Abstract: A Raman fiber laser source (RFLS) is configured with a feeding fiber delivering MM pump radiation to an inner cladding of double-clad MM Raman fiber laser. The MM pump radiation has a sufficient power to produce Raman scattering in the MM Raman fiber converting the pump radiation to a MM signal radiation at a Raman-shifted wavelength ?ram which is longer than a wavelength ?pump of the pump radiation. The RFLS further has a pair of spaced reflectors defining therebetween a resonator for the signal radiation at a 1st Stokes wavelength and flanking at least part of the MM core of the Raman fiber which is provided with a central core region which is doped with impurities for enhancing Raman process. The reflectors and central core region are dimensioned to correspond to the fundamental mode of the MM signal radiation.

Abstract: A terahertz full-polarization-state detection spectrograph is provided, which comprises a terahertz wave generator, a polarizer, a polarizing beam-splitting sheet, a horizontal terahertz detector, and a vertical terahertz detector. The terahertz wave generator produces a terahertz wave, and the purity of the terahertz wave is optimized by the polarizer; a detected sample modulates the terahertz wave, the purity of which is optimized, to obtain a terahertz modulated wave; the polarizing beam-splitting sheet decomposes the terahertz modulated wave into a horizontal terahertz wave and a vertical terahertz wave which are vertical to each other in a polarization state; the two corresponding terahertz detectors are used for detecting the two terahertz waves respectively, and then the characteristics of the detected sample are analyzed according to the detection result.

Abstract: In an example, an apparatus to tandem pump a fiber laser or fiber amplifier may include a combiner; a power amplifier or a power oscillator, or a combination thereof, coupled to an output of the combiner; a seed laser to output light to the power amplifier or the power oscillator, or the combination thereof, via the combiner; and a tandem pump to generate light of a pump source signal, wherein the light of the pump source signal is output to the combiner to cladding pump the power amplifier or the power oscillator, or the combination thereof. Other embodiments may be disclosed and/or claimed.

Abstract: The present application provides an optical system. The optical system includes a fiber amplifier with an optically active doped fiber, a source of seed pulses, and a pump source. The doped fiber is doped with one or more active element(s) selected such that the seed pulses are amplified in intensity. The doped fiber has a negative (anomalous) group velocity dispersion in the region from the wavelength of the seed pulses to a threshold wavelength at which the magnitude of the optical loss of the doped fiber is greater than a gain due to stimulated Raman scattering.

Abstract: In some embodiments, an optical transmission system includes a few-mode fiber that supports at least 2 spatial modes but no more than 50 spatial modes.

Abstract: System for converting relatively long pulses from rep-rate variable ultrafast optical sources to shorter, high-energy pulses suitable for sources in high-energy ultrafast lasers. Fibers with positive group velocity dispersion (GVD) and self phase modulation are advantageously employed with the optical sources. These systems take advantage of the need for higher pulse energies at lower repetition rates so that such sources can be cost effective.

Abstract: A supercontinuum generation system comprises a noise-like pulse fiber laser structure, an amplification unit and a broadening medium. The noise-like pulse fiber laser structure generates at lease one noise-like pulse of the wavelength less than 1300 nm. The amplification unit includes a gain fiber with which the noise-like pulse is coupled. The broadening medium is coupled with the gain fiber. A supercontinuum is generated when the noise-like pulse is amplified by the amplification unit and broadened in spectrum by the broadening medium.

Abstract: A peak value detector detects power of an output light pulse which is output from the light amplifying fiber. A light receiving element receives a group of light pulses including a plurality of pulses and converts the group of light pulses into a current signal. The current/voltage converter circuit converts the current output from the light receiving element to voltage. The integration circuit integrates the voltage output from the current/voltage converter circuit. A programmable gain amplifier (PGA) amplifies the signal output from the integration circuit and provides the signal for the A/D converter circuit. The gain of the PGA is set by a gain setting signal from the signal processing circuit. The signal processing circuit adjusts the gain of the PGA so that the gain increases as the repetition frequency of the group of pulses increases.

Abstract: Stimulating emission via thulium's lasing transition from the 3H4 manifold to the 3H6 manifold yields light at wavelength of about 820 nm. Unfortunately, excited thulium ions also transition from the 3H4 manifold to the long-lived 3F4 manifold, where they become trapped and can no longer participate in the lasing transition. If the enough of the thulium population becomes trapped in the 3F4 manifold, the gain medium becomes transparent at the pump wavelength, rendering population inversion difficult or impossible. Fortunately, the size of the population in the 3F4 manifold can be limited by selecting an appropriate crystal host and thulium doping concentration, pumping the thulium with pulses shorter than the 3F4 manifold's lifetime, cooling the gain medium to low temperature (e.g., 77 K), stimulating emission from the 3F4 manifold, upconversion pumping of the thulium from the 3F4 manifold to the 3H4 manifold, or transferring energy from thulium in the 3F4 manifold to a co-dopant.

Abstract: An optical pumping apparatus for few-mode fiber amplification is provided. The optical pumping apparatus includes an optical pump source configured to generate an optical pump; an optical power divider configured to divide an optical power of the optical pump from the optical pump source so as to output several optical pumps with uniformly distributed optical power; and a modal multiplexer configured to receive the optical pumps from the optical power divider through a plurality of single-mode fibers, multiplex the received optical pumps, apply a multiplexed optical pump to each mode of a few-mode fiber (FMF) amplifier, and adjust a gain difference among modes, wherein the FMF amplifier obtains a gain by amplifying an optical signal with the optical pump.

Abstract: An optical amplifier includes: a temperature-adjustment-unit that is provided in a wavelength-fixing-unit that fixes a center-wavelength of an excitation-light-source, and adjusts a temperature of the wavelength-fixing-unit, which causes the center-wavelength of the excitation-light-source to vary; a temperature-measurement-unit that measures the temperature of the wavelength-fixing-unit and a temperature of a gain-equalization-unit that equalizes gains of the signal-light on which the Raman amplification is performed using the excitation-light-source; a shift-amount-obtaining-unit that obtains a shift amount data of the center-wavelength of the excitation-light-source from a first-storage-unit and obtains a shift amount of the center-wavelength of the wavelength-band from a second-storage-unit; and a control unit that obtains a temperature-data of the-wavelength-fixing-unit, which corresponds to a difference between two shift amounts that are obtained by the shift amount obtaining unit, from the first-storag

Abstract: A high-power pulse light generator includes: a master oscillator generating oscillated pulse light in synchronization with a master clock signal; an optical amplifier amplifying the oscillated pulse light output from the master oscillator and outputting high-power pulsed light; a driving unit driving a pumping semiconductor laser in synchronization with the master clock signal; and a control unit controlling the driving unit so that the driving current to be supplied to the pumping semiconductor laser becomes lower than or equal to a set value at which the pumping semiconductor laser is not in a laser oscillation state when returning light from an irradiated body with the high-power pulsed light reaches the pumping semiconductor laser connected to the optical amplifier, the control unit determining a timing of the control in accordance with an optical path length between the irradiated body and the pumping semiconductor laser.

Abstract: An optical fiber coupler connects transmission multicore optical fiber (TMCF) with an amplifier multicore optical fiber (AMCF) and a plurality of optical pump fibers. The coupler includes a plurality of signal cores extending between a multicore input endface and a coupler output endface, and a plurality of pump cores extending between a pump input and the coupler output endface. The multicore input endface is connectable to the TMCF, and the pump input is connectable to the optical pump fibers. Each pump core is paired with a corresponding signal core to form a core pair that is adiabatically tapered such that signal light carried by the signal core is combined with pump light carried by the pump core. The coupler output endface is connectable to the AMCF such that the combined light output of each core pair is provided as an input to a respective AMCF core.

Abstract: The invention can include an apparatus for producing optical pulses, comprising an oscillator for producing optical pulses at a first optical pulse repetition frequency, the optical pulses having a first wavelength; a first optical fiber amplifier; a second optical fiber amplifier; a pulse picker located between the first and second optical fiber amplifiers, the pulse picker operable to reduce the optical pulse repetition frequency of optical pulses, wherein the first amplifier amplifies optical pulses at the first optical pulse repetition frequency and the second amplifier amplifies optical pulses at a reduced optical pulse repetition frequency that is less than the first optical pulse repetition frequency; a nonlinear optical fiber receiving amplified optical pulses having the reduced optical pulse repetition frequency and the first wavelength to produce, at the reduced optical pulse frequency, optical pulses that include one or more nonlinearly produced wavelengths different than the first wavelength; and

Abstract: An amplifying optical fiber includes a core containing oxides of elements selected from the group consisting of silicon, germanium, phosphorus, bismuth, aluminum, gallium with a concentration of bismuth oxide of 10-4-5 mol %, a total concentration of silicon and germanium oxides of 70-99.8999 mol %, a total concentration of aluminum and gallium oxides of 0.1-20 mol % wherein both aluminum and gallium oxide are present and a ratio of aluminum oxide to gallium oxide is at least two, and a concentration of phosphorus oxide from 0 to 10 mol %, and provides a maximum optical gain at least 10 times greater than the nonresonant loss factor in the optical fiber. An outside oxide glass cladding comprises fused silica. The core has an absorption band in the 1000 nm region, pumping to which region provides an increased efficiency of power conversion of pump light into luminescence light in the 1000-1700 nm range.

Abstract: An optical amplifier includes a rare-earth doped optical fiber for receiving input light through one end and outputting output light through another end, the input light being input from an input port; an excitation light source for generating excitation light; an optical coupler for supplying the generated excitation light to the one end and/or the another end of the rare-earth doped optical fiber; and a reflector for reflecting an amplified spontaneous emission light out of a signal band traveling in opposite direction to the input light, the amplified spontaneous emission light being generated in the rare-earth doped optical fiber.

Abstract: A very large more area active double clad optical waveguide doped with Nd3+ at a concentration of at least 0.1% by weight can be used to effectively amplify light at a wavelength of between 1050 nm and 1120 nm. At a doping concentration sufficient to provide a net optical absorption of at least 3 dB/m for the pump light at the wavelength of 795 to 815 nm or 883 to 887 nm, Nd3+ operates under much lower inversion levels than Yb3+. Due to the lower inversion levels, the Nd3+ doped waveguide is subject to reduced pump bleaching or photodarkening.

Abstract: A Raman amplifier includes at least a first and a second optical Raman-active fiber disposed in series with each other. A first pump source is connected to the first Raman-active fiber, and is adapted for emitting and coupling into the first Raman-active fiber a first pump radiation including a first group of frequencies. A second pump source is connected to the second Raman-active fiber, and is adapted for emitting and coupling into the second Raman-active fiber a second pump radiation including a second group of frequencies. The whole of said first and second group of frequencies extends over a pump frequency range having a width of at least the 40% of the Raman shift. The minimum and the maximum frequency in each of said first and second group of frequencies differ with each other of at most the 70% of said Raman shift.

Abstract: The alteration of the bandwidth of an optical amplifier. Before alteration, optical signals having a first set of wavelengths are provided through a gain medium of the optical amplifier. In addition, a first pump having a set of pump wavelengths is propagated through the gain medium to thereby amplify the optical signals. After alteration, optical signals having at least a partially different set of wavelengths are able to be optically amplified by coupling a second pump into the optical medium. The second pump is at least partially distinct from the first pump in that the second pump includes at least one pump wavelength that was not included in the first pump.

Abstract: A modulator includes an electro-optical substrate and a first and second waveguide formed of a doped semiconductor material positioned on a surface of an electro-optical substrate forming a slot therebetween. A doping level of the semiconductor material being chosen to make the first and second waveguide conductive. A dielectric material is positioned in the slot which increases confinement of both an optical field and an electrical field inside the slot. A refractive index of the semiconductor material and a refractive index of the dielectric material positioned in the slot being chosen to reduce the V?·L product of the modulator.

Abstract: An apparatus and that provide an optical-fiber amplifier having at least one erbium-doped fiber section and an optical pump coupled to the erbium-doped fiber section, wherein the apparatus is operable to amplify signal pulses to high energy in the erbium-doped fiber section, the pulses having a wavelength in the range of about 1565 nm to about 1630 nm. In some embodiments, the amplifying fiber is ytterbium free.

Abstract: A Raman amplifier comprises at least a first and a second optical Raman-active fiber disposed in series with each other. A first pump source is connected to the first Raman-active fiber, and is adapted for emitting and coupling into the first Raman-active fiber a first pump radiation including a first group of frequencies. A second pump source is connected to the second Raman-active fiber, and is adapted for emitting and coupling into the second Raman-active fiber a second pump radiation including a second group of frequencies. The whole of said first and second group of frequencies extends over a pump frequency range having a width of at least the 40% of the Raman shift. The minimum and the maximum frequency in each of said first and second group of frequencies differ with each other of at most the 70% of said Raman shift.

Abstract: A Raman amplifier includes a pumping light source, an optical coupler, and a Raman amplifier medium. The pumping light source outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz. The optical coupler couples the pumping light with a carrier light. The Raman amplification medium is pumped by the pumping light to amplify the carrier light. The Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light.

Abstract: The invention is directed to a high power short optical pulse source 10 comprising a master oscillator 12 and a Ytterbium doped fibre amplifier (YDFA) preamplifier 14, a pump light source 16, an optical head 18, high power optical fibre amplifier means 20, an optical signal delivery fibre 22, and a pump light delivery fibre 24. The master oscillator 12, preamplifier 14, and pump laser 16, together with their associated drive and control electronics, and cooling systems, are provided within a first enclosure 28 at a first location. The high power fibre amplifier means 20 comprises a Ytterbium doped amplifier fibre and a pump signal combiner. The high power fibre amplifier means 20 is provided within the optical head 18, which is located at a second location, remote from the first location. The optical head 18 has a small footprint and can be positioned at the intended target of the optical pulses.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Peak power handling capability of the fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers.

Abstract: The present invention relates to an optical amplifier provided with a plurality of optically cascade-connected amplification units and also with a structure for enabling suppression of transient gain variations as a whole. Each of the plurality of amplification units in the optical amplifier has a pumping light source and an amplifying optical fiber, and at least one selected from the plurality of amplification units includes a timing adjustment system for temporally moving back or forth the variation timing of pumping light power accompanying the signal light power variation due to the variation of the number of signal channels, with respect to the variation timing of signal light power at a light incident end of the amplifying optical fiber contained in the own amplification unit.

Abstract: A reliable optical transmission system with an improved signal control mechanism that avoids abrupt power variations of light beams, thereby preventing optical supervisory channel (OSC) signals from experiencing errors. An optical amplifier amplifies main signals under the control of an optical amplifier controller, which spends a first predetermined time to raise the output power of the optical amplifier up to a desired level. A pump light source produces a pump beam for injection to a fiber-optic transmission line so as to make it serve as an amplifying medium. The pump light source is controlled by a pump light source controller that spends a second predetermined time to raise the pump beam to a desired power level. This stepwise start-up process of the amplifier power and pump beam power prevents OSC signals from experiencing abrupt power variations.

Abstract: The present invention relates to an optical amplification module having a construction which effectively suppresses photodarkening, and to a laser light source including the same. The laser light source comprises a light source for outputting light to be amplified, and an optical amplification module. The optical amplification module comprises two types of optical amplification media having different rare earth element concentrations, and a pumping light source. The low concentration medium and the high concentration medium are disposed in the propagation direction of pumping light such that the population inversion of the low concentration medium is higher than that of the high concentration medium.

Abstract: Provided is an optical fiber. The optical fiber includes a core and a cladding, the core containing a first element for inducing non-linear Raman phenomenon, and the cladding containing a second element which is a rare earth element, wherein when the optical fiber is pumped by two pumping light sources having different wavelengths with each other, the optical signals in the first and third band are Raman-amplified by the first element and the signals in the second band are amplified by a direct transition of the second element.

Abstract: Control of average wavelength-converted power and/or wavelength converted pulse energy is described. One or more seed pulses may be generated and amplified with an optical amplifier to produce one or more amplified pulses. The amplified pulses may be wavelength converted to produce one or more wavelength converted pulses characterized by an average wavelength-converted power or pulse energy. Wavelength-converted power or pulse energy may be controlled by adjusting wavelength conversion efficiency without substantially changing the amplified power or pulse energy. Average wavelength-converted power may be controlled over a time scale comparable to a pulse period of the amplified pulses without adjusting an average power of the amplified pulses over the time scale comparable to a pulse period of the amplified pulses.

Abstract: An erbium-doped (Er-doped) superfluorescent fiber source (SFS) has an enhanced mean wavelength stability. A method determines an estimated mean wavelength of a SFS. The method includes providing an Er-doped SFS having an actual mean wavelength. The method further includes configuring the SFS such that the actual mean wavelength has a dependence on the temperature of the EDF. The method further includes obtaining the dependence of the actual mean wavelength on the temperature of the EDF. The method further includes measuring the temperature of the EDF. The method further includes calculating the estimated mean wavelength using the measured temperature of the EDF and the dependence of the actual mean wavelength on the temperature of the EDF.

Abstract: A Raman amplifier having at least a first and a second optical Raman-active fiber disposed in series with each other is disclosed. A first pump source is connected to the first Raman-active fiber, and is adapted for emitting and coupling into the first Raman-active fiber a first pump radiation including a first group of frequencies. A second pump source is connected to the second Raman-active fiber, and is adapted for emitting and coupling into the second Raman-active fiber a second pump radiation including a second group of frequencies. The whole of the first and second group of frequencies extends over a pump frequency range having a width of at least 40% of the Raman shift. The minimum and the maximum frequency in each of the first and second group of frequencies differ from each other by at most 70% of the Raman shift.

Abstract: The device comprises an optical waveguide and an acoustic wave generating device. The waveguide has an optical band gap and a sharp electronic transition (e.g. an excitonic transition) in the band gap, and the acoustic wave generating device generates acoustic waves within the waveguide. Light passing through the waveguide is of a frequency within the band gap of the waveguide and is nearly resonant with the sharp electronic transition. The wave generating device is arranged to generate acoustic waves so as to induce optical band gas in the polariton spectrum, thereby affecting the transmission of the light passing through the waveguide, the transmission of which is thereby affected.

Abstract: An arrangement and method provide an optical thulium doped fiber amplifier utilizing a dual wavelength pumping scheme for amplifying an optical signal. The method includes the steps of: a first deposition (a) of energy into the fiber amplifier by pumping with radiation of a first wavelength; and a second deposition (b) of energy into the fiber amplifier by pumping with radiation of a second wavelength. The radiation of the first wavelength is arranged to induce, by single photon absorption, a population to the 3H4 level of the thulium dopant, and the radiation of the second wavelength primarily depopulates the 3F4 level, by excited absorption of a single photon, preferably by strong excited state absorption to the 3F2 level. The steps gives a population inversion between the 3H4 and the 3F4 levels and facilitate a power efficient high gain amplification.

Abstract: In a one-fiber bidirectional optical transmission system in which output optical signals of optical transmitter-receivers respectively connected to the opposite ends of one optical fiber transmission line are bidirectionally transmitted in the optical fiber transmission line, which utilizes a Raman amplification effect by backward pumping, a frequency satisfying the conditions of |fs1?f0|?|fp2?f0| and |fs2?f0|?|fp1?f0| is selected, where f0 is a zero dispersion frequency of the optical fiber transmission line, fs1 and fs2 are the frequencies of the first signal and the second signal, respectively, and fp1 and fp2 are frequencies of the first Raman pump light and the second Raman pump light, respectively.

Abstract: In a Raman optical amplification system in which WDM optical signals comprising two or more signal bands are transmitted in a transmission line, and in which a plurality of pumping lightwaves are introduced into said transmission line so that WDM optical signals in the shortest signal band are Raman-amplified by said plurality of pumping lightwaves, the interval between the longest pumping wavelength and the next-longest pumping wavelength differs by 0.2 to 1.4 THz in frequency. This makes it possible to flatten the level of the WDM signals by means of canceling the Raman gain ripple on the longer wavelength region of the distributed amplification.

Abstract: An optical module comprises a multiplexer for combining a signal and a pump radiation and having an output coupled to an optical fiber and a signal over the optical fiber with the pump lightwave that has a frequency three times of that of the signal and phase index equal to that of the signal. Phase matching between the pump and signal is realized for example by employing a microstructured optical fiber as the optical fiber.

Abstract: A source and/or method of generating quantum-correlated and/or entangled photon pairs using parametric fluorescence in a fiber Sagnac loop. The photon pairs are generated in the 1550 nm fiber-optic communication band and detected by a detection system including InGaAs/InP avalanche photodiodes operating in a gated Geiger mode. A generation rate>103 pairs/s is observed, a rate limited only by available detection electronics. The nonclassical nature of the photon correlations in the pairs is demonstrated. This source, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks. The detection system also provides high rate of photon counting with negligible after pulsing and associated high quantum efficiency and also low dark count rate.

Abstract: An optical amplifier is provided for performing amplification of optical signals of two wavelength bands, where deterioration in the optical SN ratio relative to one wavelength band is reduced, with a simple construction which can deal with restrictions on installation space, power consumption and the like. To this end, the present optical amplifier has a C/L band optical amplifying section for amplifying respective optical signals of a C band and an L band, a demultiplexer for demultiplexing output light from the C/L band optical amplifying section into the C band and the L band, an L band optical amplifying section for amplifying L band optical signals which have been demultiplexed by the demultiplexer, and a multiplexer for multiplexing the C band optical signals which have been demultiplexed by the demultiplexer and the L band optical signals which have been amplified by the L band optical amplifying section.

Abstract: Optical amplifier according to the present invention is provided with an EDF, a light source device having a semiconductor laser element that generates an excitation beam and a housing that accommodates this, and an optical multiplexer having an input optically coupled with light source device, an input that receives the signal beam, and an output that provides an excitation beam and signal beam to EDF. Semiconductor laser element has an active layer, provided between cladding layers and including compound semiconductors of mutually different conductivity types, that includes a compound semiconductor and is constructed such that the oscillation wavelength at 20° C. of this semiconductor laser element is less than 1470 nm but not less 1440 nm. If this is done, the change of gain in EDF with respect to oscillation wavelength can be made satisfactorily small and the NF can be made satisfactorily small.

Abstract: The present invention has an object to provide a Raman amplifier, a WDM optical communication system and a method of controlling the Raman amplification, capable of optimizing amplification characteristics in response to a change of operating conditions of the system so that transmission quality of the WDM signal light can be maintained in good.

Abstract: An apparatus has first and second light sources, a plurality of filters, and an optical switch. The light sources output a light beam having a spectrum determined by a gain band thereof. The plurality of filters each have a reflection band included in the gain band. The optical switch selectively couples the filters to the light source. The first and second light sources provide pumping light to a single transmission line. The first and second filters are configured so as to not reflect signal light to be amplified.

Abstract: An apparatus and method are described for exploiting almost the full almost 25TH% of bandwidth available in the low-loss window in optical fibers (from 1430 nm-1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths &lgr;r should lie in close proximity to the zero-dispersion wavelength &lgr;0 of the amplifying fiber.

Abstract: The invention concerns a method for the amplification of wavelength division multiplex (WDM) signals in a WDM transmission system, pump light being injected into an optical waveguide of the optical transmission system contrary to the transmission direction of the WDM signals, the pump light being designed so that at least one WDM signal is individually amplified by a stimulated Brillouin scattering process in the optical waveguide produced by the pump light, as well as an optical amplifier, an optical broadband amplifier system and a WDM transmission system for it.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A tunable multimode wavelength division multiplex Raman pump and amplifier, and a system, method, and computer program product for controlling a tunable Raman pump and amplifier. The tunability of the pump source is accomplished by either straining or heating an external fiber grating, thereby causing a different wavelength of light to be emitted by the pump source. The system includes a microprocessor-based controller that monitors an amplifier's performance and adjusts the drive current and/or wavelength of the tunable pumps of an amplifier to achieve a target performance.

Abstract: The present application relates to a doped fiber amplifier having an increased dynamic range, and particularly for laser pump sources and a method of pumping erbium doped fiber amplifiers over a greater dynamic range. In a multi-channel optical system, optical amplifiers must be able to provide gain over a larger range of signal powers, the dynamic range corresponding to the number of channels in the link. The present invention has found that the dynamic range of an EDFA can be significantly increased by using pulse width modulation to pulse pump current at or near the minimum current stability threshold, in order to produce lower power output. The duty cycle of the pulsed current is selected to achieve a time-averaged operating condition taking advantage of the relatively long relaxation time of the erbium. Thus the time averaged pump power can be reduced in a linear fashion well below the capability of a continuous wave system.

Abstract: The invention provides an optical fiber amplifier which assures stable operation of a pump light source and efficiently makes use of residual pump power to achieve improvement in conversion efficiency. The optical fiber amplifier includes a rare earth doped fiber. Pump light from a pump light source is introduced into one end of the rare earth doped fiber by way of a first optical coupler, and residual pump light originating from the pump light and arriving at the other end of the rare earth doped fiber is applied to the other rare earth doped fiber amplifier or the loss compensation of a dispersion compensating fiber by Raman amplification.

Abstract: In a distributed Raman amplification system, the pump laser and the fiber are chosen so as to have characteristics which result in broadening of the DRBS. For example, with a transmission fiber through which signal light of a wavelength &lgr;s propagates, and having zero dispersion at a wavelength &lgr;o; a pump laser producing counterpropagating pump light at a wavelength &lgr;p; where &lgr;p and &lgr;s are on opposite sides of the zero dispersion wavelength is used. The transmission fiber may be large effective area fiber. In a Raman amplification system suitable for use in a WDM optical fiber communication system, pump lasers having mode spacing which is less than the optical bandwidth of the signal channel have been found to be advantageous.