong attenuation of one polarization direction while the other one is nearly unaffected....

  12. Electrically tunable liquid crystal photonic bandgap fiber laser

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Scolari, Lara; Wei, Lei

    2010-01-01

    We demonstrate electrical tunability of a fiber laser by using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an al...

  13. Gas sensing using air-guiding photonic bandgap fibers

    DEFF Research Database (Denmark)

    Ritar, Tuomo; Tuominen, J.; Ludvigsen, Hanne

    2004-01-01

    We demonstrate the high sensitivity of gas sensing using a novel air-guiding photonic bandgap fiber. The bandgap fiber is spliced to a standard single-mode fiber at the input end for easy coupling and filled with gas through the other end placed in a vacuum chamber. The technique is applied...

  14. Modeling of realistic cladding structures for photonic bandgap fibers

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger; Nielsen, Martin Dybendal

    2004-01-01

    Cladding structures of photonic bandgap fibers often have airholes of noncircular shape, and, typically, close-to-hexagonal airholes with curved corners are observed. We study photonic bandgaps in such structures by aid of a two-parameter representation of the size and curvature. For the fundamen......Cladding structures of photonic bandgap fibers often have airholes of noncircular shape, and, typically, close-to-hexagonal airholes with curved corners are observed. We study photonic bandgaps in such structures by aid of a two-parameter representation of the size and curvature....... For the fundamental bandgap we find that the bandgap edges (the intersections with the air line) shift toward shorter wavelengths when the air-filling fraction f is increased. The bandgap also broadens, and the relative bandwidth increases exponentially with f2. Compared with recent experiments [Nature 424, 657 (2003...

  15. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  16. Electrically controlled broadband liquid crystal photonic bandgap fiber polarimeter

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2007-01-01

    We demonstrate a liquid crystal photonic bandgap fiber based polarizer integrated in a double silicon v-groove assembly. The polarizer axis can be electrically controlled as well as switched on and off.......We demonstrate a liquid crystal photonic bandgap fiber based polarizer integrated in a double silicon v-groove assembly. The polarizer axis can be electrically controlled as well as switched on and off....

  17. A 98 W 1178 nm Yb-doped solid-core photonic bandgap fiber oscillator

    International Nuclear Information System (INIS)

    Fan, Xinyan; Chen, Mingchen; Shirakawa, Akira; Ueda, Ken-ichi; Olausson, Christina B; Broeng, Jes

    2013-01-01

    A high-power ytterbium-doped solid-core photonic bandgap fiber laser directly oscillating at 1178 nm is reported. The sharp-cut bandpass distributed filtering effect of photonic bandgap fiber can suppress amplified spontaneous emission (ASE) in the conventional high-gain spectral region. The oscillator is composed of a high reflection fiber Bragg grating spliced with a 39 m gain fiber and a Fresnel fiber end surface. A model based on rate equations is investigated numerically. A record output power of 98 W is achieved with a slope efficiency of 54%. The laser linewidth is 0.5 nm. The spectrum at 98 W indicates that ASE and parasitic lasing are suppressed effectively. (letter)

  18. Photonic bandgap fiber lasers and multicore fiber lasers for next generation high power lasers

    DEFF Research Database (Denmark)

    Shirakawa, A.; Chen, M.; Suzuki, Y.

    2014-01-01

    Photonic bandgap fiber lasers are realizing new laser spectra and nonlinearity mitigation that a conventional fiber laser cannot. Multicore fiber lasers are a promising tool for power scaling by coherent beam combination. © 2014 OSA....

  19. Electrically tunable Yb-doped fiber laser based on a liquid crystal photonic bandgap fiber device

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Scolari, Lara; Wei, Lei

    2010-01-01

    We demonstrate electrical tunability of a fiber laser using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a tunable liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate...... an all-spliced laser cavity based on the liquid crystal photonic bandgap fiber mounted on a silicon assembly, a pump/signal combiner with single-mode signal feed-through and an ytterbium-doped photonic crystal fiber. The laser cavity produces a single-mode output and is tuned in the range 1040-1065 nm...

  20. Ultrasensitive twin-core photonic bandgap fiber refractive index sensor

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Town, Graham; Bang, Ole

    2009-01-01

    We propose a microfluidic refractive index sensor based on new polymer twin-core photonic bandgap fiber (PBGF). The sensor can achieve ultrahigh detection limit, i.e. >1.4times10-7RIU refractive index unit (RIU), by measuring the coupling wavelength shift.......We propose a microfluidic refractive index sensor based on new polymer twin-core photonic bandgap fiber (PBGF). The sensor can achieve ultrahigh detection limit, i.e. >1.4times10-7RIU refractive index unit (RIU), by measuring the coupling wavelength shift....

  1. Compact electrically controlled broadband liquid crystal photonic bandgap fiber polarizer

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2009-01-01

    An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm.......An electrically controlled liquid crystal photonic-bandgap fiber polarizer is experimentally demonstrated. A maximum 21.3dB electrically tunable polarization extinction ratio is achieved with 45° rotatable transmission axis as well as switched on and off in 1300nm–1600nm....

  2. Polarization Maintaining Hybrid TIR/Bandgap All-Solid Photonic Crystal Fiber

    DEFF Research Database (Denmark)

    Lyngsøe, Jens Kristian; Mangan, Brian J.; Roberts, John

    2008-01-01

    We report on fabricated all-solid fibers which guide by a combination of bandgap and TIR mechanisms. The fibers show high birefringence and possess a dispersion characteristic similar to the pure bandgap guiding form....

  3. Dispersion properties of photonic bandgap guiding fibers

    DEFF Research Database (Denmark)

    Barkou, Stig Eigil; Broeng, Jes; Bjarklev, Anders Overgaard

    1999-01-01

    We investigate low-index core photonic crystal fibers. Dispersion properties very different from standard fibers are found. Both Zero dispersion are very large dispersion is shown possible at 1550 nm wavelength....

  4. Polarization Maintaining Hybrid TIR/Bandgap All-Solid Photonic Crystal Fiber

    DEFF Research Database (Denmark)

    Lyngsøe, Jens Kristian; Mangan, Brian J.; Roberts, John

    2008-01-01

    We report on fabricated all-solid fibers which guide by a combination of bandgap and TIR mechanisms. The fibers show high birefringence and possess a dispersion characteristic similar to the pure bandgap guiding form.......We report on fabricated all-solid fibers which guide by a combination of bandgap and TIR mechanisms. The fibers show high birefringence and possess a dispersion characteristic similar to the pure bandgap guiding form....

  5. Distributed mode filtering rod fiber amplifier delivering 292W with improved mode stability

    DEFF Research Database (Denmark)

    Laurila, Marko; Jørgensen, Mette Marie; Hansen, Kristian Rymann

    2012-01-01

    We demonstrate a high power fiber (85μm core) amplifier delivering up to 292Watts of average output power using a mode-locked 30ps source at 1032nm. Utilizing a single mode distributed mode filter bandgap rod fiber, we demonstrate 44% power improvement before the threshold-like onset of mode inst...

  6. Liquid Crystal Photonic bandgap Fibers: Modeling and Devices

    DEFF Research Database (Denmark)

    Weirich, Johannes

    In this PhD thesis an experimental and numerical investigation of liquid crystal infiltrated photonic bandgap fibers (LCPBGs) is presented. A simulation scheme for modeling LCPBG devices including electrical tunability is presented. New experimental techniques, boundary coating and the applications...

  7. Monolithic all-PM femtosecond Yb-doped fiber laser using photonic bandgap fibers

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2009-01-01

    We present a monolithic Yb fiber laser, dispersion managed by an all-solid photonic bandgap fiber, and pulse compressed in a hollow-core photonic crystal fiber. The laser delivers 9 nJ, 275-fs long pulses at 1035 nm.......We present a monolithic Yb fiber laser, dispersion managed by an all-solid photonic bandgap fiber, and pulse compressed in a hollow-core photonic crystal fiber. The laser delivers 9 nJ, 275-fs long pulses at 1035 nm....

  8. Biased liquid crystal photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2008-01-01

    We simulate the director structure of all capillaries in a biased photonic crystal fiber infiltrated with liquid crystals. Various mode simulations for different capillaries show the necessity to consider the entire structure.......We simulate the director structure of all capillaries in a biased photonic crystal fiber infiltrated with liquid crystals. Various mode simulations for different capillaries show the necessity to consider the entire structure....

  9. Soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2009-01-01

    The formation of solitons upon compression of linearly chirped pulses in hollow-core photonic bandgap fibers is investigated numerically. The dependence of soliton duration on the chirp and power of the input pulse and on the dispersion slope of the fiber is investigated, and the validity...... of an approximate scaling relation is tested. It is concluded that compression of input pulses of several ps duration and sub-MW peak power can lead to a formation of solitons with ∼100 fs duration and multi-megawatt peak powers. The dispersion slope of realistic hollow-core fibers appears to be the main obstacle...... for forming still shorter solitons...

  10. Self-pulsation in Raman fiber amplifiers

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard; Ott, Johan Raunkjær; Rottwitt, Karsten

    2009-01-01

    Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated.......Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated....

  11. Biased liquid crystal infiltrated photonic bandgap fiber

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Scolari, Lara

    2009-01-01

    A simulation scheme for the transmission spectrum of a photonic crystal fiber infiltrated with a nematic liquid crystal and subject to an external bias is presented. The alignment of the biased liquid crystal is simulated using the finite element method to solve the relevant system of coupled...... element based finite element method. We demonstrate results for a splay aligned liquid crystal infiltrated into the capillaries of a four-ring photonic crystal fiber and compare them to corresponding experiments....... partial differential equations. From the liquid crystal alignment the full tensorial dielectric permittivity in the capillaries is derived. The transmission spectrum for the photonic crystal fiber is obtained by solving the generalized eigenvalue problem deriving from Maxwell’s equations using a vector...

  12. Photonic bandgap fibers: theory and experiments

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Libori, Stig E. Barkou

    2000-01-01

    to localize modes in the core region by the photonic band gap (PBG) effect. The photonic crystal fibers (PCFs) were first proposed for a high-index-core region, surrounded by a periodic dielectric structure consisting of a matrix of microscopic holes placed in a silica-glass-base material....

  13. Optical devices based on liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard

    2005-01-01

    hole. The presence of a LC in the holes of the PCF transforms the fiber from a Total Internal Reflection (TIR) guiding type into a Photonic BandGap (PBG) guiding type, where light is confined to the silica core by coherent scattering from the LC-billed holes. The high dielectric and optical anisotropy...... of LCs combined with the unique waveguiding features of PBG fibers gives the LC filled PCFs unique tunable properties. PBG guidance has been demonstrated for different mesophases of LCs and various functional compact fibers has been demonstrated, which utilitzes the high thermo-optical and electro......-optical effects of LCs. Thermally controlled spectral filters and broadband switching functionalities, electrically controlled switches, polarizers and polarization rotators and an all-optical modulator has been demonstrated. The waveguiding mechanism of anistotropic PBGs fibers has been analyzed and spectral...

  14. Electrically controllable liquid crystal photonic bandgap fiber with dual-frequency control

    DEFF Research Database (Denmark)

    Scolari, Lara; Alkeskjold, Thomas Tanggaard; Riishede, Jesper

    2005-01-01

    We present an electrically tunable liquid crystal photonic bandgap fiber device based on a dual frequency liquid crystal with pre-tilted molecules that allows the bandgaps to be continuously tuned. The frequency dependent behavior of the liquid crystal enables active shifting of the bandgaps toward...

  15. Design of photonic bandgap fibers by topology optimization

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Sigmund, Ole; Feurer, Thomas

    2010-01-01

    A method based on topology optimization is presented to design the cross section of hollow-core photonic bandgap fibers for minimizing energy loss by material absorption. The optical problem is modeled by the timeharmonic wave equation and solved with the finite element program Comsol Multiphysics...... distribution and the lossy silica material is reduced and the energy flow is increased 375% in the core. Simplified designs inspired from optimized geometry are presented, which will be easier to fabricate. The energy flow is increased up to almost 300% for these cases....

  16. Dynamics of soliton cascades in fiber amplifiers.

    Science.gov (United States)

    Arteaga-Sierra, F R; Antikainen, A; Agrawal, Govind P

    2016-11-15

    We study numerically the formation of cascading solitons when femtosecond optical pulses are launched into a fiber amplifier with less energy than required to form a soliton of equal duration. As the pulse is amplified, cascaded fundamental solitons are created at different distances, without soliton fission, as each fundamental soliton moves outside the gain bandwidth through the Raman-induced spectral shifts. As a result, each input pulse creates multiple, temporally separated, ultrashort pulses of different wavelengths at the amplifier output. The number of pulses depends not only on the total gain of the amplifier but also on the width of the input pulse.

  17. Optimization of Pr3+:ZBLAN fiber amplifiers

    DEFF Research Database (Denmark)

    Pedersen, B.; Miniscalco, J. W.; Quimby, R. S.

    1992-01-01

    Experimental parameters have been measured and used in a quantitative model of Pr3+-doped fluorozirconate fiber amplifiers. The optimum cutoff wavelength was determined to be 800 nm and the gain for 400 mW of pump was found to increase from 12 to 34 dB if the NA was increased from 0.15 to 0...

  18. Thermal tunability of photonic bandgaps in liquid crystal infiltrated microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wei, Lei; Alkeskjold, Thomas Tanggaard

    2009-01-01

    We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used to demons......We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used...... to demonstrate that both signs of the thermal tunability of the bandgaps are possible. The useful bandgaps are ultimately bounded to the visible range by the transparency window of the polymer....

  19. Highly tunable large core single-mode liquid crystal photonic bandgap fiber

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper; Bjarklev, Anders Overgaard

    2006-01-01

    We demonstrate a highly tunable photonic bandgap fiber, which has a core diameter of 25mm, and a bandgap tuning sensitivity of 27nm/°C at room temperature. The insertion loss is estimated to be less than 0.5dB....

  20. Power-scalable long-wavelength Yb-doped photonic bandgap fiber sources

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Shirakawa, Akira; Maurayama, Hiroki

    2010-01-01

    Ytterbium-doped photonic-bandgap fiber sources operationg at the long-wavelength edge of the ytterbium gain band are being investigated for high power amplification. Artificial shaping of the gain spectrum by the characteristic distributed filtering effect of the photonic bandgap enables spontane...

  1. Electrially tunable photonic bandgap guidance in a liquid crystal filled photonic crystal fiber

    DEFF Research Database (Denmark)

    Haakestad, Magnus W.; Alkeskjold, Thomas Tanggaard; Nielsen, Martin Dybendal

    2005-01-01

    Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range.......Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range....

  2. Low loss liquid crystal photonic bandgap fiber in the near-infrared region

    DEFF Research Database (Denmark)

    Scolari, Lara; Wei, Lei; Gauza, S.

    2010-01-01

    We infiltrate a photonic crystal fiber with a perdeuterated liquid crystal, which has a reduced infrared absorption. The lowest loss ever reported (about 1 dB) in the middle of the near-infrared bandgap is achieved.......We infiltrate a photonic crystal fiber with a perdeuterated liquid crystal, which has a reduced infrared absorption. The lowest loss ever reported (about 1 dB) in the middle of the near-infrared bandgap is achieved....

  3. Electrically tunable photonic bandgap guidance in a liquid crystal filled photonic crystal fiber

    DEFF Research Database (Denmark)

    Haakestad, Magnus W.; Alkeskjold, Thomas Tanggaard; Nielsen, Martin Dybendal

    2005-01-01

    Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range.......Tunable bandgap guidance is obtained by filling the holes of a solid core photonic crystal fiber with a nematic liquid crystal and applying an electric field. The response times are measured and found to be in the millisecond range....

  4. Gain characteristics of erbium doped fiber amplifier

    Science.gov (United States)

    Zhang, Lihua; Du, Yungang; Xi, Ying; Li, Jijun; Zhao, Chunwang

    2008-12-01

    In the design of Erbium Doped Fiber Amplifier (EDFA), improving flat-gain has great important significance. The working principle and gain characteristics of EDFA are introduced briefly, the influence of the factors such as Erbium doped fiber (EDF) length and pump power on the gain of EDFA is analyzed in detail, and the simulation experiments were carried out with Optisystem software. The result shows that, when pump power is constant, with EDF length departing the optimal value, the gain of each channel decreases at different degrees; when EDF length is constant, with pump power departing the optimal value, the gain of each channel changes at different degrees. Moreover, Er3+ concentration has significant effect on the gain, and there is an optimal Er3+ concentration to get the largest gain.

  5. Coherent combination of ultrafast fiber amplifiers

    International Nuclear Information System (INIS)

    Hanna, Marc; Guichard, Florent; Druon, Frédéric; Georges, Patrick; Zaouter, Yoann; Papadopoulos, Dimitris N

    2016-01-01

    We review recent progress in coherent combining of femtosecond pulses amplified in optical fibers as a way to scale the peak and average power of ultrafast sources. Different methods of achieving coherent pulse addition in space (beam combining) and time (divided pulse amplification) domains are described. These architectures can be widely classified into active methods, where the relative phases between pulses are subject to a servomechanism, and passive methods, where phase matching is inherent to the geometry. Other experiments that combine pulses with different spectral contents, pulses that have been nonlinearly broadened or successive pulses from a mode-locked laser oscillator, are then presented. All these techniques allow access to unprecedented parameter range for fiber ultrafast sources. (topical review)

  6. Spaceflight 2 um Tm Fiber MOPA Amplifier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Fibertek proposes to design, develop, and test a spaceflight prototype 2051 nm thulium (Tm)-doped fiber amplifier (TDFA) optical master oscillator power amplifier...

  7. Hybrid air-core photonic bandgap fiber ring resonator and implications for resonant fiber optic gyro

    Science.gov (United States)

    Yan, Yuchao; Wang, Linglan; Ma, Huilian; Ying, Diqing; Jin, Zhonghe

    2015-07-01

    A novel hybrid polarization-maintaining (PM) air-core photonic bandgap fiber (PBF) ring resonator is demonstrated by using a conventional PM fiber coupler formed by splicing a section of air-core PBF into the resonator. The coupling loss between the PM air-core PBF and the conventional solid-core PM fiber is reduced down to ˜1.8 dB per junction. With the countermeasures proposed to reduce the backscattering induced noise, a bias stability of approximately 0.007 °/s was observed over a 1 hour timeframe, which is the best result reported to date, to the best of our knowledge, for RFOGs equipped with a hybrid air-core PBF ring resonator.

  8. Pump to signal noise transfer in parametric fiber amplifiers

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Rottwitt, Karsten; Peucheret, Christophe

    2010-01-01

    Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal.......Fiber optic parametric amplifiers have been suggested due to their potential low spontaneous emission. However, by nature the parametric amplifier only work in a forward pumped configuration, which result in transfer of relative intensity noise in the pump to the signal....

  9. Enhancement of transmission efficiency in a photonic bandgap fiber introducing nonlinearity

    Science.gov (United States)

    Panda, Abhilash; Hota, Mihir; Tripathy, Sukanta Kumar

    2015-06-01

    This paper introduces the importance of nonlinearity in a Photonic Bandgap (PBG) Fiber using Finite Difference Time Domain (FDTD) simulation. It is shown that, the amplification of the weaker optical signal in a PBG fiber due to the constructive interference between two incoming signals can be controlled using nonlinearity.

  10. Highly tunable large core single-mode liquid crystal photonic bandgap fiber

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper; Bjarklev, Anders Overgaard

    2006-01-01

    We demonstrate a highly tunable photonic bandgap fiber, which has a large-core diameter of 25 mu m and an effective mode area of 440 mu m(2). The tunability is achieved by infiltrating the air holes of a photonic crystal fiber with an optimized liquid-crystal mixture having a large temperature...

  11. Optical tuning of photonic bandgaps in dye-doped nematic liquid crystal photonic crystal fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard; Hermann, David Sparre

    2005-01-01

    An all-optical modulator is demonstrated, which utilizes a pulsed 532 nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid crystal. In order to investigate the time response of the LCPBG fiber device, a low-power CW probe...

  12. Low index-contrast photonic bandgap fiber for transmission of short pulsed light

    DEFF Research Database (Denmark)

    Riishede, Jesper; Lægsgaard, Jesper; Broeng, Jes

    2004-01-01

    The use of low-index-contrast photonic bandgap (PBG) fiber for transmission of short pulsed light is discussed. PBG fibers have positive waveguide dispersion at long wavelengths at which conventional index-guiding fibers have negative waveguide dispersion. PBG fibers with low-index contrast can...... be used to obtain fibers with zero dispersion and a large mode area below 800 nm$+3$/. The results show that the PBG fiber is less sensitive to nonlinear effects and allows transmission of considerably larger intensities....

  13. All-optical dynamic photonic bandgap control in an all-solid double-clad tellurite photonic bandgap fiber.

    Science.gov (United States)

    Cheng, Tonglei; Tanaka, Shunta; Tuan, Tong Hoang; Suzuki, Takenobu; Ohishi, Yasutake

    2017-06-15

    All-optical dynamic photonic bandgap (PBG) control by an optical Kerr effect (OKE) is investigated in an all-solid double-clad tellurite photonic bandgap fiber (PBGF) which is fabricated based on TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN, high-index rod) glass, TeO2-ZnO-Na2O-La2O3 (TZNL, inner cladding) glass, and TeO2-ZnO-Li2O-K2O-Al2O3-P2O5 (TZLKAP, outer cladding) glass. To the best of our knowledge, this is the first demonstration of all-optical dynamic PBG control in optical fibers. This PBGF has a high nonlinear refractive index which can lead to a significant OKE and induce the generation of all-optical dynamic PBG control. The transmission spectrum is simulated with the pump peak power increasing from 0 to 300 kW, which shows an obvious PBG shift. Dynamic PBG control is demonstrated both numerically and experimentally at the pump peak power of 200 kW (ON or OFF) at the signal of 1570 nm.

  14. A Ka-Band Wide-Bandgap Solid-State Power Amplifier: Architecture Performance Estimates

    Science.gov (United States)

    Epp, L.; Khan, P.; Silva, A.

    2005-01-01

    Motivated by recent advances in wide-bandgap (WBG) gallium nitride (GaN) semiconductor technology, there is considerable interest in developing efficient solidstate power amplifiers (SSPAs) as an alternative to the traveling-wave tube amplifier (TWTA) for space applications. This article documents the results of a study to investigate power-combining technology and SSPA architectures that can enable a 120-W, 40 percent power-added efficiency (PAE) SSPA. Results of the study indicate that architectures based on at least three power combiner designs are likely to enable the target SSPA. The proposed architectures can power combine 16 to 32 individual monolithic microwave integrated circuits (MMICs) with >80 percent combining efficiency. This corresponds to MMIC requirements of 5- to 10-W output power and >48 percent PAE. For the three proposed architectures [1], detailed analysis and design of the power combiner are presented. The first architecture studied is based on a 16-way septum combiner that offers low loss and high isolation over the design band of 31 to 36 GHz. Analysis of a 2-way prototype septum combiner had an input match >25 dB, output match >30 dB, insertion loss 30 dB over the design band. A 16-way design, based on cascading this combiner in a binary fashion, is documented. The second architecture is based on a 24-way waveguide radial combiner. A prototype 24-way radial base was analyzed to have an input match >30 dB (under equal excitation of all input ports). The match of the mode transducer that forms the output of a radial combiner was found to be >27 dB. The functional bandwidth of the radial base and mode transducer, which together will form a radial combiner/divider, exceeded the design band. The third architecture employs a 32-way, parallel-plate radial combiner. Simulation results indicated an input match >24 dB, output match >22 dB, insertion loss 20 dB over the design band. All three architectures utilize a low-loss MMIC amplifier module

  15. Thermal-recovery of modal instability in rod fiber amplifiers

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Laurila, Marko; Noordegraaf, Danny

    2013-01-01

    We investigate the temporal dynamics of Modal instabilities (MI) in ROD fiber amplifiers using a 100 μm core rod fiber in a single-pass amplifier configuration, and we achieve ~200W of extracted output power before the onset of MI. Above the MI threshold, we investigate the temporal dynamics...

  16. Compact Electrically tunable Waveplate Based on Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Keller, Stephan Urs

    2009-01-01

    A compact tunable waveplate based on negative dielectric liquid crystal photonic bandgap fibers is presented. The birefringence can be tuned electrically to work as a quarter-wave or a half-wave plate in the wavelength range 1520nm-1600nm.......A compact tunable waveplate based on negative dielectric liquid crystal photonic bandgap fibers is presented. The birefringence can be tuned electrically to work as a quarter-wave or a half-wave plate in the wavelength range 1520nm-1600nm....

  17. Fabrication and characterization of porous-core honeycomb bandgap THz fibers

    DEFF Research Database (Denmark)

    Bao, Hualong; Nielsen, Kristian; Rasmussen, Henrik K.

    2012-01-01

    We present a numerical and experimental investigation of a low-loss porous-core honeycomb fiber for terahertz wave guiding. The introduction of a porous core with hole size of the same dimension as the holes in the surrounding honeycomb cladding results in a fiber that can be drawn with much higher...... precision and reproducibility than a corresponding air-core fiber. The high-precision hole structure provides very clear bandgap guidance and the location of the two measured bandgaps agree well with simulations based on finite-element modeling. Fiber loss measurements reveal the frequency......-dependent coupling loss and propagation loss, and we find that the fiber propagation loss is much lower than the bulk material loss within the first band gap between 0.75 and 1.05 THz....

  18. Hollow core photonic bandgap fiber with microfluid-infiltrated air holes for slow-light propagation

    Science.gov (United States)

    Ren, Liyong; Liang, Jian; Yun, Maojin

    2012-10-01

    Slow light plays an important role in the fields of all-optical signal processing and integration photonics. It has shown many potential applications, such as realizing optical delay lines or buffers, enhancing linear and nonlinear light-matter interactions, as well as increasing the sensitivity of the interferometers and transducers. In this paper, hollow-core photonic bandgap fibers made from high index glasses are designed by infiltrating microfluid into the air-holes to tailor the fiber dispersion for slow-light propagation under low pulse distortion. In such a fiber made from Si material, group index ng~8 is obtained with a bandwidth up to 30 nm, where the group index fluctuation is restricted in ±10 % of the ng, while ng~6 is obtained with a bandwidth over 100 nm when the chalcogenide material is selected instead. Such a ±10 % criterion determines a regarded flatland region accordingly, and in this region the group velocity dispersion can be negligible. It is found that for the same fiber length the slow-light time delay in the photonic bandgap fiber is much larger as compared with that in the single mode fiber. This kind of photonic bandgap fiber may have many potential applications in short-distance fiber communications and delay lines.

  19. Modal instabilities in very large mode area rod fiber amplifiers

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Hansen, Kristian Rymann; Laurila, Marko

    with the finite element method to allow complex micro structured fibers to be considered. Thereby the modal instability threshold is estimated for very large mode area fiber amplifiers of various photonic crystal fiber designs. Experimentally the modal instability threshold for very large mode area fiber......Optical fiber amplifiers have gained increased scientific and commercial interest due to high output powers with easy operation and maintenance. The main advantages of fiber amplifiers are good thermal properties, due to a large surface/volume ratio, excellent beam quality and stability [1]. Very...... large core fiber areas are highly desirable to mitigate various nonlinear processes, such as Kerr, four-wave mixing, Raman, and Brillouin effects. It is difficult to scale up the core area without going into a multi-moded regime. Microstructured fiber technology has allowed core diameters of 60...

  20. Fiber optic signal amplifier using thermoelectric power generation

    Science.gov (United States)

    Hart, Mark M.

    1995-01-01

    A remote fiber optic signal amplifier for use as a repeater/amplifier, such as in transoceanic communications, powered by a Pu.sub.238 or Sr.sub.90 thermoelectric generator. The amplifier comprises a unit with connections on the receiving and sending sides of the communications system, and an erbium-doped fiber amplifier connecting each sending fiber to each receiving fiber. The thermoelectric generator, preferably a Pu.sub.238 or Sr.sub.90 thermoelectric generator delivers power to the amplifiers through a regulator. The heat exchange surfaces of the thermoelectric generator are made of materials resistant to corrosion and biological growth and are directly exposed to the outside, such as the ocean water in transoceanic communications.

  1. On-chip tunable long-period grating devices based on liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Weirich, Johannes; Alkeskjold, Thomas Tanggaard

    2009-01-01

    We design and fabricate an on-chip tunable long-period grating device by integrating a liquid crystal photonic bandgap fiber on silicon structures. The transmission axis of the device can be electrically rotated in steps of 45° as well as switched on and off with the response time...

  2. Theory of adiabatic pressure-gradient soliton compression in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, John

    2009-01-01

    Adiabatic soliton compression by means of a pressure gradient in a hollow-core photonic bandgap fiber is investigated theoretically and numerically. It is shown that the dureation of the compressed pulse is limited mainly by the interplay between third-order dispersion and the Raman-induced soliton...

  3. Thermally tunable bandgaps in a hybrid As2S3/silica photonic crystal fiber

    DEFF Research Database (Denmark)

    Markos, Christos; Stefani, Alessio; Bang, Ole

    2015-01-01

    We report the fabrication and characterization of a hybrid silica photonic crystal fiber (PCF) with integrated chalcogenide glass layers and we show how the bandgaps of the fiber can be thermally tuned. The formation of the high-index chalcogenide films on the inner surface of the PCF holes...... revealed resonances as strong as similar to 35 dB both in the visible and infrared regime. Temperature measurements indicate that the transmission windows can be tuned with a sensitivity as high as similar to 3.5 nm/degrees C. The proposed fiber has potential for all-fiber filtering and temperature sensing....

  4. Higher order mode optical fiber Raman amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Friis, Søren Michael Mørk; Usuga Castaneda, Mario A.

    2016-01-01

    We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations.......We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations....

  5. Ultrasensitive refractive index sensor based on twin-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Town, Graham E.; Bang, Ole

    We have theoretically investigated twin-core all-solid photonic bandgap fibers (PBGFs) for evanescent wave sensing of refractive index within one single microfluidic analyte channel centered between the two cores. The sensor can achieve ultrahigh sensitivity by detecting the change in transmission....... We find novel features in the sensing characteristics: the sensitivity is higher at the short wavelength edge of a bandgap than at the long wavelength edge, the effective index of the odd supermode (nodd) is more sensitive to ambient refractive index change compared with that of the even supermode...

  6. Fiber amplifiers under thermal loads leading to transverse mode instability

    DEFF Research Database (Denmark)

    Johansen, Mette Marie; Hansen, Kristian Rymann; Alkeskjold, Thomas Tanggaard

    2014-01-01

    Transverse mode instability (TMI) in rare-earth doped fiber amplifiers operating above an average power threshold is caused by intermodal stimulated thermal Rayleigh scattering due to quantum defect heating. We investigate thermally induced longitudinal waveguide perturbations causing power trans...

  7. 1.55 Micron High Peak Power Fiber Amplifier Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this proposal, we propose to demonstrate and build a 1.55 micron single frequency high energy and high peak power fiber amplifier by developing an innovative...

  8. Multiple-Output Fiber-Ring Lasers and Amplifiers in a Hybrid CATV and ADSL Broadcasting Optical Fiber Communication System

    Science.gov (United States)

    Lin, Huang-Cuang; Kuo, Shu-Tsung

    In this article we propose two kinds of new fiber ring structure with a semiconductor optical amplifier. The first structure is a one-fiber-ring amplifier with an 8 × 8 fiber coupler and a semiconductor optical amplifier (SOA). The second fiber ring structure is a two-fiber-ring laser including an 8 × 8 fiber coupler, a 2 × 2 E/O modulator, and an SOA. The 14-output spectra of the fiber laser are measured. The gain coefficients of each port of the multiple-output-fiber-ring amplifiers are also measured. We apply these two kinds of fiber ring structures in a hybrid CATV and ADSL broadcasting optical fiber communication system. This application can develop a broadcasting system with large coverage area without using many laser diodes and optical amplifiers. The performance of such a system is also analyzed in this article.

  9. Gain characteristics of a saturated fiber optic parametric amplifier

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Lorenzen, Michael Rodas; Noordegraaf, Danny

    2008-01-01

    In this work we discuss saturation performance of a fiber optic parametric amplifier. A simple numerical model is described and applied to specific cases. A system experiment using a saturated amplifier illustrates a 4 dB improvement in required signal to noise ratio for a fixed bit error ratio....

  10. Tunable photonic bandgap fiber based devices for optical networks

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Scolari, Lara; Rottwitt, Karsten

    2005-01-01

    In future all optical networks one of the enabling technologies is tunable elements including reconfigurable routers, switches etc. Thus, the development of a technology platform that allows construction of tuning components is critical. Lately, microstructured optical fibers, filled with liquid...... crystals, have proven to be a candidate for such a platform. Microstructured optical fibers offer unique wave-guiding properties that are strongly related to the design of the air holes in the cladding of the fiber. These wave-guiding properties may be altered by filling the air holes with a material......, for example a liquid crystal that changes optical properties when subjected to, for example, an optical or an electrical field. The utilization of these two basic properties allows design of tunable optical devices for optical networks. In this work, we focus on applications of such devices and discuss recent...

  11. Fiber optical parametric amplifiers in optical communication systems

    DEFF Research Database (Denmark)

    Marhic, Michel E.; Andrekson, Peter A.; Petropoulos, Periklis

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time...... in excess of 14,000 Tb/s x km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed....

  12. THz Photonic Band-Gap Prisms Fabricated by Fiber Drawing

    DEFF Research Database (Denmark)

    Busch, Stefan F.; Xu, Lipeng; Stecher, Matthias

    2012-01-01

    We suggest a novel form of polymeric based 3D photonic crystal prisms for THz frequencies which could be fabricated using a standard fiber drawing technique. The structures are modeled and designed using a finite element analyzing technique. Using this simulation software we theoretically study...

  13. Liquid crystal parameter analysis for tunable photonic bandgap fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei

    2010-01-01

    We investigate the tunability of splay-aligned liquid crystals for the use in solid core photonic crystal fibers. Finite element simulations are used to obtain the alignment of the liquid crystals subject to an external electric field. By means of the liquid crystal director field the optical...

  14. Microstructured and Photonic Bandgap Fibers for Applications in the Resonant Bio- and Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Maksim Skorobogatiy

    2009-01-01

    Full Text Available We review application of microstructured and photonic bandgap fibers for designing resonant optical sensors of changes in the value of analyte refractive index. This research subject has recently invoked much attention due to development of novel fiber types, as well as due to development of techniques for the activation of fiber microstructure with functional materials. Particularly, we consider two sensors types. The first sensor type employs hollow core photonic bandgap fibers where core guided mode is confined in the analyte filled core through resonant effect in the surrounding periodic reflector. The second sensor type employs metalized microstructured or photonic bandgap waveguides and fibers, where core guided mode is phase matched with a plasmon propagating at the fiber/analyte interface. In resonant sensors one typically employs fibers with strongly nonuniform spectral transmission characteristics that are sensitive to changes in the real part of the analyte refractive index. Moreover, if narrow absorption lines are present in the analyte transmission spectrum, due to Kramers-Kronig relation this will also result in strong variation in the real part of the refractive index in the vicinity of an absorption line. Therefore, resonant sensors allow detection of minute changes both in the real part of the analyte refractive index (10−6–10−4 RIU, as well as in the imaginary part of the analyte refractive index in the vicinity of absorption lines. In the following we detail various resonant sensor implementations, modes of operation, as well as analysis of sensitivities for some of the common transduction mechanisms for bio- and chemical sensing applications. Sensor designs considered in this review span spectral operation regions from the visible to terahertz.

  15. Photonic Bandgap Propagation in All-Solid Chalcogenide Microstructured Optical Fibers

    Directory of Open Access Journals (Sweden)

    Celine Caillaud

    2014-08-01

    Full Text Available An original way to obtain fibers with special chromatic dispersion and single-mode behavior is to consider microstructured optical fibers (MOFs. These fibers present unique optical properties thanks to the high degree of freedom in the design of their geometrical structure. In this study, the first all-solid all-chalcogenide MOFs exhibiting photonic bandgap transmission have been achieved and optically characterized. The fibers are made of an As38Se62 matrix, with inclusions of Te20As30Se50 glass that shows a higher refractive index (n = 2.9. In those fibers, several transmission bands have been observed in mid infrared depending on the geometry. In addition, for the first time, propagation by photonic bandgap effect in an all-chalcogenide MOF has been observed at 3.39 µm, 9.3 µm, and 10.6 µm. The numerical simulations based on the optogeometric properties of the fibers agree well with the experimental characterizations.

  16. Characteristics research on self-amplified distributed feedback fiber laser

    Science.gov (United States)

    Song, Zhiqiang; Qi, Haifeng; Guo, Jian; Wang, Chang; Peng, Gangding

    2014-09-01

    A distributed feedback (DFB) fiber laser with a ratio of the backward to forward output power of 1:100 was composed by a 45-mm-length asymmetrical phase-shifted fiber grating fabricated on the 50-mm erbium-doped photosensitive fiber. Forward output laser was amplified using a certain length of Nufern EDFL-980-Hp erbium-doped fiber to absorb the surplus pump power after the active phase-shifted fiber grating and get population inversion. By using OptiSystem software, the best fiber length of the EDFL to get the highest gain was simulated. In order to keep the amplified laser with the narrow line-width and low noise, a narrow-band light filter consisting of a fiber Bragg grating (FBG) with the same Bragg wavelength as the laser and an optical circulator was used to filter the amplified spontaneous emission (ASE) noise of the out-cavity erbium-doped fiber. The designed laser structure sufficiently utilized the pump power, and a DFB fiber laser with the 32.5-mW output power, 11.5-kHz line width, and -87-dB/Hz relative intensity noise (RIN) at 300 mW of 980 nm pump power was brought out.

  17. In-line flat-top comb filter based on a cascaded all-solid photonic bandgap fiber intermodal interferometer.

    Science.gov (United States)

    Geng, Youfu; Li, Xuejin; Tan, Xiaoling; Deng, Yuanlong; Yu, Yongqin

    2013-07-15

    In this paper, an in-line comb filter with flat-top spectral response is proposed and constructed based on a cascaded all-solid photonic bandgap fiber modal interferometer. It consists of two short pieces of all-solid photonic bandgap fiber and two standard single-mode fibers as lead fibers with core-offset splices between them. The theoretical and experimental results demonstrated that by employing a cut and resplice process on the central position of all-solid photonic bandgap fiber, the interference spectra are well tailored and flat-top spectral profiles could be realized by the controllable offset amount of the resplice. The channel position also could be tuned by applying longitudinal torsion with up to 4 nm tuning range. Such a flat-top fiber comb filter is easy-to-fabricate and with a designable passband width and flat-top profile.

  18. Gaussian Filtering with Tapered Oil-Filled Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Scolari, Lara; Weirich, Johannes

    2008-01-01

    A tunable Gaussian filter based on a tapered oil-filled photonic crystal fiber is demonstrated. The filter is centered at X=1364nm with a bandwidth (FWHM) of 237nm. Tunability is achieved by changing the temperature of the filter. A shift of 210nm of the central wavelength has been observed by in...... by increasing the temperature from 25°C to 100°C. The measurements are compared to a simulated spectrum obtained by means of a vectorial Beam Propagation Method model....

  19. Influence of air pressure on soliton formation in hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Roberts, Peter John

    2009-01-01

    Abstract Soliton formation during dispersive compression of chirped few-picosecond pulses at the microjoule level in a hollow-core photonic bandgap (HC-PBG) fiber is studied by numerical simulations. Long-pass filtering of the emerging frequency-shifted solitons is investigated with the objective...... of obtaining pedestal-free output pulses. Particular emphasis is placed on the influence of the air pressure in the HC-PBG fiber. It is found that a reduction in air pressure enables an increase in the fraction of power going into the most redshifted soliton and also improves the quality of the filtered pulse...

  20. All-optical modulation in dye-doped nematic liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper; Bjarklev, Anders Overgaard

    2004-01-01

    Photonic crystal fibers (PCFs) have attracted significant attention during the last years and much research has been devoted to develop fiber designs for various applications, hereunder tunable fiber devices. Recently, thermally and electrically tunable PCF devices based on liquid crystals (LCs......) have been demonstrated. However, optical tuning of the LC PCF has until now not been demonstrated. Here we demonstrate an all-optical modulator, which utilizes a pulsed 532nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid...... crystal. We demonstrate a modulation frequency of 2kHz for a moderate pump power of 2-3mW and describe two pump pulse regimes in which there is an order of magnitude difference between the decay times....

  1. Fabrication and characterization of porous-core honeycomb bandgap THz fibers

    DEFF Research Database (Denmark)

    Bao, Hualong; Nielsen, Kristian; Rasmussen, Henrik K.

    We have fabricated a porous-core honeycomb fiber in the cyclic olefin copolymer (COC) Topas® by drill-draw technology [1]. A cross-sectional image of the fabricated fiber is shown in the left Panel of Fig. 1. Simulation of the electromagnetic properties of the fiber shows two wide bandgaps within...... the frequency range 0.1 to 2 THz, and numerous sharp resonant features are visible in the core power ratio, indicative of resonant coupling between the reflected field from the outer interface of the fiber and the core mode. The fiber is experimentally characterized with a commercial fiber-coupled THz......-TDS system (Picometrix T-Ray 4000). The reference pulse before coupling into the fiber is shown in Fig. 1(a) and the time trace of the THz pulse after propagation through a 5-cm long segment of fiber is shown in Fig. 1(b) (blue curve). After adding some water on the outside of the fiber surface...

  2. Spatial and spectral imaging of LMA photonic crystal fiber amplifiers

    DEFF Research Database (Denmark)

    Laurila, Marko; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2011-01-01

    We demonstrate modal characterization using spatial and spectral resolved (S2) imaging, on an Ytterbium-doped large-mode-area photonic crystal fiber (PCF) amplifier and compare results with conventional cut-off methods. We apply numerical simulations and step-index fiber experiments to calibrate...... our mathematical and experimental routines of our S2 imaging system. We systematically analyze higher order mode (HOM) content of a polarizing 40μm core double-clad PCF amplifier with various launching and coiling configurations. We demonstrate a HOM suppression of more than -24dB with variance of 2...

  3. Estimating modal instability threshold for photonic crystal rod fiber amplifiers

    DEFF Research Database (Denmark)

    Johansen, Mette Marie; Hansen, Kristian Rymann; Laurila, Marko

    2013-01-01

    We present a semi-analytic numerical model to estimate the transverse modal instability (TMI) threshold for photonic crystal rod amplifiers. The model includes thermally induced waveguide perturbations in the fiber cross section modeled with finite element simulations, and the relative intensity...... noise (RIN) of the seed laser, which seeds mode coupling between the fundamental and higher order mode. The TMI threshold is predicted to ~370 W – 440 W depending on RIN for the distributed modal filtering rod fiber....

  4. Short-pulse propagation in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina

    Fiber optical parametric amplifiers (FOPAs) are attractive because they can provide large gain over a broad range of central wavelengths, depending only on the availability of a suitable pump laser. In addition, FOPAs are suitable for the realization of all-optical signal processing functionalities...... is implemented to obtain an all-fiber system. The advantages of all fiber-systems are related to their reliability, long-term stability and compactness. Fiber optical parametric chirped pulse amplification is promising for the amplification of such signals thanks to the inherent compatibility of FOPAs with fiber...... optical systems and high gain over broad bandwidths. In particular, the amplification of 400 fs pulses is investigated in a single-pump fiber optical chirped pulse amplification sc heme. First, a dynamic characterization is carried out both in unsaturated and saturated regimes and, then, amplification...

  5. Characteristics research of self-amplified distributed feedback fiber laser

    Science.gov (United States)

    Song, Zhiqiang; Qi, Haifeng; Guo, Jian; Wang, Chang; Peng, Gangding

    2013-09-01

    A distributed feedback (DFB) fiber laser with a ratio of backward to forward output power of 1:100 was composed by a 45mm length asymmetrical phase-shifted fiber grating fabricated on 50mm erbium-doped photosensitive fiber. Forward output laser was amplified using a certain length of Nufern EDFL980-Hp erbium-doped fiber to absorb surplus pump power after the active phase-shifted fiber grating and get population inversion. Using OptiSystem software, the best fiber length of the EDFL to get the highest gain was simulated. In order to keep the amplified laser with narrow line-width and low noise, a narrow-band light filter consisted of a FBG with the same Bragg wavelength as the laser and an optical circulator was used to filter the ASE noise of the out-cavity erbium-doped fiber. The designed laser structure sufficiently utilized the pump power, a DFB fiber laser of 32.5mW output power, 11.5 kHz line width, and -87dB/Hz relative intensity noise (RIN) at 300mW of 980 nm pump power was brought out.

  6. Transmission and radiation of an accelerating mode in a photonic band-gap fiber

    Directory of Open Access Journals (Sweden)

    C.-K. Ng

    2010-12-01

    Full Text Available A hollow-core photonic band-gap (PBG lattice in a dielectric fiber has been proposed as a high-gradient low-cost particle accelerator operating in the optical regime where the accelerating mode confined to a defect in the PBG fiber can be excited by high-power lasers [X. Lin, Phys. Rev. ST Accel. Beams 4, 051301 (2001PRABFM1098-440210.1103/PhysRevSTAB.4.051301]. Developing efficient methods of coupling laser power into these structures requires a thorough examination of the propagating mode and its near and far-field radiation. In this paper, we develop a simulation method using the parallel finite-element electromagnetic suite ACE3P to calculate the radiation of the propagating accelerator mode into free space at the end of the fiber. The far-field radiation will be calculated and the mechanism of coupling power from an experimental laser setup will be discussed.

  7. Thermally controlled mid-IR band-gap engineering in all-glass chalcogenide microstructured fibers: a numerical study

    DEFF Research Database (Denmark)

    Barh, Ajanta; Varshney, Ravi K.; Pal, Bishnu P.

    2017-01-01

    Presence of photonic band-gap (PBG) in an all-glass low refractive index (RI) contrast chalcogenide (Ch) microstructured optical fibers (MOFs) is investigated numerically. The effect of external temperature on the position of band-gap is explored to realize potential fiber-based wavelength filters....../sensors at functional mid-IR spectral range. The cross-sectional geometry of the MOF is formed by considering a Ch glass to form the overall background cross-section as well as the central fiber core. The core region is surrounded by periodically arranged (hexagonal pattern) smaller holes, which are assumed...

  8. Demodulation of DPSK signals up to 40 Gb/s using a highly birefringent photonic bandgap fiber

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Geng, Yan; Zsigri, Beata

    2006-01-01

    Phase-to-intensity modulation conversion of differential phase-shift keying signals is successfully demonstrated at 10 and 40 Gb/s using a polarization Mach-Zehnder delay interferometer implemented with only 2.4 m of a highly birefringent air-guiding photonic bandgap (PBG) fiber. Such a PBG fiber...

  9. Self-pulsation threshold of Raman amplified Brillouin fiber cavities

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær; Pedersen, Martin Erland Vestergaard; Rottwitt, Karsten

    2009-01-01

    An implicit equation for the oscillation threshold of stimulated Brillouin scattering from Raman amplified signals in fibers with external feedback is derived under the assumption of no depletion. This is compared to numerical investigations of Raman amplification schemes showing good agreement...

  10. Frequency resolved transverse mode instability in rod fiber amplifiers

    DEFF Research Database (Denmark)

    Johansen, Mette Marie; Laurila, Marko; Maack, Martin D.

    2013-01-01

    Frequency dynamics of transverse mode instabilities (TMIs) are investigated by testing three 285/100 rod fibers in a single-pass amplifier setup reaching up to ~200W of extracted output power without beam instabilities. The pump power is increased well above the TMI threshold to uncover output dy...

  11. Optimum design of Nd-doped fiber optical amplifiers

    DEFF Research Database (Denmark)

    Rasmussen, Thomas; Bjarklev, Anders Overgaard; Lumholt, Ole

    1992-01-01

    The waveguide parameters for a Nd-doped fluoride (Nd:ZBLANP) fiber amplifier have been optimized for small-signal and booster operation using an accurate numerical model. The optimum cutoff wavelength is shown to be 800 nm and the numerical aperture should be made as large as possible. Around 80...

  12. Processing of optical combs with fiber optic parametric amplifiers

    Czech Academy of Sciences Publication Activity Database

    Slavík, Radan; Kakande, J.; Richardson, D.J.; Petropoulos, P.

    2012-01-01

    Roč. 20, č. 9 (2012), s. 10059-10070 ISSN 1094-4087 Institutional support: RVO:67985882 Keywords : Fiber - optic parametric amplifier * Phase sensitive * Spectral coverage Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.546, year: 2012

  13. Asymmetric gain-saturated spectrum in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Rottwitt, Karsten; Galili, Michael

    2012-01-01

    We demonstrate experimentally and numerically an unexpected spectral asymmetry in the saturated-gain spectrum of single-pump fiber optical parametric amplifiers. The interaction between higher-order four-wave mixing products and dispersive waves radiated as an effect of third-order dispersion...

  14. New interferometric fiber-optic gyroscope with amplified optical feedback.

    Science.gov (United States)

    Shi, C X; Yuhara, T; Iizuka, H; Kajioka, H

    1996-01-20

    A novel interferometric fiber-optic gyroscope with amplified optical feedback by an Er-doped fiber amplifier (EDFA) is proposed and theoretically investigated (the proposed gyroscope is named the feedback EDFA-FOG, FE-FOG in what follows). The FE-FOG functions like a resonant fiber-optic gyro (R-FOG) because of its multiple utilization of the Sagnac loop; however, it is completely different because a low-coherence light source is used. In addition, the gyro output signal is pulsed because the modulation frequency of the phase modulator placed in the Sagnac loop is selected to match the total round-trip time delay of the light, which includes the Sagnac-loop delay plus that of the feedback loop of the fiber amplifier. The sharpness of the output pulse can be adjusted by both the gain of an EDFA and the modulation depth of the phase modulator. When rotation occurs the peak position of the output pulse is shifted as a result of the Sagnac effect. The resolution of the rotation measurement depends on the sharpness of the output pulse. The techniques of both the open-loop and closed-loop methods are described in detail, which shows the great advantage of the proposed gyroscope over the to the conventional interferometric fiber-optical gyroscope (I-FOG).

  15. High Power Narrow Linewidth 1.26 Micron Ho-Doped Fiber Amplifier, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of an innovative, high power, and extremely reliable 1.26-micron Ho-doped fluoride fiber amplifier. The proposed fiber amplifier...

  16. High Power Narrow Linewidth 1.26 Micron Ho-Doped Fiber Amplifier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of an innovative, high power, and extremely reliable 1.26-micron Ho-doped fluoride fiber amplifier. The proposed fiber amplifier...

  17. Reduced thermal sensitivity of hybrid air-core photonic band-gap fiber ring resonator

    Science.gov (United States)

    Feng, Li-shuang; Wang, Kai; Jiao, Hong-chen; Wang, Jun-jie; Liu, Dan-ni; Yang, Zhao-hua

    2018-01-01

    A novel hybrid air-core photonic band-gap fiber (PBF) ring resonator with twin 90° polarization-axis rotated splices is proposed and demonstrated. Frist, we measure the temperature dependent birefringence coefficient of air-core PBF and Panda fiber. Experimental results show that the relative temperature dependent birefringence coefficient of air-core PBF is 1.42×10-8/°C, which is typically 16 times less than that of Panda fiber. Then, we extract the geometry profile of air-core PBF from scanning electron microscope (SEM) images. Numerical modal is built to distinguish the fast axis and slow axis in the fiber. By precisely setting the length difference in air-core PBF and Panda fiber between two 90° polarization-axis rotated splicing points, the hybrid air-core PBF ring resonator is constructed, and the finesse of the resonator is 8.4. Environmental birefringence variation induced by temperature change can be well compensated, and experimental results show an 18-fold reduction in thermal sensitivity, compared with resonator with twin 0° polarization-axis rotated splices.

  18. Strain and temperature sensitivities of an elliptical hollow-core photonic bandgap fiber based on Sagnac interferometer.

    Science.gov (United States)

    Kim, Gilhwan; Cho, Taiyong; Hwang, Kyujin; Lee, Kwanil; Lee, Kyung S; Han, Young-Geun; Lee, Sang Bae

    2009-02-16

    We fabricated an elliptical hollow-core photonic bandgap fiber (EC-PBGF) by controlling lateral tension in the hollow core region during the fiber drawing process. The absolute value of group modal birefringence becomes relatively high near the bandgap boundaries. We also experimentally measured the strain and temperature sensitivities of the fabricated EC-PBGF-based Sagnac loop interferometer. The strain and temperature sensitivities were very much dependent upon the wavelength. Moreover this PBGF-based interferometer can be a good sensor of physical parameters such as strain and temperature.

  19. High power pulsed sources based on fiber amplifiers

    Science.gov (United States)

    Canat, Guillaume; Jaouën, Yves; Mollier, Jean-Claude; Bouzinac, Jean-Pierre; Cariou, Jean-Pierre

    2017-11-01

    Cladding-pumped rare-earth-doped fiber laser technologies are currently among the best sources for high power applications. Theses extremely compact and robust sources appoint them as good candidate for aeronautical and space applications. The double-clad (DC) fiber converts the poor beamquality of high-power large-area pump diodes from the 1st cladding to laser light at another wavelength guided in an active single-mode core. High-power coherent MOPA (Master Oscillator Power Amplifier) sources (several 10W CW or several 100W in pulsed regime) will soon be achieved. Unfortunately it also brings nonlinear effects which quickly impairs output signal distortions. Stimulated Brillouin scattering (SBS) and optical parametric amplification (OPA) have been shown to be strong limitations. Based on amplifier modeling and experiments we discuss the performances of these sources.

  20. Thermally controlled mid-IR band-gap engineering in all-glass chalcogenide microstructured fibers: a numerical study

    Science.gov (United States)

    Barh, A.; Varshney, R. K.; Pal, B. P.; Sanghera, J.; Shaw, L. B.

    2017-06-01

    Presence of photonic band-gap (PBG) in an all-glass low refractive index (RI) contrast chalcogenide (Ch) microstructured optical fibers (MOFs) is investigated numerically. The effect of external temperature on the position of band-gap is explored to realize potential fiber-based wavelength filters/sensors at functional mid-IR spectral range. The cross-sectional geometry of the MOF is formed by considering a Ch glass to form the overall background cross-section as well as the central fiber core. The core region is surrounded by periodically arranged (hexagonal pattern) smaller holes, which are assumed to be filled up with another Ch glass. Thermally compatible and fabrication suitable, two Ch glasses are chosen, one (higher RI) as background material and the other (of lower RI) to fill up the holes. Two sets of such pairs of thermally compatible Ch-glasses are considered as fiber structural materials with relative RI contrast of ∼12% and ∼24%. For both such low RI contrast hexagonal structures, PBG appears only for suitable finite values of longitudinal wave vector. The structures are suitable to realize band-gap at mid-IR wavelengths and specifically optimized for operation around the ∼2 μm region. Then the temperature sensitivity of band-gaps is investigated to design fiber-based mid-IR wavelength filters/sensors.

  1. Design of a Polymer-Based Hollow-Core Bandgap Fiber for Low-Loss Terahertz Transmission

    DEFF Research Database (Denmark)

    Barh, Ajanta; Varshney, Ravi K.; Pal, Bishnu P.

    2016-01-01

    wavelength-scale circular air holes in a hexagonal pattern, embedded in a uniform Teflon matrix. The THz guidance in this fiber is achieved by exploiting the photonic bandgap (PBG) effect. In our low index contrast Teflon-air (1.44:1) hexagonal periodic lattice, the PBG appears only for a certain range...

  2. Experimental investigation of backreflection at air-core photonic bandgap fiber terminations

    Science.gov (United States)

    Xu, Xiaobin; Yan, Ming; Wu, Chunxiao; Song, Ningfang; Zhang, Chunxi

    2017-07-01

    Backreflection from the termination of air-core photonic bandgap fibers (PBFs) is experimentally investigated based on a range-extended Mach-Zehnder and Michelson hybrid (M2) interferometer. For primary waves generated by the fundamental modes, the reflectivity is about -90 dB; for secondary waves caused by other modes, the reflectivity is less than -80 dB when compared to the intensity of the primary wave and -20 to -50 dB when compared to their own incident intensity. To suppress the reflection, 3-centimeter PBF at the end is filled with alcohol through the capillary effect, and this proposed method is shown to be much more convenient and effective than the conventional angle cleaving method.

  3. Fiber optical parametric amplifiers in optical communication systems

    Science.gov (United States)

    Marhic (†), Michel E; Andrekson, Peter A; Petropoulos, Periklis; Radic, Stojan; Peucheret, Christophe; Jazayerifar, Mahmoud

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed. PMID:25866588

  4. Large-scale interferometric fiber sensor arrays with erbium-doped fiber amplifier telemetry

    Science.gov (United States)

    Hodgson, Craig Warren

    Underwater acoustic sensing for mapping energy resources below the ocean floor involves measuring weak reflections of acoustic pulses from the rock layers. The acoustic pulses are generated by a ship-mounted air gun. The reflected acoustic signals are detected by thousands of acoustic hydrophones distributed along miles of bulky electrical wires and towed behind a large ship. For the last two decades, fiber optics has held the promise of providing longer arrays, more sensors, and higher sensitivity, on a 'pencil-thin' fiber optic cable. Fiber sensors with high sensitivity and wide dynamic range have been available for years, but multiplexing many sensors on a single pair of fibers has been difficult. Until recently, only passive multiplexing of fiber sensors was available, with its inherent limit of approximately 10 sensors per pair of fibers, due to passive splitting and dissipative losses. A separate fiber pair for each group of 10 sensors leads to an unmanageable fiber count for a practical passive array with thousands of sensors. The general objective of our work is to design and test new fiber array topologies that maximize the number of sensors per fiber pair while maintaining high signal-to- noise ratio and meeting all operational requirements. We discovered that multiplexing hundreds of sensors per fiber is possible by adding low-gain fiber amplifiers to compensate for the losses. The amplifiers are distributed throughout an array and pumped by a remote source. This application uses erbium-doped fiber amplifiers, borrowed from the communication industry. We demonstrated a sensor array, incorporating 20 amplifiers, that exhibits excellent signal-to-noise ratio, confirming our theory. We predict that this new design can be scaled to support 300 sensors per fiber pair, and achieve a great reduction in cost, complexity, and weight. We also investigated a second array topology using fiber optic switches to route the signals dynamically through the array. Both a

  5. Optical Spectra Tuning of All-Glass Photonic Bandgap Fiber Infiltrated with Silver Fast-Ion-Conducting Glasses

    Directory of Open Access Journals (Sweden)

    Ioannis Konidakis

    2014-08-01

    Full Text Available Silver iodide metaphosphate glasses of the xAgI + (1−xAgPO3 family are embedded inside the air capillaries of a commercial silica photonic crystal fiber (PCF by means of vacuum-assisted infiltration technique. In this paper, we report on tuning the photonic bandgap (PBG guidance characteristics of the fabricated all-glass photonic bandgap fibers, by varying the composition of the fast-ion-conducting phosphate glass infiltration medium. Doping AgPO3 metaphosphate glass with AgI significantly alters the PBG guidance patterns in the examined range between 350 and 1750 nm, as it leads to the introduction of numerous additional transmission stop-bands, while affecting scattering dependant losses. The effect of phosphate glass cooling method during sample fabrication on the transmission behavior of the xAgI + (1−xAgPO3/PCFs is also considered.

  6. Optical Spectra Tuning of All-Glass Photonic Bandgap Fiber Infiltrated with Silver Fast-Ion-Conducting Glasses.

    Science.gov (United States)

    Konidakis, Ioannis; Pissadakis, Stavros

    2014-08-07

    Silver iodide metaphosphate glasses of the x AgI + (1- x )AgPO₃ family are embedded inside the air capillaries of a commercial silica photonic crystal fiber (PCF) by means of vacuum-assisted infiltration technique. In this paper, we report on tuning the photonic bandgap (PBG) guidance characteristics of the fabricated all-glass photonic bandgap fibers, by varying the composition of the fast-ion-conducting phosphate glass infiltration medium. Doping AgPO₃ metaphosphate glass with AgI significantly alters the PBG guidance patterns in the examined range between 350 and 1750 nm, as it leads to the introduction of numerous additional transmission stop-bands, while affecting scattering dependant losses. The effect of phosphate glass cooling method during sample fabrication on the transmission behavior of the x AgI + (1- x )AgPO₃/PCFs is also considered.

  7. Spectral shaping of a 10 W diode laser-Yb-fiber amplifier system

    NARCIS (Netherlands)

    Adhimoolam, B.; Lindsay, I.D.; Lee, Christopher James; Gross, P.; Boller, Klaus J.; Klein, M.E.

    2006-01-01

    We describe a continuous-wave master-oscillator power-amplifier system based on a distributed Bragg reflection diode laser and an Yb doped fiber amplifier. The observed optical spectrum of the amplified seed source can be tailored to arbitrary shapes and widths between 30 MHz and greater than 1 GHz

  8. 40 W picosecond fiber amplifier with the large mode-area polarized crystal fiber

    International Nuclear Information System (INIS)

    Yu, H; Zhou, J; Wushouer, X; Yan, P; Wang, D; Gong, M

    2009-01-01

    We reported the 5W picosecond laser with pulse width of 30 ps and the repetition rate of 100 MHz, which was amplified to 40.2 W with the linear polarized Yb-doped photonic crystal fiber (PCF), with the slope efficiency of about 58%. As much as 17.3 W second-harmonic power was achieved corresponding to the conversion efficiency of 43%

  9. All-Glass Fiber Amplifier Pumped by Ultra-High Brightness Pumps

    Science.gov (United States)

    2016-02-15

    established. While kW- class Yb-doped cw fiber lasers are inherently nonlinear devices [7], using phase-modulated input to seed these fiber amplifiers ...Ding J., Holten, R., Ahmadi P., Wang C., Guintrand C., Farley, K., Christensen S., Tankala, K., "Performance of kW class fiber amplifiers spanning a...Goldizen, K., Murphy, D ., Sanchez, A. and Fan, T. Y., "Coherent combining of a 4 kW, eight-element fiber amplifier array," Opt. Lett., 36(14), 2686 (2011

  10. Performance analysis of an optical passive ring-resonator gyro with a hollow-core photonic bandgap fiber sensing coil

    Science.gov (United States)

    Zhang, X. L.; Jin, W.; Ying, D. Q.

    2010-11-01

    We evaluate the measurement errors induced by various deleterious effects in an optical passive ring-resonator gyro (OPRG) with a hollow-core photonic bandgap fiber (HC-PBF) sensing coil. The uncertainties in measuring rotation rate due to Kerr, Shupe, and Faraday effects are found to be reduced respectively by 2~3, 1, and 1~2 orders of magnitude as compared with an OPRG with a conventional single mode fiber (SMF) sensing coil of similar parameters. The errors due to shot and coherent backscatter noises are larger for the OPRG made of the current state-of-the-art HC-PBF than for the OPRG with a conventional SMF coil, but are expected to reduce in future with improved fiber manufacture technologies.

  11. On the Theory of the Modulation Instability in Optical Fiber and Laser Amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Rubenchik, A M; Turitsyn, S K; Fedoruk, M P

    2010-11-03

    The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW beam breakup and the growth of multiple pulses. This can be both a detrimental effect, limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model, and the range of applicability of the latter is determined. The same technique is applicable to the study of spatial MI in solid state laser amplifiers and MI in non-uniform media.

  12. Optimizing single mode robustness of the distributed modal filtering rod fiber amplifier

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko

    2012-01-01

    High-power fiber amplifiers for pulsed applications require large mode area (LMA) fibers having high pump absorption and near diffraction limited output. Photonic crystal fibers allow realization of short LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled...... from the outer fiber diameter. However, achieving ultra low NA for single mode (SM) guidance is challenging, thus different design strategies must be applied. The distributed modal filtering (DMF) design enables SM guidance in ultra low NA fibers with very large cores, where large preform tolerances...... can be compensated during the fiber draw. Design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared to previous results, achieved by utilizing the first band of cladding modes, which can cover...

  13. Low-NA single-mode LMA photonic crystal fiber amplifier

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Laurila, Marko; Scolari, Lara

    2011-01-01

    Enabling Single-Mode (SM) operation in Large-Mode-Area (LMA) fiber amplifiers and lasers is critical, since a SM output ensures high beam quality and excellent pointing stability. In this paper, we demonstrate and test a new design approach for achieving ultra-low NA SM rod fibers by using...... a spatially Distributed Mode Filter (DMF). This approach achieves SM performance in a short and straight rod fiber and allows preform tolerances to be compensated during draw. A low-NA SM rod fiber amplifier having a mode field diameter of ~60μm at 1064nm and a pump absorption of 27dB/m at 976nm...

  14. Theoretical study of fiber Raman amplifiers by broadband pumps through moment method

    International Nuclear Information System (INIS)

    Teimorpour, M. H.; Pourmoghadas, A.; Rahimi, L.; Farman, F.; Bahrampour, A.

    2007-01-01

    The governing equations of Raman optical fiber amplifier with broadband pumps in the steady state are a system of Uncountable Nonlinear Ordinary Differential Equations. In this paper, the Moment Method is used to reduce the uncountable system of Nonlinear Ordinary Differential Equations to a system of finite number of Nonlinear Ordinary Differential Equations. This system of equations is solved numerically. It is shown that the Moment Method is a precise and fast technique for analysis of optical fiber Raman Amplifier with broadband pumps.

  15. Wavefront control of a multicore ytterbium-doped pulse fiber amplifier by digital holography.

    Science.gov (United States)

    Paurisse, Mathieu; Hanna, Marc; Druon, Frédéric; Georges, Patrick

    2010-05-01

    We demonstrate the active wavefront control of a 19-core ytterbium-doped fiber amplifier by the digital holography technique. The output wavefront is corrected even in the presence of large externally induced perturbations, with a measured output Strehl ratio of 0.6 in all cases. The wavefront-controlled multicore fiber is used to amplify 800 ps pulses at 1064 nm at a repetition rate of 40?kHz, and a gain of 23 dB is obtained.

  16. Dynamic characterization and amplification of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard

    2013-01-01

    We show a first-time demonstration of amplification of 400 fs pulses in a fiber optical parametric amplifier. The 400 fs signal is stretched in time, amplified by 26 dB and compressed back to 500 fs. A significant broadening of the pulses is experimentally shown due to dispersion and limited gain...

  17. Hybrid Ytterbium-doped large-mode-area photonic crystal fiber amplifier for long wavelengths

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas T.; Poli, Federica

    2012-01-01

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with build-in gain shaping is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes define the large-mode-area core. ...

  18. Thermo-optical effects in high-power Ytterbium-doped fiber amplifiers

    DEFF Research Database (Denmark)

    Hansen, Kristian Rymann; Alkeskjold, Thomas Tanggaard; Broeng, Jes

    2011-01-01

    We investigate the effect of temperature gradients in high-power Yb-doped fiber amplifiers by a numerical beam propagation model, which takes thermal effects into account in a self-consistent way. The thermally induced change in the refractive index of the fiber leads to a thermal lensing effect...

  19. Solid-Core Photonic Bandgap Fibers for Cladding-Pumped Raman Amplification

    Science.gov (United States)

    2011-06-03

    that the cladding is uniformly-pumped at its maximum numerical aperture and that the photonic band gap ( PBG ) structure comprised of a triangular array...published 3 Jun 2011 (C) 2011 OSA 6 June 2011 / Vol. 19, No. 12 / OPTICS EXPRESS 11855 beyond the PBG structure. In this case, the high pump cladding...exhibit lower loss [16]. For high order bandgaps to exist in the cladding, the inclusions forming the PBG structure must support a large number of guided

  20. 1-MHz high power femtosecond Yb-doped fiber chirped-pulse amplifier

    Science.gov (United States)

    Hu, Zhong-Qi; Yang, Pei-Long; Teng, Hao; Zhu, Jiang-Feng; Wei, Zhi-Yi

    2018-01-01

    A practical femtosecond polarization-maintaining Yb-doped fiber amplifier enabling 153 fs transform-limited pulse duration with 32 μJ pulse energy at 1 MHz repetition rate corresponding to a peak power of 0.21 GW is demonstrated. The laser system based on chirped-pulse amplification (CPA) technique is seeded by a dispersion managed, nonlinear polarization evolution (NPE) mode-locked oscillator with spectrum bandwidth of 31 nm at 1040 nm and amplified by three fiber pre-amplifying stages and a rod type fiber main amplifying stage. The laser works with beam quality of M2 of 1.3 and power stability of 0.63% (root mean square, RMS) over 24 hours will be stable sources for industrial micromachining, medical therapy and scientific research.

  1. Investigation on the Effect of Underwater Acoustic Pressure on the Fundamental Mode of Hollow-Core Photonic Bandgap Fibers

    Directory of Open Access Journals (Sweden)

    Adel Abdallah

    2015-01-01

    Full Text Available Recently, microstructured optical fibers have become the subject of extensive research as they can be employed in many civilian and military applications. One of the recent areas of research is to enhance the normalized responsivity (NR to acoustic pressure of the optical fiber hydrophones by replacing the conventional single mode fibers (SMFs with hollow-core photonic bandgap fibers (HC-PBFs. However, this needs further investigation. In order to fully understand the feasibility of using HC-PBFs as acoustic pressure sensors and in underwater communication systems, it is important to study their modal properties in this environment. In this paper, the finite element solver (FES COMSOL Multiphysics is used to study the effect of underwater acoustic pressure on the effective refractive index neff of the fundamental mode and discuss its contribution to NR. Besides, we investigate, for the first time to our knowledge, the effect of underwater acoustic pressure on the effective area Aeff and the numerical aperture (NA of the HC-PBF.

  2. Design of a transimpedance amplifier for a bio-optical fiber sensor

    International Nuclear Information System (INIS)

    Pola, L.; Camasa, J.; Gomez B, J.

    2012-01-01

    In this work we present a fairly detailed model for a photodiode coupled to an operational amplifier in the trans impedance circuit configuration, for the applications in Biotechnology. An optical signal of the fiber optic biosensor is detected by a photodiode and its photocurrent generated is introduced in the trans impedance amplifier. The proposed design uses a photodiode in photovoltaic mode, and its photocurrent is coupled to an amplifier with positive output. Finally, the trans impedance amplifier presents reliable design characteristics such as accuracy, stability, low noise, and the ability to measure photocurrent from 1nA to 100μA. (Author)

  3. A 23-dB bismuth-doped optical fiber amplifier for a 1700-nm band

    Science.gov (United States)

    Firstov, Sergei V.; Alyshev, Sergey V.; Riumkin, Konstantin E.; Khopin, Vladimir F.; Guryanov, Alexey N.; Melkumov, Mikhail A.; Dianov, Evgeny M.

    2016-01-01

    It is now almost twenty-five years since the first Erbium-Doped Fiber Amplifier (EDFA) was demonstrated. Currently, the EDFA is one of the most important elements widely used in different kinds of fiber-optic communication systems. However, driven by a constantly increasing demand, the network traffic, growing exponentially over decades, will lead to the overload of these systems (“capacity crunch”) because the operation of the EDFA is limited to a spectral region of 1530–1610 nm. It will require a search for new technologies and, in this respect, the development of optical amplifiers for new spectral regions can be a promising approach. Most of fiber-optic amplifiers are created using rare-earth-doped materials. As a result, wide bands in shorter (1150–1530 nm) and longer wavelength (1600–1750 nm) regions with respect to the gain band of Er-doped fibers are still uncovered. Here we report on the development of a novel fiber amplifier operating in a spectral region of 1640–1770 nm pumped by commercially available laser diodes at 1550 nm. This amplifier was realized using bismuth-doped high-germania silicate fibers fabricated by MCVD technique. PMID:27357592

  4. High repetition rate tunable femtosecond pulses and broadband amplification from fiber laser pumped parametric amplifier.

    Science.gov (United States)

    Andersen, T V; Schmidt, O; Bruchmann, C; Limpert, J; Aguergaray, C; Cormier, E; Tünnermann, A

    2006-05-29

    We report on the generation of high energy femtosecond pulses at 1 MHz repetition rate from a fiber laser pumped optical parametric amplifier (OPA). Nonlinear bandwidth enhancement in fibers provides the intrinsically synchronized signal for the parametric amplifier. We demonstrate large tunability extending from 700 nm to 1500 nm of femtosecond pulses with pulse energies as high as 1.2 muJ when the OPA is seeded by a supercontinuum generated in a photonic crystal fiber. Broadband amplification over more than 85 nm is achieved at a fixed wavelength. Subsequent compression in a prism sequence resulted in 46 fs pulses. With an average power of 0.5 W these pulses have a peak-power above 10 MW. In particular, the average power and pulse energy scalability of both involved concepts, the fiber laser and the parametric amplifier, will enable easy up-scaling to higher powers.

  5. Air-Guiding Photonic Bandgap Fibers: Spectral Properties, Macrobending Loss, and Practical Handling

    DEFF Research Database (Denmark)

    Hansen, Theis Peter; Broeng, Jes; Jakobsen, Christian

    2004-01-01

    For development of hollow-core transmission fibers, the realizable fibers lengths, bandwidth, characterization, and compatibility with standard technology are important issues. We report record-length air-guiding fiber, spectral properties, splicing, and optical time domain reflectometer (OTDR) m...

  6. High peak power picosecond hybrid fiber and solid-state amplifier system

    International Nuclear Information System (INIS)

    Wushouer, X; Yan, P; Yu, H; Liu, Q; Fu, X; Yan, X; Gong, M

    2010-01-01

    We report the high peak power picosecond hybrid fiber and solid-state laser amplifier system. The passively mode-locked solid-state seed source produced an average power of 1.8 W with pulse width of 14 ps and repetition rate of 86 MHz. It was directly coupled into the first Yb-doped polarized photonic crystal fiber amplifier stage. To avoid the nonlinear effects in fiber, the output power from the first stage was merely amplified to 24 W with the narrow spectra broadening of 0.21 nm. For the improvement of the peak power, the dual-end pumped composite Nd:YVO 4 amplifier system has been chosen at the second stage. To reduce the serious thermal effect, the thermally bonded composite YVO 4 – Nd:YVO 4 – YVO 4 rod crystal was used as the gain medium. The 53 W TEM 00 mode with the peak power of 40 kW, beam quality of M 2 < 1.15, corresponding to the optical-optical efficiency of 42.4% was obtained at the hybrid amplifier laser system. The system allows using a low power seed source and demonstrates an increase in the peak power beyond a fiber master oscillator power amplifier's (MOPA's) limit

  7. Fiber Lasers and Amplifiers for Space-based Science and Exploration

    Science.gov (United States)

    Yu, Anthony W.; Krainak, Michael A.; Stephen, Mark A.; Chen, Jeffrey R.; Coyle, Barry; Numata, Kenji; Camp, Jordan; Abshire, James B.; Allan, Graham R.; Li, Steven X.; hide

    2012-01-01

    We present current and near-term uses of high-power fiber lasers and amplifiers for NASA science and spacecraft applications. Fiber lasers and amplifiers offer numerous advantages for the deployment of instruments on exploration and science remote sensing satellites. Ground-based and airborne systems provide an evolutionary path to space and a means for calibration and verification of space-borne systems. NASA fiber-laser-based instruments include laser sounders and lidars for measuring atmospheric carbon dioxide, oxygen, water vapor and methane and a pulsed or pseudo-noise (PN) code laser ranging system in the near infrared (NIR) wavelength band. The associated fiber transmitters include high-power erbium, ytterbium, and neodymium systems and a fiber laser pumped optical parametric oscillator. We discuss recent experimental progress on these systems and instrument prototypes for ongoing development efforts.

  8. Broadband Fiber Raman Power-Amplifier for Narrow Linewidth Tunable Seed Lasers Used in Spectroscopic Sensing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an energy and space efficient high power continuous wave (cw) narrow linewidth broadband fiber Raman amplifier (FRA) with spectrally tunable...

  9. 32-core Inline Multicore Fiber Amplifier for Dense Space Division Multiplexed Transmission Systems

    DEFF Research Database (Denmark)

    Jain, S.; Mizuno, T.; Jung, Y.

    2016-01-01

    We present a high-core-count SDM amplifier, i.e. 32-core multicore-fiber amplifier, in a cladding-pumped configuration. An average gain of 17dB and NF of 7dB is obtained for -5dBm input signal power in the wavelength range 1544nm-1564nm.......We present a high-core-count SDM amplifier, i.e. 32-core multicore-fiber amplifier, in a cladding-pumped configuration. An average gain of 17dB and NF of 7dB is obtained for -5dBm input signal power in the wavelength range 1544nm-1564nm....

  10. High-performance polymer optical fiber lasers and amplifiers

    Science.gov (United States)

    Kuriki, Ken; Kobayashi, Takeyuki; Imai, Nana; Tamura, Toshihiko; Tagaya, Akihiro; Koike, Yasuhiro; Okamoto, Yoshiyuki

    2000-05-01

    We report on the lasing action of the graded-index polymer optical fibers containing dyes, such as Rhodamine B, Rhodamine 6G, Perylene Orange, and Pyrromethene 567. These dyes have been incorporated into poly(methyl methacrylate- co-2-hydroxythyl methacrylate). These fibers were transversely pumped at 532 nm with a frequency-doubled Q- switched Nd:YAG laser. Slope efficiency of 24 percent and output of 1.2 mJ were obtained with a Rhodamine 6G-doped fiber. A lifetime of 200,000 pulses at 10 Hz was achieved with a Rhodamine B-doped fiber. GI POF containing a Nd- chelate have also been fabricated. The absorption spectrum of the fiber exhbit3ed several strong bands in the visible and IR regions. We have observed IR fluorescence of the Nd3+ ion of the fiber at room temperature when it was pumped with an Ar+-pumped dye laser at 580 nm. The Judd-Ofelt theory was applied to the absorption spectrum of Nd3+ in polymer to determine the Judd-Ofelt parameters. From the theory, various radiative properties, such as transition probability, branching ratio, and emission cross section for various emission levels, have been determined and reported.

  11. Pulse-shaping strategies in short-pulse fiber amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Schimpf, Damian Nikolaus

    2010-02-09

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  12. Pulse-shaping strategies in short-pulse fiber amplifiers

    International Nuclear Information System (INIS)

    Schimpf, Damian Nikolaus

    2010-01-01

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  13. Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

    Science.gov (United States)

    Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong

    2018-03-01

    A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

  14. Stability of a 500 km erbium-doped fiber amplifier cascade

    DEFF Research Database (Denmark)

    Lumholt, Ole; Bjarklev, Anders Overgaard; Povlsen, Jørn Hedegaard

    1992-01-01

    seven times as high increase of the bit error rate then for the fallout of other amplifier pumps, showing that the fallout of the forward pump is by far the most critical. The stability to simultaneous changes in pump and signal power is examined and can be increased remarkably insertion......The stability of a cascade system of erbium-doped fiber amplifiers, due to pump and signal power variations, has been examined by use of a very accurate model. Even with an automatic gain control loop included, a fallout of a pump laser in the first inline amplifier is shown to produce a more than...

  15. High power all-polarization-maintaining photonic crystal fiber monolithic femtosecond nonlinear chirped-pulse amplifier

    Science.gov (United States)

    Lv, Zhiguo; Yang, Zhi; Li, Feng; Yang, Xiaojun; Li, Qianglong; Zhang, Xin; Wang, Yishan; Zhao, Wei

    2018-03-01

    We report on an experimental study on fully fusion spliced high power all-polarization-maintaining Yb-doped photonic crystal fiber (PCF) femtosecond nonlinear chirped-pulse amplifier (CPA), which features large values of the positive third-order dispersion (TOD) superposed from the single-mode fiber stretcher (SMFs) and grating-pair compressor. Compensation of the TOD is realized by means of self-phase modulation (SPM) induced nonlinear phase shift during amplification. Up to 9.8 W of compressed average power at 275 kHz repetition rates with 36 μJ pulse energy and 495 fs pulse width has been obtained. To the best of our knowledge, this is the highest output power generated from the strictly all-fiber nonlinear CPA amplifier in femtosecond domain, which provides a possibility for the industrialized promotion and development of the high energy femtosecond fiber laser.

  16. Electrically tunable bandpass filter based on liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2010-01-01

    An electrically tunable bandpass filter based on two photonic crystal fibers filled with different liquid crystals is demonstrated. Both the short-wavelength and long-wavelength edge are tuned individually or simultaneously with the response time in milliseconds.......An electrically tunable bandpass filter based on two photonic crystal fibers filled with different liquid crystals is demonstrated. Both the short-wavelength and long-wavelength edge are tuned individually or simultaneously with the response time in milliseconds....

  17. Electrically tunable long-period gratings in liquid crystal photonic bandgap fibers

    DEFF Research Database (Denmark)

    Noordegraaf, Danny; Scolari, Lara; Lægsgaard, Jesper

    2007-01-01

    We demonstrate an aLl-electrically tunable long period grating in a photonic crystal fiber infiltrated with a nematic liquid crystal. The spectral dips and the resonance wavelengths are tuned electrically and thermally, respectively.......We demonstrate an aLl-electrically tunable long period grating in a photonic crystal fiber infiltrated with a nematic liquid crystal. The spectral dips and the resonance wavelengths are tuned electrically and thermally, respectively....

  18. New Trends in Amplifiers and Sources via Chalcogenide Photonic Crystal Fibers

    Directory of Open Access Journals (Sweden)

    L. Mescia

    2012-01-01

    Full Text Available Rare-earth-doped chalcogenide glass fiber lasers and amplifiers have great applicative potential in many fields since they are key elements in the near and medium-infrared (mid-IR wavelength range. In this paper, a review, even if not exhaustive, on amplification and lasing obtained by employing rare-earth-doped chalcogenide photonic crystal fibers is reported. Materials, devices, and feasible applications in the mid-IR are briefly mentioned.

  19. 32-core erbium/ytterbium-doped multicore fiber amplifier for next generation space-division multiplexed transmission system

    DEFF Research Database (Denmark)

    Jain, Saurabh; Castro, Carlos; Jung, Yongmin

    2017-01-01

    We present a high-core-count 32-core multicore erbium/ytterbium-doped fiber amplifier (32c-MC-EYDFA) in a cladding pumped configuration. A side pumping technique is employed for ease of pump coupling in this monolithic all-fiber amplifier. A minimum gain of >17 dB and an average noise figure (NF)...

  20. Ytterbium-doped large-mode-area photonic crystal fiber amplifier with gain shaping for use at long wavelengths

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas T.; Poli, Federica

    2012-01-01

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with efficient suppression of amplified spontaneous emission is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes...

  1. Raman and loss induced quantum noise in depleted fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Rottwitt, Karsten; McKinstrie, C. J.

    2013-01-01

    We present a semi-classical approach for predicting the quantum noise properties of fiber optical parametric amplifiers. The unavoidable contributors of noise, vacuum fluctuations, loss-induced noise, and spontaneous Raman scattering, are included in the analysis of both phase-insensitive and phase...

  2. Polymer-Optical-Fiber Lasers and Amplifiers Doped with Organic Dyes

    Directory of Open Access Journals (Sweden)

    Joseba Zubia

    2011-07-01

    Full Text Available Polymer optical fibers (POFs doped with organic dyes can be used to make efficient lasers and amplifiers due to the high gains achievable in short distances. This paper analyzes the peculiarities of light amplification in POFs through some experimental data and a computational model capable of carrying out both power and spectral analyses. We investigate the emission spectral shifts and widths and on the optimum signal wavelength and pump power as functions of the fiber length, the fiber numerical aperture and the radial distribution of the dopant. Analyses for both step-index and graded-index POFs have been done.

  3. Polarization Properties of Elliptical-Hole Liquid Crystal Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Tartarini, Giovanni; Pansera, Marco; Alkeskjold, Thomas Tanggaard

    2007-01-01

    The characteristics of triangular photonic crystal fibers (PCFs) with elliptical holes filled with a nematic liquid crystal (LC) are investigated theoretically. The analysis that is carried out using the finite-element method, including material dispersion effects, shows that LC anisotropy and hole...

  4. Low loss liquid crystal photonic bandgap fiber in the near-infrared region

    DEFF Research Database (Denmark)

    Scolari, Lara; Wei, Lei; Gauza, Sebastian

    2011-01-01

    We infiltrate a perdeuterated liquid crystal with a reduced infrared absorption in a photonic crystal fiber. The H atoms of this liquid crystal were substituted with D atoms in order to move the vibration bands which cause absorption loss to longer wavelengths and therefore reduce the absorption...

  5. Modeling loss and backscattering in a photonic-bandgap fiber using strong perturbation

    Science.gov (United States)

    Zamani Aghaie, Kiarash; Digonnet, Michel J. F.; Fan, Shanhui

    2013-02-01

    We use coupled-mode theory with strong perturbation to model the loss and backscattering coefficients of a commercial hollow-core fiber (NKT Photonics' HC-1550-02 fiber) induced by the frozen-in longitudinal perturbations of the fiber cross section. Strong perturbation is used, for the first time to the best of our knowledge, because the large difference between the refractive indices of the two fiber materials (silica and air) makes conventional weak-perturbation less accurate. We first study the loss and backscattering using the mathematical description of conventional surface-capillary waves (SCWs). This model implicitly assumes that the mechanical waves on the core wall of a PBF have the same power spectral density (PSD) as the waves that develop on an infinitely thick cylindrical tube with the same diameter as the PBF core. The loss and backscattering coefficients predicted with this thick-wall SCW roughness are 0.5 dB/km and 1.1×10-10 mm-1, respectively. These values are more than one order of magnitude smaller than the measured values (20-30 dB/km and ~1.5×10-9 mm-1, respectively). This result suggests that the thick-wall SCW PSD is not representative of the roughness of our fiber. We found that this discrepancy occurs at least in part because the effect of the finite thickness of the silica membranes (only ~120 nm) is neglected. We present a new expression for the PSD that takes into account this finite thickness and demonstrates that the finite thickness substantially increases the roughness. The predicted loss and backscattering coefficients predicted with this thin-film SCW PSD are 30 dB/km and 1.3×10-9 mm-1, which are both close to the measured values. We also show that the thin-film SCW PSD accurately predicts the roughness PSD measured by others in a solid-core photonic-crystal fiber.

  6. Theoretical and simulation analysis of the fiber optical parametric amplifier (FOPA) with cascaded structure

    Science.gov (United States)

    Gao, Jie; Cao, Yongsheng; Chen, Fushen; Sun, Bao; Hu, Zhefeng

    2012-02-01

    A novel scheme is proposed to obviously improve the amplified gain, gain flatness and bandwidth characteristics of FOPA by applying a cascaded fiber structure. The basic structure of the cascaded fiber optical parametric amplifier (CFOPA) is introduced. Then, the expression of signals pass gain characteristic is obtained by utilizing a set of coupled equations. The gain, bandwidth and gain flatness characteristics of the CFOPA with the different parameters of DCF, such as fiber length l/, dispersion slope dD//dλ, and so on, are theoretical analyzed and optimized. Furthermore, simulation analysis is applied to verify the theoretical results by using Optisystem 7.0 software. Although, there are a few deviations between the simulation and the theoretical results, the simulation results effectively demonstrate the validity and feasibility of the theoretical analysis.

  7. Theoretical Investigation of Oxazine 170 Perchlorate Doped Polymeric Optical Fiber Amplifier

    Directory of Open Access Journals (Sweden)

    Piotr Miluski

    2017-01-01

    Full Text Available Optical signal amplification in the waveguiding structure of optical fibers can be used for optical telecommunication systems and new light sources constructions. Organic dyes doped materials are interesting for new applications in polymeric optical fibers technology due to their benefits (efficient fluorescence, high absorption cross section, and easy processing. This article presents a numerical simulation of gain in poly(methyl methacrylate optical fiber doped by Oxazine 170 Perchlorate. The calculated gain characteristic for the used dye molar concentration (0.2·10-6–1.4·10-6 and pump power (1–10 kW is presented. The fabricated fluorescent polymeric optical fiber is also shown. The presented analysis can be used for optical amplifier construction based on dye-doped polymeric optical fiber (POF.

  8. Temperature assisted band-gap engineering in all-solid chalcogenide holey fiber for mid-IR application

    Science.gov (United States)

    Barh, Ajanta; Varshney, R. K.; Pal, B. P.; Sanghera, J.; Shaw, L. B.

    2015-06-01

    Presence of photonic band-gap (PBG) in an all-solid microstructured optical fiber (MOF), made of two fabrication compatible chalcogenide (Ch) glasses is theoretically investigated for potential application in the functional mid-infrared (IR) wavelength range. Cross-section of the MOF is formed by assuming periodically arranged wavelength scale circular air holes in a hexagonal pattern embedded in a uniform matrix. One type of Ch-glass is considered as the background material whereas another type of Ch-glass is assumed to fill the air holes. The relative index contrast between these two Ch-glasses is ~ 24%, for which PBG appears only for a suitable range of non-zero longitudinal wave vector. We have studied the scalability of this PBG by varying the lattice parameter of MOF and optimized the cross-section to attain the PBG at ~ 2 μm wavelength. Then by utilizing the thermo-optic properties of the glasses, the effect of external temperature (T) on the PBG is studied, and finally we have proposed a T-tunable wavelength filter/sensor at mid-IR wavelength with tuning sensitivity as high as ~ 140 pm/°C.

  9. Design of single-polarization coupler based on dual-core photonic band-gap fiber implied in resonant fiber optic gyro

    Science.gov (United States)

    Xu, Zhenlong; Li, Xuyou; Zhang, Chunmei; Ling, Weiwei; Liu, Pan; Xia, Linlin; Yang, Hanrui

    2016-12-01

    A novel (to our knowledge) type of single-polarization (SP) coupler based on a dual-core photonic band-gap fiber (PBF) is proposed. The effects of structure parameters on the performance of this coupler are studied numerically based on the full vector finite element method (FEM). Finally, an optimal design with a length of 0.377 mm at the wavelength of 1.55 μm is achieved, and its implication in PBF-based fiber ring resonator (FRR), the effect of angular misalignment on the SP coupler are analyzed as well. When the SP coupler is incorporated into a PBF-based FRR, it functions as the power splitter and the polarizer simultaneously, and can extinct the secondary eigenstate of polarization (ESOP) propagating in the FRR. The mode field of SP coupler can match with the polarization-maintaining (PM) PBF with ultra-low temperature sensitivity proposed in previous study, and an all PM-PBF based FRR can be established, which is of great significance in suppressing the temperature-related polarization fluctuation and improving the long-term stability for RFOG, and the SP coupler has high angular misalignment tolerance as well.

  10. Comparison of wavelength-division-multiplexed distributed fiber Raman amplifier networks for sensors.

    Science.gov (United States)

    Diaz, Silvia; Lopez-Amo, Manuel

    2006-02-20

    A novel distributed fiber Raman amplified star topology used for optical sensor wavelength-division multiplexing is proposed. The performance of this star configuration is compared to an optically amplified bus topology. The two different network topologies are compared and demonstrated experimentally and theoretically as means of gathering information from four wavelength-division-multiplexed photonic sensors. We report how the star configuration yields better signal-to-noise ratios than the bus topology. Furthermore, this improvement is made without increasing the complexity of the regular star topologies.

  11. Optimization of Multiple Active Ion Doped Fiber Amplifiers for Three Communication Windows

    Directory of Open Access Journals (Sweden)

    Chun Jiang

    2009-01-01

    Full Text Available We present for the first time a theoretical model of Er3+-Tm3+-Pr3+ codoped fiber pumped with both 800 nm and 980 nm lasers to explore possibility of this co-doped system as all-wave fiber amplifier. The rate and power propagation equations of the model are solved numerically and the dependence of the gains at 1310, 1470, 1530, 1600, 1650 nm windows on fiber length is calculated. The results show that with pump power of 200 mW/200 mW, when the concentrations of Pr3+, Tm3+, Er3+ are around 1.7×1024, 3.9×1024, 1.2×1024 (ions/m3, respectively, the signals at 1310, 1470, 1530, 1600, 1650 nm may be nearly equally amplified with gain of 13–16.0 dB in the active fiber with length of 23.5 m; the co-doping concentrations and fiber length and pump powers may be further optimized to reduce the ripple.

  12. Extension of semi-analytical Erbium-doped fiber amplifier model to self-saturation regime

    DEFF Research Database (Denmark)

    Nissov, Morten

    1997-01-01

    demonstrate very good agreement between measurements and simulations based on measured fiber data for both high-gain EDFAs (small-signal gain of 35 dB) and isolator EDFAs (small-signal gain of 43 dB) with deviations Academic Press.......We show in this paper that the analytical erbium-doped fiber amplifier (EDFA) model presented by Jopson and Saleh in 1991 can be extended to the self-saturation regime, making it capable of simulating all practical EDFAs. We show that an Intel Pentium 66 based computer can calculate gain and noise...

  13. Static thermo-optic instability in double-pass fiber amplifiers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2016-01-01

    A coupled-mode formalism, earlier used to describe transverse mode instabilities in single-pass optical fiber amplifiers, is extended to the case of double-pass amplifiers. Contrary to the single-pass case, it is shown that the thermo-optic nonlinearity can couple light at the same frequency...... between the LP01 and LP11 modes, leading to a static deformation of the output beam profile. This novel phenomenon is caused by the interaction of light propagating in either direction with thermo-optic index perturbations caused by light propagating in the opposite direction. The threshold power...... for the static deformation is found to be several times lower than what is typically found for the dynamic modal instabilities observed in single-pass amplifiers. (C) 2016 Optical Society of America...

  14. Variation method for optimization of Raman fiber amplifier pumped by continuous-spectrum radiation

    International Nuclear Information System (INIS)

    Ghasempour Ardekani, A.; Bahrampour, A. R.; Feizpour, A.

    2007-01-01

    In Raman fiber amplifiers, reduction of gain ripple versus frequency has a great importance. In this article using variational method and continuous pump, gain ripple is optimized. It is shown here that for a 40 km line the average gain is 1.3dB and the gain ripple is 0.12 dB, that is lower than the latest published data.

  15. Raman laser amplifier in methane-filled hollow-core fiber

    Science.gov (United States)

    Chen, Yubin; Wang, Zefeng; Lu, Qisheng

    2017-10-01

    We report on an ultra-efficient 1.5 μm Raman amplifier in methane-filled negative curvature hollow-core fiber. A 1.5 μm tunable CW DFB seed laser is coupled into the fiber together with a 1064 nm pump laser using a shortpass dichromic mirror, and then stimulated amplified by Raman scattering of methane. The maximum Raman conversion efficiency of 66.4 % was obtained in the 2 bar methane gas filled, 2 m long hollow core fiber with 50 mW coupled pump power and 22.6 mW coupled seed laser power, and the corresponding quantum efficiency is as high as to 96.3 %, which almost approaches the quantum limit. The introduction of the single frequency seed laser not only reduced the Raman threshold from 17.5 mW to 9.5 mW, but also narrowed the Stokes linewidth from 3.4 GHz to 2.1 GHz with a factor of 60%. This kind of gas filled hollow core Raman amplifier can be a potential method to obtain low threshold, narrow linewidth and high efficiency mid infrared laser source in various application.

  16. Real-time polarization mode dispersion monitoring system for a multiple-erbium-doped fiber amplifier, dense wavelength division multiplexing optical fiber transmission by amplified spontaneous emission modulation and acousto-optic tunable fiber scanning techniques.

    Science.gov (United States)

    Tseng, Bao-Jang; Tarn, Chen-Wen

    2009-03-01

    Without interruption or affecting the transmission of ordinary payload channels, we propose a real time polarization mode dispersion (PMD) monitoring system for long-haul, multiple erbium-doped fiber amplifier (EDFA), dense wavelength division multiplexing (DWDM) optical fiber transmission using modulated amplified spontaneous emission (ASE) of one of the EDFAs as the supervisory (SV) signal source. An acousto-optic tunable filter (AOTF) at the receiver side is adopted to scan the spectrum of the transmitted ASE SV signal. Using the fixed-analyzer method, PMDs of different wavelength bands that range from 1545 to 1580 nm of a DWDM fiber-optic communication system can be found by adaptively changing the radio frequency of the AOTF. The resolution and the measuring range of the proposed monitoring system can be significantly improved by cascading the AOTFs at the receiver side.

  17. Radiation-induced loss studies in Er-doped fiber amplifier systems

    Science.gov (United States)

    Goltsos, William C.

    1996-04-01

    Radiation-induced loss in erbium-doped fiber and fiber-based components used in optical amplifiers at 1.5 micrometer has been studied under electron and gamma irradiation up to total doses of 100 krad(Si). Radiation sources used to simulate the natural space environment were a Van de Graaff generator for 1.5 MeV electrons, and Cobalt-60 for 1.17 and 1.33 MeV photons. Induced-loss and 60-hour anneal were measured in Er-doped fiber while simultaneously illuminated with 0.7 W of 980-nm pump, and 1 mW of 1550-nm signal light in an operating amplifier configuration. Initial induced loss from electron irradiation was found to decrease under intense photoillumination to 0.010 dB/m-krad at 980 nm and .007 dB/m- krad at 1550 nm, versus 0.017 dB/m-krad and 0.008 dB/m-krad respectively when unilluminated, and showed a more rapid anneal in some tested fibers. Individual components of an optical isolator were tested for gamma-irradiation sensitivity. A 1 degree change in polarization rotation angle was found in a garnet-film Faraday rotator after exposure, and the GRIN lens showed an initial induced loss of 0.5 dB that annealed to 0.1 dB after 2 weeks under conditions of 1 mW, 1550-nm photoillumination.

  18. Fiber Based Optical Amplifier for High Energy Laser Pulses Final Report CRADA No. TC02100.0

    Energy Technology Data Exchange (ETDEWEB)

    Messerly, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Cunningham, P. [Boeing Company, Springfield, VA (United States)

    2017-09-06

    This was a collaborative effort between Lawrence Livermore National Security, LLC (formerly The Regents of the University of California)/Lawrence Livermore National Laboratory (LLNL), and The Boeing Company to develop an optical fiber-based laser amplifier capable of producing and sustaining very high-energy, nanosecond-scale optical pulses. The overall technical objective of this CRADA was to research, design, and develop an optical fiber-based amplifier that would meet specific metrics.

  19. Highly Doped Phosphate Glass Fibers for Compact Lasers and Amplifiers: A Review

    Directory of Open Access Journals (Sweden)

    Nadia Giovanna Boetti

    2017-12-01

    Full Text Available In recent years, the exploitation of compact laser sources and amplifiers in fiber form has found extensive applications in industrial and scientific fields. The fiber format offers compactness, high beam quality through single-mode regime and excellent heat dissipation, thus leading to high laser reliability and long-term stability. The realization of devices based on this technology requires an active medium with high optical gain over a short length to increase efficiency while mitigating nonlinear optical effects. Multicomponent phosphate glasses meet these requirements thanks to the high solubility of rare-earth ions in their glass matrix, alongside with high emission cross-sections, chemical stability and high optical damage threshold. In this paper, we review recent advances in the field thanks to the combination of highly-doped phosphate glasses and innovative fiber drawing techniques. We also present the main performance achievements and outlook both in continuous wave (CW and pulsed mode regimes.

  20. Perspectives of Long-Haul WDM Transmission Systems Based on Phase-Insensitive Fiber-Optic Parametric Amplifiers

    DEFF Research Database (Denmark)

    Jazayerifar, M.; Sackey, I.; Elschner, R.

    2015-01-01

    The deployment of phase-insensitive fiber-opticparametric amplifiers (PI-FOPAs) as inline amplifiers in longhaul WDM transmission systems is discussed, and it is outlined how to design PI-FOPAs to be a valuable upgrade option for this application....

  1. Power Scaling Fiber Amplifiers Using Very-Large-Mode-Area Fibers

    Science.gov (United States)

    2016-02-23

    fiber as a function of core diameter. The line is a guide for the eye, and the error bars represent the 25 W pump increment. The trend observed in...The lines are guides for the eye, and the error bars represent the pump increment. The dual points for the confined-gain fiber are explained in the...compared to conventional (step-index) LMA fiber (blue). The lines are guides for the eye, and the error bars represent the pump increment. The CLING

  2. Long wavelength mid-infrared from mixing two colors from a fiber amplifier

    Science.gov (United States)

    Bian, Siyuan; Loranger, Sébastien; Kashyap, Raman; Strickland, Donna

    2015-05-01

    At Waterloo, we are developing a high power, short pulse, two-color, Yb:fiber amplifier system to generate the long wavelength (TATP) occur between 15 and 20 μm. To date, we have achieved a tuning range from 16 to 20 μm with a maximum average power of 1.7 mW. On the short wavelength side, the two colors would need to be pulled further apart, which requires a higher power seed to beat the amplified spontaneous emission that appears at the gain peak of the amplifiers between the two seed colors. On the long wavelength side, we are limited to 20 μm by the transparency region of the nonlinear crystals. We would like to find new nonlinear materials that have transparency from 1 to 30μm. If we could generate wavelengths from 15 to 30 μm with sufficient power, we could extend the spectral region to also cover 8 to 15μm by frequency doubling the longer wavelengths. We are currently working on replacing bulk optics in the system with fiber based optical elements to select the wavelengths as well as stretch and recompress the pulses in order to make the system compact and stable.

  3. Spectral broadening in narrow linewidth, continuous-wave high power fiber amplifiers

    Science.gov (United States)

    Feng, Yujun; Wang, Xiaojun; Ke, Weiwei; Sun, Yinhong; Zhang, Kai; Ma, Yi; Li, Tenglong; Wang, Yanshan; Wu, Juan

    2017-11-01

    We present an investigation on the spectrum broadening in continuous-wave, sub-nanometer linewidth high power fiber amplifiers caused by the multiple four-wave mixing (FWM) process. The spectrum broadening employing two different types of narrow linewidth seeds, including the multi-longitudinal-mode seed and the broadened single frequency seed generated by high speed phase modulation, is studied. It is shown both theoretically and experimentally that the multi-longitudinal-mode seed experiences serious spectrum broadening induced by the FWM among various longitudinal modes, while the modulated seed can maintain the spectrum profile during the amplifying process even with some noise fluctuation. The different broadening results are mainly caused by the random phase distribution of the multiple waves. It is further explained by an exact solution of the degenerate FWM with three waves. The theoretical predictions on the spectrum and power dependence of the output laser linewidth are in quantitative agreement with the experimental results up to kilowatt.

  4. Active polarization control of a 1.43 kW narrow linewidth fiber amplifier based on SPGD algorithm

    Science.gov (United States)

    Su, Rongtao; Liu, Yakun; Yang, Baolai; Ma, Pengfei; Wang, Xiaolin; Zhou, Pu; Xu, Xiaojun

    2017-04-01

    Active polarization control of a high power fiber amplifier has been demonstrated. The master oscillator power amplifier system consisted of a narrow linewidth laser seed and a three-stage Yb-fiber amplifier. The narrow linewidth laser seed was generated by phase modulating a single frequency fiber laser using a white noise source. Maximum power of 1437 W was obtained from the main amplifier, which was limited by the available pump power. When the polarization state of the narrow linewidth (∼0.17 nm) laser was actively controlled by using a polarization controller based on stochastic parallel gradient descent algorithm, the polarization extinction ratio of the laser beam was more than 11.1 dB at the maximum output power.

  5. Performance analysis of bi-directional broadband passive optical network using erbium-doped fiber amplifier

    Science.gov (United States)

    Almalaq, Yasser; Matin, Mohammad A.

    2014-09-01

    The broadband passive optical network (BPON) has the ability to support high-speed data, voice, and video services to home and small businesses customers. In this work, the performance of bi-directional BPON is analyzed for both down and up streams traffic cases by the help of erbium doped fiber amplifier (EDFA). The importance of BPON is reduced cost. Because PBON uses a splitter the cost of the maintenance between the providers and the customers side is suitable. In the proposed research, BPON has been tested by the use of bit error rate (BER) analyzer. BER analyzer realizes maximum Q factor, minimum bit error rate, and eye height.

  6. Radiation-hardened Erbium-doped optical fibers and amplifiers for future high-dose space missions

    Science.gov (United States)

    Girard, S.; Laurent, A.; Pinsard, E.; Robin, T.; Cadier, B.; Boutillier, M.; Marcandella, C.; Boukenter, A.; Ouerdane, Y.

    2014-03-01

    We present a new class of Erbium-doped optical fibers: the Hole-Assisted Carbon-Coated, HACC fibers. Optical fibers with this particular structure have been made by iXFiber on the basis of an appropriate choice of codopants in their core and claddings. By using an additional pre-treatment with deuterium (D2) loading authorized by the HACC structure, we highlight the efficiency of such components and demonstrated that this new type of fiber presents a strongly enhanced radiation resistance compared to the other types of erbium-doped optical fibers studied in litterature. We also built an Erbium-doped Fiber Amplifier (EDFA) with one of these HACC fibers and compared its radiation response to the one of the same fiber composition but without the HACC structure and D2 loading. We tested the performances of this EDFA under Υ-rays and characterize its gain degradation up to doses of 315 krad. Before irradiation, the amplifier presents a gain of about 31 dB that is comparable to the optical performances of amplifiers based on HACC fibers without the D2 pre-treatment and the HACC structure. During irradiation, our results demonstrate that the tested amplifier is nearly unaffected by radiations. Its gain slowly decreases with the dose at a slope rate of about -2.2×10-3 dB/krad. This strong radiation resistance (enhancement of a factor of ×10 compared to the previous or conventional radiation tolerant EDFA) will authorize the use of HACC doped fibers and amplifiers for various applications in space for missions associated both with low or large irradiation doses.

  7. Optimized design of six-wave fiber optical parametric amplifiers by using a genetic algorithm.

    Science.gov (United States)

    Li, Peipei; Zhu, Hongna; Taccheo, Stefano; Gao, Xiaorong; Wang, Zeyong

    2017-05-20

    A governing equation of the six-wave fiber optical parametric amplifier (FOPA) for the power and phase difference evolution of the six interacting waves is deduced. To optimize the gain of the six-wave FOPA, a multivariate stochastic optimization algorithm, i.e., the genetic algorithm (GA), is applied. The effect of pump depletion on the gain characteristic of the six-wave FOPA is emphasized and the effect of the fiber length, the wavelength, and the power of two pumps on bandwidth, flatness, and magnitude of the gain spectrum has also been studied. A broader and flatter six-wave FOPA gain is obtained by adopting optimum design parameters, which theoretically provide a uniform gain of 65 dB with 0.3 dB uniformity over a 110 nm bandwidth for the six-wave FOPA.

  8. Power scaling analysis of fiber lasers and amplifiers based on non-silica materials

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, J W; Messerly, M J; Heebner, J E; Pax, P H; Sridharan, A K; Bullington, A L; Beach, R J; Siders, C W; Barty, C P; Dubinskii, M

    2010-03-30

    A developed formalism for analyzing the power scaling of diffraction limited fiber lasers and amplifiers is applied to a wider range of materials. Limits considered include thermal rupture, thermal lensing, melting of the core, stimulated Raman scattering, stimulated Brillouin scattering, optical damage, bend induced limits on core diameter and limits to coupling of pump diode light into the fiber. For conventional fiber lasers based upon silica, the single aperture, diffraction limited power limit was found to be 36.6kW. This is a hard upper limit that results from an interaction of the stimulated Raman scattering with thermal lensing. This result is dependent only upon physical constants of the material and is independent of the core diameter or fiber length. Other materials will have different results both in terms of ultimate power out and which of the many limits is the determining factor in the results. Materials considered include silica doped with Tm and Er, YAG and YAG based ceramics and Yb doped phosphate glass. Pros and cons of the various materials and their current state of development will be assessed. In particular the impact of excess background loss on laser efficiency is discussed.

  9. Very large mode area ytterbium fiber amplifier with aluminum-doped pump cladding made by powder sinter technology

    International Nuclear Information System (INIS)

    He, Wenbin; Leich, Martin; Grimm, Stephan; Kobelke, Jens; Zhu, Yuan; Bartelt, Hartmut; Jäger, Matthias

    2015-01-01

    We demonstrate amplification experiments using a very large mode area Yb-doped double-clad fiber with 100 µm aluminum-cer codoped core and 440 µm pump cladding realized by high aluminum codoping. The material for core and pump cladding was fabricated by reactive powder sinter technology. A high numerical aperture (NA) of the pump cladding with NA = 0.21 and a low one of the core with NA = 0.084 could be realized. Using a 0.55 m short fiber sample as the main amplifier in a three-stage ns pulsed fiber master oscillator power amplifier system we achieved 3 ns, 2 mJ output pulses with 360 kW peak power limited by the available pump power. Stimulated Raman scattering effects and amplified spontaneous emission were successfully suppressed. (letter)

  10. 26 nJ picosecond solitons from thulium-doped single-mode master oscillator power fiber amplifier.

    Science.gov (United States)

    Renard, William; Canat, Guillaume; Bourdon, Pierre

    2012-02-01

    We report on an all single-mode master oscillator power fiber amplifier delivering high energy picosecond solitons at 1960 nm. The Bragg stabilized and self-starting oscillator delivers 62 pJ transform-limited pulses at 11.2 MHz pulse repetition frequency. Solitons are amplified in a core-pumped single-mode heavily thulium-doped fiber up to 26 nJ. The average and peak power are 291 mW and 7.4 kW, respectively. Pulses remain transform limited without significant self-phase-modulation distortion. We discuss the limitations of picosecond pulse amplification in a core-pumped single-mode fiber amplifier.

  11. Amplification of DWDM channels at 1.28 Tb/s in a bidirectional fiber optical parametric amplifier.

    Science.gov (United States)

    Lei, Gordon K P; Marhic, Michel E

    2014-04-07

    We experimentally demonstrate amplification of 1.28 Tb/s DWDM channels using a bidirectional fiber optical parametric amplifier. The amplifier can provide more than 13 dB on-off gain on all 32 DWDM channels. Error-free operation has been achieved for all data streams, with an average power penalty of 2.5 dB compared with conventional unidirectional configuration.

  12. Development and applications of femtosecond monolithic Yb-doped fiber chirped-pulse amplifiers

    International Nuclear Information System (INIS)

    Zhu, L.

    2011-01-01

    In the past few years, compact and environmentally stable high-energy ultrashort pulse laser sources have been broadly utilized in many different applications. Fiber lasers offer big practical advantages over bulk solid-state laser systems in terms of flexibility, compactness, reliability, cost effectiveness and turn-key operability. Moreover, thermal effects are dramatically reduced due to the large surface-to-volume ratio of an optical fiber, and good spatial mode quality can be ensured by its waveguiding property. Therefore, a fiber-based laser system is considered to be the preferred laser architecture. The main theme of this thesis is the development of various femtosecond monolithic Yb-doped fiber chirped-pulse-amplification (FCPA) system and their applications. We demonstrate an ultrafast high-energy monolithic Yb-doped FCPA system in which the pulse fidelity is preserved by weakening the nonlinear effects via a substantial level of temporal stretching of the seed pulses and by using highly doped active fibers as amplifying media. The presented monolithic FCPA delivers up to ∼ 25 μJ diffraction-limited pulses that can be recompressed to sub-200 fs duration, and the pulse quality has been confirmed through the second-harmonic-generation (SHG) conversion efficiency of over 52%. Improved dispersion and nonlinearity management schemes of the FCPA system allowing substantial pulse energy scaling in the monolithic format as well as methods for overcoming a series of technological challenges are reported. Three different types of Yb-doped fiber oscillators have been developed and built in the course of this PhD work. First, we compare two oscillator types that are based on the all-normal-dispersion (ANDi) regime and the dispersion-managed (DM) regime. Both of them have been tested as the seed-pulse source of the monolithic Yb-doped FCPA system. Then we introduce another novel design based on higher-order-mode (HOM) dispersion management that competes with a

  13. Semiconductor optical amplifier direct modulation with double-stage birefringent fiber loop

    Science.gov (United States)

    Engel, Thomas; Rizou, Zoe V.; Zoiros, Kyriakos E.; Morel, Pascal

    2016-06-01

    The feasibility of cascading two birefringent fiber loops (BFLs) for directly modulating a conventional semiconductor optical amplifier (SOA) at a faster data rate than that being possible by its limited electrical bandwidth is demonstrated for the first time. The experimental results reveal the improvements in the quality characteristics of the encoded signal compared to those achieved with a single-stage BFL. The observed trends are complemented by numerical simulations, which allow to investigate the impact of the double-stage BFL detuning and specify how this critical parameter must be selected for enhanced performance. Provided that it is properly tailored, the proposed optical notch filtering scheme efficiently compensates for the pattern-dependent SOA response and enables this element to be employed as intensity modulator with improved performance at enhanced data speeds.

  14. A flexible receiver with fiber optical parametric amplifier in OCDMA-FSO communication system

    Science.gov (United States)

    Xia, Min; Yuan, Jin-hui; Sang, Xin-zhu; Yin, Xiao-li; Rao, Lan; Yu, Chong-xiu

    2014-11-01

    A new receiver is proposed, which uses the fiber optical parametric amplifier (FOPA) in optical code division multiple access (OCDMA) over free space optic (FSO) communication system. The noise tolerance as the performance index in this receiver is derived. The receiver can not only improve the noise tolerance but also change the pump data conveniently for adapting to the length variation of the coding sequence under a complex and fast-changing weather condition. The influence of different factors on the noise tolerance is analyzed, and a significant improvement of about 18.77 dB for the noise tolerance can be achieved when the pump power and the length of coding sequence are 5 W and 256, respectively.

  15. Simulation and measurement of optical access network with different types of optical-fiber amplifiers

    Science.gov (United States)

    Latal, Jan; Vogl, Jan; Koudelka, Petr; Vitasek, Jan; Siska, Petr; Liner, Andrej; Papes, Martin; Vasinek, Vladimir

    2012-01-01

    The optical access networks are nowadays swiftly developing in the telecommunications field. These networks can provide higher data transfer rates, and have great potential to the future in terms of transmission possibilities. Many local internet providers responded to these facts and began gradually installing optical access networks into their originally built networks, mostly based on wireless communication. This allowed enlargement of possibilities for end-users in terms of high data rates and also new services such as Triple play, IPTV (Internet Protocol television) etc. However, with this expansion and building-up is also related the potential of reach in case of these networks. Big cities, such as Prague, Brno, Ostrava or Olomouc cannot be simply covered, because of their sizes and also because of their internal regulations given by various organizations in each city. Standard logical and also physical reach of EPON (IEEE 802.3ah - Ethernet Passive Optical Network) optical access network is about 20 km. However, for networks based on Wavelength Division Multiplex the reach can be up to 80 km, if the optical-fiber amplifier is inserted into the network. This article deals with simulation of different types of amplifiers for WDM-PON (Wavelength Division Multiplexing-Passive Optical Network) network in software application Optiwave OptiSystem and than are the values from the application and from real measurement compared.

  16. Performance tolerance analysis of birefringent fiber loop for semiconductor optical amplifier pattern effect suppression

    Science.gov (United States)

    Rizou, Zoe V.; Zoiros, Kyriakos E.; Hatziefremidis, Antonios; Connelly, Michael J.

    2015-05-01

    In this paper, we analyze the performance of the birefringent fiber loop (BFL) when the settings of the components that construct this module are not perfect. The BFL is employed for suppressing the pattern effect on directly amplified data in a semiconductor optical amplifier (SOA). The analysis is conducted by describing the non-optimum BFL transmission response using Jones matrix method. This allows to formulate a comprehensive model, which is validated by comparing it to the experiment. Then we investigate and specify how sensitive the BFL is to imperfections of its building components by assessing its performance against the output amplitude modulation, power penalty, and crosstalk. For each critical operating parameter, we derive the tolerance range within which these performance metrics are acceptable. The obtained results suggest that the BFL can efficiently mitigate the SOA pattern effect even if it is built from non-ideal components. This can be achieved provided that these components are designed according to their extracted operating conditions, which are practically satisfiable.

  17. Shot Noise and Fiber Amplifier Effects in Photonic-Doppler Velocimetry Systems

    Science.gov (United States)

    Miller, Edward Kirk; Larson, Eric; Lee, Kevin

    2017-06-01

    We present theoretical and experimental data to show the effects of shot noise and erbium-doped fiber amplifiers (EDFA's) on the achievable dynamic range of photonic-Doppler velocimetry (PDV) systems. We show that many common system configurations are very nearly shot noise limited. Heterodyne gain from strong local-oscillator (LO) light creates a signal amplitude that can be recorded on high-speed digitizers, and the shot noise from the LO sets the system noise floor above the levels of electronic noise in the photoreceiver and digitizer. We show that boosting weak signal returns using an EDFA creates noise in the same proportion that it increases signal, leaving the signal-to-noise ratio (SNR) unchanged. Amplified spontaneous emission (ASE) from the EDFA, when mixed with the LO light, creates a noise term proportional to the LO shot noise and to the EDFA gain. The net result is that EDFA's are useful for boosting heterodyne signal levels for recording, and they can be used to boost weak return light before lossy components, but they do not improve the fundamental SNR of the system.

  18. Pulse quality analysis on soliton pulse compression and soliton self-frequency shift in a hollow-core photonic bandgap fiber.

    Science.gov (United States)

    González-Baquedano, N; Torres-Gómez, I; Arzate, N; Ferrando, A; Ceballos-Herrera, D E

    2013-04-08

    A numerical investigation of low-order soliton evolution in a proposed seven-cell hollow-core photonic bandgap fiber is reported. In the numerical simulation, we analyze the pulse quality evolution in soliton pulse compression and soliton self-frequency shift in three fiber structures with different cross-section sizes. In the simulation, we consider unchirped soliton pulses (of 400 fs) at the wavelength of 1060 nm. Our numerical results show that the seven-cell hollow-core photonic crystal fiber, with a cross-section size reduction of 2%, promotes the pulse quality on the soliton pulse compression and soliton self-frequency shift. For an input soliton pulse of order 3 (which corresponds to an energy of 1.69 μJ), the pulse gets compressed with a factor of up to 5.5 and a quality factor of 0.73, in a distance of 12 cm. It also experiences a soliton-self frequency shift of up to 28 nm, in a propagation length of 6 m, with a pulse shape quality of ≈ 0.80.

  19. Demonstration of Cascaded In-Line Single-Pump Fiber Optical Parametric Amplifiers in Recirculating Loop Transmission

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Ozolins, Oskars; An, Yi

    2012-01-01

    The performance of cascaded single-pump fiber optical parametric amplifiers (FOPAs) is experimentally studied for the first time using recirculating loop transmission with 80-km dispersion managed spans. Error-free performance has been achieved over 320 km for 40-Gbit/s CSRZ-OOK and CSRZ...

  20. Adaptive Neuro-Fuzzy Based Gain Controller for Erbium-Doped Fiber Amplifiers

    Directory of Open Access Journals (Sweden)

    YUCEL, M.

    2017-02-01

    Full Text Available Erbium-doped fiber amplifiers (EDFA must have a flat gain profile which is a very important parameter such as wavelength division multiplexing (WDM and dense WDM (DWDM applications for long-haul optical communication systems and networks. For this reason, it is crucial to hold a stable signal power per optical channel. For the purpose of overcoming performance decline of optical networks and long-haul optical systems, the gain of the EDFA must be controlled for it to be fixed at a high speed. In this study, due to the signal power attenuation in long-haul fiber optic communication systems and non-equal signal amplification in each channel, an automatic gain controller (AGC is designed based on the adaptive neuro-fuzzy inference system (ANFIS for EDFAs. The intelligent gain controller is implemented and the performance of this new electronic control method is demonstrated. The proposed ANFIS-based AGC-EDFA uses the experimental dataset to produce the ANFIS-based sets and the rule base. Laser diode currents are predicted within the accuracy rating over 98 percent with the proposed ANFIS-based system. Upon comparing ANFIS-based AGC-EDFA and experimental results, they were found to be very close and compatible.

  1. Q-switching and efficient harmonic generation from a single-mode LMA photonic bandgap rod fiber laser

    DEFF Research Database (Denmark)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas T.

    2011-01-01

    We demonstrate a Single-Mode (SM) Large-Mode-Area (LMA) ytterbium-doped PCF rod fiber laser with stable and close to diffraction limited beam quality with 110W output power. Distributed-Mode-Filtering (DMF) elements integrated in the cladding of the rod fiber provide a robust spatial mode with a ...

  2. S-band multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier in the ring cavity

    Science.gov (United States)

    Anwar, Nur Elina; Ahmad Hambali, N. A. M.; Sohaimi, M. Syazwan; M. Shahimin, M.; A. Wahid, M. H.; Yusof, N. Roshidah; Malek, A. Zakiah

    2015-08-01

    This paper is focusing on simulation and analyzed of S-band multi-wavelength Brillouin-Raman fiber laser performance utilizing fiber Bragg grating and Raman amplifier in ring cavity by using Optisystem software. Raman amplifieraverage power model is employed for signal amplification. This laser system is operates in S-band wavelength region due to vast demanding on transmitting the information. Multi-wavelength fiber lasers based on hybrid Brillouin-Raman gain configuration supported by Rayleigh scattering effect have attracted significant research interest due to its ability to produced multi-wavelength signals from a single light source. In multi-wavelength Brillouin-Raman fiber, single mode fiber is utilized as the nonlinear gain medium. From output results, 90 % output coupling ratio has ability to provide the maximum average output power of 43 dBm at Brillouin pump power of 20 dBm and Raman pump power of 14 dBm. Furthermore, multi-wavelength Brillouin-Raman fiber laser utilizing fiber Bragg grating and Raman amplifier is capable of generated 7 Brillouin Stokes signals at 1480 nm, 1510 nm and 1530 nm.

  3. Numerical simulation of passively mode-locked fiber laser based on semiconductor optical amplifier

    Science.gov (United States)

    Yang, Jingwen; Jia, Dongfang; Zhang, Zhongyuan; Chen, Jiong; Liu, Tonghui; Wang, Zhaoying; Yang, Tianxin

    2013-03-01

    Passively mode-locked fiber laser (MLFL) has been widely used in many applications, such as optical communication system, industrial production, information processing, laser weapons and medical equipment. And many efforts have been done for obtaining lasers with small size, simple structure and shorter pulses. In recent years, nonlinear polarization rotation (NPR) in semiconductor optical amplifier (SOA) has been studied and applied as a mode-locking mechanism. This kind of passively MLFL has faster operating speed and makes it easier to realize all-optical integration. In this paper, we had a thorough analysis of NPR effect in SOA. And we explained the principle of mode-locking by SOA and set up a numerical model for this mode-locking process. Besides we conducted a Matlab simulation of the mode-locking mechanism. We also analyzed results under different working conditions and several features of this mode-locking process are presented. Our simulation shows that: Firstly, initial pulse with the peak power exceeding certain threshold may be amplified and compressed, and stable mode-locking may be established. After about 25 round-trips, stable mode-locked pulse can be obtained which has peak power of 850mW and pulse-width of 780fs.Secondly, when the initial pulse-width is greater, narrowing process of pulse is sharper and it needs more round-trips to be stable. Lastly, the bias currents of SOA affect obviously the shape of mode-locked pulse and the mode-locked pulse with high peak power and narrow width can be obtained through adjusting reasonably the bias currents of SOA.

  4. Compact Design of an Electrically Tunable and Rotatable Polarizer Based on a Liquid Crystal Photonic Bandgap Fiber

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard

    2009-01-01

    fixing structures during the device assembly. The total insertion loss of this all-in-fiber device is 2.7 dB. An electrically tunable polarization extinction ratio of 21.3 dB is achieved with 45$^{circ}$ rotatable transmission axis as well as switched on and off in the wavelength range of 1300–1600 nm....

  5. Characterization of an erbium doped fiber amplifier starting from its experimental parameters; Caracterizacion de un amplificador de fibra dopada con erbio a partir de sus parametros experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Bello J, M.; Kuzin, E.A.; Ibarra E, B. [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Luis Enrique Erro No. 1, TonantzintIa, 72000 Puebla (Mexico); Tellez G, R. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No 152, Delegacion Gustavo A. Madero, 07730 Mexico D.F. (Mexico)]. e-mail: mabello@inaoep.mx

    2007-07-01

    In this paper we describe a method to characterize the gain of an erbium-doped fiber amplifier (EDFA) through the numerical simulation of the signal beam along the amplifier. The simulation is based on a model constituted by the propagation and rate equations for an erbium-doped fiber. The manipulation of these equations allows us to regroup the parameters present in an EDFA, which we have named the A, B, C, D parameters, and they can be obtained experimentally from an erbium-doped fiber. Experimental results show that the measurement of these parameters allow us to estimate with very good correspondence the amplifier gain. (Author)

  6. Efficient phase locking of two dual-wavelength fiber amplifiers by an all-optical self-feedback loop

    Science.gov (United States)

    Lei, Bing; Chen, Keshan; Yao, Tianfu; Shi, Jianhua; Hu, Haojun

    2017-10-01

    Efficient phase locking of two dual-wavelength fiber amplifiers has been demonstrated by using a self-feedback coupling and intracavity filtering configuration, and the effect of bandwidth and wavelength spacing on their phase locking performances have been investigated in experiment. Two independent fiber lasers with different operating wavelength were combined incoherently by a 3 dB fiber coupler to form a dual-wavelength seed source laser, which was injected into the fiber amplifiers' coupling array through the self-feedback loop. The effect of bandwidth and wavelength spacing was researched by altering the seed laser's pump power and operating wavelengths respectively. As long as the feedback loop and the single-mode fiber filtering configuration were well constructed in the unidirectional ring laser cavity, stable phase locking states and high fringe visibility interference patterns could always be obtained in our experiment. When the spacing of two operating wavelength was varied from 1.6 nm to 19.6 nm, the fringe visibility decreased slightly with the increase of wavelength spacing, and the corresponding fringe visibility was always larger than 0.6. In conclusion, we believe that efficient phase locking of several multi-wavelength laser sources is also feasible by passive self-adjusting methods, and keeping the component laser beams' phase relationship stable and fixed is more important than controlling their operating wavelengths.

  7. High-power all fiber-integrated linearly polarized picosecond ytterbium-doped master-oscillator power amplifier

    Science.gov (United States)

    Hong, Chang; Liu, Jiang; Sun, Ruoyu; Shi, Yuhang; Wang, Yu; Wang, Pu

    2018-01-01

    We demonstrated an all-fiber-integrated linearly-polarized picosecond ytterbium-doped master-oscillator power-amplifier system, which yielded 225-W of average output power and the corresponding slope efficiency is 70.5%. The seed source was a compact passively mode-locked polarization-maintaining ytterbium-doped all-fiber oscillator with a pulse duration of 80-ps at 58.2-MHz repetition rate. In combination with two pre-amplifiers and a large-mode-area polarization-maintaining ytterbium-doped all-fiber master amplifier, output pulse energy up to 3.8-μJ with 48.3-kW pulse peak power was obtained without the need of complex free-space coupling and output setups. The polarization extinction ratio were measured to be 14.5 dB and the beam quality M2 factors was less than 1.49 in the both orthogonal directions at maximum output power.

  8. A comprehensive study on gain stabilization of Er-doped fiber amplifier in C-band with uniform fiber Bragg grating-pair

    Science.gov (United States)

    Yang, Jiuru; Ma, Yu; OuYang, Yunlun; Liu, Chunyu; Zhang, Jiaxiao

    2014-07-01

    Fiber grating-pair is one of the efficient methods for gain stabilization of erbium doped fiber amplifier (EDFA) but with a gain-reduction of signals, especially in C-band. In order to overcome it, in this article, we establish a configuration of EDFA based uniform fiber grating-pair and conduct a comprehensive study on gain stabilization by varying the reflectivity, center wavelength and 3dB bandwidth of grating, and by varying the channel number and pump power. The numerical results show that under the optimal parameters of grating the gain stabilization at 1550nm is +/-0.044dB with high gain and large dynamic range.

  9. Multi-channel, fiber-based seed pulse distribution system for femtosecond-level synchronized chirped pulse amplifiers.

    Science.gov (United States)

    Horáček, Martin; Indra, Lukáš; Green, Jonathan T; Naylon, Jack A; Tykalewicz, Boguslaw; Novák, Jakub; Batysta, František; Mazanec, Tomáš; Horáček, Jakub; Antipenkov, Roman; Hubka, Zbyněk; Boge, Robert; Bakule, Pavel; Rus, Bedřich

    2017-01-01

    We report on the design and performance of a fiber-based, multi-channel laser amplifier seed pulse distribution system. The device is designed to condition and distribute low energy laser pulses from a mode-locked oscillator to multiple, highly synchronized, high energy amplifiers integrated into a laser beamline. Critical functions such as temporal pulse stretching well beyond 100 ps/nm, pulse picking, and fine control over the pulse delay up to 300 ps are all performed in fiber eliminating the need for bulky and expensive grating stretchers, Pockels cells, and delay lines. These functions are characterized and the system as a whole is demonstrated by seeding two high energy amplifiers in the laser beamline. The design of this system allows for complete computer control of all functions, including tuning of dispersion, and is entirely hands-free. The performance of this device and its subsystems will be relevant to those developing lasers where reliability, size, and cost are key concerns in addition to performance; this includes those developing large-scale laser systems similar to ours and also those developing table-top experiments and commercial systems.

  10. Quantum and Raman Noise in a Depleted Fiber Optical Parametric Amplifier

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Rottwitt, Karsten; McKinstrie, Colin J.

    2013-01-01

    The noise properties of both phase-sensitive and phase-insensitive saturated parametric amplifiers are studied using a semi-classical approach. Vacuum fluctuations as well as spontaneous Raman scattering are included in the analysis....

  11. Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten

    2011-01-01

    The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

  12. Pulse energy of 151 nJ from ultrafast thulium-doped chirped-pulse fiber amplifier.

    Science.gov (United States)

    Haxsen, Frithjof; Wandt, Dieter; Morgner, Uwe; Neumann, Joerg; Kracht, Dietmar

    2010-09-01

    We report on chirped-pulse amplification of an ultrafast thulium-doped fiber laser. Pulses with an energy of 3.3 nJ and a bandwidth-limited pulse duration of 195 fs could be amplified to 151 nJ, which corresponds to an average power of 5.7 W at 37.6 MHz pulse repetition rate. The maximum output power was limited by the available pump power. The pulses could be dechirped to a duration of 258 fs.

  13. Gain optimization in fiber optical parametric amplifiers by combining standard and high-SBS threshold highly nonlinear fibers

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Rottwitt, Karsten; Peucheret, Christophe

    2012-01-01

    Combining Al-doped and Ge-doped HNLFs as gain media in FOPAs is proposed and optimized, resulting in efficient SBS mitigation while circumventing the additional loss of the high SBS threshold Al-doped fiber.......Combining Al-doped and Ge-doped HNLFs as gain media in FOPAs is proposed and optimized, resulting in efficient SBS mitigation while circumventing the additional loss of the high SBS threshold Al-doped fiber....

  14. Performance comparison of pre-, boost-, and inline-multimode erbium-doped fiber amplifier configurations to boost mode-division multiplexed multimode fiber link

    Science.gov (United States)

    Gupta, Rajan; Kaler, Rajinder Singh

    2016-05-01

    The performance of 3×3, 4×4, 5×5, and 6×6 optical multi-input multioutput (MIMO) mode-division multiplexed multimode fiber (MMF) systems has been investigated using pre-, boost-, and inline-multimode erbium-doped fiber amplifier configuration methods with LPlm (linearly polarized) modes. The outcome of these configurations has been compared in terms of quality factor (Q-factor) and bit error rate (BER). It is reported that inline-configuration provides best results for all MIMO mode-division multiplexing (MDM) systems covering transmission distance of 100 km with acceptable BER (10 dB) over MMF link to boost performance of MDM system.

  15. 85 μm core rod fiber amplifier delivering 350 W/m

    DEFF Research Database (Denmark)

    Johansen, Mette Marie; Michieletto, Mattia; Kristensen, Torben

    2016-01-01

    An improved version of the distributed modal filtering (DMF) rod fiber is tested in a high power setup delivering 350 W/m of extracted signal average power limited by the available pump power. The rod fiber is thoroughly tested to record the transverse modal instability (TMI) behavior and also me...

  16. Efficient design of gain-flattened multi-pump Raman fiber amplifiers using least squares support vector regression

    Science.gov (United States)

    Chen, Jing; Qiu, Xiaojie; Yin, Cunyi; Jiang, Hao

    2018-02-01

    An efficient method to design the broadband gain-flattened Raman fiber amplifier with multiple pumps is proposed based on least squares support vector regression (LS-SVR). A multi-input multi-output LS-SVR model is introduced to replace the complicated solving process of the nonlinear coupled Raman amplification equation. The proposed approach contains two stages: offline training stage and online optimization stage. During the offline stage, the LS-SVR model is trained. Owing to the good generalization capability of LS-SVR, the net gain spectrum can be directly and accurately obtained when inputting any combination of the pump wavelength and power to the well-trained model. During the online stage, we incorporate the LS-SVR model into the particle swarm optimization algorithm to find the optimal pump configuration. The design results demonstrate that the proposed method greatly shortens the computation time and enhances the efficiency of the pump parameter optimization for Raman fiber amplifier design.

  17. Fiber-Amplifier-Enhanced QEPAS Sensor for Simultaneous Trace Gas Detection of NH3 and H2S

    Directory of Open Access Journals (Sweden)

    Hongpeng Wu

    2015-10-01

    Full Text Available A selective and sensitive quartz enhanced photoacoustic spectroscopy (QEPAS sensor, employing an erbium-doped fiber amplifier (EDFA, and a distributed feedback (DFB laser operating at 1582 nm was demonstrated for simultaneous detection of ammonia (NH3 and hydrogen sulfide (H2S. Two interference-free absorption lines located at 6322.45 cm−1 and 6328.88 cm−1 for NH3 and H2S detection, respectively, were identified. The sensor was optimized in terms of current modulation depth for both of the two target gases. An electrical modulation cancellation unit was equipped to suppress the background noise caused by the stray light. An Allan-Werle variance analysis was performed to investigate the long-term performance of the fiber-amplifier-enhanced QEPAS sensor. Benefitting from the high power boosted by the EDFA, a detection sensitivity (1σ of 52 parts per billion by volume (ppbv and 17 ppbv for NH3 and H2S, respectively, were achieved with a 132 s data acquisition time at atmospheric pressure and room temperature.

  18. 20 dB net-gain polarization-insensitive fiber optical parametric amplifier with >2 THz bandwidth.

    Science.gov (United States)

    Stephens, M F C; Gordienko, V; Doran, N J

    2017-05-01

    A black-box polarization insensitive fiber optical parametric amplifier (PI-FOPA) is characterized for the first time using a commercial 127 Gb/s polarization-division multiplexed PDM-QPSK transponder within a multiplex of twenty-two equivalent DWDM signals across a 2.3 THz bandwidth portion of the C-band. The PI-FOPA employs a recently demonstrated diversity loop arrangement comprising two lengths of highly nonlinear fiber (HNLF) with the parametric pump being removed after the first HNLF in both directions about the loop. This arrangement is named the Half-Pass Loop FOPA or HPL-FOPA. In total, a record equivalent 2.3 Tb/s of data is amplified within the HPL-FOPA for three different pump power regimes producing net-gains of 10 dB, 15 dB and 20 dB (averaged over all signals). For the latter two regimes, the gain bandwidth is observed to extend considerably beyond the C-band, illustrating the potential for this design to amplify signals over bandwidths commensurate with the EDFA and beyond. Under the 15 dB gain condition, the average OSNR penalty to achieve 10-3 bit error rate for all twenty three signals was found to be 0.5 ± 0.3 dB. Worst case penalty was 0.8 ± 0.3 dB, verifying the use of the architecture for polarization insensitive operation. The growth of four-wave mixing signal-signal crosstalk is additionally characterized and found to be gain independent for a fixed output power per signal. A simple effective length model is developed which predicts this behavior and suggests a new configuration for significantly reduced crosstalk.

  19. High performance polarization-independent Quantum Dot Semiconductor Optical Amplifier with 22 dB fiber to fiber gain using Mode Propagation Tuning without additional polarization controller

    Science.gov (United States)

    Farmani, Ali; Farhang, Mahmoud; Sheikhi, Mohammad H.

    2017-08-01

    A detailed numerical investigation of polarization-independent quantum dot InAs/GaAs semiconductor optical amplifier (PIQS) based on a technique called mode propagation tuning (MPT) without the need for the polarization controller (PC) is reported, which can solve the limitation caused by polarization sensitivity in a semiconductor optical amplifier (SOA). Our calculations show that by a suitable tuning of the thickness of the active layer, only the TE0 and TM0 modes can propagate. Moreover, the gain saturation behavior of this SOA was measured at 1.55 μ m and found to be polarization-independent (PI). At active layer thickness of 1.7 μ m, the confinement factor was 0.75 and 0.7 for TE0 and TM0 modes, respectively, which leads to a gain difference up to 0.1 dB. The rate equations of the QD-SOA were also solved and a fiber to fiber gain of 22 dB was obtained. Additionally, a numerical simulation is presented which shows that the residual gain ripple and polarization sensitivity are sufficiently reduced when residual facet reflectivities of the SOA are in the range below 10-4 . In addition, the full-width at half-maximum of the horizontal and vertical far-field patterns (FFPs) are measured as 30° × 30°. The proposed structure can be used for logical applications.

  20. Serial topology of wide-band erbium-doped fiber amplifier for WDM applications

    Czech Academy of Sciences Publication Activity Database

    Karásek, Miroslav; Menif, M.

    2001-01-01

    Roč. 13, č. 9 (2001), s. 939-941 ISSN 1041-1135 R&D Projects: GA ČR GA102/99/0393 Institutional research plan: CEZ:AV0Z2067918 Keywords : erbium * wavelength division multiplexing * optical fibre amplifiers * optical fibre communication Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.004, year: 2001

  1. Protection of surviving channels in pump-controlled gain-locked Raman fiber amplifier

    Czech Academy of Sciences Publication Activity Database

    Karásek, Miroslav; Menif, M.

    2002-01-01

    Roč. 210, 1/2 (2002), s. 57-65 ISSN 0030-4018 R&D Projects: GA AV ČR IAA2067202 Institutional research plan: CEZ:AV0Z2067918 Keywords : optical fibre amplifiers * wavelength division multiplexing * optical communication Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.488, year: 2002

  2. Channel addition/removal response in all-optical gain-clamped lumped Raman fiber amplifier

    Czech Academy of Sciences Publication Activity Database

    Karásek, Miroslav; Kaňka, Jiří; Honzátko, Pavel; Radil, J.

    2004-01-01

    Roč. 16, č. 3 (2004), s. 771-773 ISSN 1041-1135 Institutional research plan: CEZ:AV0Z2067918 Keywords : optical communication * optical fibre amplifiers * wavelength division multiplexing Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.552, year: 2004

  3. Cross-gain modulation in Raman fiber amplifier: experimentation and modeling

    Czech Academy of Sciences Publication Activity Database

    Menif, M.; Karásek, Miroslav; Rusch, L. A.

    2002-01-01

    Roč. 14, č. 9 (2002), s. 1261-1263 ISSN 1041-1135 R&D Projects: GA MŠk OC 265.10 Institutional research plan: CEZ:AV0Z2067918 Keywords : wavelength division multiplexing * optical communication * optical fibre amplifiers Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.100, year: 2002

  4. Suppression of dynamic cross saturation in cascades of overpumped erbium-doped fiber amplifiers

    Czech Academy of Sciences Publication Activity Database

    Karásek, Miroslav; Willems, F. W.

    1998-01-01

    Roč. 10, č. 7 (1998), s. 1036-1038 ISSN 0162-8828 Grant - others:EU COST(XE) OC 241.10 Keywords : optical communication * amplifiers Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.417, year: 1998

  5. High energy single frequency Yb:YAG crystalline fiber waveguide master oscillator power amplifier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall objective is to demonstrate the concept of Yb:YAG crystalline fiber MOPA laser and investigation the technical feasibility toward 50 mJ single frequency...

  6. Frequency dependence of the pump-to-signal RIN transfer in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Pakarzadeh Dezfuli Nezhad, Hassan; Rottwitt, Karsten; Zakery, A.

    2009-01-01

    Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams.......Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams....

  7. Brillouin suppression in a fiber optical parametric amplifier by combining temperature distribution and phase modulation

    DEFF Research Database (Denmark)

    Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel

    2008-01-01

    We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation.......We demonstrate an increased gain in optical parametric amplier through suppression of stimulated Brillouin scattering by applying a temperature distribution along the fiber resulting in a reduction of the required phase modulation....

  8. Fiber chirped pulse amplifier at 2.08 μm emitting 383-fs pulses at 10 nJ and 7 MHz.

    Science.gov (United States)

    Hoogland, H; Wittek, S; Hänsel, W; Stark, S; Holzwarth, R

    2014-12-01

    An all-polarization maintaining (PM) fiber chirped pulse amplifier system at 2.08 μm based on thulium:holmium codoped gain fibers is reported. An inhouse built oscillator emits pulses at a repetition rate of 7 MHz with a spectral full width at half-maximum (FWHM) bandwidth of 23.5 nm at 2.8 mW average output power. The pulses are temporally stretched and subsequently amplified in a double-stage amplifier setup. The stretched pulses are compressed to 383 fs by use of a Martinez-style setup at an output pulse energy of 10.2 nJ. By neglecting temporal stretching, high peak powers in a single amplifier stage led to Raman soliton formation at 2.3 μm.

  9. Flat supercontinuum generation pumped by amplified noise-like pulses from a figure-eight erbium-doped fiber laser

    Science.gov (United States)

    Hernández-Escobar, E.; Bello-Jiménez, M.; Pottiez, O.; Ibarra-Escamilla, B.; López-Estopier, R.; Durán-Sánchez, M.; Kuzin, E. A.; Andrés, M. V.

    2017-10-01

    The conditions to obtain noise-like pulses (NLPs) from a figure-eight fiber laser (F8L) and their application for supercontinuum (SC) generation in the anomalous dispersion regime are reported. The F8L is designed to remove the undesired low-intensity background radiation from pulse emission, generating NLPs with a 3 dB spectral bandwidth of 17.43 nm at the fundamental repetition frequency of 0.8 MHz. After amplification, NLPs reach a maximum average power of 9.2 mW and 123.32 nm spectral bandwidth. By controlling the amplifier pump power, flat SC generation is demonstrated through both a 800 m long spool of SMF-28 fiber and a piece of 5 m long highly nonlinear optical fiber. The results demonstrate a satisfactory flatness of ~3 dB over a bandwidth of ~1000 nm in the range from 1261 to 2261 nm, achieving to the best of our knowledge, one of the flattest SC generated from noise-like pulses.

  10. A Robust Distributed Multipoint Fiber Optic Gas Sensor System Based on AGC Amplifier Structure.

    Science.gov (United States)

    Zhu, Cunguang; Wang, Rende; Tao, Xuechen; Wang, Guangwei; Wang, Pengpeng

    2016-07-28

    A harsh environment-oriented distributed multipoint fiber optic gas sensor system realized by automatic gain control (AGC) technology is proposed. To improve the photoelectric signal reliability, the electronic variable gain can be modified in real time by an AGC closed-loop feedback structure to compensate for optical transmission loss which is caused by the fiber bend loss or other reasons. The deviation of the system based on AGC structure is below 4.02% when photoelectric signal decays due to fiber bending loss for bending radius of 5 mm, which is 20 times lower than the ordinary differential system. In addition, the AGC circuit with the same electric parameters can keep the baseline intensity of signals in different channels of the distributed multipoint sensor system at the same level. This avoids repetitive calibrations and streamlines the installation process.

  11. Analysis of a realistic and idealized dispersion compensating photonic crystal fiber Raman Amplifier

    DEFF Research Database (Denmark)

    Varshney, S.K.; Saitoh, K.; Koshiba, M.

    2007-01-01

    In the present paper, the highly efficient Raman amplification properties of a realistic and idealized dispersion compensating photonic crystal fiber (DCPCF) are described numerically. We have used an accurate full-vectorial finite element modal solver with hybrid curvilinear edge/nodal elements...... and anisotropic perfectly matched layers for an accurate modal characterization of the realistic as well as idealized DCPCF. A good agreement is observed between numerically evaluated and experimentally [P.J. Roberts, B.J. Mangan, H. Sabert, F. Couny, et al., J. Opt. Fiber Commun. Rep. 2 (2005) 435-461] measured...... dispersion values. A high peak Raman gain efficiency of 10.5 W-¹?km-¹ is obtained at 13.1 THz frequency shift for a 1455 nm depolarized pump. A DCPCF module of 1-km length can compensate for the dispersion accumulated over 70-km of conventional single mode fiber link with a residual dispersion of +/-50 ps...

  12. Analysis of a broadband dispersion compensating photonic crystal fiber raman amplifier

    DEFF Research Database (Denmark)

    Varshney, Shailendra K.; Saitoh, K.; Koshiba, M.

    2006-01-01

    Using an accurate full-vectorial finite element method, a realistic model of a fabricated dispersion compensating photonic crystal fiber is analyzed. An almost flat Raman-gain spectrum (gain-ripples at just ±0.48-dB) is obtained using a single pump.......Using an accurate full-vectorial finite element method, a realistic model of a fabricated dispersion compensating photonic crystal fiber is analyzed. An almost flat Raman-gain spectrum (gain-ripples at just ±0.48-dB) is obtained using a single pump....

  13. Mode-locked 1.5 micrometers semiconductor optical amplifier fiber ring

    DEFF Research Database (Denmark)

    Pedersen, Niels V.; Jakobsen, Kaj Bjarne; Vaa, Michael

    1996-01-01

    The dynamics of a mode-locked SOA fiber ring are investigated experimentally and numerically. Generation of near transform-limited (time-bandwidth product=0.7) 1.5 μm 54 ps FWHM pulses with a peak power of 2.8 mW at a repetition rate of 960 MHz is demonstrated experimentally. The experimental...

  14. Modal instability of rod fiber amplifiers: a semi-analytic approach

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Hansen, Kristian Rymann; Laurila, Marko

    2013-01-01

    The modal instability (MI) threshold is estimated for four rod fiber designs by combining a semi-analytic model with the finite element method. The thermal load due to the quantum defect is calculated and used to numerically determine the mode distributions on which the expression for the onset o...

  15. Experimental investigation of saturation effect on pump-to-signal intensity modulation transfer in single-pump phase-insensitive fiber optic parametric amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke

    2013-01-01

    We present an experimental characterization of how signal gain saturation affects the transfer of intensity modulation from the pump to the signal in single-pump, phase-insensitive fiber optic parametric amplifiers (FOPAs). In this work, we demonstrate experimentally for the first time, to our...

  16. Photonic Lantern Adaptive Spatial Mode Control in LMA Fiber Amplifiers using SPGD

    Science.gov (United States)

    2015-12-15

    Saval, T. A. Birks, J. Bland- Hawthorn , and M. Englund, "Multimode fiber devices with single-mode performance," Opt. Lett. 30, 2545-2547 (2005). 7. D...Noordegraaf, P. M. Skovgaard, M. D. Nielsen, and J. Bland- Hawthorn , "Efficient multi-mode to single-mode coupling in a photonic lantern," Opt...Express 17, 1988-1994 (2009). 8. S. G. Leon-Saval, A. Argyros, and J. Bland- Hawthorn , "Photonic lanterns: a study of light propagation in multimode to

  17. Controlling mode instabilities at 628 W average output power in an Yb-doped rod-type fiber amplifier by active modulation of the pump power

    Science.gov (United States)

    Stihler, Christoph; Jauregui, Cesar; Otto, Hans-Jürgen; Limpert, Jens; Tünnermann, Andreas

    2017-02-01

    The phenomenon of transverse mode instabilities (TMI) is currently the most limiting effect for the scaling of the average output power of fiber laser systems with nearly diffraction-limited beam quality. Thus, it is of high interest to develop efficient mitigation strategies to further enhance the performance of fiber laser systems. By actively modulating the pump power of an Yb-doped rod-type fiber amplifier, it was possible to weaken the thermally-induced refractive index grating along the fiber and, thus, to mitigate TMI to a large extent. A significant advantage of this approach is that it can be easily integrated in any existing fiber-laser system since no further optical components are needed. A function generator connected to the pump diode driver was used to achieve the modulation. With this setup we were able to extract a fully stabilized beam at 1.5 times above the TMI threshold. Furthermore, a stabilization of the beam was still feasible at an average output power of 628 W, which is more than three times higher than the free-running TMI threshold of that particular fiber under identical conditions (e.g. seed power). This is the highest average output power reported from a single-channel rod-type fiber amplifier with a high-quality stabilized beam, to the best of our knowledge.

  18. Diode-laser-pump module with integrated signal ports for pumping amplifying fibers and method

    Science.gov (United States)

    Savage-Leuchs,; Matthias, P [Woodinville, WA

    2009-05-26

    Apparatus and method for collimating pump light of a first wavelength from laser diode(s) into a collimated beam within an enclosure having first and second optical ports, directing pump light from the collimated beam to the first port; and directing signal light inside the enclosure between the first and second port. The signal and pump wavelengths are different. The enclosure provides a pump block having a first port that emits pump light to a gain fiber outside the enclosure and that also passes signal light either into or out of the enclosure, and another port that passes signal light either out of or into the enclosure. Some embodiments use a dichroic mirror to direct pump light to the first port and direct signal light between the first and second ports. Some embodiments include a wavelength-conversion device to change the wavelength of at least some of the signal light.

  19. True photonic band-gap mode-control in VCSEL structures

    DEFF Research Database (Denmark)

    Romstad, F.; Madsen, M.; Birkedal, Dan

    2003-01-01

    Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect.......Photonic band-gap mode confinement in novel nano-structured large area VCSEL structures is confirmed by the amplified spontaneous emission spectrum. Both guide and anti-guide VCSEL structures are experimentally characterised to verify the photonic band-gap effect....

  20. Switchable dual-wavelength single-longitudinal-mode erbium-doped fiber laser using an inverse-Gaussian apodized fiber Bragg grating filter and a low-gain semiconductor optical amplifier.

    Science.gov (United States)

    Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Tang, Dingyuan; Hao, Jianzhong; Dong, Bo; Liang, Sheng

    2010-12-20

    We present a stable and switchable dual-wavelength erbium-doped fiber laser. In the ring cavity, an inverse-Gaussian apodized fiber Bragg grating serves as an ultranarrow dual-wavelength passband filter, a semiconductor optical amplifier biased in the low-gain regime reduces the gain competition of the two wavelengths, and a feedback fiber loop acts as a mode filter to guarantee a stable single-longitudinal-mode operation. Two lasing lines with a wavelength separation of approximately 0.1 nm are obtained experimentally. A microwave signal at 12.51 GHz is demonstrated by beating the dual wavelengths at a photodetector.

  1. Experimental and theoretical studies in non-linear optical applications. Fiber oscillatiors, regenerative amplifiers, simulations on white-light generation

    Energy Technology Data Exchange (ETDEWEB)

    Zia, Haider

    2015-12-15

    Compact and stable ultrafast laser sources for electron diffraction experiments are the first step in accomplishing the dream experiment of producing a molecular movie. This thesis work focuses on developing new robust laser sources to enable arbitrary scaling in laser repetition rate, pulse energy, duration and stability as needed to provide sufficient integrated detected electrons for high quality diffraction patterns that can be inverted to real space movies. In chapter 2, the construction of a novel stable and high power stretched pulse fiber oscillator outputting 300 mW at 31 MHz and compressible pulses to below 90 fs will be described. Chapter 3 describes the construction of a solid-state regenerative amplifier that was developed to achieve pulse energies above 1mJ with 0.40 mJ already achieved at 1 kHz. Novel simulation techniques were explored that aided the construction of the amplifier. Chapter 4 derives a new, fast and powerful numerical theory that is implemented for generalized non-linear Schrodinger equations in all spatial dimensions and time. This new method can model complicated terms in these equations that outperforms other numerical methods with respect to minimizing numerical error and increased speed. These advantages are due to this method's Fourier nature. A simulation tool was created, employing this numerical technique to simulate white-light generation in bulk media. The simulation matches extremely well with published experimental data, and is superior to the original simulation method used to match the experiment. The use of this tool enables accurate calculations of continuum or white light generation as needed for different experimental protocols and serves as the primary input to generate wide bandwidth coherent light.This work has solved the problem of predictably designing continuum generation within targeted wavelength ranges. This information is needed as part of an overall scheme in laser source development to coherently

  2. Experimental and theoretical studies in non-linear optical applications. Fiber oscillatiors, regenerative amplifiers, simulations on white-light generation

    International Nuclear Information System (INIS)

    Zia, Haider

    2015-12-01

    Compact and stable ultrafast laser sources for electron diffraction experiments are the first step in accomplishing the dream experiment of producing a molecular movie. This thesis work focuses on developing new robust laser sources to enable arbitrary scaling in laser repetition rate, pulse energy, duration and stability as needed to provide sufficient integrated detected electrons for high quality diffraction patterns that can be inverted to real space movies. In chapter 2, the construction of a novel stable and high power stretched pulse fiber oscillator outputting 300 mW at 31 MHz and compressible pulses to below 90 fs will be described. Chapter 3 describes the construction of a solid-state regenerative amplifier that was developed to achieve pulse energies above 1mJ with 0.40 mJ already achieved at 1 kHz. Novel simulation techniques were explored that aided the construction of the amplifier. Chapter 4 derives a new, fast and powerful numerical theory that is implemented for generalized non-linear Schrodinger equations in all spatial dimensions and time. This new method can model complicated terms in these equations that outperforms other numerical methods with respect to minimizing numerical error and increased speed. These advantages are due to this method's Fourier nature. A simulation tool was created, employing this numerical technique to simulate white-light generation in bulk media. The simulation matches extremely well with published experimental data, and is superior to the original simulation method used to match the experiment. The use of this tool enables accurate calculations of continuum or white light generation as needed for different experimental protocols and serves as the primary input to generate wide bandwidth coherent light.This work has solved the problem of predictably designing continuum generation within targeted wavelength ranges. This information is needed as part of an overall scheme in laser source development to coherently

  3. Superconducting switch and amplifier device

    International Nuclear Information System (INIS)

    Faris, S.M.

    1982-01-01

    An amplifying or switching superconductive device is described whose current-voltage characteristic is drastically altered by heavy injection of excess energetic quasi-particles. In this device, the superconducting bandgap of a superconducting layer is greatly altered by overinjection of energetic quasi-particles so that the bandgap changes greatly with respect to its thermal equilibrium value, and in most cases is made to vanish. In a preferred embodiment, a three electrode device is fabricated where at least one of the electrodes is a superconductor. Tunnel barriers are located between the electrodes. A first tunnel junction is used to heavily inject energetic quasi-particles into the superconducting electrode to change its superconducting bandgap drastically. In turn, this greatly modifies the currentvoltage characteristics of the second tunnel junction. This device can be used to provide logic circuits, or as an amplifier, and has an output sufficiently large that it can drive other similar devices

  4. Power and Efficiency Scaling of Fiber OPO Around 700 to 850 nm and Power-scaling of High Coherence Fiber Raman Amplifiers

    Science.gov (United States)

    2013-10-01

    6468 ( cell ) Email jn@orc.soton.ac.uk Abstract We report results on fiber Raman lasers at near-infrared wavelengths directly diode-pumped by high...air:silica micro-structured fiber, LMA-8 from NKT Photonics. However these lengths (in particular the PGF) were changed in order to try to improve the fiber

  5. 95 nJ dispersion-mapped amplifier similariton fiber laser at 8.6 MHz repetition rate with linear cavity configuration.

    Science.gov (United States)

    Shi, Junkai; Chai, Lu; Zhao, Xiaowei; Liu, Bowen; Hu, Minglie; Li, Yanfeng; Wang, Chingyue

    2015-07-13

    A high-energy and low repetition rate dispersion-mapped amplifier similariton oscillator with a large net intracavity anomalous dispersion and a linear cavity configuration is demonstrated experimentally at 1 μm. The numerical results confirm that self-similar evolution is accomplished in the gain fiber, and both the parabolic- and Gauss-shaped pulses can be emitted at different ports of the cavity, respectively. The maximum output power of 820 mW at a repetition rate of 8.6 MHz under a pump power of 12.76 W, corresponding to a pulse energy as high as of 95 nJ has been obtained.

  6. Compensation of nonlinearity in a fiber-optic transmission system using frequency-degenerate phase conjugation through counter-propagating dual pump FWM in a semiconductor optical amplifier

    Science.gov (United States)

    Anchal, Abhishek; K, Pradeep Kumar; O'Duill, Sean; Anandarajah, Prince M.; Landais, Pascal

    2018-04-01

    We present a scheme of frequency-degenerate mid-span spectral inversion (MSSI) for nonlinearity compensation in fiber-optic transmission systems. The spectral inversion is obtained by using counter-propagating dual pump four-wave mixing in a semiconductor optical amplifier (SOA). Frequency-degeneracy between signal and conjugate is achieved by keeping two pump frequencies symmetrical about the signal frequency. We simulate the performance of MSSI for nonlinearity compensation by scrutinizing the improvement of the Q-factor of a 200 Gbps QPSK signal transmitted over a standard single mode fiber, as a function of launch power for different span lengths and number of spans. We demonstrate a 7.5 dB improvement in the input power dynamic range and an almost 83% increase in the transmission length for optimum MSSI parameters of -2 dBm pump power and 400 mA SOA current.

  7. 1.7  μm band narrow-linewidth tunable Raman fiber lasers pumped by spectrum-sliced amplified spontaneous emission.

    Science.gov (United States)

    Zhang, Peng; Wu, Di; Du, Quanli; Li, Xiaoyan; Han, Kexuan; Zhang, Lizhong; Wang, Tianshu; Jiang, Huilin

    2017-12-10

    A 1.7 μm band tunable narrow-linewidth Raman fiber laser based on spectrally sliced amplified spontaneous emission (SS-ASE) and multiple filter structures is proposed and experimentally demonstrated. In this scheme, an SS-ASE source is employed as a pump source in order to avoid stimulated Brillouin scattering. The ring configuration includes a 500 m long high nonlinear optical fiber and a 10 km long dispersion shifted fiber as the gain medium. A segment of un-pumped polarization-maintaining erbium-doped fiber is used to modify the shape of the spectrum. Furthermore, a nonlinear polarization rotation scheme is applied as the wavelength selector to generate lasers. A high-finesse ring filter and a ring filter are used to narrow the linewidth of the laser, respectively. We demonstrate tuning capabilities of a single laser over 28 nm between 1652 nm and 1680 nm by adjusting the polarization controller (PC) and tunable filter. The tunable laser has a 0.023 nm effective linewidth with the high-finesse ring filter. The stable multi-wavelength laser operation of up to four wavelengths can be obtained by adjusting the PC carefully when the pump power increases.

  8. Analysis of channel addition/removal response in all-optical gain-clamped cascade of lumped Raman fiber amplifiers

    Czech Academy of Sciences Publication Activity Database

    Karásek, Miroslav; Kaňka, Jiří; Radil, J.

    2004-01-01

    Roč. 22, č. 10 (2004), s. 2271-2278 ISSN 0733-8724 R&D Projects: GA AV ČR IAA2067202 Institutional research plan: CEZ:AV0Z2067918 Keywords : optical communication * optical fibre amplifiers * wavelength division multiplexing Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.113, year: 2004

  9. Analysis of dynamic pump-loss controlled gain-locking system for erbium-doped fiber amplifiers

    Czech Academy of Sciences Publication Activity Database

    Karásek, Miroslav; Plaats van der, J.C.

    1998-01-01

    Roč. 10, č. 8 (1998), s. 1171-1173 ISSN 1041-1135 Grant - others:EU COST(XE) OC 241.10 Keywords : optical communication * amplifiers * fibre lasers Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.791, year: 1998

  10. Efficient fiber-laser-pumped Ho:YLF oscillator and amplifier utilizing the transmitted pump power of the oscillator

    CSIR Research Space (South Africa)

    Strauss, HJ

    2009-06-01

    Full Text Available In this paper, researchers have demonstrated that a Ho:YLF oscillator and amplifier system can be designed in a compact setup where the pump power from an unpolarized fibre laser utilized efficiently. The system produced more than 20 mJ energy per...

  11. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  12. Multi-channel, fiber-based seed pulse distribution system for femtosecond-level synchronized chirped pulse amplifiers

    Czech Academy of Sciences Publication Activity Database

    Horáček, Martin; Indra, Lukáš; Green, Jonathan T.; Naylon, Jack A.; Tykalewicz, Boguslav; Novák, Jakub; Batysta, František; Mazanec, Tomáš; Horáček, Jakub; Antipenkov, Roman; Hubka, Zbyněk; Boge, Robert; Bakule, Pavel; Rus, Bedřich

    2017-01-01

    Roč. 88, č. 1 (2017), s. 1-6, č. článku 013109. ISSN 0034-6748 R&D Projects: GA MŠk LQ1606; GA MŠk EF15_008/0000162 Grant - others:ELI Beamlines(XE) CZ.02.1.01/0.0/0.0/15_008/0000162 Institutional support: RVO:68378271 Keywords : disk amplifier * timing jitter * 1 khz * amplification Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 1.515, year: 2016

  13. Fabrication of an electro-absorption transceiver with a monolithically integrated optical amplifier for fiber transmission of 40–60 GHz radio signals

    International Nuclear Information System (INIS)

    Zhang, Andy Zhenzhong; Wang, Qin; Fonjallaz, Pierre-Yves; Almqvist, Susanne; Karlsson, Stefan; Kjebon, Olle; Schatz, Richard; Chacinski, Marek; Thylén, Lars; Berggren, Jesper; Hammar, Mattias; Honecker, Jörg; Steffan, Andreas

    2011-01-01

    We report on the fabrication of a monolithically integrated semiconductor optical amplifier (SOA) and a reflective electro-absorption transceiver (EAT) for 40–60 GHz radio-over-fiber applications. The EAT can either function as a transmitter (reflective modulator) or as a receiver (photodetector) depending on operation mode. The SOA and the EAT sections are based on different InGaAsP multiple quantum-well active layers connected by a butt joint. Benzocyclobutene is used to reduce the capacitance beside the ridge mesa. Devices are designed to have a peaked response at the operating frequency through the design of microwave waveguides on top of the devices. The packaged device exhibits at 0.1 mW optical input power an amplified DC responsivity of 18.5 mA mW −1 and a modulation efficiency of 0.67 mW V −1 . The estimated radio frequency loss at 40 GHz of an optical link consisting of two SOA–EAT devices was 23 dB using an unmodulated optical input carrier to the transmitter of 0.94 mW

  14. Fiber nonlinearity mitigation of WDM-PDM QPSK/16-QAM signals using fiber-optic parametric amplifiers based multiple optical phase conjugations

    DEFF Research Database (Denmark)

    Hu, Hao; Jopson, Robert M.; Gnauck, Alan H.

    2017-01-01

    We demonstrate fiber nonlinearity mitigation by using multiple optical phase conjugations (OPCs) in the WDM transmission systems of both 8 x 32-Gbaud PDM QPSK channels and 8 x 32-Gbaud PDM 16-QAM channels, showing improved performance over a single mid-span OPC and no OPC in terms of nonlinear...... threshold and a best achievable Q(2) factor after transmission. In addition, after an even number of OPCs, the signal wavelength can be preserved after transmission. The performance of multiple OPCs for fiber nonlinearity mitigation was evaluated independently for WDM PDM QPSK signals and WDM PDM 16QAM...... to 1 dB compared to the case of mid-span OPC. The improvements in the best achievable Q(2) factors were more modest, ranging from 0.2 dB to 1.1 dB for the results presented. (C) 2017 Optical Society of America...

  15. In-line and cascaded DWDM transmission using a 15dB net-gain polarization-insensitive fiber optical parametric amplifier.

    Science.gov (United States)

    Stephens, M F C; Tan, M; Gordienko, V; Harper, P; Doran, N J

    2017-10-02

    We demonstrate and characterize polarization-division multiplexed (PDM) DWDM data transmission for the first time in a range of systems incorporating a net-gain polarization-insensitive fiber optical parametric amplifier (PI-FOPA) for loss compensation. The PI-FOPA comprises a modified diversity-loop architecture to achieve 15dB net-gain, and up to 2.3THz (~18nm) bandwidth. Three representative systems are characterized using a 100Gb/s PDM-QPSK signal in conjunction with emulated DWDM neighbouring channels: (a) a 4x75km in-line fiber transmission system incorporating multiple EDFAs and a single PI-FOPA (b) N cascaded PI-FOPA amplification stages in an unlevelled Nx25km recirculating loop arrangement, with no EDFAs used within the loop signal path, and (c) M cascaded PI-FOPA amplification stages as part of an Mx75.6km gain-flattened recirculating loop system with the FOPA compensating for the transmission fiber loss, and EDFA compensation for loop switching and levelling loss. For the 4x75km in-line system (a), we transmit 45x50GHz-spaced signals ('equivalent' data-rate of 4.5Tb/s) with average OSNR penalty of 1.3dB over the band at 10 -3 BER. For the unlevelled 'FOPA-only' 25.2km cascaded system (b), we report a maximum of eight recirculations for all 10x100GHz-spaced signals, and five recirculations for 20x50GHz-spaced signals. For the 75.6km levelled system (c), we achieve eight recirculations for all 20x50GHz signals resulting in a total transmission distance of 604.8km.

  16. Design of a robust thin-film interference filter for erbium-doped fiber amplifier gain equalization.

    Science.gov (United States)

    Verly, Pierre G

    2002-06-01

    Gain-flattening filters (GFFs) are key wavelength division multiplexing components in fiber-optics telecommunications. Challenging issues in the design of thin-film GFFs were recently the subject of a contest organized at the 2001 Conference on Optical Interference Coatings. The interest and main difficulty of the proposed problem was to minimize the sensitivity of a GFF to simulated fabrication errors. A high-yield solution and its design philosophy are described. The approach used to control the filter robustness is explained and illustrated by numerical results.

  17. Coupled Acoustic-Mechanical Bandgaps

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard; Kook, Junghwan

    2016-01-01

    In this work, we study the existence of coupled bandgaps for corrugated plate structures and acoustic channels. The study is motivated by the observation that the performance of traditional bandgap structures, such as periodic plates, may be compromised due to the coupling to a surrounding acoustic...... medium and the presence of acoustic resonances. It is demonstrated that corrugation of the plate structure can introduce bending wave bandgaps and bandgaps in the acoustic domain in overlapping and audible frequency ranges. This effect is preserved also when taking the physical coupling between the two...... domains into account. Additionally, the coupling is shown to introduce extra gaps in the band structure due to modal interaction and the appearance of a cut-on frequency for the fundamental acoustic mode....

  18. Thermal effect on CFRP ablation with a 100-W class pulse fiber laser using a PCF amplifier

    Science.gov (United States)

    Sato, Yuji; Tsukamoto, Masahiro; Matsuoka, Fumihiro; Ohkubo, Tomomasa; Abe, Nobuyuki

    2017-09-01

    An experimental study on CFRP processing is presented using a high-power pulsed fiber laser operated at a 1064-nm fundamental wavelength, a 100-W average power, a 1-MHz repetition rate, and a 10-ns pulse width under ambient air, a dry air jet, or a nitrogen gas jet. Raman spectroscopy and scanning electron microscopy are conducted to measure the heat-affected zone (HAZ) quantitatively. Here, the HAZ is defined as the sum of the matrix evaporation zone (MEZ) and the resin alteration zone (RAZ). The MEZ, RAZ, and HAZ in air exceed 600, 2550, and 3150 μm, respectively. In the case of N2 gas jet, the MEZ, RAZ, and HAZ are 30, 88, and 118 μm, respectively. The results show that a nitrogen gas jet most effectively suppresses the HAZ by suppressing oxidization of the carbon fiber and cooling of heat accumulation. Additionally, the cutting speed with a dry air jet or a nitrogen gas jet increases by about 10% compared to that in ambient air.

  19. Operation amplifier

    NARCIS (Netherlands)

    Tetsuya, Saito; Nauta, Bram

    2008-01-01

    To provide an operation amplifier which improves power source voltage removal ratios while assuring phase compensation characteristics, and therefore can be realized with a small-scale circuit and low power consumption. SOLUTION: The operation amplifier comprises: a differential amplifier circuit 1;

  20. Photonic Bandgap (PBG) Shielding Technology

    Science.gov (United States)

    Bastin, Gary L.

    2007-01-01

    Photonic Bandgap (PBG) shielding technology is a new approach to designing electromagnetic shielding materials for mitigating Electromagnetic Interference (EM!) with small, light-weight shielding materials. It focuses on ground planes of printed wiring boards (PWBs), rather than on components. Modem PSG materials also are emerging based on planar materials, in place of earlier, bulkier, 3-dimensional PBG structures. Planar PBG designs especially show great promise in mitigating and suppressing EMI and crosstalk for aerospace designs, such as needed for NASA's Constellation Program, for returning humans to the moon and for use by our first human visitors traveling to and from Mars. Photonic Bandgap (PBG) materials are also known as artificial dielectrics, meta-materials, and photonic crystals. General PBG materials are fundamentally periodic slow-wave structures in I, 2, or 3 dimensions. By adjusting the choice of structure periodicities in terms of size and recurring structure spacings, multiple scatterings of surface waves can be created that act as a forbidden energy gap (i.e., a range of frequencies) over which nominally-conductive metallic conductors cease to be a conductor and become dielectrics. Equivalently, PBG materials can be regarded as giving rise to forbidden energy gaps in metals without chemical doping, analogous to electron bandgap properties that previously gave rise to the modem semiconductor industry 60 years ago. Electromagnetic waves cannot propagate over bandgap regions that are created with PBG materials, that is, over frequencies for which a bandgap is artificially created through introducing periodic defects

  1. The physics of transverse mode instability-induced nonlinear phase distortions in large area optical fiber amplifiers and their mitigation with applications in scaling of pulsed and continuous wave high-energy lasers

    Science.gov (United States)

    2016-12-13

    Technol.Lett.11, 39 (1999) 21. Y. Panbiharwala, C. S. Kumar, D. Venkitesh, and B. Srinivasan in International Conference on Fibre Optics and Photonics...24. Y. Panbiharwala, C. S. Kumar, D. Venkitesh, and B. Srinivasan in International Conference on Fibre Optics and Photonics, OSA Technical Digest...AFRL-AFOSR-JP-TR-2017-0001 The physics of transverse mode instability-induced nonlinear phase distortions in large area optical fiber amplifiers and

  2. Fiber

    Science.gov (United States)

    ... for the treatment of diverticulosis , diabetes , and heart disease . ... fiber is found in oat bran, barley, nuts, seeds, beans, lentils, peas, ... heart disease. Insoluble fiber is found in foods such as ...

  3. Operational amplifiers

    CERN Document Server

    Dostal, Jiri

    1993-01-01

    This book provides the reader with the practical knowledge necessary to select and use operational amplifier devices. It presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits.Provides the reader with practical knowledge necessary to select and use operational amplifier devices. Presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits

  4. Operation Amplifier

    NARCIS (Netherlands)

    Tetsuya, Saito; Nauta, Bram

    2011-01-01

    PROBLEM TO BE SOLVED: To provide an operation amplifier which improves power source voltage removal ratios while assuring phase compensation characteristics, and therefore can be realized with a small-scale circuit and low power consumption. SOLUTION: The operation amplifier comprises: a

  5. Operation Amplifier

    NARCIS (Netherlands)

    Tetsuya, S.; Nauta, Bram

    2007-01-01

    PROBLEM TO BE SOLVED: To provide an operation amplifier which improves power source voltage removal ratios while assuring phase compensation characteristics, and therefore can be realized with a small-scale circuit and low power consumption. ; SOLUTION: The operation amplifier comprises: a

  6. Design of an 1800 nm Raman Amplifier

    DEFF Research Database (Denmark)

    Svane, Ask Sebastian; Rottwitt, Karsten

    , also extended band amplifiers are required. As a solution to the latter challenge, Raman amplifiers are suggested as promising candidates. The main hurdle when designing a long wavelength Raman amplifier is the increased intrinsic fiber attenuation which as a consequence leads to an increase...... in the pump power requirement and deteriorated noise properties. Here we demonstrate a Raman amplifier designed for signal wavelengths around 1800 nm. The amplification fiber is an OFS PM Raman fiber, and is pumped by a Raman fiber laser emitting at 1680 nm [4]. The amplifier was pumped co......-polarized and backward, with respect to the singal. In Fig. 2 a measured Raman on/off gain exceeding 9 dB for 285 mW of injected pump power is obtained in a 4.35 km long fiber. A broadband supercontinuum source was used as a signal from 1700 nm to 1900 nm....

  7. Amplifier Distortion

    Science.gov (United States)

    Keeports, David

    2006-12-01

    By definition, a high fidelity amplifier's instantaneous output voltage is directly proportional to its instantaneous input voltage. While high fidelity is generally valued in the amplification of recorded music, nonlinearity, also known as distortion, is desirable in the amplification of some musical instruments. In particular, guitar amplifiers exploit nonlinearity to increase both the harmonic content and sustain of a guitar's sound. I will discuss how both modifications in sound result from saturation of triode tubes and transistors. Additionally, I will describe the difference in the symmetry of saturation curves for transistors and tubes and the reason why tube guitar amplifiers are generally considered to be superior to solid-state amplifiers. Finally, I will discuss attempts to use solid-state electronics to replicate the sound of tube amplifiers.

  8. Fiber

    Science.gov (United States)

    ... not getting enough fiber. According to the 2010 Dietary Guidelines, teen girls (14 to 18 years) should get 25 grams of fiber per day and teen boys (14 to 18 years) should get 31 grams of fiber per day. The best sources are fresh fruits and vegetables, nuts and legumes, ...

  9. Optical self-injection mode-locking of semiconductor optical amplifier fiber ring with electro-absorption modulation—fundamentals and applications

    Science.gov (United States)

    Chi, Yu-Chieh; Lin, Gong-Ru

    2013-04-01

    The optical self-injection mode-locking of a semiconductor optical amplifier incorporated fiber ring laser (SOAFL) with spectrally sliced multi-channel carriers is demonstrated for applications. The synthesizer-free SOAFL pulse-train is delivered by optical injection mode-locking with a 10 GHz self-pulsed electro-absorption modulator (EAM). Such a coupled optical and electronic resonator architecture facilitates a self-feedback oscillation with a higher Q-factor and lower phase/intensity noises when compared with conventional approaches. The theoretical model of such an injection-mode-locking SOAFL is derived to improve the self-pulsating performance of the optical return-to-zero (RZ) carrier, thus providing optimized pulsewidth, pulse extinction ratio, effective Q-factor, frequency variation and timing jitter of 11.4 ps, 9.1 dB, 4 × 105, pulsed carrier is also employed for the application in a 10 Gbit s-1 bi-directional WDM transmission network with down-stream RZ binary phase-shift keying (RZ-BPSK) and up-stream re-modulated RZ on-off-keying (RZ-OOK) formats. Under BPSK/OOK bi-directional data transmission, the self-pulsed harmonic mode-locking SOAFL simultaneously provides four to six WDM channels for down-stream RZ-BPSK and up-stream RZ-OOK formats with receiving sensitivities of -17 and -15.2 dBm at a bit error rate of 10-9, respectively.

  10. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [State Univ. of New York (SUNY), Plattsburgh, NY (United States); Univ. of California, Davis, CA (United States)

    2012-01-20

    Photoconductive semiconductor switches (PCSS) have been investigated since the late 1970s. Some devices have been developed that withstand tens of kilovolts and others that switch hundreds of amperes. However, no single device has been developed that can reliably withstand both high voltage and switch high current. Yet, photoconductive switches still hold the promise of reliable high voltage and high current operation with subnanosecond risetimes. Particularly since good quality, bulk, single crystal, wide bandgap semiconductor materials have recently become available. In this chapter we will review the basic operation of PCSS devices, status of PCSS devices and properties of the wide bandgap semiconductors 4H-SiC, 6H-SiC and 2H-GaN.

  11. Graded bandgap perovskite solar cells

    Science.gov (United States)

    Ergen, Onur; Gilbert, S. Matt; Pham, Thang; Turner, Sally J.; Tan, Mark Tian Zhi; Worsley, Marcus A.; Zettl, Alex

    2017-05-01

    Organic-inorganic halide perovskite materials have emerged as attractive alternatives to conventional solar cell building blocks. Their high light absorption coefficients and long diffusion lengths suggest high power conversion efficiencies, and indeed perovskite-based single bandgap and tandem solar cell designs have yielded impressive performances. One approach to further enhance solar spectrum utilization is the graded bandgap, but this has not been previously achieved for perovskites. In this study, we demonstrate graded bandgap perovskite solar cells with steady-state conversion efficiencies averaging 18.4%, with a best of 21.7%, all without reflective coatings. An analysis of the experimental data yields high fill factors of ~75% and high short-circuit current densities up to 42.1 mA cm-2. The cells are based on an architecture of two perovskite layers (CH3NH3SnI3 and CH3NH3PbI3-xBrx), incorporating GaN, monolayer hexagonal boron nitride, and graphene aerogel.

  12. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-07-03

    Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.

  13. Generation of 1.024-Tb/s Nyquist-WDM phase-conjugated twin vector waves by a polarization-insensitive optical parametric amplifier for fiber-nonlinearity-tolerant transmission

    DEFF Research Database (Denmark)

    Liu, Xiang; Hu, Hao; Chandrasekhar, S.

    2014-01-01

    We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all......-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled...

  14. Low Noise Optical Amplifiers

    Science.gov (United States)

    2010-05-01

    Technical University of Denmark, Oersteds Plads 343, DK-2800 Kgs. Lyngby, Denmark lris@fotonik.dtu.dk, karo@fotonik.dtu.dk Abstract: Impact on the second...1990). 9. P. Kylemark, H. Sunnerud, M. Karlsson, and P. A. Andrekson, “Semi-analytic saturation theory of fiber optical parametric amplifiers,” J...a flat broadband gain over 87 nm. 2. Theory In general we consider an electric field consisting of four CW waves, at frequencies ω1 through ω4. In non

  15. Distributed optical fibre devices based on liquid crystal infiltrated photonic crystal fibers

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Broeng, Jes; Hermann, D.S.

    2004-01-01

    We describe a new class of hybrid photonic crystal fibers, which are liquid crystal infiltrated fibers. Using these fibers, we demonstrate 'distributed' tunable filter and switching functionalities operating by the photonic bandgap effect....

  16. Analysis of liquid crystal properties for photonic crystal fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei

    2009-01-01

    We analyze the bandgap structure of Liquid Crystal infiltrated Photonic Crystal Fibers depending on the parameters of the Liquid Crystals by means of finite element simulations. For a biased Liquid Crystal Photonic Crystal Fiber, we show how the tunability of the bandgap position depends...... on the Liquid Crystal parameters....

  17. Monolithically Integrated Fiber Optic Coupler

    Science.gov (United States)

    2013-01-14

    single fused fiber 52 and drawn into ferrule 54 in order to provide an output as a photonic crystal fiber (PCF) or photonic bandgap ( PBG ) fiber 56...the reduced diameter air-silica photonic crystal fiber 56 (PCF) or photonic band gap ( PBG ), which is connected by a continuous transition of the... PBG 56 with a negative index of refraction includes metamaterials of superlattices formed by metal nanoparticles. The binary superlattices are

  18. Wide Bandgap Nanostructured Space Photovoltaics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Firefly, in collaboration with Rochester Institute of Technology, proposes an STTR program for the development of a wide-bandgap GaP-based space solar cell capable...

  19. Generation of 1.024-Tb/s Nyquist-WDM phase-conjugated twin vector waves by a polarization-insensitive optical parametric amplifier for fiber-nonlinearity-tolerant transmission.

    Science.gov (United States)

    Liu, Xiang; Hu, Hao; Chandrasekhar, S; Jopson, R M; Gnauck, A H; Dinu, M; Xie, C; Winzer, P J

    2014-03-24

    We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled reach in a dispersion-managed transmission link. We further study the impact of polarization-mode dispersion on the performance gain brought by the phase-conjugated twin waves, showing a gain of ~3.8 dB in signal quality factors.

  20. Wide Bandgap Extrinsic Photoconductive Switches

    Science.gov (United States)

    Sullivan, James Stephen

    Wide Bandgap Extrinsic Photoconductive Switches Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6H-SiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators. The successful development of a vanadium compensated, 6H-SiC extrinsic photoconductive switch for use as a closing switch for compact accelerator applications was realized by improvements made to the vanadium, nitrogen and boron impurity densities. The changes made to the impurity densities were based on the physical intuition outlined and simple rate equation models. The final 6H-SiC impurity 'recipe' calls for vanadium, nitrogen and boron densities of 2.5 e17 cm-3, 1.25e17 cm-3 and ≤ 1e16 cm-3, respectively. This recipe was originally developed to maximize the quantum efficiency of the vanadium compensated 6H-SiC, while maintaining a thermally stable semi-insulating material. The rate equation models indicate that, besides increasing the quantum efficiency, the impurity recipe should be expected to also increase the carrier recombination time. Three generations of 6H-SiC materials were tested. The

  1. Coupled-resonator-induced plasmonic bandgaps.

    Science.gov (United States)

    Wang, Yujia; Sun, Chengwei; Gong, Qihuang; Chen, Jianjun

    2017-10-15

    By drawing an analogy with the conventional photonic crystals, the plasmonic bandgaps have mainly employed the periodic metallic structures, named as plasmonic crystals. However, the sizes of the plasmonic crystals are much larger than the wavelengths, and the large sizes considerably decrease the density of the photonic integration circuits. Here, based on the coupled-resonator effect, the plasmonic bandgaps are experimentally realized in the subwavelength waveguide-resonator structure, which considerably decreases the structure size to subwavelength scales. An analytic model and the phase analysis are established to explain this phenomenon. Both the experiment and simulation show that the plasmonic bandgap structure has large fabrication tolerances (>20%). Instead of the periodic metallic structures in the bulky plasmonic crystals, the utilization of the subwavelength plasmonic waveguide-resonator structure not only significantly shrinks the bandgap structure to be about λ 2 /13, but also expands the physics of the plasmonic bandgaps. The subwavelength dimension, together with the waveguide configuration and robust realization, makes the bandgap structure easy to be highly integrated on chips.

  2. Amplification and ASE suppression in a polarization-maintaining ytterbium-doped solid-core photonic bandgap fibre

    DEFF Research Database (Denmark)

    Olausson, Christina Bjarnal Thulin; Falk, Charlotte Ijeoma; Lyngsøe, Jens Kristian

    2009-01-01

    We demonstrate suppression of amplified spontaneous emission at the conventional ytterbium gain wavelengths around 1030 nm in a cladding-pumped polarization-maintaining ytterbium-doped solid core photonic crystal fibre. The fibre works through combined index and bandgap guiding. Furthermore, we...... show that the peak of the amplified spontaneous emission can be shifted towards longer wavelengths by rescaling the fibre dimensions. Thereby one can obtain lasing or amplification at longer wavelengths (1100 nm - 1200 nm) as the amount of amplification in the fibre is shown to scale with the power...... of the amplified spontaneous emission....

  3. High SBS-Threshold Er/Yb Co-Doped Phosphate Glass Fiber Amplifiers for High Power, Sub-us Pulsed, Narrow Linewidth, All Fiber-Based Laser Transmitter, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase I, NP Photonics has achieved 1.2 kW peak power for 105 ns fiber laser pulses, and successfully demonstrated the feasibility to produce monolithic high SBS...

  4. High SBS-Threshold Er/Yb Co-Doped Phosphate Glass Fiber Amplifiers for High Power, Sub-us Pulsed, Narrow Linewidth, All Fiber-Based Laser Transmitter, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In order to implement the monolithic high power narrow linewidth pulsed all fiber-based laser transmitter by using a MOPA configuration for NASA's active remote...

  5. Photonic crystal fibers -

    DEFF Research Database (Denmark)

    Libori, Stig E. Barkou

    2002-01-01

    During this ph.d. work, attention has been focused on understanding and analyzing the modal behavior of micro-structured fibers. Micro-structured fibers are fibers with a complex dielectric toplogy, and offer a number of novel possibilities, compared to standard silica based optical fibers......, and nonlinear fibers with zero dispersion wavelength well below 1300 nm. This thesis dexcribes the functionalities of these fibers, and further point to novel application areas, such as new efficient fiber amplifiers and fibers with new possibilities within dispersion management. When pointing toward novel...

  6. Medium-gain erbium doped fiber amplifier ring laser passively mode-locked by graphite nano-powder adhered thin PVA film

    Science.gov (United States)

    Lin, Yung-Hsiang; Lin, Gong-Ru

    2012-06-01

    A direct brushing process of graphite nano-powder adhered on the single-mode fiber end-face with the use of an ultrathin PVA film is demonstrated, such a graphite nano-powder adhered ultra-thin PVA film is introduced to passively mode-lock a medium-gain Erbium-doped fiber laser (EDFL). The structural property of the graphite nano-powder is investigated by Raman spectroscopy. Numerous structural defects induced when abrading the graphite into nano-powder are found to broaden the 2D band Raman scattered signal and attenuate its peak intensity. The graphite nano-powders exhibit the featureless transmittance to show the potential as being a broadband tuning saturable absorber. In addition, the modulation depth of 0.43 is comparable with the graphene saturable absorber. The central wavelength of the passively mode-locked medium-gain EDFL is at 1561.2 nm with the full width at half maximum (FHWM) of 1.62 nm, and the pulsewidth is 1.58 ps. Under the limited intra-cavity power of 18 dBm, a nearly transform-limited passively mode-locking EDFL with TBP of 0.32 is generated.

  7. Frequency conversion through spontaneous degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Olausson, Christina Bjarnal Thulin

    2014-01-01

    Frequency conversion through spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers. Different FWM processes are observed, phasematching between fiber modes of orthogonal polarization, intermodal phasematching across bandgaps, and intramoda...

  8. Design of an 1800nm Raman amplifier

    DEFF Research Database (Denmark)

    Svane, Ask Sebastian; Rottwitt, Karsten

    2013-01-01

    We present the experimental results for a Raman amplifier that operates at 1810 nm and is pumped by a Raman fiber laser at 1680 nm. Both the pump laser and the Raman amplifier is polarization maintaining. A challenge when scaling Raman amplifiers to longer wavelengths is the increase...... in transmission loss, but also the reduction in the Raman gain coefficient as the amplifier wavelength is increased. Both polarization components of the Raman gain is characterized, initially for linearly co-polarized signal and pump, subsequently linearly polarized orthogonal signal and pump. The noise...... performance of the amplifier is also investigated for both configurations. Our results show an on/off gain exceeding 20 dB at 1810 nm for which the obtained effective noise figure is below 3 dB....

  9. Rapid ionic liquid-supported nano-hybrid composite reinforced hollow-fiber electromembrane extraction followed by field-amplified sample injection-capillary electrophoresis: An effective approach for extraction and quantification of Imatinib mesylate in human plasma.

    Science.gov (United States)

    Forough, Mehrdad; Farhadi, Khalil; Eyshi, Ali; Molaei, Rahim; Khalili, Hedayat; Javan Kouzegaran, Vahid; Matin, Amir Abbas

    2017-09-22

    The focus of this study is development of a new, convenient, rapid and sensitive electromembrane extraction approach (based on an ionic liquid-supported MWCNTs/ZnO reinforced hollow fiber, for the first time) as an off-line sample clean-up/preconcentration method coupled with capillary electrophoresis (CE-UV) using field-amplified sample injection (FASI) for quantification of Imatinib mesylate in human plasma. The nano-hybrid sorbent, coated by 1-octyl-3-methylimidazolium bromide ionic liquid ([OMIm]Br) in this research, was prepared by a feasible basic catalyzed sol-gel method. Then, it was immobilized (supported by capillary forces and sonication) in pores of a segment of a polypropylene hollow fiber membrane as the extraction unit after dispersing in 2-nitrophenyl octyl ether (NPOE) solvent and subsequently served as the supported liquid membrane (SLM) composition. Significant variables affecting the proposed method were evaluated and optimized to achieve the maximum extraction performance. Optimal conditions were obtained by NPOE with 4mgmL -1 nano-sorbent as the SLM composition, 105V as the driving force, pH 2 and 1.8 of the donor and acceptor phases, respectively, an extraction time of 15min and an agitation rate of 800rpm. The developed method was validated according to FDA guidelines. Regarding the validation results, the method is proved to be linear (R 2 =0.998) over concentrations ranging from 25 to 1500ngmL -1 (LOD=6.24ngmL -1 ). The mean RSD values for intra- and inter-day precision studies were 6.83 and 7.71%, respectively and the mean recoveries ranged between 98 and 106%. Finally, the validated method was successfully applied for sensitive, selective and rapid determination of Imatinib in patient's plasma samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Mode Division Multiplexing Exploring Hollow-Core Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Xu, Jing; Lyngso, Jens Kristian; Leick, Lasse

    2013-01-01

    -return to zero (NRZ) data signals over a 30 m 7-cell HC-PBGF using the offset mode launching method. In another experiment, a short piece of 19-cell HC-PBGF was used to transmit two 20 Gbit/s NRZ channels using a spatial light modulator for precise mode excitation. Bit-error-ratio (BER) performances below...

  11. Amplifier for nuclear spectrometry

    International Nuclear Information System (INIS)

    Suarez Canner, E.

    1996-01-01

    The spectroscopy amplifier model AE-020 is designed to adjust suitable the pulses coming from nuclear radiation detectors. Due to is capacity and specifications, the amplifier can be used together with high and medium resolution spectroscopy system

  12. Amplification factor variable amplifier

    NARCIS (Netherlands)

    Akitsugu, Oshita; Nauta, Bram

    2007-01-01

    PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ; SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and

  13. Amplification factor variable amplifier

    NARCIS (Netherlands)

    Akitsugu, Oshita; Nauta, Bram

    2010-01-01

    PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ;SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and can

  14. RF power amplifiers

    CERN Document Server

    Albulet, Mihai

    2001-01-01

    This text presents a full account of RF amplifiers and provides a thorough understanding of power amplifier principles and their applications. This comprehensive book covers all important design techniques for power amplifiers and includes mathematical derivations and the assumptions used to develop design rules.

  15. Two-dimensional Kagome photonic bandgap waveguide

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou

    2000-01-01

    The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....

  16. Monolithic, multi-bandgap, tandem, ultra-thin, strain-counterbalanced, photovoltaic energy converters with optimal subcell bandgaps

    Science.gov (United States)

    Wanlass, Mark W [Golden, CO; Mascarenhas, Angelo [Lakewood, CO

    2012-05-08

    Modeling a monolithic, multi-bandgap, tandem, solar photovoltaic converter or thermophotovoltaic converter by constraining the bandgap value for the bottom subcell to no less than a particular value produces an optimum combination of subcell bandgaps that provide theoretical energy conversion efficiencies nearly as good as unconstrained maximum theoretical conversion efficiency models, but which are more conducive to actual fabrication to achieve such conversion efficiencies than unconstrained model optimum bandgap combinations. Achieving such constrained or unconstrained optimum bandgap combinations includes growth of a graded layer transition from larger lattice constant on the parent substrate to a smaller lattice constant to accommodate higher bandgap upper subcells and at least one graded layer that transitions back to a larger lattice constant to accommodate lower bandgap lower subcells and to counter-strain the epistructure to mitigate epistructure bowing.

  17. Selective mode excitation in hollow-core photonic crystal fiber

    Science.gov (United States)

    Galea, A. D.; Couny, F.; Coupland, S.; Roberts, P. J.; Sabert, H.; Knight, J. C.; Birks, T. A.; Russell, Philip St. J.

    2005-04-01

    Modes are selectively excited by launching light through the cladding from the side into a hollow-core photonic crystal fiber. Measuring the total output power at the end of the fiber as a function of the angle of incidence of the exciting laser beam provides a powerful diagnostic for characterizing the cladding bandgap. Furthermore, various types of modes on either side of the bandgap are excited individually, and their near-field images are obtained.

  18. 2 micron femtosecond fiber laser

    Science.gov (United States)

    Liu, Jian; Wan, Peng; Yang, Lihmei

    2014-07-29

    Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

  19. Fiber Lasers V

    DEFF Research Database (Denmark)

    Hansen, Kim P.; Olausson, Christina Bjarnal Thulin; Broeng, Jes

    2008-01-01

    High-power fiber lasers and amplifiers have gained tremendous momentum in the last five years, and many of the traditional manufactures of gas and solid-state lasers are pursuing the attractive fiber-based systems, which are now displacing the old technology in many areas. High-power fiber laser...... systems require specially designed fibers with large cores and good power handling capabilities – requirements that are all met by the airclad fiber technology. In the present paper we go through many of the building blocks needed to build high-power systems and we show an example of a complete airclad...... laser system. We present the latest advancements within airclad fiber technology including a new 70 μm single-mode polarization-maintaining rod-type fiber capable of amplifying to MW power levels. Furthermore we describe the novel airclad based pump combiners and their use in a completely monolithic 350...

  20. Airclad fiber laser technology

    DEFF Research Database (Denmark)

    Hansen, Kim P.; Olausson, Christina Bjarnal Thulin; Broeng, Jes

    2008-01-01

    High-power fiber lasers and amplifiers have gained tremendous momentum in the last five years, and many of the traditional manufactures of gas and solid-state lasers are pursuing the attractive fiber-based systems, which are now displacing the old technology in many areas. High-power fiber laser...... systems require specially designed fibers with large cores and good power handling capabilities - requirements that are all met by the airclad fiber technology. In the present paper we go through many of the building blocks needed to build high-power systems and we show an example of a complete airclad...... laser system. We present the latest advancements within airclad fiber technology including a new 70 μm single-mode polarization-maintaining rod-type fiber capable of amplifying to MW power levels. Furthermore we describe the novel airclad based pump combiners and their use in a completely monolithic 350...

  1. High-Power Fiber Lasers Using Photonic Band Gap Materials

    Science.gov (United States)

    DiDomenico, Leo; Dowling, Jonathan

    2005-01-01

    High-power fiber lasers (HPFLs) would be made from photonic band gap (PBG) materials, according to the proposal. Such lasers would be scalable in the sense that a large number of fiber lasers could be arranged in an array or bundle and then operated in phase-locked condition to generate a superposition and highly directed high-power laser beam. It has been estimated that an average power level as high as 1,000 W per fiber could be achieved in such an array. Examples of potential applications for the proposed single-fiber lasers include welding and laser surgery. Additionally, the bundled fibers have applications in beaming power through free space for autonomous vehicles, laser weapons, free-space communications, and inducing photochemical reactions in large-scale industrial processes. The proposal has been inspired in part by recent improvements in the capabilities of single-mode fiber amplifiers and lasers to produce continuous high-power radiation. In particular, it has been found that the average output power of a single strand of a fiber laser can be increased by suitably changing the doping profile of active ions in its gain medium to optimize the spatial overlap of the electromagnetic field with the distribution of active ions. Such optimization minimizes pump power losses and increases the gain in the fiber laser system. The proposal would expand the basic concept of this type of optimization to incorporate exploitation of the properties (including, in some cases, nonlinearities) of PBG materials to obtain power levels and efficiencies higher than are now possible. Another element of the proposal is to enable pumping by concentrated sunlight. Somewhat more specifically, the proposal calls for exploitation of the properties of PBG materials to overcome a number of stubborn adverse phenomena that have impeded prior efforts to perfect HPFLs. The most relevant of those phenomena is amplified spontaneous emission (ASE), which causes saturation of gain and power

  2. Bandgap Optimization of Perovskite Semiconductors for Photovoltaic Applications.

    Science.gov (United States)

    Xiao, Zewen; Zhou, Yuanyuan; Hosono, Hideo; Kamiya, Toshio; Padture, Nitin P

    2018-02-16

    The bandgap is the most important physical property that determines the potential of semiconductors for photovoltaic (PV) applications. This Minireview discusses the parameters affecting the bandgap of perovskite semiconductors that are being widely studied for PV applications, and the recent progress in the optimization of the bandgaps of these materials. Perspectives are also provided for guiding future research in this area. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Wireless Josephson amplifier

    International Nuclear Information System (INIS)

    Narla, A.; Sliwa, K. M.; Hatridge, M.; Shankar, S.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.

    2014-01-01

    Josephson junction parametric amplifiers are playing a crucial role in the readout chain in superconducting quantum information experiments. However, their integration with current 3D cavity implementations poses the problem of transitioning between waveguide, coax cables, and planar circuits. Moreover, Josephson amplifiers require auxiliary microwave components, like directional couplers and/or hybrids, that are sources of spurious losses and impedance mismatches that limit measurement efficiency and amplifier tunability. We have developed a wireless architecture for these parametric amplifiers that eliminates superfluous microwave components and interconnects. This greatly simplifies their assembly and integration into experiments. We present an experimental realization of such a device operating in the 9–11 GHz band with about 100 MHz of amplitude gain-bandwidth product, on par with devices mounted in conventional sample holders. The simpler impedance environment presented to the amplifier also results in increased amplifier tunability.

  4. Erbium-doped integrated waveguide amplifiers and lasers

    NARCIS (Netherlands)

    Bradley, J.; Pollnau, Markus

    Erbium-doped fiber devices have been extraordinarily successful due to their broad optical gain around 1.5–1.6 μm. Er-doped fiber amplifiers enable efficient, stable amplification of high-speed, wavelength-division-multiplexed signals, thus continue to dominate as part of the backbone of longhaul

  5. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Black, Marcie [Bandgap Engineering, Lincoln, MA (United States)

    2014-10-30

    This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

  6. Fiber MOPA for Ascends, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — CO2 sensing using absorption bands near 1570nm is very attractive by taking advantage of the mature fiber-amplifier technology derived from fiber-optic telecom...

  7. Fiber MOPA for Ascends, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — CO2 sensing using absorption bands near 1570nm is very attractive by taking advantage of the mature fiber-amplifier technology derived from fiber-optic telecom...

  8. A general theory for bandgap estimation in locally resonant metastructures

    Science.gov (United States)

    Sugino, C.; Xia, Y.; Leadenham, S.; Ruzzene, M.; Erturk, A.

    2017-10-01

    Locally resonant metamaterials are characterized by bandgaps at wavelengths that are much larger than the lattice size, enabling low-frequency vibration attenuation. Typically, bandgap analyses and predictions rely on the assumption of traveling waves in an infinite medium, and do not take advantage of modal representations typically used for the analysis of the dynamic behavior of finite structures. Recently, we developed a method for understanding the locally resonant bandgap in uniform finite metamaterial beams using modal analysis. Here we extend that framework to general locally resonant 1D and 2D metastructures (i.e. locally resonant metamaterial-based finite structures) with specified boundary conditions using a general operator formulation. Using this approach, along with the assumption of an infinite number of resonators tuned to the same frequency, the frequency range of the locally resonant bandgap is easily derived in closed form. Furthermore, the bandgap expression is shown to be the same regardless of the type of vibration problem under consideration, depending only on the added mass ratio and target frequency. For practical designs with a finite number of resonators, it is shown that the number of resonators required for the bandgap to appear increases with increased target frequency, i.e. more resonators are required for higher vibration modes. Additionally, it is observed that there is an optimal, finite number of resonators which gives a bandgap that is wider than the infinite-resonator bandgap, and that the optimal number of resonators increases with target frequency and added mass ratio. As the number of resonators becomes sufficiently large, the bandgap converges to the derived infinite-resonator bandgap. Furthermore, the derived bandgap edge frequencies are shown to agree with results from dispersion analysis using the plane wave expansion method. The model is validated experimentally for a locally resonant cantilever beam under base

  9. Antares laser power amplifier

    International Nuclear Information System (INIS)

    Stine, R.D.; Ross, G.F.; Silvernail, C.

    1979-01-01

    The overall design of the Antares laser power amplifier is discussed. The power amplifier is the last stage of amplification in the 100-kJ Antares laser. In the power amplifier a single, cylindrical, grid-controlle, cold-cathode electron gun is surrounded by 12 large-aperture CO 2 electron-beam sustained laser discharge sectors. Each power amplifier will deliver 18 kJ and the six modules used in Antares will produce the required 100 kJ for delivery to the target. A large-scale interaction between optical, mechanical, and electrical disciplines is required to meet the design objectives. Significant component advances required by the power amplifier design are discussed

  10. Digital automatic gain amplifier

    Science.gov (United States)

    Holley, L. D.; Ward, J. O. (Inventor)

    1978-01-01

    A circuit is described for adjusting the amplitude of a reference signal to a predetermined level so as to permit subsequent data signals to be interpreted correctly. The circuit includes an operational amplifier having a feedback circuit connected between an output terminal and an input terminal; a bank of relays operably connected to a plurality of resistors; and a comparator comparing an output voltage of the amplifier with a reference voltage and generating a compared signal responsive thereto. Means is provided for selectively energizing the relays according to the compared signal from the comparator until the output signal from the amplifier equals to the reference signal. A second comparator is provided for comparing the output of the amplifier with a second voltage source so as to illuminate a lamp when the output signal from the amplifier exceeds the second voltage.

  11. Electrically Tunable Bandgaps in Bilayer MoS₂.

    Science.gov (United States)

    Chu, Tao; Ilatikhameneh, Hesameddin; Klimeck, Gerhard; Rahman, Rajib; Chen, Zhihong

    2015-12-09

    Artificial semiconductors with manufactured band structures have opened up many new applications in the field of optoelectronics. The emerging two-dimensional (2D) semiconductor materials, transition metal dichalcogenides (TMDs), cover a large range of bandgaps and have shown potential in high performance device applications. Interestingly, the ultrathin body and anisotropic material properties of the layered TMDs allow a wide range modification of their band structures by electric field, which is obviously desirable for many nanoelectronic and nanophotonic applications. Here, we demonstrate a continuous bandgap tuning in bilayer MoS2 using a dual-gated field-effect transistor (FET) and photoluminescence (PL) spectroscopy. Density functional theory (DFT) is employed to calculate the field dependent band structures, attributing the widely tunable bandgap to an interlayer direct bandgap transition. This unique electric field controlled spontaneous bandgap modulation approaching the limit of semiconductor-to-metal transition can open up a new field of not yet existing applications.

  12. Review of wide band-gap semiconductors technology

    Directory of Open Access Journals (Sweden)

    Jin Haiwei

    2016-01-01

    Full Text Available Silicon carbide (SiC and gallium nitride (GaN are typical representative of the wide band-gap semiconductor material, which is also known as third-generation semiconductor materials. Compared with the conventional semiconductor silicon (Si or gallium arsenide (GaAs, wide band-gap semiconductor has the wide band gap, high saturated drift velocity, high critical breakdown field and other advantages; it is a highly desirable semiconductor material applied under the case of high-power, high-temperature, high-frequency, anti-radiation environment. These advantages of wide band-gap devices make them a hot spot of semiconductor technology research in various countries. This article describes the research agenda of United States and European in this area, focusing on the recent developments of the wide band-gap technology in the US and Europe, summed up the facing challenge of the wide band-gap technology.

  13. Electrically dependent bandgaps in graphene on hexagonal boron nitride

    International Nuclear Information System (INIS)

    Kaplan, D.; Swaminathan, V.; Recine, G.

    2014-01-01

    We present first-principles calculations on the bandgap of graphene on a layer of hexagonal boron nitride in three different stacking configurations. Relative stability of the configurations is identified and bandgap tunability is demonstrated through the application of an external, perpendicularly applied electric field. We carefully examine the bandgap's sensitivity to both magnitude of the applied field as well as separation between the graphene and hexagonal boron nitride layers. Features of the band structure are examined and configuration-dependent relationships between the field and bandgap are revealed and elucidated through the atom-projected density of states. These findings suggest the potential for opening and modulating a bandgap in graphene as high as several hundred meV

  14. Electrically dependent bandgaps in graphene on hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, D., E-mail: daniel.b.kaplan.civ@mail.mil; Swaminathan, V. [U.S. Army RDECOM-ARDEC, Fuze Precision Armaments and Technology Directorate, Picatinny Arsenal, New Jersey 07806 (United States); Recine, G. [Department of Applied Physics, Polytechnic Institute of New York University, Brooklyn, New York 11201 (United States); Department of Physics and Engineering Physics, Fordham University, Bronx, New York 10458 (United States)

    2014-03-31

    We present first-principles calculations on the bandgap of graphene on a layer of hexagonal boron nitride in three different stacking configurations. Relative stability of the configurations is identified and bandgap tunability is demonstrated through the application of an external, perpendicularly applied electric field. We carefully examine the bandgap's sensitivity to both magnitude of the applied field as well as separation between the graphene and hexagonal boron nitride layers. Features of the band structure are examined and configuration-dependent relationships between the field and bandgap are revealed and elucidated through the atom-projected density of states. These findings suggest the potential for opening and modulating a bandgap in graphene as high as several hundred meV.

  15. Auto-Zero Differential Amplifier

    Science.gov (United States)

    Quilligan, Gerard T. (Inventor); Aslam, Shahid (Inventor)

    2017-01-01

    An autozero amplifier may include a window comparator network to monitor an output offset of a differential amplifier. The autozero amplifier may also include an integrator to receive a signal from a latched window comparator network, and send an adjustment signal back to the differential amplifier to reduce an offset of the differential amplifier.

  16. Large Bandgap Semiconductors for Solar Water Splitting

    DEFF Research Database (Denmark)

    Malizia, Mauro

    Photoelectrochemical water splitting represents an eco-friendly technology that could enable the production of hydrogen using water as reactant and solar energy as primary energy source. The exploitation of solar energy for the production of hydrogen would help modern society to reduce the reliance...... (bismuth vanadate) was investigated in view of combining this 2.4 eV large bandgap semiconductor with a Si back-illuminated photocathode. A device obtained by mechanical stacking of BiVO4 photoanode and standard Si photocathode performs non-assisted water splitting under illumination with Solar......-to-Hydrogen efficiency lower than 0.5%. In addition, BiVO4 was synthesized on the back-side of a Si back-illuminated photocathode to produce a preliminary monolithic solar water splitting device.The Faradaic efficiency of different types of catalysts for the electrochemical production of hydrogen or oxygen was evaluated...

  17. Photonic Bandgap Structures as Meta-Materials

    Science.gov (United States)

    Yablonovitch, Eli

    2000-03-01

    Engineering design is sometimes inspired by Nature. The natural world is filled with crystals, periodic structures which interact with Schrodinger Waves. Drawing on this analogy, we are designing artificial crystal structures which are intended for Electromagnetic Waves instead. This has now unleashed the collective scientific imagination, engendering a profusion of synthetic electromagnetic crystal structures. In correspondence to semiconductor crystals these usually have an electromagnetic bandgap, a band of frequencies in which electromagnetic waves are forbidden. We will present here a portfolio of various 2 and 3 dimensional crystal structures which have been conceived, and indicate the applications, such as opto-electronic light emitters, radio antennas, and color pigments, for which they are intended.

  18. Model Hamiltonian for predicting the bandgap of conjugated systems

    Science.gov (United States)

    Leitao Botelho, Andre; Shin, Yongwoo; Lin, Xi

    2012-02-01

    We calculate the bandgaps for conjugated systems using the adapted Su-Schrieffer-Heeger Hamiltonian and find good agreement with 130 independent experimental points. The 2D version of the model correctly demonstrates the decrease in bandgap from the addition of vinylene bridges to both poly(p-phenylene) and polythiophene indicating that planarization is not a significant effect. Expanding the model to 3D shows that interchain interactions systematically reduces the bandgap. In fused rings sharing dissimilar bonds, such as in isothianaphthene, the bond length dimerization along the carbon backbone decreases leading to a decrease in the bandgap. In contrast, when fusing two of the same rings along equivalent bonds, for example thienoacene, the bandgap change is less than 10% at best when normalized by the number of carbon atoms in the conjugation path. From porphyrin and pyrrole-benzothiadiazole we learn that tautomerization significantly affects the bandgap, as the ɛ value for NH had to be used for both NH and N, indicating that H is being shared by both. In modeling donor-acceptor co-polymers we accurately calculate the reduction in the bandgaps when compared to their parent homopolymers.

  19. Noise in Optical Amplifiers

    DEFF Research Database (Denmark)

    Jeppesen, Palle

    1997-01-01

    Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....

  20. A New Digital to Analog Converter Based on Low-Offset Bandgap Reference

    Directory of Open Access Journals (Sweden)

    Jinpeng Qiu

    2017-01-01

    Full Text Available This paper presents a new 12-bit digital to analog converter (DAC circuit based on a low-offset bandgap reference (BGR circuit with two cascade transistor structure and two self-contained feedback low-offset operational amplifiers to reduce the effects of offset operational amplifier voltage effect on the reference voltage, PMOS current-mirror mismatch, and its channel modulation. A Start-Up circuit with self-bias current architecture and multipoint voltage monitoring is employed to keep the BGR circuit working properly. Finally, a dual-resistor ladder DAC-Core circuit is used to generate an accuracy DAC output signal to the buffer operational amplifier. The proposed circuit was fabricated in CSMC 0.5 μm 5 V 1P4M process. The measured differential nonlinearity (DNL of the output voltages is less than 0.45 LSB and integral nonlinearity (INL less than 1.5 LSB at room temperature, consuming only 3.5 mW from a 5 V supply voltage. The DNL and INL at −55°C and 125°C are presented as well together with the discussion of possibility of improving the DNL and INL accuracy in future design.

  1. New amplifying laser concept for inertial fusion driver

    International Nuclear Information System (INIS)

    Mourou, G A; Hulin, D; Labaune, C; Galvanauskas, A

    2008-01-01

    This paper presents a new amplifying laser concept designed to produce high energy in either short or long pulses using coherent or incoherent addition of few millions fibers. These are called respectively CAN for Coherent Amplification Network and FAN for Fiber Amplification Network. The fibers would be large core or Large Mode Area (LMA) which have demonstrated up to 10, mJ output energy per fiber 1 . Such a system could meet the driver criteria of Inertial Fusion Energy (IFE) power plants based on Inertial Confinement Fusion (ICF), in particular high efficiency and high repetition rate

  2. Use of a photonic crystal for optical amplifier gain control

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shawn-Yu [Albuquerque, NM; Fleming, James G [Albuquerque, NM; El-Kady, Ihab [Albuquerque, NM

    2006-07-18

    An optical amplifier having a uniform gain profile uses a photonic crystal to tune the density-of-states of a gain medium so as to modify the light emission rate between atomic states. The density-of-states of the gain medium is tuned by selecting the size, shape, dielectric constant, and spacing of a plurality of microcavity defects in the photonic crystal. The optical amplifier is particularly useful for the regeneration of DWDM signals in long optical fibers.

  3. Metallic photonic band-gap materials

    International Nuclear Information System (INIS)

    Sigalas, M.M.; Chan, C.T.; Ho, K.M.; Soukoulis, C.M.

    1995-01-01

    We calculate the transmission and absorption of electromagnetic waves propagating in two-dimensional (2D) and 3D periodic metallic photonic band-gap (PBG) structures. For 2D systems, there is substantial difference between the s- and p-polarized waves. The p-polarized waves exhibit behavior similar to the dielectric PBG's. But, the s-polarized waves have a cutoff frequency below which there are no propagating modes. For 3D systems, the results are qualitatively the same for both polarizations but there are important differences related to the topology of the structure. For 3D structures with isolated metallic scatterers (cermet topology), the behavior is similar to that of the dielectric PBG's, while for 3D structures with the metal forming a continuous network (network topology), there is a cutoff frequency below which there are no propagating modes. The systems with the network topology may have some interesting applications for frequencies less than about 1 THz where the absorption can be neglected. We also study the role of the defects in the metallic structures

  4. Bandgap calculations and trends of organometal halide perovskites

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; García Lastra, Juan Maria; Thygesen, Kristian Sommer

    2014-01-01

    of Cs, CH3NH3, and HC(NH2)2 as A-cation, Sn and Pb as B-ion, and a combination of Cl, Br, and I as anions. The calculated gaps span over a region from 0.5 to 5.0 eV. In addition, the trends over bandgaps have been investigated: the bandgap increases with an increase of the electronegativities...

  5. Airclad fiber laser technology

    DEFF Research Database (Denmark)

    Hansen, Kim P.; Olausson, Christina Bjarnal Thulin; Broeng, Jes

    2011-01-01

    High-power fiber lasers and amplifiers have gained tremendous momentum in the last 5 years. Many of the traditional manufacturers of gas and solid-state lasers are now pursuing the fiber-based systems, which are displacing the conventional technology in many areas. High-power fiber laser systems ...... monolithic 350 W cw fiber laser system with an M2 of less than 1.1. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).......High-power fiber lasers and amplifiers have gained tremendous momentum in the last 5 years. Many of the traditional manufacturers of gas and solid-state lasers are now pursuing the fiber-based systems, which are displacing the conventional technology in many areas. High-power fiber laser systems...... require reliable fibers with large cores, stable mode quality, and good power handling capabilities-requirements that are all met by the airclad fiber technology. In the present paper we go through many of the building blocks needed to build high-power systems and we show an example of a complete airclad...

  6. FDML swept source at 1060 nm using a tapered amplifier

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang

    2010-01-01

    We present a novel frequency-swept light source working at 1060nm that utilizes a tapered amplifier as gain medium. These devices feature significantly higher saturation power than conventional semiconductor optical amplifiers and can thus improve the limited output power of swept sources...... in this wavelength range. We demonstrate that a tapered amplifier can be integrated into a fiber-based swept source and allows for high-speed FDML operation. The developed light source operates at a sweep rate of 116kHz with an effective average output power in excess of 30mW. With a total sweep range of 70 nm...

  7. Fast pulse amplifier

    International Nuclear Information System (INIS)

    Lepetit, J.; Poussier, E.

    1984-01-01

    This amplifier comprises an inverter transformer, the primary circuit of which receives a pulse and the secondary circuit of which is connected to several amplifying elements in parallel. The inverter transformer is made of coaxial cable segments winded around a magnetic torus; the cable cores connected in series constitute the primary circuit and the braiding of cables, connected in parallel, are the secondary circuit. The transformer comprises, besides, delay lines in series with each braiding of the secondary circuit, these ones are such that pulses issued from each braiding arrive together to the secondary circuit connectors. This invention applies, noticeably in the case of a high voltage amplifier, to the control of deflection blocks of particles used in medicine or in particle accelerators [fr

  8. A micropower electrocardiogram amplifier.

    Science.gov (United States)

    Fay, L; Misra, V; Sarpeshkar, R

    2009-10-01

    We introduce an electrocardiogram (EKG) preamplifier with a power consumption of 2.8 muW, 8.1 muVrms input-referred noise, and a common-mode rejection ratio of 90 dB. Compared to previously reported work, this amplifier represents a significant reduction in power with little compromise in signal quality. The improvement in performance may be attributed to many optimizations throughout the design including the use of subthreshold transistor operation to improve noise efficiency, gain-setting capacitors versus resistors, half-rail operation wherever possible, optimal power allocations among amplifier blocks, and the sizing of devices to improve matching and reduce noise. We envision that the micropower amplifier can be used as part of a wireless EKG monitoring system powered by rectified radio-frequency energy or other forms of energy harvesting like body vibration and body heat.

  9. Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten

    2012-01-01

    Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation.......Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

  10. Local resonance bandgaps in periodic media: theory and experiment.

    Science.gov (United States)

    Raghavan, L; Phani, A Srikantha

    2013-09-01

    Periodic composites such as acoustic metamaterials use local resonance phenomenon in designing low frequency sub-Bragg bandgaps. These bandgaps emerge from a resonant scattering interaction between a propagating wave and periodically arranged resonators. This paper develops a receptance coupling technique to combine the dynamics of the resonator with the unit cell dynamics of the background medium to analyze flexural wave transmission in a periodic structure, involving a single degree of freedom coupling between the medium and the resonator. Receptance techniques allow for a straightforward extension to higher dimensional systems with multiple degrees of freedom coupling and for easier experimental measurements. Closed-form expressions for the location and width of sub-Bragg bandgaps are obtained. Rigid body modes of the unit cell of the background medium are shown to set the bounding frequencies for local resonance bandgaps. Results from the receptance analysis compare well with Bloch wave analysis and experiments performed on a finite structural beam with periodic masses and resonators. Stronger coupling and inertia of the resonator increase the local resonance bandgap width. Two-fold periodicity widens the Bragg bandgap, narrowed by local resonators, thus expanding the design space and highlighting the advantages of hierarchical periodicity.

  11. Birefringent all-solid hybrid microstructured fiber.

    Science.gov (United States)

    Goto, Ryuichiro; Jackson, Stuart D; Fleming, Simon; Kuhlmey, Boris T; Eggleton, Benjamin J; Himeno, Kuniharu

    2008-11-10

    We report the characterization of a birefringent all-solid hybrid microstructured fiber, in which the core-modes are guided by both the photonic bandgap (PBG) effect and total internal reflection (TIR). Due to the twofold symmetry, modal birefringence of 1.5 x 10(-4) and group birefringence of 2.1 x 10(-4) were measured at 1.31 microm, which is in the middle of the second bandgap. The band structure was calculated to be different from conventional 2-D PBG fibers due to the 1-D arrangement of high-index regions. The bend loss has a strong directional dependence due to the coexistence of the two guiding mechanisms. The fiber has two important properties pertinent to PBG fibers; spectral filtering, and chromatic dispersion specific to PBG fibers. The number of high-index regions, which trap pump power (by index guiding) when the fiber is used in cladding-pumped fiber lasers, is greatly reduced so that this fiber should enable efficient cladding pumping. This structure is suitable for linearly-polarized, cladding-pumped fiber lasers utilizing the properties of PBG fibers.

  12. On the Suppression Band and Bandgap of Planar Electromagnetic Bandgap Structures

    Directory of Open Access Journals (Sweden)

    Baharak Mohajer-Iravani

    2014-01-01

    Full Text Available Electromagnetic bandgap structures are considered a viable solution for the problem of switching noise in printed circuit boards and packages. Less attention, however, has been given to whether or not the introduction of EBGs affects the EMI potential of the circuit to couple unwanted energy to neighboring layers or interconnects. In this paper, we show that the bandgap of EBG structures, as generated using the Brillouin diagram, does not necessarily correspond to the suppression bandwidth typically generated using S-parameters. We show that the reactive near fields radiating from openings within the EBG layers can be substantial and are present in the entire frequency band including propagating and nonpropagating mode regions. These fields decay fast with distance; however, they can couple significant energy to adjacent layers and to signal lines. The findings are validated using full-wave three-dimensional numerical simulation. Based on this work, design guidelines for EBG structures can be drawn to insure not only suppression of switching noise but also minimization of EMI and insuring signal integrity.

  13. Wide Bandgap Semiconductor Opportunities in Power Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sujit [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Marlino, Laura D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Armstrong, Kristina O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2018-01-01

    The report objective is to explore the Wide Bandgap (WBG) Power Electronics (PE) market, applications, and potential energy savings in order to identify key areas where further resources and investments of the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (DOE EERE) would have the most impact on U.S. competiveness. After considering the current market, several potential near-term application areas were identified as having significant market and energy savings potential with respect to clean energy applications: (1) data centers (uninterruptible power supplies and server power supplies); (2) renewable energy generation (photovoltaic-solar and wind); (3) motor drives (industrial, commercial and residential); (4) rail traction; and, (5) hybrid and electric vehicles (traction and charging). After the initial explorative analyses, it became clear that, SiC, not GaN, would be the principal WBG power device material for the chosen markets in the near future. Therefore, while GaN is discussed when appropriate, this report focuses on SiC devices, other WBG applications (e.g., solid-state transformers, combined heat and power, medical, and wireless power), the GaN market, and GaN specific applications (e.g., LiDAR, 5G) will be explored at a later date. In addition to the market, supply and value chain analyses addressed in Section 1 of this report, a SWOT (Strength, Weakness, Opportunity, Threat) analysis and potential energy savings analysis was conducted for each application area to identify the major potential WBG application area(s) with a U.S. competitiveness opportunity in the future.

  14. Densely Aligned Graphene Nanoribbon Arrays and Bandgap Engineering

    Energy Technology Data Exchange (ETDEWEB)

    Su, Justin [Stanford Univ., CA (United States); Chen, Changxin [Stanford Univ., CA (United States); Gong, Ming [Stanford Univ., CA (United States); Kenney, Michael [Stanford Univ., CA (United States)

    2017-01-04

    Graphene has attracted great interest for future electronics due to its high mobility and high thermal conductivity. However, a two-dimensional graphene sheet behaves like a metal, lacking a bandgap needed for the key devices components such as field effect transistors (FETs) in digital electronics. It has been shown that, partly due to quantum confinement, graphene nanoribbons (GNRs) with ~2 nm width can open up sufficient bandgaps and evolve into semiconductors to exhibit high on/off ratios useful for FETs. However, a challenging problem has been that, such ultra-narrow GNRs (~2 nm) are difficult to fabricate, especially for GNRs with smooth edges throughout the ribbon length. Despite high on/off ratios, these GNRs show very low mobility and low on-state conductance due to dominant scattering effects by imperfections and disorders at the edges. Wider GNRs (>5 nm) show higher mobility, higher conductance but smaller bandgaps and low on/off ratios undesirable for FET applications. It is highly desirable to open up bandgaps in graphene or increase the bandgaps in wide GNRs to afford graphene based semiconductors for high performance (high on-state current and high on/off ratio) electronics. Large scale ordering and dense packing of such GNRs in parallel are also needed for device integration but have also been challenging thus far. It has been shown theoretically that uniaxial strains can be applied to a GNR to engineer its bandgap. The underlying physics is that under uniaxial strain, the Dirac point moves due to stretched C-C bonds, leading to an increase in the bandgap of armchair GNRs by up to 50% of its original bandgap (i.e. bandgap at zero strain). For zigzag GNRs, due to the existence of the edge states, changes of bandgap are smaller under uniaxial strain and can be increased by ~30%. This work proposes a novel approach to the fabrication of densely aligned graphene nanoribbons with highly smooth edges afforded by anisotropic etching and uniaxial strain for

  15. Phosphorene nanoribbons: Passivation effect on bandgap and effective mass

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Li-Chun, E-mail: xulichun@tyut.edu.cn; Song, Xian-Jiang; Yang, Zhi; Cao, Ling; Liu, Rui-Ping; Li, Xiu-Yan

    2015-01-01

    Highlights: • Hydrogenation and fluorination can passivate the metallic edge states of zPNRs. • The bandgap of each type of zPNRs decreases as the ribbon's width increases duo to the quantum confinement effect. • Two local configurations of passivated atoms can coexist in nanoribbons and affect the bandgap of narrow nanoribbons. • New passivation configuration can effectively reduce the effective mass of electrons. - Abstract: The edge passivation effect of phosphorene nanoribbons is systematically investigated using density functional theory. Hydrogen and fluorine atoms passivate the metallic edge states of nanoribbons and can open a bandgap up to 2.25 eV. The two configurations of passivated atoms can exist at two edges and affect the bandgap of narrow nanoribbons. The bandgap of each type of zPNRs decreases as the ribbon's width increases, which can be attributed to the quantum confinement effect. The new configuration, named C{sub b}, can effectively reduce the effective mass of electrons, which benefits the future design of phosphorene-based electronic devices.

  16. RAMAN amplifier gain dynamics with ASE : Numerical analysis and ...

    African Journals Online (AJOL)

    DR OKE

    Raman fiber amplifier (RFA) has merit of arbitrary gain bandwidth, which were recently being recognized as an enabling ... has several advantages including lower noise figure (NF), flexibility on the selection of gain medium, and wide gain bandwidth ..... The Signal Gain (Gs) characteristic for varying Pump Power (Pp).

  17. Bandgap engineering of coal-derived graphene quantum dots.

    Science.gov (United States)

    Ye, Ruquan; Peng, Zhiwei; Metzger, Andrew; Lin, Jian; Mann, Jason A; Huang, Kewei; Xiang, Changsheng; Fan, Xiujun; Samuel, Errol L G; Alemany, Lawrence B; Martí, Angel A; Tour, James M

    2015-04-01

    Bandgaps of photoluminescent graphene quantum dots (GQDs) synthesized from anthracite have been engineered by controlling the size of GQDs in two ways: either chemical oxidative treatment and separation by cross-flow ultrafiltration, or by a facile one-step chemical synthesis using successively higher temperatures to render smaller GQDs. Using these methods, GQDs were synthesized with tailored sizes and bandgaps. The GQDs emit light from blue-green (2.9 eV) to orange-red (2.05 eV), depending on size, functionalities and defects. These findings provide a deeper insight into the nature of coal-derived GQDs and demonstrate a scalable method for production of GQDs with the desired bandgaps.

  18. Optimum design of band-gap beam structures

    DEFF Research Database (Denmark)

    Olhoff, Niels; Niu, Bin; Cheng, Gengdong

    2012-01-01

    in the present paper that such an a priori assumption is not necessary since, in general, just the maximization of the gap between two consecutive natural frequencies leads to significant design periodicity. The aim of this paper is to maximize frequency gaps by shape optimization of transversely vibrating......The design of band-gap structures receives increasing attention for many applications in mitigation of undesirable vibration and noise emission levels. A band-gap structure usually consists of a periodic distribution of elastic materials or segments, where the propagation of waves is impeded...... or significantly suppressed for a range of external excitation frequencies. Maximization of the band-gap is therefore an obvious objective for optimum design. This problem is sometimes formulated by optimizing a parameterized design model which assumes multiple periodicity in the design. However, it is shown...

  19. Bandgap Opening in Graphene Induced by Patterned Hydrogen Adsorption

    DEFF Research Database (Denmark)

    Balog, Richard; Jørgensen, Bjarke; Nilsson, Louis

    2010-01-01

    Graphene, a single layer of graphite, has recently attracted considerable attention owing to its remarkable electronic and structural properties and its possible applications in many emerging areas such as graphene-based electronic devices. The charge carriers in graphene behave like massless Dirac...... fermions, and graphene shows ballistic charge transport, turning it into an ideal material for circuit fabrication. However, graphene lacks a bandgap around the Fermi level, which is the defining concept for semiconductor materials and essential for controlling the conductivity by electronic means. Theory...... predicts that a tunable bandgap may be engineered by periodic modulations of the graphene lattice, but experimental evidence for this is so far lacking. Here, we demonstrate the existence of a bandgap opening in graphene, induced by the patterned adsorption of atomic hydrogen onto the Moiré superlattice...

  20. Extinction Ratio and Gain Optimization of Dual- Pump Degenerate-Idler Phase Sensitive Amplifiers

    DEFF Research Database (Denmark)

    Kang, Ning; Lund-Hansen, Toke; Seoane, Jorge

    2011-01-01

    Numerical optimization of dual-pump degenerateidler phase sensitive amplifiers is performed for Al-doped and standard highly nonlinear fibers. Design considerations for operating the PSAs at an optimum combination of gain and extinction ratio are discussed.......Numerical optimization of dual-pump degenerateidler phase sensitive amplifiers is performed for Al-doped and standard highly nonlinear fibers. Design considerations for operating the PSAs at an optimum combination of gain and extinction ratio are discussed....

  1. Frequency selective bistable switching in metamaterial based photonic bandgap medium

    Science.gov (United States)

    Jose, Jolly

    2014-10-01

    We present frequency selective bistable response at the defect mode of the zero-nbar bandgap of a photonic bandgap (PBG) material made of negative and positive index media. The nonlinear (Kerr) layer acts as the defect layer in the periodic PBG material. Incorporating metamaterial based electromagnetically induced transparency (EIT) like resonance in the positive layer leads to unprecedented line narrowing of the defect mode which in turn facilitates narrow frequency selective bistable operation, wherein all the bistable characteristics can be effectively engineered. Thresholding the output intensity selects the narrow band of frequencies that exhibit bistability.

  2. Experimental Methods for Implementing Graphene Contacts to Finite Bandgap Semiconductors

    DEFF Research Database (Denmark)

    Meyer-Holdt, Jakob

    Present Ph.D. thesis describes my work on implanting graphene as electrical contact to finite bandgap semiconductors. Different transistor architectures, types of graphene and finite bandgap semiconductors have been employed. The device planned from the beginning of my Ph.D. fellowship...... contacts to semiconductor nanowires, more specifically, epitaxially grown InAs nanowires. First, we tried a top down method where CVD graphene was deposited on substrate supported InAs nanowires followed by selective graphene ashing to define graphene electrodes. While electrical contact between...

  3. Photonic Bandgaps in Mie Scattering by Concentrically Stratified Spheres

    Science.gov (United States)

    Smith, David D.; Fuller, Kirk A.; Curreri, Peter A.

    2002-01-01

    The Mie formulation for homogeneous spheres is generalized to handle core/shell systems and multiple concentric layers in a manner that exploits an analogy with stratified planar systems, thereby allowing concentric multi-layered structures to be treated as photonic bandgap materials. Representative results from a Mie code employing this analogy demonstrate that photonic bands are present for periodic concentric spheres, though not readily apparent in extinction spectra. Rather, the periodicity simply alters the scattering profile, enhancing the ratio of backscattering to forward scattering inside the bandgap, whereas modification of the interference structure is evident in extinction spectra in accordance with the optical theorem

  4. Electronic amplifiers for automatic compensators

    CERN Document Server

    Polonnikov, D Ye

    1965-01-01

    Electronic Amplifiers for Automatic Compensators presents the design and operation of electronic amplifiers for use in automatic control and measuring systems. This book is composed of eight chapters that consider the problems of constructing input and output circuits of amplifiers, suppression of interference and ensuring high sensitivity.This work begins with a survey of the operating principles of electronic amplifiers in automatic compensator systems. The succeeding chapters deal with circuit selection and the calculation and determination of the principal characteristics of amplifiers, as

  5. Simplified design of IC amplifiers

    CERN Document Server

    Lenk, John

    1996-01-01

    Simplified Design of IC Amplifiers has something for everyone involved in electronics. No matter what skill level, this book shows how to design and experiment with IC amplifiers. For experimenters, students, and serious hobbyists, this book provides sufficient information to design and build IC amplifier circuits from 'scratch'. For working engineers who design amplifier circuits or select IC amplifiers, the book provides a variety of circuit configurations to make designing easier.Provides basics for all phases of practical design.Covers the most popular forms for amplif

  6. A curvature calibrated bandgap reference with base—emitter current compensating in a 0.13 μm CMOS process

    Science.gov (United States)

    Zhuo, Ma; Xiaoqiang, Tan; Lunguo, Xie; Yang, Guo

    2010-11-01

    In bandgap references, the effect caused by the input offset of the operational amplifier can be effectively reduced by the utilization of cascade bipolar junction transistors (BJTs). But in modern CMOS logic processes, due to the small value of β, the base—emitter path of BJTs has a significant streaming effect on the collector current, which leads to a large temperature drift for the reference voltage. To solve this problem, a base—emitter current compensating technique is proposed in a cascade BJT bandgap reference structure to calibrate the curvature of the output voltage to temperature. Experimental results based on the 0.13 μm logic CMOS process show that the reference voltage is 1.238 V and the temperature coefficient is 6.2 ppm/°C within the range of -40 to 125 °C.

  7. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  8. Wideband amplifier design

    CERN Document Server

    Hollister, Allen L

    2007-01-01

    In this book, the theory needed to understand wideband amplifier design using the simplest models possible will be developed. This theory will be used to develop algebraic equations that describe particular circuits used in high frequency design so that the reader develops a ""gut level"" understanding of the process and circuit. SPICE and Genesys simulations will be performed to show the accuracy of the algebraic models. By looking at differences between the algebraic equations and the simulations, new algebraic models will be developed that include parameters originally left out of the model

  9. Superconducting digital logic amplifier

    International Nuclear Information System (INIS)

    Przybysz, J.X.

    1989-01-01

    This paper describes a superconducting digital logic amplifier for interfacing between a Josephson junction logic circuit having output current and a higher voltage semiconductor circuit input. The amplifier comprising: an input terminal for connection to a; an output terminal for connection to a semiconductor circuit input; an input, lower critical current, Josephson junction having first and second terminals; a first series string of at least three lower critical current Josephson junctions. The first series string being connected to the first terminal of the input Josephson junction such that the first series string is in series with the input Josephson junction to provide a series combination. The input terminal being connected to the first terminal of the input Josephson junction, and with the critical current of the lower critical current Josephson junctions of the input Josephson junction and the first series Josephson junctions being less than the output current of the low voltage Josephson junction circuit; a second series string of at least four higher critical current Josephson junctions. The second string being connected in parallel with the series combination to provide parallel strings having an upper common connection and a lower common connection. The lower common connection being connected to the second terminal of the input Josephson junction and the upper common connection being connected to the output terminal; and a pulsed DC current source connected the parallel strings at the upper common connection. The DC current source having a current at least equal to the critical current of the higher critical current Josephson junctions

  10. The Wide Band-Gap Semiconductors: A Brief Survey | Ottaviani ...

    African Journals Online (AJOL)

    The wide band-gap semiconductors are promising materials in the fields of power electronics, high-energy radiation detection and optoelectronics. They have attracted much attention thanks to their physical properties, allowing them to get better performances than silicon for some specific uses (high temperature, high ...

  11. Advances in wide bandgap SiC for optoelectronics

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Argyraki, Aikaterini

    2014-01-01

    Silicon carbide (SiC) has played a key role in power electronics thanks to its unique physical properties like wide bandgap, high breakdown field, etc. During the past decade, SiC is also becoming more and more active in optoelectronics thanks to the progress in materials growth and nanofabrication...

  12. Tailoring the bandgap and magnetic properties by bismuth ...

    Indian Academy of Sciences (India)

    2017-11-30

    Nov 30, 2017 ... the structural distortions through Cr–O polyhedral, which are evident from Raman scattering studies. The observed structural and magnetic ... Raman spectroscopy; magnetic properties; optical bandgap. 1. Introduction. Orthochromites, RCrO3 ... and their complex magnetic interactions. These compounds.

  13. Two-dimensional microwave band-gap structures of different ...

    Indian Academy of Sciences (India)

    Abstract. We report the use of low dielectric constant materials to form two- dimensional microwave band-gap structures for achieving high gap-to-midgap ratio. The variable parameters chosen are the lattice spacing and the geometric structure. The se- lected geometries are square and triangular and the materials chosen ...

  14. Automating Energy Bandgap Measurements in Semiconductors Using LabVIEW

    Science.gov (United States)

    Garg, Amit; Sharma, Reena; Dhingra, Vishal

    2010-01-01

    In this paper, we report the development of an automated system for energy bandgap and resistivity measurement of a semiconductor sample using Four-Probe method for use in the undergraduate laboratory of Physics and Electronics students. The automated data acquisition and analysis system has been developed using National Instruments USB-6008 DAQ…

  15. CMOS bandgap references and temperature sensors and their applications

    NARCIS (Netherlands)

    Wang, G.

    2005-01-01

    Two main parts have been presented in this thesis: device characterization and circuit. In integrated bandgap references and temperature sensors, the IC(VBE, characteristics of bipolar transistors are used to generate the basic signals with high accuracy. To investigate the possibilities to

  16. Design for maximum band-gaps in beam structures

    DEFF Research Database (Denmark)

    Olhoff, Niels; Niu, Bin; Cheng, Gengdong

    2012-01-01

    This paper aims to extend earlier optimum design results for transversely vibrating Bernoulli-Euler beams by determining new optimum band-gap beam structures for (i) different combinations of classical boundary conditions, (ii) much larger values of the orders n and n-1 of adjacent upper and lowe...

  17. Photon recycling in the graded bandgap solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Rafat, N.H. [Cairo Univ., Dept. of Mathematics and Engineering Physics, Giza (Egypt); Haleem, A.M. Abdel [Cairo Univ., Dept. of Mathematics and Engineering Physics, EIFayoum (Egypt); Habib, S.E.D. [Cairo Univ., Electronics and Communication Dept., Giza (Egypt)

    2006-07-01

    We derived a general integral expression for the carrier radiative recombination rate in solar cells. The photon Boltzmann equation is solved taking into account the photon recycling effect inside the cell and assuming arbitrary spatial variation of the absorption coefficient. This expression can thus be used for graded bandgap solar cells. (Author)

  18. Modeling FWM and impairments aware amplifiers placement technique for an optical MAN/WAN: Inline amplifiers case

    Science.gov (United States)

    Singh, Gurpreet; Singh, Maninder Lal

    2015-08-01

    A new four wave mixing (FWM) model for an optical network with amplifiers and a comparative analysis among three proposed amplifiers placement techniques have been presented in this paper. The FWM model is validated with the experimental measured data. The novelty of this model is its uniqueness that on direct substitutions of network parameters like length, it works even for unequal inter amplifier separations. The novelty of the analysis done among three schemes is that it presents fair choice of amplifiers placement methods for varied total system length. The appropriateness of these three schemes has been analyzed on the basis of critical system length, critical number of amplifiers and critical bit error rate (10-9) in presence of four wave mixing (FWM) and amplified spontaneous emission noise (ASE). The implementation of analysis done has been given with the help of an example of a regenerative metropolitan area network (MAN). The results suggest that the decreasing fiber section scheme should be avoided for placements of amplifiers and schemes IUFS and EFS shows their importance interchangeably for different set of parameters.

  19. Optimization of Beam Properties with Respect to Maximum Band-Gap

    DEFF Research Database (Denmark)

    Halkjær, Søren; Sigmund, Ole

    2004-01-01

    We study numerically the frequency band-gap phenomenon for bending waves in an infinite periodic beam. The outcome of the analysis is then subjected to an optimization problem in order to maximize these band-gaps. The band-gap maximization may be performed with respect to material parameters and ...

  20. Combined Yb/Nd driver for optical parametric chirped pulse amplifiers.

    Science.gov (United States)

    Michailovas, Kirilas; Baltuska, Andrius; Pugzlys, Audrius; Smilgevicius, Valerijus; Michailovas, Andrejus; Zaukevicius, Audrius; Danilevicius, Rokas; Frankinas, Saulius; Rusteika, Nerijus

    2016-09-19

    We report on the developed front-end/pump system for optical parametric chirped pulse amplifiers. The system is based on a dual output fiber oscillator/power amplifier which seeds and assures all-optical synchronization of femtosecond Yb and picosecond Nd laser amplifiers operating at a central wavelength of 1030 nm and 1064 nm, respectively. At the central wavelength of 1030 nm, the fiber oscillator generates partially stretched 4 ps pulses with the spectrum supporting a scaling currently is prevented by limited dimensions of the diffraction gratings, which, because of the fast progress in MLD grating manufacturing technologies is only a temporary obstacle.

  1. On the Theory of the Modulation Instability in Optical Fibre Amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Turitsyn, S K; Rubenchik, A M; Fedoruk, M P

    2010-05-10

    The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW radiation break-up and growth of multiple pulses. This can be both a detrimental effect limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model and the range of applicability of the later is determined.

  2. Fiber-Optic Optical-Microwave Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Used to conduct programs of basic science and applied research in the development of laser sources, high-power fiber amplifiers, photonic control of phased...

  3. Optimal design of tunable phononic bandgap plates under equibiaxial stretch

    International Nuclear Information System (INIS)

    Hedayatrasa, Saeid; Abhary, Kazem; Uddin, M S; Guest, James K

    2016-01-01

    Design and application of phononic crystal (PhCr) acoustic metamaterials has been a topic with tremendous growth of interest in the last decade due to their promising capabilities to manipulate acoustic and elastodynamic waves. Phononic controllability of waves through a particular PhCr is limited only to the spectrums located within its fixed bandgap frequency. Hence the ability to tune a PhCr is desired to add functionality over its variable bandgap frequency or for switchability. Deformation induced bandgap tunability of elastomeric PhCr solids and plates with prescribed topology have been studied by other researchers. Principally the internal stress state and distorted geometry of a deformed phononic crystal plate (PhP) changes its effective stiffness and leads to deformation induced tunability of resultant modal band structure. Thus the microstructural topology of a PhP can be altered so that specific tunability features are met through prescribed deformation. In the present study novel tunable PhPs of this kind with optimized bandgap efficiency-tunability of guided waves are computationally explored and evaluated. Low loss transmission of guided waves throughout thin walled structures makes them ideal for fabrication of low loss ultrasound devices and structural health monitoring purposes. Various tunability targets are defined to enhance or degrade complete bandgaps of plate waves through macroscopic tensile deformation. Elastomeric hyperelastic material is considered which enables recoverable micromechanical deformation under tuning finite stretch. Phononic tunability through stable deformation of phononic lattice is specifically required and so any topology showing buckling instability under assumed deformation is disregarded. Nondominated sorting genetic algorithm (GA) NSGA-II is adopted for evolutionary multiobjective topology optimization of hypothesized tunable PhP with square symmetric unit-cell and relevant topologies are analyzed through finite

  4. Optical amplifier exhibiting net phase-mismatch selected to at least partially reduce gain-induced phase-matching during operation and method of operation

    Science.gov (United States)

    Feve, Jean-Philippe [Cupertino, CA; Kliner, Dahv A. V. [San Ramon, CA; Farrow,; Roger, L [Pleasanton, CA

    2011-02-01

    An optical amplifier, such as an optical waveguide amplifier (e.g., an optical fiber amplifier or a planar waveguide) or a non-guiding optical amplifier, that exhibits a net phase-mismatch selected to at least partially reduce gain-induced phase-matching during operation thereof is disclosed. In one aspect of the invention, an optical amplifier structure includes at least one optical amplifier having a length and a gain region. The at least one optical amplifier exhibits a net phase-mismatch that varies along at least part of the length thereof selected to at least partially reduce gain-induced phase-matching during operation thereof.

  5. High energy nanosecond laser pulses delivered single-mode through hollow-core PBG fibers.

    Science.gov (United States)

    Shephard, Jonathan; Jones, J; Hand, D; Bouwmans, G; Knight, J; Russell, P; Mangan, B

    2004-02-23

    We report on the development of hollow-core photonic bandgap fibers for the delivery of high energy pulses for precision micromachining applications. Short pulses of (65ns pulse width) and energies of the order of 0.37mJ have been delivered in a single spatial mode through hollow-core photonic bandgap fibers at 1064nm using a high repetition rate (15kHz) Nd:YAG laser. The ultimate laser-induced damage threshold and practical limitations of current hollow-core fibers for the delivery of short optical pulses are discussed.

  6. Metatronic transistor amplifier

    Science.gov (United States)

    Chettiar, Uday K.; Engheta, Nader

    2015-10-01

    Utilizing the notion of metamaterials, in recent years the concept of a circuit and lumped circuit elements have been extended to the optical domains, providing the paradigm of optical metatronics, i.e., metamaterial-inspired optical nanocircuitry, as a powerful tool for design and study of more complex systems at the nanoscale. In this paper we present a design for a new metatronic element, namely, a metatronic transistor that functions as an amplifier. As shown by our analytical and numerical paper here, this metatronic transistor provides gain as well as isolation between the input and output ports of such two-port device. The cascadability and fan-out aspects of this element are also explored.

  7. Quantum Dot Semiconductor Optical Amplifiers - Physics and Applications

    DEFF Research Database (Denmark)

    Berg, Tommy Winther

    2004-01-01

    respects is comparable to those of fiber amplifiers. The possibility of inverting the optically active states to a large degree is essential in order to achieve this performance. Optical signal processing through cross gain modulation and four wave mixing is modeled and described. For both approaches...... quantum dot amplifiers are found to be able to operate with high efficiency and at high bitrates. Strong spectral hole-burning arising from a relatively slow carrier capture time, is shown to play a dominant role is this context. The results obtained numerically are compared to the properties of bulk...

  8. Modeling of semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Mørk, Jesper; Bischoff, Svend; Berg, Tommy Winther

    We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed.......We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed....

  9. The bandgap controlling by geometrical symmetry design in hybrid phononic crystal

    Science.gov (United States)

    Zhang, Z.; Han, X. K.; Ji, G. M.

    2018-02-01

    The effects of symmetries on the bandgap in a newly designed hybrid phononic crystal plate composed of rubber slab and epoxy resin stub are studied for better controlling of bandgaps. The point group symmetry is changed by changing the orientation of the stub. The translation group symmetry is changed by changing the side length and the height of adjacent stubs. Results show that the point group symmetry and translation group symmetry can be important factors for controlling of the bandgaps of phononic crystal. Wider bandgap is obtained by suitable orientation of the stub. Lower bandgap appears when the differences between the adjacent stubs become bigger in supercell.

  10. Ultrasensitive tunability of the direct bandgap of 2D InSe flakes via strain engineering

    Science.gov (United States)

    Li, Yang; Wang, Tianmeng; Wu, Meng; Cao, Ting; Chen, Yanwen; Sankar, Raman; Ulaganathan, Rajesh K.; Chou, Fangcheng; Wetzel, Christian; Xu, Cheng-Yan; Louie, Steven G.; Shi, Su-Fei

    2018-04-01

    InSe, a member of the layered materials family, is a superior electronic and optical material which retains a direct bandgap feature from the bulk to atomically thin few-layers and high electronic mobility down to a single layer limit. We, for the first time, exploit strain to drastically modify the bandgap of two-dimensional (2D) InSe nanoflakes. We demonstrated that we could decrease the bandgap of a few-layer InSe flake by 160 meV through applying an in-plane uniaxial tensile strain to 1.06% and increase the bandgap by 79 meV through applying an in-plane uniaxial compressive strain to 0.62%, as evidenced by photoluminescence (PL) spectroscopy. The large reversible bandgap change of ~239 meV arises from a large bandgap change rate (bandgap strain coefficient) of few-layer InSe in response to strain, ~154 meV/% for uniaxial tensile strain and ~140 meV/% for uniaxial compressive strain, representing the most pronounced uniaxial strain-induced bandgap strain coefficient experimentally reported in 2D materials. We developed a theoretical understanding of the strain-induced bandgap change through first-principles DFT and GW calculations. We also confirmed the bandgap change by photoconductivity measurements using excitation light with different photon energies. The highly tunable bandgap of InSe in the infrared regime should enable a wide range of applications, including electro-mechanical, piezoelectric and optoelectronic devices.

  11. CERN: Energy amplifier

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    Even under the heavy burden of responsibility as CERN's Director General from 1989-3 the fertile mind of Carlo Rubbia the scientist was never still. A long-time Rubbia 'hobby' has been the search for new sources of nuclear energy, exploiting knowledge and skills from high energy physics. An initial objective was to adopt heavy ion techniques to induce controlled thermonuclear fusion, but in 1994 this quest changed direction. Putting the problems of thermonuclear fusion aside, Rubbia began to explore an alternative route to energy production through controlled nuclear fission. The idea is to use a particle accelerator producing neutrons by spallation (interaction of particles with a target) to feed a fuel/moderator assembly where the neutrons multiply by fission chain reactions. If the energy liberated becomes substantially greater than that needed to drive the accelerator, the process has a net gain and becomes selfsupporting. Hence the name ''Energy Amplifier'' (EA). Similar systems for energy production or for nuclear waste incineration have been proposed at Los Alamos and in Japan and Russia, but appear to require the prior development of innovative linear accelerators. For Rubbia's Amplifier, the requisite accelerator is a reasonable extrapolation of an existing cyclotron such that at the Swiss Paul Scherrer Institute. Moreover, the EA would require fuel rods very similar to those of conventional reactors, rather than demand-ing new technology using liquid fuel loops (molten salts) with on-line separation of radioactive products. Unlike a reactor, the EA's fission reaction is not self-sustaining: it is sub-critical and needs a continuous supply of neutrons from the accelerator. This makes Chernobyl-type meltdowns unlikely: if the accelerator stops, the reaction stops too. Another major advantage is that the old dream of using thorium as a fuel is now made possible. Thorium is not itself fissile, but under neutron

  12. Quantum electrodynamics near a photonic band-gap

    Science.gov (United States)

    Liu, Yanbing; Houck, Andrew

    Quantum electrodynamics predicts the localization of light around an atom in photonic band-gap (PBG) medium or photonic crystal. Here we report the first experimental realization of the strong coupling between a single artificial atom and an one dimensional PBG medium using superconducting circuits. In the photonic transport measurement, we observe an anomalous Lamb shift and a large band-edge avoided crossing when the artificial atom frequency is tuned across the band-edge. The persistent peak within the band-gap indicates the single photon bound state. Furthermore, we study the resonance fluorescence of this bound state, again demonstrating the breakdown of the Born-Markov approximation near the band-edge. This novel architecture can be directly generalized to study many-body quantum electrodynamics and to construct more complicated spin chain models.

  13. Comparison of Wide-Bandgap Semiconductors for Power Electronics Applications

    Energy Technology Data Exchange (ETDEWEB)

    Ozpineci, B.

    2004-01-02

    Recent developmental advances have allowed silicon (Si) semiconductor technology to approach the theoretical limits of the Si material; however, power device requirements for many applications are at a point that the present Si-based power devices cannot handle. The requirements include higher blocking voltages, switching frequencies, efficiency, and reliability. To overcome these limitations, new semiconductor materials for power device applications are needed. For high power requirements, wide-bandgap semiconductors like silicon carbide (SiC), gallium nitride (GaN), and diamond, with their superior electrical properties, are likely candidates to replace Si in the near future. This report compares wide-bandgap semiconductors with respect to their promise and applicability for power applications and predicts the future of power device semiconductor materials.

  14. Fully differential cryogenic transistor amplifier

    Science.gov (United States)

    Beev, Nikolai; Kiviranta, Mikko

    2013-10-01

    We have constructed a dc-coupled differential amplifier capable of operating in the 4.2 K-300 K temperature range. The amplifier can be operated at high-bias setting, where it dissipates 5 mW, has noise temperature TN ≈ 0.7 K at RS ≈ 5 kΩ and >40 MHz bandwidth at 4.2 K bath temperature. The bias setting can be adjusted: at our lowest tested setting the amplifier dissipates 2 MHz bandwidth. The 1/f noise corner frequency is a few times 10 kHz. We foresee the amplifier to have an application in the readout of Superconducting Quantum Interference Devices (SQUIDs), Superconducting Tunnel Junction Detectors (STJs) and Transition Edge Sensors (TESes). We have verified the practical use of the amplifier by reading out a 4.2 K 480-SQUID array with 40 MHz bandwidth and <8 × 10-8 Φ0/Hz1/2 flux noise.

  15. Millimeter-wave power amplifiers

    CERN Document Server

    du Preez, Jaco

    2017-01-01

    This book provides a detailed review of millimeter-wave power amplifiers, discussing design issues and performance limitations commonly encountered in light of the latest research. Power amplifiers, which are able to provide high levels of output power and linearity while being easily integrated with surrounding circuitry, are a crucial component in wireless microwave systems. The book is divided into three parts, the first of which introduces readers to mm-wave wireless systems and power amplifiers. In turn, the second focuses on design principles and EDA concepts, while the third discusses future trends in power amplifier research. The book provides essential information on mm-wave power amplifier theory, as well as the implementation options and technologies involved in their effective design, equipping researchers, circuit designers and practicing engineers to design, model, analyze, test and implement high-performance, spectrally clean and energy-efficient mm-wave systems.

  16. Waveguidance by the photonic bandgap effect in optical fibres

    DEFF Research Database (Denmark)

    Broeng, Jes; Søndergaard, Thomas; Barkou, Stig Eigil

    1999-01-01

    technology for such photonic bandgap (PBG) waveguides is in optical fibre configurations. These new fibres can be classified in a fundamentally different way to all optical waveguides and possess radically different guiding properties due to PBG guidance, as opposed to guidance by total internal refelction....... In this paper we summarize and review our theoretical work demonstrating the underlying physical principles of PBG guiding optical fibres and discuss some of their unique waveguiding properties....

  17. Ultrasonic bandgaps in 3D-printed periodic ceramic microlattices

    Czech Academy of Sciences Publication Activity Database

    Kruisová, Alena; Ševčík, Martin; Seiner, Hanuš; Sedlák, Petr; Román-Manso, B.; Miranzo, P.; Belmonte, M.; Landa, Michal

    January (2018), s. 91-100 ISSN 0041-624X R&D Projects: GA ČR GA17-01618S Institutional support: RVO:61388998 Keywords : phononic crystals * ceramics * additive manufacturing * bandgaps * wave propagation * finite elements method Subject RIV: BI - Acoustics OBOR OECD: Applied mechanics Impact factor: 2.327, year: 2016 http://dx. doi . org /10.1016/j.ultras.2017.07.017

  18. Direct bandgap silicon: tensile-strained silicon nanocrystals

    Czech Academy of Sciences Publication Activity Database

    Kůsová, Kateřina; Hapala, Prokop; Valenta, J.; Jelínek, Pavel; Cibulka, Ondřej; Ondič, Lukáš; Pelant, Ivan

    2014-01-01

    Roč. 1, č. 2 (2014), "1300042-1"-"1300042-9" ISSN 2196-7350 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GPP204/12/P235; GA ČR GAP204/10/0952 Institutional support: RVO:68378271 Keywords : silicon nanocrystals * badstructure * light emission * direct bandgap * surface capping Subject RIV: BM - Solid Matter Physics ; Magnetism

  19. Bandgap control with local and interconnected LC piezoelectric shunts

    Science.gov (United States)

    Flores Parra, Edgar A.; Bergamini, Andrea; Lossouarn, Boris; Van Damme, Bart; Cenedese, Mattia; Ermanni, Paolo

    2017-09-01

    This paper reports on the control of longitudinal wave propagation, in the kHz frequency range, using local and interconnected LC (inductance-capacitance) shunts distributed periodically along a rod. The LC shunts are connected to piezoelectric inserts and tuned to engender narrow or broad-band pass-bands in the forbidden band frequency range. The Bragg-scattering bandgaps are the result of the periodic mechanical mismatch between PMMA (polymethyl-methacrylate) of the rod and PZT (lead-zirconate-titanate). The narrow pass-bands correspond to the local configuration, where an equivalence between the mechanical impedance of the PMMA and PZT occurs around the shunt resonance frequency. Conversely, the interconnected shunts give a way to an electrical medium through which energy can propagate parallel to its mechanical counterpart, leading to broad pass-bands. This paper presents analytical models for calculating the dispersion and displacements of the 1D medium with interconnected LC shunts. An analytical formulation is also introduced to expediently identify the location of bandgaps and pass-bands in the medium comprised of local LC shunts. Moreover, analytical investigations are carried out to elucidate different physical phenomena giving rise to these pass-bands. The findings are experimentally validated using a finite periodic rod. The ability to tune the dispersion properties of the medium to control the width or depth of the bandgap, by utilizing local or interconnected shunts, offers a new and powerful application for piezoelectric shunts.

  20. Recent Advances in Wide-Bandgap Photovoltaic Polymers.

    Science.gov (United States)

    Cai, Yunhao; Huo, Lijun; Sun, Yanming

    2017-06-01

    The past decade has witnessed significant advances in the field of organic solar cells (OSCs). Ongoing improvements in the power conversion efficiency of OSCs have been achieved, which were mainly attributed to the design and synthesis of novel conjugated polymers with different architectures and functional moieties. Among various conjugated polymers, the development of wide-bandgap (WBG) polymers has received less attention than that of low-bandgap and medium-bandgap polymers. Here, we briefly summarize recent advances in WBG polymers and their applications in organic photovoltaic (PV) devices, such as tandem, ternary, and non-fullerene solar cells. Addtionally, we also dissuss the application of high open-circuit voltage tandem solar cells in PV-driven electrochemical water dissociation. We mainly focus on the molecular design strategies, the structure-property correlations, and the photovoltaic performance of these WBG polymers. Finally, we extract empirical regularities and provide invigorating perspectives on the future development of WBG photovoltaic materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Structure and optical bandgap relationship of π-conjugated systems.

    Directory of Open Access Journals (Sweden)

    André Leitão Botelho

    Full Text Available In bulk heterojunction photovoltaic systems both the open-circuit voltage as well as the short-circuit current, and hence the power conversion efficiency, are dependent on the optical bandgap of the electron-donor material. While first-principles methods are computationally intensive, simpler model Hamiltonian approaches typically suffer from one or more flaws: inability to optimize the geometries for their own input; absence of general, transferable parameters; and poor performance for non-planar systems. We introduce a set of new and revised parameters for the adapted Su-Schrieffer-Heeger (aSSH Hamiltonian, which is capable of optimizing geometries, along with rules for applying them to any [Formula: see text]-conjugated system containing C, N, O, or S, including non-planar systems. The predicted optical bandgaps show excellent agreement to UV-vis spectroscopy data points from literature, with a coefficient of determination [Formula: see text], a mean error of -0.05 eV, and a mean absolute deviation of 0.16 eV. We use the model to gain insights from PEDOT, fused thiophene polymers, poly-isothianaphthene, copolymers, and pentacene as sources of design rules in the search for low bandgap materials. Using the model as an in-silico design tool, a copolymer of benzodithiophenes along with a small-molecule derivative of pentacene are proposed as optimal donor materials for organic photovoltaics.

  2. Bandgap tunability at single-layer molybdenum disulphide grain boundaries

    KAUST Repository

    Huang, Yu Li

    2015-02-17

    Two-dimensional transition metal dichalcogenides have emerged as a new class of semiconductor materials with novel electronic and optical properties of interest to future nanoelectronics technology. Single-layer molybdenum disulphide, which represents a prototype two-dimensional transition metal dichalcogenide, has an electronic bandgap that increases with decreasing layer thickness. Using high-resolution scanning tunnelling microscopy and spectroscopy, we measure the apparent quasiparticle energy gap to be 2.40±0.05 eV for single-layer, 2.10±0.05 eV for bilayer and 1.75±0.05 eV for trilayer molybdenum disulphide, which were directly grown on a graphite substrate by chemical vapour deposition method. More interestingly, we report an unexpected bandgap tunability (as large as 0.85±0.05 eV) with distance from the grain boundary in single-layer molybdenum disulphide, which also depends on the grain misorientation angle. This work opens up new possibilities for flexible electronic and optoelectronic devices with tunable bandgaps that utilize both the control of two-dimensional layer thickness and the grain boundary engineering.

  3. High-power picosecond pulse delivery through hollow core photonic band gap fibers

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Johansen, Mette Marie; Lyngsø, Jens Kristian

    2016-01-01

    setup. It provided 22ps pulses with a maximum average power of 95W, 40MHz repetition rate at 1032nm (~2.4μJ pulse energy), with M2 cells hollow core photonic bandgap fiber and showed up to 59W average power output for a 5 meters fiber. The damage...... threshold for a 19-cell hollow core photonic bandgap fiber exceeded the maximum power provided by the light source and up to 76W average output power was demonstrated for a 1m fiber. In both cases, no special attention was needed to mitigate bend sensitivity. The fibers were coiled on 8 centimeters radius...... spools and even lower bending radii were present. In addition, stimulated rotational Raman scattering arising from nitrogen molecules was measured through a 42m long 19 cell hollow core fiber. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract...

  4. Dietary Fiber

    Science.gov (United States)

    ... label as soluble fiber or insoluble fiber. Both types have important health benefits. Good sources of dietary fiber include Whole grains Nuts and seeds Fruit and vegetables Dietary fiber adds bulk to ...

  5. Small signal microwave amplifier design

    CERN Document Server

    Grosch, Theodore

    2000-01-01

    This book explains techniques and examples for designing stable amplifiers for high-frequency applications in which the signal is small and the amplifier circuit is linear. An in-depth discussion of linear network theory provides the foundation needed to develop actual designs. Examples throughout the book will show you how to apply the knowledge gained in each chapter leading to the complex design of low noise amplifiers. Many exercises at the end of each chapter will help students to practice their skills. The solutions to these design problems are available in an accompanying solutions book

  6. Fiber webs

    Science.gov (United States)

    Roger M. Rowell; James S. Han; Von L. Byrd

    2005-01-01

    Wood fibers can be used to produce a wide variety of low-density three-dimensional webs, mats, and fiber-molded products. Short wood fibers blended with long fibers can be formed into flexible fiber mats, which can be made by physical entanglement, nonwoven needling, or thermoplastic fiber melt matrix technologies. The most common types of flexible mats are carded, air...

  7. New Packaging for Amplifier Slabs

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thorsness, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Suratwala, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Steele, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rogowski, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-03-18

    The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.

  8. Operational amplifiers theory and design

    CERN Document Server

    Huijsing, Johan

    2017-01-01

    This proven textbook guides readers to a thorough understanding of the theory and design of operational amplifiers (OpAmps). The core of the book presents systematically the design of operational amplifiers, classifying them into a periodic system of nine main overall configurations, ranging from one gain stage up to four or more stages. This division enables circuit designers to recognize quickly, understand, and choose optimal configurations. Characterization of operational amplifiers is given by macro models and error matrices, together with measurement techniques for their parameters. Definitions are given for four types of operational amplifiers depending on the grounding of their input and output ports. Many famous designs are evaluated in depth, using a carefully structured approach enhanced by numerous figures. In order to reinforce the concepts introduced and facilitate self-evaluation of design skills, the author includes problems with detailed solutions, as well as simulation exercises. Provides te...

  9. TARC: Carlo Rubbia's Energy Amplifier

    CERN Multimedia

    Laurent Guiraud

    1997-01-01

    Transmutation by Adiabatic Resonance Crossing (TARC) is Carlo Rubbia's energy amplifier. This CERN experiment demonstrated that long-lived fission fragments, such as 99-TC, can be efficiently destroyed.

  10. Efficient Tm-Fiber-Pumped Ho:YLF Laser System for Coherent LIDAR Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to employ a recently developed, efficient, high-power, heavily-doped Tm:silica-fiber technology as a high-gain fiber pre-amplifier and as a...

  11. Wide bandgap engineering of (AlGa)2O3 films

    International Nuclear Information System (INIS)

    Zhang, Fabi; Saito, Katsuhiko; Tanaka, Tooru; Nishio, Mitsuhiro; Guo, Qixin; Arita, Makoto

    2014-01-01

    Bandgap tunable (AlGa) 2 O 3 films were deposited on sapphire substrates by pulsed laser deposition (PLD). The deposited films are of high transmittance as measured by spectrophotometer. The Al content in films is almost the same as that in targets. The measurement of bandgap energies by examining the onset of inelastic energy loss in core-level atomic spectra using X-ray photoelectron spectroscopy is proved to be valid for determining the bandgap of (AlGa) 2 O 3 films as it is in good agreement with the bandgap values from transmittance spectra. The measured bandgap of (AlGa) 2 O 3 films increases continuously with the Al content covering the whole Al content range from about 5 to 7 eV, indicating PLD is a promising growth technology for growing bandgap tunable (AlGa) 2 O 3 films.

  12. Monolithic Yb-fiber femtosecond laser with intracavity all-solid PBG fiber and ex-cavity HC-PCF

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

    2010-01-01

    We demonstrate an all-fiber femtosecond master oscillator / power amplifier operating at the central wavelength of 1033 nm, based on Yb-doped fiber as gain medium, and two different kinds of photonic crystal fibers for dispersion control and stabilization. An all-solid (AS) polarization maintaini...

  13. High-efficiency, monolithic, multi-bandgap, tandem photovoltaic energy converters

    Science.gov (United States)

    Wanlass, Mark W [Golden, CO

    2011-11-29

    A monolithic, multi-bandgap, tandem solar photovoltaic converter has at least one, and preferably at least two, subcells grown lattice-matched on a substrate with a bandgap in medium to high energy portions of the solar spectrum and at least one subcell grown lattice-mismatched to the substrate with a bandgap in the low energy portion of the solar spectrum, for example, about 1 eV.

  14. Efficient and Compact Optical Amplifier Using EYDF

    Directory of Open Access Journals (Sweden)

    Sulaiman Wadi Harun

    2010-09-01

    Full Text Available An efficient Erbium/Ytterbium doped fiber amplifier (EYDFA is demonstrated using a 1058nm pumping wavelength, where the amplification is assisted by energy transfer between Yb and Er ions. The energy transfer increases the limit of erbium doping concentration that is imposed by concentration quenching in Erbium-doped fiber (EDF. Therefore, the gain and noise figure are severely degraded with 1480 nm pumping, where the energy transfer cannot be achieved. The use of optical isolator improves the small signal gain and noise figure by about 4.8 dB and 1.6 dB, respectively. By employing a double-pass configuration, a higher gain can be obtained with an expense of a noise figure penalty. The gain improvement of 17.0 dB is obtained at 20 mW and -50 dBm of pump and input signal powers. This shows that the double-pass configuration is an important aspect to consider when designing an efficient EYDFA.

  15. Urbach's rule derived from thermal fluctuations in the band-gap energy

    DEFF Research Database (Denmark)

    Skettrup, Torben

    1978-01-01

    The exponential absorption edge (known as Urbach's rule) observed in most materials is interpreted in terms of thermal fluctuations in the band-gap energy. The main contribution to the temperature shift of the band-gap energy is due to the temperature-dependent self-energies of the electrons...... and holes interacting with the phonons. Since the phonon number is fluctuating in thermal equilibrium, the band-gap energy is also fluctuating resulting in an exponential absorption tail below the average band-gap energy. These simple considerations are applied to derive Urbach's rule at high temperatures...

  16. High bandgap III-V alloys for high efficiency optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark

    2017-01-10

    High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.

  17. A superhard sp3 microporous carbon with direct bandgap

    Science.gov (United States)

    Pan, Yilong; Xie, Chenlong; Xiong, Mei; Ma, Mengdong; Liu, Lingyu; Li, Zihe; Zhang, Shuangshuang; Gao, Guoying; Zhao, Zhisheng; Tian, Yongjun; Xu, Bo; He, Julong

    2017-12-01

    Carbon allotropes with distinct sp, sp2, and sp3 hybridization possess various different properties. Here, a novel all-sp3 hybridized tetragonal carbon, namely the P carbon, was predicted by the evolutionary particle swarm structural search. It demonstrated a low density among all-sp3 carbons, due to the corresponding distinctive microporous structure. P carbon is thermodynamically stable than the known C60 and could be formed through the single-walled carbon nanotubes (SWCNTs) compression. P carbon is a direct bandgap semiconductor displaying a strong and superhard nature. The unique combination of electrical and mechanical properties constitutes P carbon a potential superhard material for semiconductor industrial fields.

  18. Regioregular narrow-bandgap-conjugated polymers for plastic electronics

    Science.gov (United States)

    Ying, Lei; Huang, Fei; Bazan, Guillermo C.

    2017-03-01

    Progress in the molecular design and processing protocols of semiconducting polymers has opened significant opportunities for the fabrication of low-cost plastic electronic devices. Recent studies indicate that field-effect transistors and organic solar cells fabricated using narrow-bandgap regioregular polymers with translational symmetries in the direction of the backbone vector often outperform those containing analogous regiorandom polymers. This review addresses the cutting edge of regioregularity chemistry, in particular how to control the spatial distribution in the molecular structures and how this order translates to more ordered bulk morphologies. The effect of regioregularity on charge transport and photovoltaic properties is also outlined.

  19. Bidirectional fiber-wireless and fiber-VLLC transmission system based on an OEO-based BLS and a RSOA.

    Science.gov (United States)

    Lu, Hai-Han; Li, Chung-Yi; Lu, Ting-Chien; Wu, Chang-Jen; Chu, Chien-An; Shiva, Ajay; Mochii, Takao

    2016-02-01

    A bidirectional fiber-wireless and fiber-visible-laser-light-communication (VLLC) transmission system based on an optoelectronic oscillator (OEO)-based broadband light source (BLS) and a reflective semiconductor optical amplifier (RSOA) is proposed and experimentally demonstrated. Through an in-depth observation of such bidirectional fiber-wireless and fiber-VLLC transmission systems, good bit error rate performances are obtained over a 40 km single-mode fiber and a 10 m RF/optical wireless transport. Such a bidirectional fiber-wireless and fiber-VLLC transmission system is an attractive option for providing broadband integrated services.

  20. Spectroscopic amplifier for pin diode

    International Nuclear Information System (INIS)

    Alonso M, M. S.; Hernandez D, V. M.; Vega C, H. R.

    2014-10-01

    The photodiode remains the basic choice for the photo-detection and is widely used in optical communications, medical diagnostics and field of corpuscular radiation. In detecting radiation it has been used for monitoring radon and its progeny and inexpensive spectrometric systems. The development of a spectroscopic amplifier for Pin diode is presented which has the following characteristics: canceler Pole-Zero (P/Z) with a time constant of 8 μs; constant gain of 57, suitable for the acquisition system; 4th integrator Gaussian order to waveform change of exponential input to semi-Gaussian output and finally a stage of baseline restorer which prevents Dc signal contribution to the next stage. The operational amplifier used is the TLE2074 of BiFET technology of Texas Instruments with 10 MHz bandwidth, 25 V/μs of slew rate and a noise floor of 17 nv/(Hz)1/2. The integrated circuit has 4 operational amplifiers and in is contained the total of spectroscopic amplifier that is the goal of electronic design. The results show like the exponential input signal is converted to semi-Gaussian, modifying only the amplitude according to the specifications in the design. The total system is formed by the detector, which is the Pin diode, a sensitive preamplifier to the load, the spectroscopic amplifier that is what is presented and finally a pulse height analyzer (Mca) which is where the spectrum is shown. (Author)

  1. The research on temperature sensing properties of photonic crystal fiber based on Liquid crystal filling

    Directory of Open Access Journals (Sweden)

    Zan Xiangzhen

    2016-01-01

    Full Text Available Based on the photonic bandgap-photonic crystal fibers( PBG-PCF fiber core fills the namitic liquid crystal. By readjusting the temperature to change the refractive index, constitute new liquid fiber-optic temperature sensor. In this paper, we use finite element COMSOL software to simulate and analyze photonic crystal optical fiber sensitive properties. The research show that after the PBG – PCF filling the liquid crystal, its mode field distribution, effective refractive index, waveguide dispersion etc changing with temperature is so big. Therefore, the properties that the refractive index of PCF mode CF changing with temperature sensitive medium, provides the theoretical basis for designing optic fiber temperature sensors.

  2. Tunable Bandgap and Optical Properties of Black Phosphorene Nanotubes

    Directory of Open Access Journals (Sweden)

    Chunmei Li

    2018-02-01

    Full Text Available Black phosphorus (BP, a new two-dimensional material, has been the focus of scientists’ attention. BP nanotubes have potential in the field of optoelectronics due to their low-dimensional effects. In this work, the bending strain energy, electronic structure, and optical properties of BP nanotubes were investigated by using the first-principles method based on density functional theory. The results show that these properties are closely related to the rolling direction and radius of the BP nanotube. All the calculated BP nanotube properties show direct bandgaps, and the BP nanotubes with the same rolling direction express a monotone increasing trend in the value of bandgap with a decrease in radius, which is a stacking effect of the compression strain on the inner atoms and the tension strain on the outer atoms. The bending strain energy of the zigzag phosphorene nanotubes (zPNTs is higher than that of armchair phosphorene nanotubes (aPNT with the same radius of curvature due to the anisotropy of the BP’s structure. The imaginary part of the dielectric function, the absorption range, reflectivity, and the imaginary part of the refractive index of aPNTs have a wider range than those of zPNTs, with higher values overall. As a result, tunable BP nanotubes are suitable for optoelectronic devices, such as lasers and diodes, which function in the infrared and ultra-violet regions, and for solar cells and photocatalysis.

  3. Bandgap engineering in semiconductor alloy nanomaterials with widely tunable compositions

    Science.gov (United States)

    Ning, Cun-Zheng; Dou, Letian; Yang, Peidong

    2017-12-01

    Over the past decade, tremendous progress has been achieved in the development of nanoscale semiconductor materials with a wide range of bandgaps by alloying different individual semiconductors. These materials include traditional II-VI and III-V semiconductors and their alloys, inorganic and hybrid perovskites, and the newly emerging 2D materials. One important common feature of these materials is that their nanoscale dimensions result in a large tolerance to lattice mismatches within a monolithic structure of varying composition or between the substrate and target material, which enables us to achieve almost arbitrary control of the variation of the alloy composition. As a result, the bandgaps of these alloys can be widely tuned without the detrimental defects that are often unavoidable in bulk materials, which have a much more limited tolerance to lattice mismatches. This class of nanomaterials could have a far-reaching impact on a wide range of photonic applications, including tunable lasers, solid-state lighting, artificial photosynthesis and new solar cells.

  4. Wide bandgap collector III-V double heterojunction bipolar transistors

    International Nuclear Information System (INIS)

    Flitcroft, R.M.

    2000-10-01

    This thesis is devoted to the study and development of Heterojunction Bipolar Transistors (HBTs) designed for high voltage operation. The work concentrates on the use of wide bandgap III-V semiconductor materials as the collector material and their associated properties influencing breakdown, such as impact ionisation coefficients. The work deals with issues related to incorporating a wide bandgap collector into double heterojunction structures such as conduction band discontinuities at the base-collector junction and results are presented which detail, a number of methods designed to eliminate the effects of such discontinuities. In particular the use of AlGaAs as the base material has been successful in eliminating the conduction band spike at this interface. A method of electrically injecting electrons into the collector has been employed to investigate impact ionisation in GaAs, GaInP and AlInP which has used the intrinsic gain of the devices to extract impact ionisation coefficients over a range of electric fields beyond the scope of conventional optical injection techniques. This data has enabled the study of ''dead space'' effects in HBT collectors and have been used to develop an analytical model of impact ionisation which has been incorporated into an existing Ebers-Moll HBT simulator. This simulator has been shown to accurately reproduce current-voltage characteristics in both the devices used in this work and for external clients. (author)

  5. Low-Noise Band-Pass Amplifier

    Science.gov (United States)

    Kleinberg, L.

    1982-01-01

    Circuit uses standard components to overcome common limitation of JFET amplifiers. Low-noise band-pass amplifier employs JFET and operational amplifier. High gain and band-pass characteristics are achieved with suitable choice of resistances and capacitances. Circuit should find use as low-noise amplifier, for example as first stage instrumentation systems.

  6. Natural fibers

    Science.gov (United States)

    Craig M. Clemons; Daniel F. Caulfield

    2005-01-01

    The term “natural fibers” covers a broad range of vegetable, animal, and mineral fibers. However, in the composites industry, it usually refers to wood fiber and agrobased bast, leaf, seed, and stem fibers. These fibers often contribute greatly to the structural performance of the plant and, when used in plastic composites, can provide significant reinforcement. Below...

  7. Wideband generation of pulses in dual-pump optical parametric amplifier: theory and experiment.

    Science.gov (United States)

    Shoaie, Mohammad Amin; Mohajerin-Ariaei, Amirhossein; Vedadi, Armand; Brès, Camille-Sophie

    2014-02-24

    The generation of pulses in dual-pump fiber optical parametric amplifier is investigated. Theoretically, it is shown that in an analogical manner to pulse generation in single-pump fiber optical parametric amplifiers, the generated pulse shape depends on the linear phase mismatch between the interacting waves. However the dual-pump architecture allows for the bounding of the phase mismatch over a wide bandwidth. This feature permits the generation of uniform pulses over a wide bandwidth, contrary to the single-pump architecture. Using the developed theory, a pulse source with uniform pulses at 5 GHz repetition rate and duty cycle of 0.265 over 40 nm is demonstrated.

  8. Capacitively-coupled chopper amplifiers

    CERN Document Server

    Fan, Qinwen; Huijsing, Johan H

    2017-01-01

    This book describes the concept and design of the capacitively-coupled chopper technique, which can be used in precision analog amplifiers. Readers will learn to design power-efficient amplifiers employing this technique, which can be powered by regular low supply voltage such as 2V and possibly having a +\\-100V input common-mode voltage input. The authors provide both basic design concepts and detailed design examples, which cover the area of both operational and instrumentation amplifiers for multiple applications, particularly in power management and biomedical circuit designs. Discusses basic working principles and details of implementation for proven designs; Includes a diverse set of applications, along with measurement results to demonstrate the effectiveness of the technique; Explains advantages and drawbacks of the technique, given particular circumstances.

  9. Assessment of commercial optical amplifiers for potential use in space applications

    Science.gov (United States)

    Barbero, Juan; Sotom, Michel; Benazet, Benoit; Esquivias, Ignacio; López Hernández, Francisco José

    2017-11-01

    This paper describes the activities and results of an ESA-funded project concerned with the assessment of optical amplifier technologies and products for applications in fiber optic subsystems of future satellite payloads. On-board applications are briefly introduced, together with associated system-level requirements. Optical amplifier technologies, research achievements and products are reviewed. They are compared in terms of current performance, perspectives and suitability for the target space applications. Optical fibre amplifiers, not limited to Erbium-doped amplifiers, Erbium-doped waveguide amplifiers and Semiconductor Optical Amplifiers are covered. The review includes analysis and trade-off of all performance parameters including saturation output power, noise figure, polarisation maintaining capability, wall-plug efficiency, and mass and size. A selection of optical amplifier products for further evaluation and testing is presented. Results of extensive testing covering both functional performance and environmental behaviour (mechanical, thermal vacuum, radiations) aspects are reported. Most of the work has been completed, but an extension has been proposed for checking and comparing the behaviour of doped fibers under gamma radiation.

  10. Investigating Bandgap Energies, Materials, and Design of Light-Emitting Diodes

    Science.gov (United States)

    Wagner, Eugene P., II

    2016-01-01

    A student laboratory experiment to investigate the intrinsic and extrinsic bandgaps, dopant materials, and diode design in light-emitting diodes (LEDs) is presented. The LED intrinsic bandgap is determined by passing a small constant current through the diode and recording the junction voltage variation with temperature. A second visible…

  11. Photorefractive Fibers

    National Research Council Canada - National Science Library

    Kuzyk, Mark G

    2003-01-01

    ... scope of the project. In addition to our work in optical limiting fibers, spillover results included making fiber-based light-sources, writing holograms in fibers, and developing the theory of the limits of the nonlinear...

  12. Investigation of complete bandgaps in a piezoelectric slab covered with periodically structured coatings.

    Science.gov (United States)

    Zou, Kui; Ma, Tian-Xue; Wang, Yue-Sheng

    2016-02-01

    The propagation of elastic waves in a piezoelectric slab covered with periodically structured coatings or the so-called stubbed phononic crystal slab is investigated. Four different models are selected and the effects of distribution forms and geometrical parameters of the structured coatings on complete bandgaps are discussed. The phononic crystal slab with symmetric coatings can generate wider complete bandgaps while that with asymmetric coatings is favorable for the generation of multi-bandgaps. The complete bandgaps, which are induced by locally resonant effects, change significantly as the geometry of the coatings changes. Moreover, the piezoelectric effects benefit the opening of the complete bandgaps. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Efficient CsF interlayer for high and low bandgap polymer solar cell

    Science.gov (United States)

    Mitul, Abu Farzan; Sarker, Jith; Adhikari, Nirmal; Mohammad, Lal; Wang, Qi; Khatiwada, Devendra; Qiao, Qiquan

    2018-02-01

    Low bandgap polymer solar cells have a great deal of importance in flexible photovoltaic market to absorb sun light more efficiently. Efficient wide bandgap solar cells are always available in nature to absorb visible photons. The development and incorporation of infrared photovoltaics (IR PV) with wide bandgap solar cells can improve overall solar device performance. Here, we have developed an efficient low bandgap polymer solar cell with CsF as interfacial layer in regular structure. Polymer solar cell devices with CsF shows enhanced performance than Ca as interfacial layer. The power conversion efficiency of 4.5% has been obtained for PDPP3T based polymer solar cell with CsF as interlayer. Finally, an optimal thickness with CsF as interfacial layer has been found to improve the efficiency in low bandgap polymer solar cells.

  14. Polarization Maintaining Ho-Doped Fiber Amplifier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The laser absorption spectrometer approach offers the potential to provide the high-accuracy carbon dioxide mixing ratio measurements with the vertical and...

  15. Coherent Combining of High-Power Yb Fiber Amplifiers

    Science.gov (United States)

    2011-04-20

    the power~in-the-bucket ( PIB ) vertical beam quality (VBQ) [J 5], which is a related to the fraction of the power within a given far-field angle...compared with a reference ideal beam (the ideal tophat in this case). The power-in- the-bucket ( PIB ) vertical beam quality (VBQ) [I 5] is given by (c/ay!ll

  16. Compact High Pulse Energy Single Frequency Fiber Amplifier, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Atmospheric methane is the second most important anthropogenic greenhouse gas. The overtone lines of methane at 1.65 micron are well suited for remote sensing of...

  17. Compact High Pulse Energy Single Frequency Fiber Amplifier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Atmospheric methane is the second most important anthropogenic greenhouse gas. The overtone lines of methane at 1.65 micron are well suited for remote sensing of...

  18. All-fiber passively mode-locked thulium-doped fiber ring oscillator operated at solitary and noiselike modes.

    Science.gov (United States)

    Wang, Q; Chen, T; Zhang, B; Heberle, A P; Chen, K P

    2011-10-01

    This Letter presents an all-fiber mode-locked thulium-doped fiber ring oscillator based on nonlinear polarization evolution (NPE). Pumped by an erbium-doped fiber amplified spontaneous emission source, the construction of the laser cavity consisting of only fiber optic components can operate under two different regimes of solitary and noiselike (NL) pulses. Autocorrelation measurements are performed to extract features of these two regimes. © 2011 Optical Society of America

  19. Application of fiber laser for a Higgs factory

    Energy Technology Data Exchange (ETDEWEB)

    Chou, W.

    2014-06-04

    This paper proposes a medium size(~6km) circular Higgs factory based on a photon collider. The recent breakthrough in fiber laser technology by means of a coherent amplifier network makes such a collider feasible and probably also affordable.

  20. MUTUAL COUPLING REDUCTION BETWEEN MICROSTRIP ANTENNAS USING ELECTROMAGNETIC BANDGAP STRUCTURE

    Directory of Open Access Journals (Sweden)

    G.N. Gaikwad

    2011-03-01

    Full Text Available When the number of antenna elements is placed in forming the arrays, mutual coupling between the antenna elements is a critical issue. This is particularly concern in phase array antennas. Mutual coupling is a potential source of performance degradation in the form of deviation of the radiation pattern from the desired one, gain reduction due to excitation of surface wave, increased side lobe levels etc. EBG (Electromagnetic Band Gap structure (also called as Photonic Bandgap Structure PBG not only enhances the performance of the patch antennas but also provides greater amount of isolation when placed between the microstrip arrays. This greatly reduces the mutual coupling between the antenna elements. The radiation efficiency, gain, antenna efficiency, VSWR, frequency, directivity etc greatly improves over the conventional patch antennas using EBG. The EBG structure and normal patch antenna is simulated using IE3D antenna simulation software.

  1. Analysis of photonic band-gap structures in stratified medium

    DEFF Research Database (Denmark)

    Tong, Ming-Sze; Yinchao, Chen; Lu, Yilong

    2005-01-01

    Purpose - To demonstrate the flexibility and advantages of a non-uniform pseudo-spectral time domain (nu-PSTD) method through studies of the wave propagation characteristics on photonic band-gap (PBG) structures in stratified medium Design/methodology/approach - A nu-PSTD method is proposed...... in solving the Maxwell's equations numerically. It expands the temporal derivatives using the finite differences, while it adopts the Fourier transform (FT) properties to expand the spatial derivatives in Maxwell's equations. In addition, the method makes use of the chain-rule property in calculus together...... with the transformed space technique in order to make the algorithm flexible in terms of non-uniform spatial sampling. Findings - Through the studies of the wave propagation characteristics on PBG structures in stratified medium, it has been found that the proposed method retains excellent accuracy in the occasions...

  2. High frequency modulation circuits based on photoconductive wide bandgap switches

    Science.gov (United States)

    Sampayan, Stephen

    2018-02-13

    Methods, systems, and devices for high voltage and/or high frequency modulation. In one aspect, an optoelectronic modulation system includes an array of two or more photoconductive switch units each including a wide bandgap photoconductive material coupled between a first electrode and a second electrode, a light source optically coupled to the WBGP material of each photoconductive switch unit via a light path, in which the light path splits into multiple light paths to optically interface with each WBGP material, such that a time delay of emitted light exists along each subsequent split light path, and in which the WBGP material conducts an electrical signal when a light signal is transmitted to the WBGP material, and an output to transmit the electrical signal conducted by each photoconductive switch unit. The time delay of the photons emitted through the light path is substantially equivalent to the time delay of the electrical signal.

  3. Waveguidance by the photonic bandgap effect in optical fibres

    DEFF Research Database (Denmark)

    Broeng, Jes; Søndergaard, Thomas; Barkou, Stig Eigil

    1999-01-01

    technology for such photonic bandgap (PBG) waveguides is in optical fibre configurations. These new fibres can be classified in a fundamentally different way to all optical waveguides and possess radically different guiding properties due to PBG guidance, as opposed to guidance by total internal refelction....... In this paper we summarize and review our theoretical work demonstrating the underlying physical principles of PBG guiding optical fibres and discuss some of their unique waveguiding properties.......Photonic crystals form a new class of intriguing building blocks to be utilized in future optoelectronics and electromagnetics. One of the most exciting possiblilties offered by phtonic crystals is the realization of new types of electromagnetic waveguides. In the optical domain, the most mature...

  4. Copper-organic/octamolybdates: structures, bandgap sizes, and photocatalytic activities.

    Science.gov (United States)

    Luo, Lan; Lin, Haisheng; Li, Le; Smirnova, Tatyana I; Maggard, Paul A

    2014-04-07

    The structures, optical bandgap sizes, and photocatalytic activities are described for three copper-octamolybdate hybrid solids prepared using hydrothermal methods, [Cu(pda)]4[β-Mo8O26] (I; pda = pyridazine), [Cu(en)2]2[γ-Mo8O26] (II; en = ethylenediamine), and [Cu(o-phen)2]2[α-Mo8O26] (III; o-phen = o-phenanthroline). The structure of I consists of a [Cu(pda)]4(4+) tetramer that bridges to neighboring [β-Mo8O26](4-) octamolybdate clusters to form two-dimensional layers that stack along the a axis. The previously reported structures of II and III are constructed from [Cu2(en)4Mo8O26] and [Cu2(o-phen)4Mo8O26] clusters. The optical bandgap sizes were measured by UV-vis diffuse reflectance techniques to be ∼1.8 eV for I, ∼3.1 eV for II, and ∼3.0 eV for III. Electronic structure calculations show that the smaller bandgap size of I originates primarily from an electronic transition between the valence and conduction band edges comprised of filled 3d(10) orbitals on Cu(I) and empty 4d(0) orbitals on Mo(VI). Both II and III contain Cu(II) and exhibit larger bandgap sizes. Accordingly, aqueous suspensions of I exhibit visible-light photocatalytic activity for the production of oxygen at a rate of ∼90 μmol O2 g(-1) h(-1) (10 mg samples; radiant power density of ∼1 W/cm(2)) and a turnover frequency per calculated surface [Mo8O26](4-) cluster of ∼36 h(-1). Under combined ultraviolet and visible-light irradiation, I also exhibits photocatalytic activity for hydrogen production in 20% aqueous methanol of ∼316 μmol H2 g(-1) h(-1). By contrast, II decomposed during the photocatalysis measurements. The molecular [Cu2(o-phen)4(α-Mo8O26)] clusters of III dissolve into the aqueous methanol solution under ultraviolet irradiation and exhibit homogeneous photocatalytic rates for hydrogen production of up to ∼8670 μmol H2·g(-1) h(-1) and a turnover frequency of 17 h(-1). The clusters of III can be precipitated out by evaporation and redispersed into solution with

  5. Optical steganography based on amplified spontaneous emission noise.

    Science.gov (United States)

    Wu, Ben; Wang, Zhenxing; Tian, Yue; Fok, Mable P; Shastri, Bhavin J; Kanoff, Daniel R; Prucnal, Paul R

    2013-01-28

    We propose and experimentally demonstrate an optical steganography method in which a data signal is transmitted using amplified spontaneous emission (ASE) noise as a carrier. The ASE serving as a carrier for the private signal has an identical frequency spectrum to the existing noise generated by the Erbium doped fiber amplifiers (EDFAs) in the transmission system. The system also carries a conventional data channel that is not private. The so-called "stealth" or private channel is well-hidden within the noise of the system. Phase modulation is used for both the stealth channel and the public channel. Using homodyne detection, the short coherence length of the ASE ensures that the stealth signal can only be recovered if the receiver closely matches the delay-length difference, which is deliberately changed in a dynamic fashion that is only known to the transmitter and its intended receiver.

  6. Low Cost RF Amplifier for Community TV

    Science.gov (United States)

    Ch, Syafaruddin; Sasongko, Sudi Mariyanto Al; Made Budi Suksmadana, I.; Mustiko Okta Muvianto, Cahyo; Ariessaputra, Suthami

    2016-01-01

    he capability of television to deliver audio video makes this media become the most effective method to spread information. This paper presents an experiment of RF amplifier design having low-cost design and providing sufficient RF power particularly for community television. The RF amplifier consists of two stages of amplifier. The first stage amplifier was used to leverage output of TV modulator from 11dBm to enable to drive next stage amplifier. CAD simulation and fabrication were run to reach optimum RF amplifier design circuit. The associated circuit was made by determining stability circle, stability gain, and matching impedance. Hence, the average power of first stage RF amplifier was 24.68dBm achieved. The second stage used RF modules which was ready match to 50 ohm for both input and output port. The experiment results show that the RF amplifier may operate at frequency ranging from 174 to 230MHz. The average output power of the 2nd stage amplifier was 33.38 Watt with the overall gain of 20.54dB. The proposed RF amplifier is a cheap way to have a stable RF amplifier for community TV. The total budget for the designed RF amplifier is only a 1/5 compared to local design of final TV amplifier.

  7. Radiation hardening of optical fibers and fiber sensors for space applications: recent advances

    Science.gov (United States)

    Girard, S.; Ouerdane, Y.; Pinsard, E.; Laurent, A.; Ladaci, A.; Robin, T.; Cadier, B.; Mescia, L.; Boukenter, A.

    2017-11-01

    In these ICSO proceedings, we review recent advances from our group concerning the radiation hardening of optical fiber and fiber-based sensors for space applications and compare their benefits to state-of-the-art results. We focus on the various approaches we developed to enhance the radiation tolerance of two classes of optical fibers doped with rare-earths: the erbium (Er)-doped ones and the ytterbium/erbium (Er/Yb)-doped ones. As a first approach, we work at the component level, optimizing the fiber structure and composition to reduce their intrinsically high radiation sensitivities. For the Erbium-doped fibers, this has been achieved using a new structure for the fiber that is called Hole-Assisted Carbon Coated (HACC) optical fibers whereas for the Er/Ybdoped optical fibers, their hardening was successfully achieved adding to the fiber, the Cerium element, that prevents the formation of the radiation-induced point defects responsible for the radiation induced attenuation in the infrared part of the spectrum. These fibers are used as part of more complex systems like amplifiers (Erbium-doped Fiber Amplifier, EDFA or Yb-EDFA) or source (Erbium-doped Fiber Source, EDFS or Yb- EDFS), we discuss the impact of using radiation-hardened fibers on the system radiation vulnerability and demonstrate the resistance of these systems to radiation constraints associated with today and future space missions. Finally, we will discuss another radiation hardening approach build in our group and based on a hardening-by-system strategy in which the amplifier is optimized during its elaboration for its future mission considering the radiation effects and not in-lab.

  8. Recent advances in semiconductor optical amplifiers and their applications

    DEFF Research Database (Denmark)

    Stubkjær, Kristian; Mikkelsen, Benny; Djurhuus, Torsten

    1992-01-01

    The authors review recent advances in SOAs (semiconductor optical amplifiers) and some of their applications. SOAs are under rapid development to achieve polarization independent gain, low facet reflectivities, good coupling to optical fibers, and high saturation power. The package SOA can be made...... compact and possibly inexpensive, but its main advantage is the potential for optoelectronic integration. SOAs may be used as boosters and preamplifiers, but in the case of multichannel systems attention must be given to the inherent nonlinear behavior that is due to the short lifetime of the injected...

  9. Linearisation of RF Power Amplifiers

    DEFF Research Database (Denmark)

    Nielsen, Per Asbeck

    2001-01-01

    This thesis deals with linearisation techniques of RF power amplifiers (PA), PA design techniques and integration of the necessary building blocks in a CMOS technology. The opening chapters introduces the theory of transmitter architectures, RF-signal representation and the principles of digital...... modulation. Furthermore different types of power amplifiers, models and measures of non-linearities are presented. A chapter is also devoted to different types of linearisation systems. The work carried out and described in this thesis can be divided into a more theoretical and system oriented treatment...... the polar loop architecture and it’s suitability to modern digital transmitters is discussed. A proposal of an architecture that is suitable for digital transmitters, which means that it has an interface to the digital back-end, defined by low-pass signals in polar form, is presented. Simulation guidelines...

  10. Single conversion stage amplifier - SICAM

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2005-12-15

    This Ph.D. thesis presents a thorough analysis of the so called SICAM - SIngle Converter stage AMplifier approach to building direct energy conversion audio power amplifiers. The mainstream approach for building isolated audio power amplifiers today consists of isolated DC power supply and Class D amplifier, which essentially represents a two stage solution, where each of the components can be viewed as separate and independent part. The proposed SICAM solution strives for direct energy conversion from the mains to the audio output, by dedicating the operation of the components one to another and integrating their functions, so that the final audio power amplifier represents a single-stage topology with higher efficiency, lower volume, less board space, lower component count and subsequently lower cost. The SICAM approach is both applicable to non-isolated and isolated audio power amplifiers, but the problems encountered in these two cases are different. Non-isolated SICAM solutions are intended for both AC mains-connected and battery-powered devices. In non-isolated mains-connected SICAMs the main idea is to simplify the power supply or even provide integrated power factor correction (PFC) functions, while still maintaining low component stress and good audio performance by generally decreasing the input voltage level to the Class D audio power amplifier. On the other hand, non-isolated battery-powered SICAMs have to cope with the ever changing battery voltage and provide output voltage levels which are both lower and higher than the battery voltage, while still being simple and single-stage energy conversion solutions. In isolated SICAMs the isolation transformer adjusts the voltage level on the secondary side to the desired level, so the main challenges here are decreasing the size of the magnetic core and reducing the number and size of bulky reactive components as much as possible. The main focus of this thesis is directed towards the isolated SICAMs and

  11. Modal dynamics in hollow-core photonic-crystal fibers with elliptical veins.

    Science.gov (United States)

    Hochman, Amit; Leviatan, Yehuda

    2005-08-08

    Modal characteristics of hollow-core photonic-crystal fibers with elliptical veins are studied by use of a recently proposed numerical method. The dynamic behavior of bandgap guided modes, as the wavelength and aspect ratio are varied, is shown to include zero-crossings of the birefringence, polarization dependent radiation losses, and deformation of the fundamental mode.

  12. Infiltration liquid crystal in microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wei, Lei; Bang, Ole

    2009-01-01

    Here, we firstly demonstrate the photonic bandgap effect with PMMA mPOF by filling the air holes with liquid crystal, and subsequently change the light guidance mechanism from index guiding to bandgap guiding. The triangular structure PMMA mPOF used in the experiment is fabricated. A 60 cm length m......POF is butt-coupled to a conventional single mode fiber (SMF) with the broadband light from a supercontinuum source. It is clear to see the colour of the guided modes is red, since some wavelengths are attenuated by the material loss of PMMA in visible region. A positive dielectric anisotropy liquid crystal E......7 is then infiltrated into about 6 cm of the length of mPOF by using capillary forces with the duration of 45 minutes. The transmission spectrum is measured by an optical spectrum analyzer with 1 nm resolution, and normalized to that of the unfilled fiber as shown by the solid line. The difference...

  13. Identification of amplified fragment length polymorphism (AFLP ...

    African Journals Online (AJOL)

    Identification of amplified fragment length polymorphism (AFLP) fragments linked to soybean mosaic virus resistance gene in Glycine soja and conversion to a sequence characterized amplified regions (SCAR) marker for rapid selection.

  14. High power regenerative laser amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Miller, John L. (Livermore, CA); Hackel, Lloyd A. (Livermore, CA); Dane, Clifford B. (Dublin, CA); Zapata, Luis E. (Livermore, CA)

    1994-01-01

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

  15. SPS RF System Amplifier plant

    CERN Multimedia

    1977-01-01

    The picture shows a 2 MW, 200 MHz amplifier plant with feeder lines. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X.

  16. Modeling of Mid-IR Amplifier Based on an Erbium-Doped Chalcogenide Microsphere

    Directory of Open Access Journals (Sweden)

    P. Bia

    2012-01-01

    Full Text Available An optical amplifier based on a tapered fiber and an Er3+-doped chalcogenide microsphere is designed and optimized. A dedicated 3D numerical model, which exploits the coupled mode theory and the rate equations, is used. The main transitions among the erbium energy levels, the amplified spontaneous emission, and the most important secondary transitions pertaining to the ion-ion interactions have been considered. Both the pump and signal beams are efficiently injected and obtained by a suitable design of the taper angle and the fiber-microsphere gap. Moreover, a good overlapping between the optical signals and the rare-earth-doped region is also obtained. In order to evaluate the amplifier performance in reduced computational time, the doped area is partitioned in sectors. The obtained simulation results highlight that a high-efficiency midinfrared amplification can be obtained by using a quite small microsphere.

  17. Bandgap Engineering of Double Perovskites for One- and Two-photon Water Splitting

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; Thygesen, Kristian Sommer; Jacobsen, Karsten Wedel

    2013-01-01

    Computational screening is becoming increasingly useful in the search for new materials. We are interested in the design of new semiconductors to be used for light harvesting in a photoelectrochemical cell. In the present paper, we study the double perovskite structures obtained by combining 46...... stable cubic perovskites which was found to have a finite bandgap in a previous screening-study. The four-metal double perovskite space is too large to be investigated completely. For this reason we propose a method for combining different metals to obtain a desired bandgap. We derive some bandgap design...

  18. Complete photonic bandgaps in the visible range from spherical layer structures in dichromate gelatin emulsions

    Science.gov (United States)

    Hung, Jenny; Kok, Mang Hin; Tam, Wing Yim

    2009-01-01

    We have fabricated spherical layer structures that exhibit complete photonic bandgaps in the visible range in dichromate gelatin emulsions by holographic interference. The complete bandgap was not a result of the high dielectric contrast but was due to the fact that the spherical layer structure was isotropic with equal spacing in all accessible directions. Angular dependence spectral measurements of the spherical layer structures were in good agreement with the expected results from an ideal structure of dielectric concentric spherical shells with equal spacing. Our fabrication technique and results could pave the way for new applications using complete bandgap photonic crystals.

  19. Improved charge amplifier using hybrid hysteresis compensation

    Science.gov (United States)

    Amin-Shahidi, Darya; Trumper, David L.

    2013-08-01

    We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design.

  20. Switching power amplifier for TAR3

    OpenAIRE

    Moore, Eric Wesley

    1995-01-01

    This thesis describes the theory, design, construction, and testing of a switching power amplifier. The major emphasis of the research and development effort reported herein is to design and construct an efficient power amplifier for varying load conditions which provides 40 Watts of power, at 85% efficiency, and with no more than 10% harmonic distortion. The power amplifier will need one voltage supply and one input audio signal. The amplifier will be used to power demonstration thermoacoust...

  1. Balanced Amplifier dengan Menggunakan Driver Op Amp

    OpenAIRE

    Khoswanto, Handry; T.D.S, Yohanes; Wahyudi, Iwan

    2004-01-01

    In Bahasa Indonesia : Pada umumnya amplifier konvensional melibatkan jalur power supply (ground) yang berhubungan dengan jalur audio. Hal ini mengakibatkan pengolahan sinyal audio akan muncul IHM (Interval Hum Modulation) noise. Oleh karena itu, untuk dapat menekan timbulnya noise seminimal mungkin, maka dibuat sebuah amplifier yang tidak bereferensi pada ground power supply. Amplifier tersebut harus benar-benar balance dari input sampai ke output. Untuk merealisasikan balance amplifier ...

  2. Challenges in higher order mode Raman amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Nielsen, Kristian; Friis, Søren Michael Mørk

    2015-01-01

    A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed......A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed...

  3. European Research on THz Vacuum Amplifiers

    DEFF Research Database (Denmark)

    Brunetti, F.; Cojocarua, C.-S.; de Rossi, A.

    2010-01-01

    The OPTHER (OPtically Driven TeraHertz AmplifiERs) project represents a considerable advancement in the field of high frequency amplification. The design and realization of a THz amplifier within this project is a consolidation of efforts at the international level from the main players of the Eu...

  4. Spontaneous emission from saturated parametric amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Ott, Johan Raunkjær; Steffensen, Henrik

    2009-01-01

    Noise performance of parametric amplifiers is typically calculated assuming un-depleted operation. However, in many applications especially when applied as regenerative amplifiers in systems based on phase shift keyed modulation schemes, this assumption is not valid. Here we show the impact...... on accumulated spontaneous emission for a parametric amplifier operated in saturation....

  5. low pump power photonic crystal fibre amplifiers

    DEFF Research Database (Denmark)

    Hougaard, Kristian G.; Broeng, Jes; Bjarklev, Anders Overgaard

    2003-01-01

    Designs of low pump power optical amplifiers, based on photonic crystal fibres are presented. The potential of these fibre amplifiers is investigated, and it is demonstrated that such amplifiers may deliver gains of more than 15 dB at 1550 nm with less than 1 mW of optical pump power....

  6. Radio frequency amplifier with effective decoupling

    NARCIS (Netherlands)

    Besling, W.F.A.; Bakker, T.W.; Lamy, Y.; Kochupurackal, J.; Roozeboom, F.

    2011-01-01

    A variety of circuits, methods and devices are implemented for radiofrequency amplifiers. According to one such implementation, a radiofrequency amplifier circuit is implemented in a SMD package. The circuit amplifies a radiofrequency signal having a base-band portion and a plurality of carrier

  7. Series transistors isolate amplifier from flyback voltage

    Science.gov (United States)

    Banks, W.

    1967-01-01

    Circuit enables high sawtooth currents to be passed through a deflection coil and isolate the coil driving amplifier from the flyback voltage. It incorporates a switch consisting of transistors in series with the driving amplifier and deflection coil. The switch disconnects the deflection coil from the amplifier during the retrace time.

  8. Remote Acquisition Amplifier For 50-Ohm Cable

    Science.gov (United States)

    Amador, Jose J.

    1995-01-01

    Buffer-amplifier unit designed to drive 50-Ohm cables up to 100 ft. (30 m) long, compensating for attenuation in cables and enabling remote operation of oscilloscopes. Variable resistor provides for adjustment of gain of amplifier, such that overall gain from input terminals of amplifier to output end of cable set to unity.

  9. Cross-correlated imaging of single-mode photonic crystal rod fiber with distributed mode filtering

    DEFF Research Database (Denmark)

    Laurila, Marko; Barankov, Roman; Jørgensen, Mette Marie

    2013-01-01

    Photonic crystal bandgap fibers employing distributed mode filtering design provide near diffraction-limited light outputs, a critical property of fiber-based high-power lasers. Microstructure of the fibers is tailored to achieve single-mode operation at specific wavelength by resonant mode...... identify regimes of resonant coupling between higher-order core modes and cladding band. We demonstrate a passive fiber design in which the higher-order modal content inside the single-mode guiding regime is suppressed by at least 20 dB even for significantly misaligned input-coupling configurations....

  10. Ring mirror fiber laser gyroscope

    Science.gov (United States)

    Shalaby, Mohamed Y.; Khalil, Kamal; Afifi, Abdelrahman E.; Khalil, Diaa

    2017-02-01

    In this work we present a new architecture for a laser gyroscope based on the use of a Sagnac fiber loop mirror. The proposed system has the unique property that its scale factor can be increased by increasing the gain of the optical amplifier used in the system as demonstrated experimentally using standard single mode fiber and explained physically by the system operation. The proposed gyroscope system is also capable of identifying the direction of rotation. This new structure opens the door for a new category of low cost optical gyroscopes.

  11. Recent progress in distributed optical fiber Raman photon sensors at China Jiliang University

    Science.gov (United States)

    Zhang, Zaixuan; Wang, Jianfeng; Li, Yi; Gong, Huaping; Yu, Xiangdong; Liu, Honglin; Jin, Yongxing; Kang, Juan; Li, Chenxia; Zhang, Wensheng; Zhang, Wenping; Niu, Xiaohui; Sun, Zhongzhou; Zhao, Chunliu; Dong, Xinyong; Jin, Shangzhong

    2012-06-01

    A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University (CJLU) is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of full distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation full distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distance full distributed fiber Raman and Rayleigh scattering photon sensors integrated with a fiber Raman amplifier, auto-correction full distributed fiber Raman photon temperature sensors based on Raman correlation dual sources, full distributed fiber Raman photon temperature sensors based on a pulse coding source, full distributed fiber Raman photon temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers (BOTDAs) integrated with a fiber Raman amplifier for replacing a fiber Brillouin amplifier, full distributed fiber Raman and Brillouin photon sensors integrated with a fiber Raman amplifier, and full distributed fiber Brillouin photon sensors integrated with a fiber Brillouin frequency shifter. The Internet of things is believed as one of candidates of the next technological revolution, which has driven hundreds of millions of class markets. Sensor networks are important components of the Internet of things. The full distributed optical fiber sensor network (Rayleigh, Raman, and Brillouin scattering) is a 3S (smart materials, smart structure, and smart skill) system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor can be embedded in the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other

  12. Status of fiber lasers study of on ytterbium doped fiber laser and laser spectroscopy of doped fibers

    International Nuclear Information System (INIS)

    Magne, S.

    1994-07-01

    This work shows all the advantages and drawbacks of the rare-earth-doped fiber lasers and fiber optical amplifiers, pointing out their potential use for instrumentation and optical fiber sensor technology. The theory of light propagation in optical fibers is presented in order to understand the manufacturing methods. A comparative study of preform surface and concentration analysis is performed. The gain behaviour is also thoroughly examined. A synthesis of all technological parameters of the fiber laser is then established and all technologies of the constituting integrated components are reviewed and compared. The experimental techniques mainly involve: site selective excitation tunability, cooperative luminescence, oxidation state changes induced by gamma irradiation, ytterbium-doped mono-mode continuous wave tunable three-level fiber laser. (TEC). 622 refs., 176 figs

  13. Semiconductor quantum-dot lasers and amplifiers

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.

    2002-01-01

    -power surface emitting VCSELs. We investigated the ultrafast dynamics of quantum-dot semiconductor optical amplifiers. The dephasing time at room temperature of the ground-state transition in semiconductor quantum dots is around 250 fs in an unbiased amplifier, decreasing to below 50 fs when the amplifier...... is biased to positive net gain. We have further measured gain recovery times in quantum dot amplifiers that are significantly lower than in bulk and quantum-well semiconductor optical amplifiers. This is promising for future demonstration of quantum dot devices with high modulation bandwidth...

  14. Multi-fidelity machine learning models for accurate bandgap predictions of solids

    International Nuclear Information System (INIS)

    Pilania, Ghanshyam; Gubernatis, James E.; Lookman, Turab

    2016-01-01

    Here, we present a multi-fidelity co-kriging statistical learning framework that combines variable-fidelity quantum mechanical calculations of bandgaps to generate a machine-learned model that enables low-cost accurate predictions of the bandgaps at the highest fidelity level. Additionally, the adopted Gaussian process regression formulation allows us to predict the underlying uncertainties as a measure of our confidence in the predictions. In using a set of 600 elpasolite compounds as an example dataset and using semi-local and hybrid exchange correlation functionals within density functional theory as two levels of fidelities, we demonstrate the excellent learning performance of the method against actual high fidelity quantum mechanical calculations of the bandgaps. The presented statistical learning method is not restricted to bandgaps or electronic structure methods and extends the utility of high throughput property predictions in a significant way.

  15. A model for the direct-to-indirect band-gap transition in monolayer ...

    Indian Academy of Sciences (India)

    2015-05-28

    , within ab-initio electronic structure calculations, that a modest biaxial tensile strain of 3% can drive it into an indirect band-gap semiconductor with the valence band maximum (VBM) shifting from point to point. An analysis ...

  16. Advanced ultrafast fiber laser sources enabled by fiber nonlinearities

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei

    2017-05-15

    Development of high power/energy ultrafast fiber lasers for scientific research and industrial applications is one of the most exciting fields in ultrafast optics. This thesis demonstrated new means to improve two essential properties - which are indispensable for novel applications such as high-harmonic generation (HHG) and multiphoton microscopy (MPM) - of an ultrafast fiber laser system: energy scaling capability and wavelength tunability. High photon-flux extreme ultraviolet sources enabled by HHG desire high power (>100 W), high repetition-rate (>1 MHz) ultrafast driving laser sources. We have constructed from scratch a high-power Yb-fiber laser system using the well-known chirped-pulse amplification (CPA) technique. Such a CPA system capable of producing ∝200-W average power consists of a monolithic Yb-fiber oscillator, an all-fiber stretcher, a pre-amplifier chain, a main amplifier constructed from rode-type large pitch fiber, and a diffraction-grating based compressor. To increase the HHG efficiency, ultrafast pulses with duration <60 fs are highly desired. We proposed and demonstrated a novel amplification technique, named as pre-chirp managed amplification (PCMA). We successfully constructed an Yb-fiber based PCMA system that outputs 75-MHz spectrally broadened pulses with >130-W average power. The amplified pulses are compressed to 60-fs pulses with 100-W average power, constituting a suitable HHG driving source. MPM is a powerful biomedical imaging tool, featuring larger penetration depth while providing the capability of optical sectioning. Although femtosecond solid-state lasers have been widely accepted as the standard option as MPM driving sources, fiber-based sources have received growing research efforts due to their superior performance. In the second part of this thesis, we both theoretically and experimentally demonstrated a new method of producing wavelength widely tunable femtosecond pulses for driving MPM. We employed self-phase modulation

  17. Advanced ultrafast fiber laser sources enabled by fiber nonlinearities

    International Nuclear Information System (INIS)

    Liu, Wei

    2017-05-01

    Development of high power/energy ultrafast fiber lasers for scientific research and industrial applications is one of the most exciting fields in ultrafast optics. This thesis demonstrated new means to improve two essential properties - which are indispensable for novel applications such as high-harmonic generation (HHG) and multiphoton microscopy (MPM) - of an ultrafast fiber laser system: energy scaling capability and wavelength tunability. High photon-flux extreme ultraviolet sources enabled by HHG desire high power (>100 W), high repetition-rate (>1 MHz) ultrafast driving laser sources. We have constructed from scratch a high-power Yb-fiber laser system using the well-known chirped-pulse amplification (CPA) technique. Such a CPA system capable of producing ∝200-W average power consists of a monolithic Yb-fiber oscillator, an all-fiber stretcher, a pre-amplifier chain, a main amplifier constructed from rode-type large pitch fiber, and a diffraction-grating based compressor. To increase the HHG efficiency, ultrafast pulses with duration <60 fs are highly desired. We proposed and demonstrated a novel amplification technique, named as pre-chirp managed amplification (PCMA). We successfully constructed an Yb-fiber based PCMA system that outputs 75-MHz spectrally broadened pulses with >130-W average power. The amplified pulses are compressed to 60-fs pulses with 100-W average power, constituting a suitable HHG driving source. MPM is a powerful biomedical imaging tool, featuring larger penetration depth while providing the capability of optical sectioning. Although femtosecond solid-state lasers have been widely accepted as the standard option as MPM driving sources, fiber-based sources have received growing research efforts due to their superior performance. In the second part of this thesis, we both theoretically and experimentally demonstrated a new method of producing wavelength widely tunable femtosecond pulses for driving MPM. We employed self-phase modulation

  18. Research on micro-sized acoustic bandgap structures.

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, James Grant; McCormick, Frederick Bossert; Su, Mehmet F.; El-Kady, Ihab Fathy; Olsson, Roy H., III; Tuck, Melanie R.

    2010-01-01

    Phononic crystals (or acoustic crystals) are the acoustic wave analogue of photonic crystals. Here a periodic array of scattering inclusions located in a homogeneous host material forbids certain ranges of acoustic frequencies from existence within the crystal, thus creating what are known as acoustic (or phononic) bandgaps. The vast majority of phononic crystal devices reported prior to this LDRD were constructed by hand assembling scattering inclusions in a lossy viscoelastic medium, predominantly air, water or epoxy, resulting in large structures limited to frequencies below 1 MHz. Under this LDRD, phononic crystals and devices were scaled to very (VHF: 30-300 MHz) and ultra (UHF: 300-3000 MHz) high frequencies utilizing finite difference time domain (FDTD) modeling, microfabrication and micromachining technologies. This LDRD developed key breakthroughs in the areas of micro-phononic crystals including physical origins of phononic crystals, advanced FDTD modeling and design techniques, material considerations, microfabrication processes, characterization methods and device structures. Micro-phononic crystal devices realized in low-loss solid materials were emphasized in this work due to their potential applications in radio frequency communications and acoustic imaging for medical ultrasound and nondestructive testing. The results of the advanced modeling, fabrication and integrated transducer designs were that this LDRD produced the 1st measured phononic crystals and phononic crystal devices (waveguides) operating in the VHF (67 MHz) and UHF (937 MHz) frequency bands and established Sandia as a world leader in the area of micro-phononic crystals.

  19. Angle-dependent bandgap engineering in gated graphene superlattices

    Energy Technology Data Exchange (ETDEWEB)

    García-Cervantes, H.; Sotolongo-Costa, O. [Centro de Investigación en Ciencias, IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, México (Mexico); Gaggero-Sager, L. M. [CIICAp, IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, México (Mexico); Naumis, G. G. [Instituto Física, Depto. de Física-Química, Universidad Nacional Autónoma de México (UNAM). Apdo. Postal 20-364, 01000, México D.F., México (Mexico); Rodríguez-Vargas, I., E-mail: isaac@fisica.uaz.edu.mx [Centro de Investigación en Ciencias, IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Morelos, México (Mexico); Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac., México (Mexico)

    2016-03-15

    Graphene Superlattices (GSs) have attracted a lot of attention due to its peculiar properties as well as its possible technological implications. Among these characteristics we can mention: the extra Dirac points in the dispersion relation and the highly anisotropic propagation of the charge carriers. However, despite the intense research that is carried out in GSs, so far there is no report about the angular dependence of the Transmission Gap (TG) in GSs. Here, we report the dependence of TG as a function of the angle of the incident Dirac electrons in a rather simple Electrostatic GS (EGS). Our results show that the angular dependence of the TG is intricate, since for moderated angles the dependence is parabolic, while for large angles an exponential dependence is registered. We also find that the TG can be modulated from meV to eV, by changing the structural parameters of the GS. These characteristics open the possibility for an angle-dependent bandgap engineering in graphene.

  20. Simulation of push-pull inverter using wide bandgap devices

    Science.gov (United States)

    Al-badri, Mustafa; Matin, Mohammed A.

    2016-09-01

    This paper discusses the use of wide bandgap devices (SiC-MOSFET) in the design of a push-pull inverter which provides inexpensive low power dc-ac inverters. The parameters used were 1200V SiC MOSFET(C2M0040120D) made by power company ROHM. This modeling was created using parameters that were provided from a device datasheet. The spice model is provided by this company to study the effect of adding this component on push-pull inverter ordinary circuit and compared results between SiC MOSFET and silicon MOSFET (IRFP260M). The results focused on Vout and Vmos stability as well as on output power and MOSFET power loss because it is a very crucial aspect on DC-AC inverter design. These results are done using the National Instrument simulation program (Multisim 14). It was found that power loss is better in the 12 and 15 vdc inverter. The Vout in the SIC MOSFET circuit shows more stability in the high current low resistance load in comparison to the Silicon MOSFET circuit and this will improve the overall performance of the circuit.

  1. High-Temperature, Wirebondless, Ultracompact Wide Bandgap Power Semiconductor Modules

    Science.gov (United States)

    Elmes, John

    2015-01-01

    Silicon carbide (SiC) and other wide bandgap semiconductors offer great promise of high power rating, high operating temperature, simple thermal management, and ultrahigh power density for both space and commercial power electronic systems. However, this great potential is seriously limited by the lack of reliable high-temperature device packaging technology. This Phase II project developed an ultracompact hybrid power module packaging technology based on the use of double lead frames and direct lead frame-to-chip transient liquid phase (TLP) bonding that allows device operation up to 450 degC. The new power module will have a very small form factor with 3-5X reduction in size and weight from the prior art, and it will be capable of operating from 450 degC to -125 degC. This technology will have a profound impact on power electronics and energy conversion technologies and help to conserve energy and the environment as well as reduce the nation's dependence on fossil fuels.

  2. High temperature charge amplifier for geothermal applications

    Energy Technology Data Exchange (ETDEWEB)

    Lindblom, Scott C.; Maldonado, Frank J.; Henfling, Joseph A.

    2015-12-08

    An amplifier circuit in a multi-chip module includes a charge to voltage converter circuit, a voltage amplifier a low pass filter and a voltage to current converter. The charge to voltage converter receives a signal representing an electrical charge and generates a voltage signal proportional to the input signal. The voltage amplifier receives the voltage signal from the charge to voltage converter, then amplifies the voltage signal by the gain factor to output an amplified voltage signal. The lowpass filter passes low frequency components of the amplified voltage signal and attenuates frequency components greater than a cutoff frequency. The voltage to current converter receives the output signal of the lowpass filter and converts the output signal to a current output signal; wherein an amplifier circuit output is selectable between the output signal of the lowpass filter and the current output signal.

  3. Soliton models in resonant and nonresonant optical fibers

    Indian Academy of Sciences (India)

    The dispersive characteristics of a fiber can be minimized in the oper- ating region of the system by ... The lower order nonlinearities manifest themselves in three different ways: self- phase modulation (SPM) ... These are mainly due to the optical losses, dispersion, nonlinearity and amplifier induced noise in the optical fiber.

  4. Photonic bandgap structures for guiding of long-range surface plasmon polaritons

    DEFF Research Database (Denmark)

    Leosson, K.; Nikolajsen, T.; Boltasseva, Alexandra

    2003-01-01

    We present the first observations of long-range plasmon polariton guiding in photonic bandgap structures. The transmission of waveguide structures is characterized at telecommunication wavelengths and a propagation loss below 4 dB/mm is determined.......We present the first observations of long-range plasmon polariton guiding in photonic bandgap structures. The transmission of waveguide structures is characterized at telecommunication wavelengths and a propagation loss below 4 dB/mm is determined....

  5. Semi-transparent polymer solar cells with excellent sub-bandgap transmission for third generation photovoltaics

    KAUST Repository

    Beiley, Zach M.

    2013-10-07

    Semi-transparent organic photovoltaics are of interest for a variety of photovoltaic applications, including solar windows and hybrid tandem photovoltaics. The figure shows a photograph of our semi-transparent solar cell, which has a power conversion efficiency of 5.0%, with an above bandgap transmission of 34% and a sub-bandgap transmission of 81%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Specific circuit design: electrocardiogram amplifier

    International Nuclear Information System (INIS)

    Laribiere, Laurent

    1991-01-01

    The electrocardiogram amplifier is a specific integrated circuit. It is based on a linear array of Raytheon. This circuit is fitted with the following functions and characteristics: - electrocardiogram signals amplification, - pacemaker detection, - electrode un-sticking detection, - defibrillator overload protection, - battery-powered, - internal regulation 5 V, - low supply current 2.5 mA, - according to French norms on electrocardiogram surveillance devices - 28 pin package, available in CMS version It can be used for any surveillance device, requiring an analog processing of cardiac signals. (author) [fr

  7. Audio power amplifier design handbook

    CERN Document Server

    Self, Douglas

    2013-01-01

    This book is essential for audio power amplifier designers and engineers for one simple reason...it enables you as a professional to develop reliable, high-performance circuits. The Author Douglas Self covers the major issues of distortion and linearity, power supplies, overload, DC-protection and reactive loading. He also tackles unusual forms of compensation and distortion produced by capacitors and fuses. This completely updated fifth edition includes four NEW chapters including one on The XD Principle, invented by the author, and used by Cambridge Audio. Cro

  8. Cathode-follower power amplifier

    International Nuclear Information System (INIS)

    Giordano, S.; Puglisi, M.

    1983-01-01

    In circular accelerators and particularly in storage rings it is essential that the total impedance, as seen by the beam, be kept below some critical value. A model of the accelerating system was built using a single-ended cathode-follower amplifier driving a ferrite-loaded cavity. The system operated at 234.5 kHz with a peak output voltage of +-10 kV on the gap. The dynamic output impedance, as measured on the gap, was < 15 ohms

  9. Research on the ϕ-OTDR fiber sensor sensitive for all of the distance

    Science.gov (United States)

    Kong, Yong; Liu, Yang; Shi, Yi; Ansari, Farhad; Taylor, Todd

    2018-01-01

    In this paper, a modified construction for the traditional ϕ-OTDR fiber sensor sensitive for all of distance is presented, the related numerical simulation and experiment analysis results show that this construction can reduce the gain imbalance for all of the distance along the fiber caused by the Rayleigh scattering loss of the fiber and the gain imbalance of Raman fiber amplifier in this fiber sensor system. In order to improve further the vibration sensitivity of this system, the possible methods to restrain the influences of modulation instability effect, Stimulated Brillouin effect, reduce the amplified spontaneous emission (ASE) noises of Raman laser (RL) and Erbium3+-doped fiber amplifiers (EDFA), double Rayleigh backscattering noise in this system are discussed, which will offer a great reference value for the science research and engineering application in the field of fiber sensor as we believe.

  10. Ultrawide bandgap pentamode metamaterials with an asymmetric double-cone outside profile

    Science.gov (United States)

    Chu, Yangyang; Li, Yucheng; Cai, Chengxin; Liu, Guangshuan; Wang, Zhaohong; Xu, Zhuo

    2018-03-01

    The band-gap characteristic is an important feature of acoustic metamaterials, which has important theoretical and practical significance in acoustic devices. Pentamode metamaterials (PMs) with phonon band-gap characteristics based on an asymmetric double-cone outside profile are presented and studied in this paper. The phonon band structures of these PMs are calculated by using the finite element method. In addition to the single-mode band-gaps, the complete 3D band-gaps are also obtained by changing the outside profile of the double-cone. Moreover, by adjusting the outside profile and the diameter of the double-cone to reduce the symmetry of the structure, the complete 3D band-gap can be widened. Further parametric analysis is presented to investigate the effect of geometrical parameters on the phonon band-gap property, the numerical simulations show that the maximum relative bandwidth is expanded by 15.14 times through reducing the symmetry of the structure. This study provides a possible way for PMs to control elastic wave propagation in the field of depressing vibration and noise, acoustic filtering and acoustic cloaking.

  11. Thermal tuning On narrow linewidth fiber laser

    Science.gov (United States)

    Han, Peiqi; Liu, Tianshan; Gao, Xincun; Ren, Shiwei

    2010-10-01

    At present, people have been dedicated to high-speed and large-capacity optical fiber communication system. Studies have been shown that optical wavelength division multiplexing (WDM) technology is an effective means of communication to increase the channel capacity. Tunable lasers have very important applications in high-speed, largecapacity optical communications, and distributed sensing, it can provide narrow linewidth and tunable laser for highspeed optical communication. As the erbium-doped fiber amplifier has a large gain bandwidth, the erbium-doped fiber laser can be achieved lasing wavelength tunable by adding a tunable filter components, so tunable filter device is the key components in tunable fiber laser.At present, fiber laser wavelength is tuned by PZT, if thermal wavelength tuning is combined with PZT, a broader range of wavelength tuning is appearance . Erbium-doped fiber laser is used in the experiments,the main research is the physical characteristics of fiber grating temperature-dependent relationship and the fiber grating laser wavelength effects. It is found that the fiber laser wavelength changes continuously with temperature, tracking several temperature points observed the self-heterodyne spectrum and found that the changes in spectra of the 3dB bandwidth of less than 1kHz, and therefore the fiber laser with election-mode fiber Bragg grating shows excellent spectral properties and wavelength stability.

  12. Passively Q-switched ytterbium- and chromium-doped all-fiber laser

    Czech Academy of Sciences Publication Activity Database

    Dussardier, B.; Maria, J.; Peterka, Pavel

    2011-01-01

    Roč. 50, č. 25 (2011), E20-E23 ISSN 0003-6935 R&D Projects: GA MŠk(CZ) ME10119 Institutional research plan: CEZ:AV0Z20670512 Keywords : optical fiber * fiber lasers * fiber amplifiers Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.703, year: 2010

  13. Air-clad fibers: pump absorption assisted by chaotic wave dynamics?

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger

    2007-01-01

    Wave chaos is a concept which has already proved its practical usefulness in design of double-clad fibers for cladding-pumped fiber lasers and fiber amplifiers. In general, classically chaotic geometries will favor strong pump absorption and we address the extent of chaotic wave dynamics in typical...

  14. Design optimization of the distributed modal filtering rod fiber for increasing single mode bandwidth

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko

    2012-01-01

    High-power fiber amplifiers for pulsed applications require large mode area (LMA) fibers having high pump absorption and near diffraction limited output. This improves the limiting factor of nonlinear effects, while maintaining good beam quality. Photonic crystal fibers allow realization of short...

  15. Pump and Signal Taper for Airclad Fibers

    National Research Council Canada - National Science Library

    Kristiansen, Rene E; Nielsen, Martin D

    2006-01-01

    This report results from a contract tasking Crystal Fibre A/S as follows: Crystal Fibre A/S will develop a taper/coupler solution to interface between a new polarization maintaining/polarizing amplifier fiber (DC-200-35-Yb-PM...

  16. BRILLOUIN INSTABILITY IN FIBER LASERS DOPED BY POWER ...

    African Journals Online (AJOL)

    30 juin 2012 ... With the emergence of rare-earth doped fibers, and especially double-clad fibers, there is a renewed ... continuous signal in a rare-earth doped fiber amplifier can generate high enough intensities to ..... signal continu dans les fibres dopées aux terres rares génère des intensités élevées qui donnent lieu à ...

  17. Radiation resistance of wide-bandgap semiconductor power transistors

    Energy Technology Data Exchange (ETDEWEB)

    Hazdra, Pavel; Popelka, Stanislav [Department of Microelectronics, Czech Technical University in Prague (Czech Republic)

    2017-04-15

    Radiation resistance of state-of-the-art commercial wide-bandgap power transistors, 1700 V 4H-SiC power MOSFETs and 200 V GaN HEMTs, to the total ionization dose was investigated. Transistors were irradiated with 4.5 MeV electrons with doses up to 2000 kGy. Electrical characteristics and introduced defects were characterized by current-voltage (I-V), capacitance-voltage (C-V), and deep level transient spectroscopy (DLTS) measurements. Results show that already low doses of 4.5 MeV electrons (>1 kGy) cause a significant decrease in threshold voltage of SiC MOSFETs due to embedding of the positive charge into the gate oxide. On the other hand, other parameters like the ON-state resistance are nearly unchanged up to the dose of 20 kGy. At 200 kGy, the threshold voltage returns back close to its original value, however, the ON-state resistance increases and transconductance is lowered. This effect is caused by radiation defects introduced into the low-doped drift region which decrease electron concentration and mobility. GaN HEMTs exhibit significantly higher radiation resistance. They keep within the datasheet specification up to doses of 2000 kGy. Absence of dielectric layer beneath the gate and high concentration of carriers in the two dimensional electron gas channel are the reasons of higher radiation resistance of GaN HEMTs. Their degradation then occurs at much higher doses due to electron mobility degradation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Radiation resistance of wide-bandgap semiconductor power transistors

    International Nuclear Information System (INIS)

    Hazdra, Pavel; Popelka, Stanislav

    2017-01-01

    Radiation resistance of state-of-the-art commercial wide-bandgap power transistors, 1700 V 4H-SiC power MOSFETs and 200 V GaN HEMTs, to the total ionization dose was investigated. Transistors were irradiated with 4.5 MeV electrons with doses up to 2000 kGy. Electrical characteristics and introduced defects were characterized by current-voltage (I-V), capacitance-voltage (C-V), and deep level transient spectroscopy (DLTS) measurements. Results show that already low doses of 4.5 MeV electrons (>1 kGy) cause a significant decrease in threshold voltage of SiC MOSFETs due to embedding of the positive charge into the gate oxide. On the other hand, other parameters like the ON-state resistance are nearly unchanged up to the dose of 20 kGy. At 200 kGy, the threshold voltage returns back close to its original value, however, the ON-state resistance increases and transconductance is lowered. This effect is caused by radiation defects introduced into the low-doped drift region which decrease electron concentration and mobility. GaN HEMTs exhibit significantly higher radiation resistance. They keep within the datasheet specification up to doses of 2000 kGy. Absence of dielectric layer beneath the gate and high concentration of carriers in the two dimensional electron gas channel are the reasons of higher radiation resistance of GaN HEMTs. Their degradation then occurs at much higher doses due to electron mobility degradation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge

    Energy Technology Data Exchange (ETDEWEB)

    Inaoka, Takeshi, E-mail: inaoka@phys.u-ryukyu.ac.jp; Furukawa, Takuro; Toma, Ryo; Yanagisawa, Susumu [Department of Physics and Earth Sciences, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213 (Japan)

    2015-09-14

    By means of a hybrid density-functional method, we investigate the tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge. We consider [001], [111], and [110] uniaxial tensility and (001), (111), and (110) biaxial tensility. Under the condition of no normal stress, we determine both normal compression and internal strain, namely, relative displacement of two atoms in the primitive unit cell, by minimizing the total energy. We identify those strain types which can induce the band-gap transition, and evaluate the critical strain coefficient where the gap transition occurs. Either normal compression or internal strain operates unfavorably to induce the gap transition, which raises the critical strain coefficient or even blocks the transition. We also examine how each type of tensile strain decreases the band-gap energy, depending on its orientation. Our analysis clearly shows that synergistic operation of strain orientation and band anisotropy has a great influence on the gap transition and the gap energy.

  20. Performance Configuration of Raman-EDFA Hybrid Optical Amplifier for WDM Applications

    Science.gov (United States)

    Saidin, N.; Taib, N. I. A.; Abidin, M. S. Z.; Hasbullah, N. F.; Ralib, A. A. M.

    2017-06-01

    A hybrid configuration of Raman amplifier and erbium-doped fiber amplifier (EDFA) is proposed to obtain a better performance in term of gain, noise figure and flat gain. It is based on the optimum parameter configuration of a singly-based Raman amplifier and EDFA. The best parameter for both amplification has been analyze in terms of its input signal power, pump power and their fiber length whereas the best erbium ion density has also been analyze in EDFA setup. All the parameters are varied to some values to get the optimum result. The simulation is done by using Optisystem 14.0 software. The hybrid amplifier consists of Raman amplifier with multi-pump power set up and bidirectional pump power of EDFA with the pump wavelength of 980 nm is designed and simulated in order to obtain higher gain and lower noise figure. From the simulation of the hybrid configuration, the optimum output has been achieved. The hybrid configurations exhibit the average gain of 46 dB and average noise figure of 3 dB. The flat gain obtained is between 1530 nm to 1600 nm which include C-Band and L-Band frequency with the gain bandwidth of 70 nm.

  1. A system for biasing a differential amplifier

    International Nuclear Information System (INIS)

    Barbier, Daniel; Ittel, J.M.; Poujois, Robert

    1975-01-01

    This invention concerns a system for biasing a differential amplifier. It particularly applies to the integrated differential amplifiers designed with MOS field effect transistors. Variations in the technological parameters may well cause the amplifying transistors to work outside their usual operational area, in other words outside the linear part of the transfer characteristic. To ensure that these transistors function correctly, it is necessary that the value of the voltage difference at the output be equally null. To do this and to centre on the so called 'rest' point of the amplifier transfer charateristic, the condition will be set that the output potentials of each amplifier transistor should have a zero value or a constant value as sum. With this in view, the bias on the source (generally a transistor powered by its grid bias voltage) supplying current to the two amplifying transistors fitted in parallel, is permanently adjusted in a suitable manner [fr

  2. An Implantable CMOS Amplifier for Nerve Signals

    DEFF Research Database (Denmark)

    Nielsen, Jannik Hammel; Lehmann, Torsten

    2001-01-01

    on the amplifier input nodes. The method for signal recovery from noisy nerve signals is presented. A prototype amplifier is realized in a standard digital 0.5 μm CMOS single poly, n-well process. The prototype amplifier features a gain of 80 dB over a 3.6 kHz bandwidth, a CMRR of more than 87 dB and a PSRR......In this paper, a low noise high gain CMOS amplifier for minute nerve signals is presented. By using a mixture of weak- and strong inversion transistors, optimal noise suppression in the amplifier is achieved. A continuous-time offset-compensation technique is utilized in order to minimize impact...... greater than 84 dB. The equivalent input referred noise in the bandwidth of interest is 5 nV/√Hz. The amplifier power consumption is 275 μW....

  3. Amplified CWDM-based Next Generation Broadband Access Networks

    Science.gov (United States)

    Peiris, Sasanthi Chamarika

    The explosive growth of both fixed and mobile data-centric traffic along with the inevitable trend towards all-IP/Ethernet transport protocols and packet switched networks will ultimately lead to an all-packet-based converged fixed-mobile optical transport network from the core all the way out to the access network. To address the increasing capacity and speed requirements in the access networks, Wavelength-Division Multiplexed (WDM) and/or Coarse WDM (CWDM)-based Passive Optical Networks (PONs) are expected to emerge as the next-generation optical access infrastructures. However, due to several techno-economic hurdles, CWDM-PONs are still considered an expensive solution and have not yet made any significant inroads into the current access area. One of the key technology hurdles is the scalability of the CWDM-based PONs. Passive component optical insertion losses limit the reach of the network or the number of served optical network units (ONUs). In the recent years, optical amplified CWDM approaches have emerged and new designs of optical amplifiers have been proposed and demonstrated. The critical design parameter for these amplifiers is the very wide optical amplification bandwidth (e.g., 340 nm combined for both directions). The objective of this PhD dissertation work is first to engineer ring and tree-ring based PON architectures that can achieve longer unamplified PON reach and/or provide service to a greater number of ONUs and customers. Secondly is to develop new novel optical amplifier schemes to further address the scalability limitation of the CWDM-based PONs. Specifically, this work proposes and develops novel ultra wide-band hybrid Raman-Optical parametric amplifier (HROPA) schemes that operate over nearly the entire specified CWDM band to provide 340 nm bidirectional optical gain bandwidth over the amplified PON's downstream and upstream CWDM wavelength bands (about 170 nm in each direction). The performance of the proposed HROPA schemes is assessed

  4. Transverse pumped laser amplifier architecture

    Science.gov (United States)

    Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary

    2013-07-09

    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  5. Monitoring the Wobbe Index of Natural Gas Using Fiber-Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Vincenz Sandfort

    2017-11-01

    Full Text Available The fast and reliable analysis of the natural gas composition requires the simultaneous quantification of numerous gaseous components. To this end, fiber-enhanced Raman spectroscopy is a powerful tool to detect most components in a single measurement using a single laser source. However, practical issues such as detection limit, gas exchange time and background Raman signals from the fiber material still pose obstacles to utilizing the scheme in real-world settings. This paper compares the performance of two types of hollow-core photonic crystal fiber (PCF, namely photonic bandgap PCF and kagomé-style PCF, and assesses their potential for online determination of the Wobbe index. In contrast to bandgap PCF, kagomé-PCF allows for reliable detection of Raman-scattered photons even below 1200 cm−1, which in turn enables fast and comprehensive assessment of the natural gas quality of arbitrary mixtures.

  6. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper

    2013-01-01

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump...... wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode...... area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions....

  7. Silicon Germanium Cryogenic Low Noise Amplifiers

    Science.gov (United States)

    Bardin, J. C.; Montazeri, S.; Chang, Su-Wei

    2017-05-01

    Silicon germanium heterojunction bipolar transistors have emerged in the last decade as an excellent option for use in cryogenic low noise amplifiers. This paper begins with a review of the critical developments that have led to today’s cryogenic low noise amplifiers. Next, recent work focused on minimizing the power consumption of SiGe cryogenic amplifiers is presented. Finally, open issues related to the cryogenic noise properties of SiGe HBTs are discussed.

  8. Short Rayleigh Range Free Electron Laser Amplifiers

    CERN Document Server

    Yu, L H; Murphy, J B; Rose, J; Shaftan, T V; Wang, X J; Watanabe, T

    2005-01-01

    An important requirement for a high average power laser system is a manageable power density on the first optical element. One possibility to achieve this is a single pass amplifier which generates a short Rayleigh range (SRL) light beam. We present design parameters and calculated performances for several SRL configurations. These include a simulation of the optically guided (pinched) MW class FEL [1], the scalloped beam FEL amplifier [2] and high gain TOK amplifiers we propose to explore at our SDL facility.

  9. Analysis of DWDM System Using DPSK Modulation Technique with Raman-EDFA Hybrid Optical Amplifier

    Science.gov (United States)

    Gill, Manveer Singh; Dewra, Sanjeev

    2017-12-01

    This paper evaluates the performance of differential phase shift keying (DPSK) optical system based on Raman-erbium-doped fiber amplifier (EDFA) hybrid optical amplifier (HOA) is obtained at 64×20 Gbps with 0.1 THz channel spacing. A DPSK signal with bit rate of 20 Gbps is transmitted up to 210 km at 0 dBm signal input power and up to 166 km at -10 dBm signal input power with acceptable quality factor and bit error rate (BER). It is also found that the transmission distance up to 264 km has been covered at 10 dBm signal input power using Raman-EDFA HOA.

  10. Reflection amplifiers in self-regulated learning

    NARCIS (Netherlands)

    Verpoorten, Dominique

    2012-01-01

    Verpoorten, D. (2012). Reflection amplifiers in self-regulated learning. Doctoral thesis. November, 9, 2012, Heerlen, The Netherlands: Open Universiteit (CELSTEC). Datawyse / Universitaire Pers Maastricht.

  11. Ultra-large bandwidth hollow-core guiding in all-silica bragg fibers with nano-supports

    DEFF Research Database (Denmark)

    Vienne, Guillaume; Xu, Yong; Jakobsen, Christian

    2004-01-01

    We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding...

  12. 7-cell core hollow-core photonic crystal fibers with low loss in the spectral region around 2 mu m

    DEFF Research Database (Denmark)

    Lyngsøe, Jens Kristian; Mangan, B.J.; Jakobsen, C.

    2009-01-01

    Several 7 cell core hollow-core photonic crystal fibers with bandgaps in the spectral range of 1.4 μm to 2.3 μm have been fabricated. The transmission loss follows the ≈ λ−3 dependency previously reported, with a minimum measured loss of 9.5 dB/km at 1.99 μm. One fiber with a transmission loss...

  13. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

  14. Multi-cavity locally resonant structure with the low frequency and broad band-gaps

    Directory of Open Access Journals (Sweden)

    Jiulong Jiang

    2016-11-01

    Full Text Available A multi-cavity periodic structure with the characteristic of local resonance was proposed in the paper. The low frequency band-gap structure was comparatively analyzed by the finite element method (FEM and electric circuit analogy (ECA. Low frequency band-gap can be opened through the dual influence of the coupling’s resonance in the cavity and the interaction among the couplings between structures. Finally, the influence of the structural factors on the band-gap was analyzed. The results show that the structure, which is divided into three parts equally, has a broader effective band-gap below the frequency of 200 Hz. It is also proved that reducing the interval between unit structures can increase the intensity of the couplings among the structures. And in this way, the width of band-gap would be expanded significantly. Through the parameters adjustment, the structure enjoys a satisfied sound insulation effect below the frequency of 500Hz. In the area of low frequency noise reduction, the structure has a lot of potential applications.

  15. Distributed feedback laser amplifiers combining the functions of amplifiers and channel filters

    DEFF Research Database (Denmark)

    Wang, Z.; Durhuus, T.; Mikkelsen, Benny

    1994-01-01

    A dynamic model for distributed feedback amplifiers, including the mode coupled equations and the carrier rate equation, is established. The presented mode coupled equations have taken into account the interaction between fast changing optical signal and the waveguide with corrugations. By showin...... the possibility of amplifying 100 ps pulses without pulse broadening, we anticipate that a distributed feedback amplifier can be used as a combined amplifier and channel filter in high bit rate transmission systems....

  16. Design and development of a spectroscopy amplifier

    International Nuclear Information System (INIS)

    Ahmad, N.; Khalaf, M.A.

    1998-01-01

    Spectroscopy amplifier is an integral part of my detection system used for the measurement and spectroscopy of nuclear radiations. Its performance determination the contribution of the electronics to the energy resolution of the system. A spectroscopy amplifier has been designed and developed using locally available components. The design and description of this unit is discussed in this article. (author)

  17. Bevalac injector final stage RF amplifier upgrades

    International Nuclear Information System (INIS)

    Howard, D.; Calvert, J.; Dwinell, R.; Lax, J.; Lindner, A.; Richter, R.; Ridgeway, W.

    1991-01-01

    With the assistance of the DOE In-house Energy Management Program, the Bevalac injector final stage RF amplifier systems have been successfully upgraded to reduce energy consumption and operating costs. This recently completed project removed the energy-inefficient plate voltage modulator circuits that were used in conjunction with the final stage RF amplifiers. Construction, design, and operating parameters are described in detail

  18. BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER

    DEFF Research Database (Denmark)

    2010-01-01

    Broadband travelling wave semiconductor optical amplifier (100, 200, 300, 400, 800) for amplification of light, wherein the amplifier (100, 200, 300, 400, 800) comprises a waveguide region (101, 201, 301, 401, 801) for providing confinement of the light in transverse directions and adapted...

  19. A CMOS current-mode operational amplifier

    DEFF Research Database (Denmark)

    Kaulberg, Thomas

    1993-01-01

    A fully differential-input, differential-output, current-mode operational amplifier (COA) is described. The amplifier utilizes three second-generation current conveyors (CCIIs) as the basic building blocks. It can be configured to provide either a constant gain-bandwidth product in a fully balanc...

  20. Enhanced Gain in Photonic Crystal Amplifiers

    DEFF Research Database (Denmark)

    Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann

    2012-01-01

    We experimentally demonstrate enhanced gain in the slow-light regime of quantum well photonic crystal amplifiers. A strong gain enhancement is observed with the increase of the group refractive index, due to light slow-down. The slow light enhancement is shown in a amplified spontaneous emission...

  1. High Average Power Optical FEL Amplifiers

    CERN Document Server

    Ben-Zvi, I; Litvinenko, V

    2005-01-01

    Historically, the first demonstration of the FEL was in an amplifier configuration at Stanford University. There were other notable instances of amplifying a seed laser, such as the LLNL amplifier and the BNL ATF High-Gain Harmonic Generation FEL. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance a 100 kW average power FEL. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting energy recovery linacs combine well with the high-gain FEL amplifier to produce unprecedented average power FELs with some advantages. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Li...

  2. An Implantable CMOS Amplifier for Nerve Signals

    DEFF Research Database (Denmark)

    Nielsen, Jannik Hammel; Lehmann, Torsten

    2003-01-01

    . A continuous-time current-steering offset-compensation technique is utilized in order to minimize the noise contribution and to minimize dynamic impact on the amplifier input nodes. The method for signal recovery from noisy nerve signals is presented. A prototype amplifier is realized in a standard digital 0...

  3. Detection of Non-Amplified Genomic DNA

    CERN Document Server

    Corradini, Roberto

    2012-01-01

    This book offers a state-of-the-art overview on non amplified DNA detection methods and provides chemists, biochemists, biotechnologists and material scientists with an introduction to these methods. In fact all these fields have dedicated resources to the problem of nucleic acid detection, each contributing with their own specific methods and concepts. This book will explain the basic principles of the different non amplified DNA detection methods available, highlighting their respective advantages and limitations. The importance of non-amplified DNA sequencing technologies will be also discussed. Non-amplified DNA detection can be achieved by adopting different techniques. Such techniques have allowed the commercialization of innovative platforms for DNA detection that are expected to break into the DNA diagnostics market. The enhanced sensitivity required for the detection of non amplified genomic DNA has prompted new strategies that can achieve ultrasensitivity by combining specific materials with specifi...

  4. Dual-range linearized transimpedance amplifier system

    Science.gov (United States)

    Wessendorf, Kurt O.

    2010-11-02

    A transimpedance amplifier system is disclosed which simultaneously generates a low-gain output signal and a high-gain output signal from an input current signal using a single transimpedance amplifier having two different feedback loops with different amplification factors to generate two different output voltage signals. One of the feedback loops includes a resistor, and the other feedback loop includes another resistor in series with one or more diodes. The transimpedance amplifier system includes a signal linearizer to linearize one or both of the low- and high-gain output signals by scaling and adding the two output voltage signals from the transimpedance amplifier. The signal linearizer can be formed either as an analog device using one or two summing amplifiers, or alternately can be formed as a digital device using two analog-to-digital converters and a digital signal processor (e.g. a microprocessor or a computer).

  5. Ultrafast disk lasers and amplifiers

    Science.gov (United States)

    Sutter, Dirk H.; Kleinbauer, Jochen; Bauer, Dominik; Wolf, Martin; Tan, Chuong; Gebs, Raphael; Budnicki, Aleksander; Wagenblast, Philipp; Weiler, Sascha

    2012-03-01

    Disk lasers with multi-kW continuous wave (CW) output power are widely used in manufacturing, primarily for cutting and welding applications, notably in the automotive industry. The ytterbium disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency, and high reliability with low investment and operating costs. Fundamental mode picosecond disk lasers are well established in micro machining at high throughput and perfect precision. Following the world's first market introduction of industrial grade 50 W picosecond lasers (TruMicro 5050) at the Photonics West 2008, the second generation of the TruMicro series 5000 now provides twice the average power (100 W at 1030 nm, or 60 W frequency doubled, green output) at a significantly reduced footprint. Mode-locked disk oscillators achieve by far the highest average power of any unamplified lasers, significantly exceeding the 100 W level in laboratory set-ups. With robust long resonators their multi-microjoule pulse energies begin to compete with typical ultrafast amplifiers. In addition, significant interest in disk technology has recently come from the extreme light laser community, aiming for ultra-high peak powers of petawatts and beyond.

  6. Effects of weak nonlinearity on dispersion relations and frequency band-gaps of periodic structures

    DEFF Research Database (Denmark)

    Sorokin, Vladislav; Thomsen, Jon Juel

    2015-01-01

    The analysis of the behaviour of linear periodic structures can be traced back over 300 years, to Sir Isaac Newton, and still attracts much attention. An essential feature of periodic struc-tures is the presence of frequency band-gaps, i.e. frequency ranges in which waves cannot propagate....... Determination of band-gaps and the corresponding attenuation levels is an im-portant practical problem. Most existing analytical methods in the field are based on Floquet theory; e.g. this holds for the classical Hill’s method of infinite determinants, and the method of space-harmonics. However, application....... The present work deals with analytically predicting dynamic responses for nonlinear continuous elastic periodic structures. Specifically, the effects of weak nonlinearity on the dispersion re-lation and frequency band-gaps of a periodic Bernoulli-Euler beam performing bending os-cillations are analyzed...

  7. Electrical determination of the bandgap energies of the emitter and base regions of bipolar junction transistors

    Science.gov (United States)

    Mimila-Arroyo, J.

    2016-10-01

    A pure electrical method is presented to extract emitter and base bandgaps of a bipolar junction transistor (BJT) at the locations where the minority carrier injection takes place. It is based on the simultaneous measurement of the collector and base currents as a function of the emitter-base forward bias (Gummer plot) and the corresponding current gain. From the obtained saturation currents as a function of temperature, we extract the bandgap energies. The accuracy of the method is demonstrated for InGaP-GaAs, Si, and Ge commercial devices. For InGaP-GaAs transistors, the results can be understood if the emitter-base heterojunction is not an abrupt but a gradual one. The presented method is a reliable tool that can aid in the development of new compound semiconductor based BJTs whose bandgap energies are highly sensitive to their composition.

  8. Numerical simulation of the limiting efficiency of the graded bandgap solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Rafat, N.H. [Department of Mathematics and Engineering Physics, Faculty of Engineering, Cairo University, Giza (Egypt); Abdel Haleem, A.M. [Department of Mathematics and Engineering Physics, Faculty of Engineering, El Fayoum University, El Fayoum (Egypt); Habib, S.E.-D. [Electronics and Communication Department, Faculty of Engineering, Cairo University, Giza (Egypt)

    2007-01-15

    The limiting efficiency of the compositionally graded bandgap solar cell is calculated using a 1-D numerical simulator. Our simulator calculates the limiting efficiency by solving the coupled semiconductor equations, namely, Poisson's equation, the current continuity equations, together with the Boltzmann photon equation, rather than the detailed balance equations that are usually used in such calculations. The non-avoidable radiative and Auger bulk losses are the only losses considered in the calculations. The effect of photon recycling on the cell's parameters is included in the calculations of radiative recombination rates. We verified numerically that bandgap grading, under optimum profile, increases the limiting efficiency of the solar cell, over the previously published values. The effect of the bandgap grading on desensitizing the surface of the cell is discussed. (author)

  9. Composite media mixing Bragg and local resonances for highly attenuating and broad bandgaps.

    Science.gov (United States)

    Kaina, Nadège; Fink, Mathias; Lerosey, Geoffroy

    2013-11-19

    In this article, we investigate composite media which present both a local resonance and a periodic structure. We numerically and experimentally consider the case of a very academic and simplified system that is a quasi-one dimensional split ring resonator medium. We modify its periodicity to shift the position of the Bragg bandgap relative to the local resonance one. We observe that for a well-chosen lattice constant, the local resonance frequency matches the Bragg frequency thus opening a single bandgap which is at the same time very wide and strongly attenuating. We explain this interesting phenomenon by the dispersive nature of the unit cell of the medium, using an analogy with the concept of white light cavities. Our results provide new ways to design wide and efficient bandgap materials.

  10. High Average Power, High Energy Short Pulse Fiber Laser System

    Energy Technology Data Exchange (ETDEWEB)

    Messerly, M J

    2007-11-13

    Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.

  11. Influence of interface preparation on minority carrier lifetime for low bandgap tandem solar cell materials

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, Nadine; Sagol, B. Erol; Seidel, Ulf; Schwarzburg, Klaus; Hannappel, Thomas [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany)

    2010-07-01

    III-V semiconductor compounds grown by MOVPE are implemented in todays state-of-the-art third generation multi-junction solar cells. The current record multi junction solar cell grown on germanium, having Ge, Ga(In)As and GaInP as subcells, reached a record efficiency of 41.6%. The efficiency of these multi junction solar cells could be significantly increased, if its low bandgap Ge subcell would be replaced by a more efficient tandem. For this purpose the low bandgap materials InGaAs and InGaAsP are suitable. The bandgap composition of these materials allows a better yield of the solar spectrum. Based on InGaAs/InGaAsP absorber materials we have developed a low bandgap tandem solar cell with optimized bandgaps. Results of time resolved photoluminescence (TRPL) for the IR-bandgap compounds InGaAsP (1.03 eV)/InGaAs (0.73 eV) are presented. The lifetime of minority carriers is one of the most important properties of solar cell absorber materials. We show on the example of the low band gap tandem cell how the choice of the materials, the quality of the bulk, the optimization of the band gap energies and the preparation of the critical interfaces are essential to build a high efficiency solar cell. The quality of the bulk and the preparation of the critical interfaces are essential for the growth of the double heterostructure (DHS).

  12. Optical Characterization of Doped Thermoplastic and Thermosetting Polymer-Optical-Fibers

    Directory of Open Access Journals (Sweden)

    Igor Ayesta

    2017-03-01

    Full Text Available The emission properties of a graded-index thermoplastic polymer optical fiber and a step-index thermosetting one, both doped with rhodamine 6G, have been studied. The work includes a detailed analysis of the amplified spontaneous emission together with a study of the optical gains and losses of the fibers. The photostability of the emission of both types of fibers has also been investigated. Comparisons between the results of both doped polymer optical fibers are presented and discussed.

  13. New Light-Harvesting Materials Using Accurate and Efficient Bandgap Calculations

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio; Hüser, Falco; Pandey, Mohnish

    2014-01-01

    of materials for different applications where the bandgaps are used as descriptors for the efficiency of a photoelectrochemical device. Here, new light harvesting materials are proposed to be used in a one-photon photoelectrochemical device for water splitting by combining the estimation of the bandgaps...... with the stability analysis using Pourbaix diagrams and with the evaluation of the position of the band edges. Using this methodology, 25 candidate materials are obtained and 5 of them appear to have a realistic possibility of being used as photocatalyst in a one-photon water splitting device. © 2014 WILEY...

  14. Novel bandgap grading technique for enhancing the limiting efficiency of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Habib, S.E.-D.; Rafat, N.H. [Cairo Univ., Giza (Egypt). Faculty of Engineering

    1997-02-01

    The efficiency of solar cells is limited by radiative and/or Auger recombination losses. Radiative recombination can be reduced by limiting the escape angle of the re-emitted rays. Auger recombination can be reduced by limiting the cells` thickness. A novel technique for reducing the Auger recombination limit is proposed in this work. We show that bandgap grading can be effectively utilized to suppress the Auger recombination limit. The optimum bandgap grading profile that maximises the limiting efficiency for an idealized, one dimensional solar cell is hence calculated under AMO irradiation conditions. (author)

  15. Phasing a Dual Optical Path System Using an Optical Fiber as a Phase Conjugate Mirror

    National Research Council Canada - National Science Library

    Willis, Shawn

    2003-01-01

    Phase conjugation properties of stimulated Brillouin scattering (SBS) in a short multimode fiber have been investigated with an eye towards its application for a multi-channel double pass master oscillator power amplifier (MOPA) system...

  16. High-efficiency resonantly pumped 1550-nm fiber-based laser transmitter, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — nLight proposes the development of high efficiency, high average power 1550-nm laser transmitter system that is based on Er-doped fiber amplifier resonantly pumped...

  17. Spectroscopy and decay kinetics of Pr3+-doped chloride crystals for 1300-nm optical amplifiers

    International Nuclear Information System (INIS)

    Page, R.H.; Schaffers, K.I.; Wilke, G.D.

    1995-01-01

    Several Pr 3+ -doped chloride crystals have been tested spectroscopically for suitability as 1300-nm optical amplifiers operating on the 1 G 4 - 3 H 5 transition. 1 G 4 lifetimes are much longer than in fluoride hosts, ranging up to 1300 μsec and suggesting a near-unity luminescence quantum yield. Emission spectra are typically broad (FWHM ∼ 70 nm) and include the 1310-nm zero-dispersion wavelength of standard telecommunications fiber

  18. Design of a flat-top fiber Bragg filter via quasi-random modulation of the refractive index.

    Science.gov (United States)

    Derevyanko, Stanislav

    2008-10-15

    The statistics of the reflection spectrum of a short-correlated disordered fiber Bragg grating are studied. The averaged spectrum appears to be flat inside the bandgap and has significantly suppressed sidelobes compared to the uniform grating of the same bandwidth. This is due to the Anderson localization of the modes of a disordered grating. This observation prompts a new algorithm for designing passband reflection gratings. Using the stochastic invariant imbedding approach it is possible to obtain the probability distribution function for the random reflection coefficient inside the bandgap and obtain both the variance of the averaged reflectivity as well as the distribution of the time delay of the grating.

  19. Fundamentals of RF and microwave transistor amplifiers

    CERN Document Server

    Bahl, Inder J

    2009-01-01

    A Comprehensive and Up-to-Date Treatment of RF and Microwave Transistor Amplifiers This book provides state-of-the-art coverage of RF and microwave transistor amplifiers, including low-noise, narrowband, broadband, linear, high-power, high-efficiency, and high-voltage. Topics covered include modeling, analysis, design, packaging, and thermal and fabrication considerations. Through a unique integration of theory and practice, readers will learn to solve amplifier-related design problems ranging from matching networks to biasing and stability. More than 240 problems are included to help read

  20. Quantum electronics maser amplifiers and oscillators

    CERN Document Server

    Fain, V M; Sanders, J H

    2013-01-01

    Quantum Electronics, Volume 2: Maser Amplifiers and Oscillators deals with the experimental and theoretical aspects of maser amplifiers and oscillators which are based on the principles of quantum electronics. It shows how the concepts and equations used in quantum electronics follow from the basic principles of theoretical physics.Comprised of three chapters, this volume begins with a discussion on the elements of the theory of quantum oscillators and amplifiers working in the microwave region, along with the practical achievements in this field. Attention is paid to two-level paramagnetic ma