Abstract: A pulse shaper includes a seed laser situated to emit laser pulses, an amplitude modulator situated to receive one or more laser pulse bursts from the seed laser, and a pulse signal generator situated to send a seed pulse signal with a predetermined delay to the seed laser so that the seed laser emits the laser pulses in one or more laser pulse bursts at a selected frequency with each laser pulse burst having a selected number of laser pulses and a selected temporal spacing between laser pulses in the laser pulse burst and situated to send an amplitude pulse signal so that the amplitude modulator adjusts the amplitude of at least one laser pulse in each laser pulse burst.

Abstract: An apparatus includes a remote optically pumped amplifier (ROPA). The ROPA includes a bypass filter configured to receive an optical signal and first pump power and to separate the optical signal and the first pump power. The ROPA also includes an amplifier configured to receive the optical signal from the bypass filter and to amplify the optical signal. The ROPA further includes an optical combiner/multiplexer configured to receive the first pump power from the bypass filter, receive at least second and third pump powers, combine at least two of the first, second and third pump powers, and provide different pump powers or combinations of pump powers to different locations within the ROPA to feed the amplifier.

Abstract: A laser ablation tomography system includes a specimen stage for supporting a specimen. A specimen axis is defined such that a specimen disposed generally on the axis may be imaged. A laser system is operable to produce a laser sheet in a plane intersecting the specimen axis and generally perpendicular thereto. An imaging system is operable to image the area where the laser sheet intersects the specimen axis.

Abstract: An optical transmission apparatus for transmitting wavelength-multiplexed light, the optical transmission apparatus includes: an optical transmitter configured to transmit light of a third wavelength to be arranged between a first wavelength and a second wavelength adjacent to the third wavelength in the wavelength-multiplexed light, and a controller configured to control a bandwidth of the light of the third wavelength to be arranged in a first bandwidth narrower than a spacing between the first wavelength and the second wavelength.

Abstract: There is provided a laser system that may include a Raman cell, a pumping light generator, and a Raman cell laser unit. The pumping light generator may include one or more optical parametric amplifiers (OPAs), and may be configured to output first Raman-cell pumping light and second Raman-cell pumping light to the Raman cell. The Raman cell laser unit may be configured to output probing light as a target of wavelength conversion to the Raman cell.

Abstract: A Raman pump laser control apparatus comprises a wavelength division multiplexer, a tap coupler, a photoelectric detector, an analog amplification processing circuit, an analog-to-digital converter, a fast Raman pump control unit, an digital-analog converter, and a Raman pump laser. The fast Raman pump control unit, after having known anticipated output light power of the Raman pump laser, based on a direct relationship between a current anticipated output light power of the Raman pump laser and input digital quantity that is needed by the digital-analog converter, uses a feedforward control mechanism so that actual output light power of the Raman pump laser fastly approximates the anticipated output light power thereof, and then synchronously combines with a feedback control mechanism so that the actual output light power of the Raman pump laser is precisely locked on the anticipated output light power, thereby achieving fast and precise control of the Raman pump laser.

Abstract: An optical transmit system, including a direct modulator configured to generate an optical signal, an optical amplifier coupled to the direct modulator configured to amplify the optical signal output by the direct modulator, and a stimulated Brillouin scattering component coupled to the optical amplifier configured to limit optical power of the optical signal output by the optical amplifier, where a stimulated Brillouin scattering threshold of the stimulated Brillouin scattering component is equal to minimum optical power of a part, which needs to be limited, of the optical signal output by the optical amplifier, and the stimulated Brillouin scattering component reflects, using a stimulated Brillouin scattering frequency difference, a part, which has optical power higher than the minimum optical power, of the optical signal output by the optical amplifier in order to limit outputting of this part of the optical signal.

Abstract: A device for the generation of supercontinuum in infrared fiber with a pump light comprising a microchip laser operating with a wavelength of 1.0 ?m or greater that can be wavelength shifted though a nonlinear element to a wavelength beyond the two-photon absorption of the infrared fiber and launched into infrared fiber whereby the spectrum is broadened in the infrared fiber through various nonlinear processes to generate a supercontinuum within the mid-IR from 2 to 14 ?m.

Abstract: The present application describes a multi wavelength apparatus. The apparatus includes a pump laser, a first seed laser and a second seed laser. Each of the first and second seed lasers had wavelengths longer than the pump laser. The apparatus also includes a first multiplexer. The apparatus also includes first and second controllers configured to respectively control outputs of the first and second seed lasers. The apparatus also includes a first fiber configured to receive an output of a first multiplexer. The apparatus also includes a second multiplexer configured to receive the output of the first fiber. The apparatus also includes a second fiber configured to receive the output of the second combiner. The second fiber can emit light at either the first seed wavelength or the second seed wavelength. The present application is also directed to a method for controlling an output of a laser apparatus.

Abstract: The embodiments of the present invention disclose a method and an apparatus for determining a gain of a Raman optical amplifier and a Raman optical amplifier. The method includes: acquiring present gain parameter information of a Raman optical amplifier; and determining a present gain of a monitoring channel of the Raman optical amplifier according to the present gain parameter information and a correspondence between a gain of the monitoring channel of the Raman optical amplifier and gain parameter information. According to the method and apparatus for determining a gain of a Raman optical amplifier and the Raman optical amplifier that are in embodiments of the present invention, a present gain of a monitoring channel can be accurately determined; therefore, a gain spectrum of the Raman optical amplifier can be accurately monitored, and the gain of the Raman optical amplifier can be accurately adjusted to a target gain.

Abstract: Techniques are described for determining, with a first optical node, a correction factor indicative of an amount of optical power loss that a Raman amplifier in a second optical node causes in an optical signal having a first wavelength that is transmitted by the first optical node and received by the second optical node, transmitting, with the first optical node to the second optical node, information, based on the determined correction factor, that is to be used for determining a gain of the Raman amplifier, and transmitting, with the first optical node to the second optical node, an optical signal having a second wavelength that is to be amplified by the Raman amplifier.

Abstract: A hybrid fiber amplifier and method of adjusting gain and gain slope of thereof. The hybrid fiber amplifier comprises: RFA and EDFA that does not comprise variable optical attenuator. The RFA comprises pump signal combiner, pump laser group, out-of-band narrow-band filter, and photodetector. The EDFA comprises input coupler, erbium-doped fiber, output coupler, input photodetector, and output photodetector that are connected in sequence. The hybrid fiber amplifier also comprises control module that coordinates and controls EDFA and/or RFA to adjust gain and/or the gain slope based on desired amplification requirements. The EDFA and/or RFA can be coordinated and controlled by using the control module to achieve desired amplification effect. In addition, the EDFA does not comprise the variable optical attenuator, which avoids problems caused by the variable optical attenuator.

Abstract: A desired Nth-order Stokes output and zeroth-order Stokes pump input are seeded into a rare-earth doped amplifier where the power of the zeroth-order Stokes signal is amplified prior to both signals entering a Raman amplifier comprised of N?1 Raman resonators, each uniquely tuned to one of the N?1 Stokes orders, in various configurations to include one or more nested and/or in-series Raman resonators. The zeroth-order Stokes signal is converted to the Nth?1-order Stokes wavelength in steps and the power level of the Nth-order Stokes wavelength is amplified as the two signals propagate through the Raman resonators. Each Raman resonator includes a photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the Stokes orders can be controlled by offsetting the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

Abstract: An optical line terminal (OLT) in a time and wavelength division multiplexed (TWDM) passive optical network (PON). The OLT comprises a first optical port, a second optical port, and a processor. The first optical port is configured to couple to a plurality of optical network units (ONUs) via an optical distribution network (ODN). The second optical port is configured to couple to the ONUs via the ODN. The processor is coupled to the first optical port and the second optical port and is configured such that, responsive to receiving information indicating that the first optical port has experienced a greater power loss over time than the second optical port, the OLT assigns to the first optical port a first wavelength with a power greater than the power of a second wavelength assigned to the second optical port.

Abstract: A laser system and method of use are provided in which the laser system may include a fiber laser oscillator and rare earth doped piece of optical fiber which may absorb unused pump light which is unabsorbed in the oscillator.

Abstract: Consistent with the present disclosure, an optical communication system is provided in which client data is input to a first node and output from a second node, spaced from the first node, with little delay. In one example, the delay is reduced by including higher order Raman amplifiers that provide a substantially uniform gain along the length of a fiber optic link, thereby reducing the number of EDFAs that may otherwise be installed along the optical fiber link or eliminating such EDFAs entirely. In another example, FEC encoding and decoding are not employed, thereby reducing the delay even further.

Abstract: The present invention discloses a method and an apparatus for detecting an optical signal-to-noise ratio, a node device, and a network system. The method includes: receiving a detected optical signal carrying amplified spontaneous emission ASE noise; detecting a first alternating current component and a first direct current component of the detected optical signal; acquiring first modulation information of the detected optical signal; acquiring first correction information corresponding to the first modulation information according to the first modulation information; and determining an optical signal-to-noise ratio OSNR of the detected optical signal according to the first alternating current component, the first direct current component, and the first correction information.

Abstract: An optical amplifier assembly for determining a parameter of an optical fiber configured to amplify an optical signal being propagated therethrough, the assembly comprising: at least one amplifier pump light source assembly configured to transmit light at a plurality of wavelengths into the optical fiber; a receiver configured to receive light that has propagated through at least part of the optical fiber; and a processor configured to determine the parameter of the optical fiber based on the received light.

Abstract: An optical fiber is optically coupled to an optical multiplexer. First and second wavelength-selective reflectors are formed onto the optical fiber. The first wavelength selective reflector is configured to reflect radiation of a first wavelength and the second wavelength reflective selector is configured to reflect radiation of a second wavelength that is longer than the first wavelength. A resonant laser cavity is formed between transmission fiber acting as distributed Rayleigh mirror and first and second wavelength selective reflectors. The first and second wavelength-selective reflectors and the optical fiber are configured such that Raman scattering and gain in the transmission fiber converts pump radiation at a pump wavelength less than the first wavelength to radiation of the first wavelength and also convert radiation of the first wavelength to radiation of the second wavelength.

Abstract: An optical transmitter includes a circuit that controls a first frequency component and a second frequency component that are contained in an optical signal to be transmitted to be in different polarization states from each other.

Abstract: The present invention relates to the field of network communications and discloses a method for calculating a nonlinear transmission impairment, including: determining that no pump channel exists in an optical fiber link, obtaining a factor of intra-band nonlinear noise that does not pass through an optical filter, and obtaining integral power in signal light bandwidth of a span; correcting the factor of intra-band nonlinear noise that does not pass through an optical filter, to obtain a factor of intra-band nonlinear noise of the span that passes through an optical filter; calculating nonlinear noise of the span; and obtaining total nonlinear noise of the optical fiber link according to the nonlinear noise of the span, and obtaining a nonlinear transmission impairment of the optical fiber link. Embodiments of the present invention further provide an apparatus for calculating a nonlinear transmission impairment of an optical fiber link.

Abstract: A boding device includes a light guiding part that guides laser beam oscillated from a laser oscillator, a bonding head that heats a chip with the laser beam, and a bonding head moving part that moves the bonding head between a supply position and a bonding position. The laser oscillator is separated from the bonding head. The light guiding part includes an irradiation barrel that is provided in the vicinity of the bonding position and, a shutter part that is provided in the irradiation barrel, and a light receiving part that is provided in the bonding head and guides the laser beam to the chip. When the bonding head moving part moves the bonding head to the bonding position, the shutter part is opened so that the laser beam from the irradiation barrel is guided to the bonding head through the light receiving part.

Abstract: Apparatus for amplifying signal such as a burst mode signal in an optical network. A doped fiber, for example an erbium-doped fiber is placed in a preferably passive module along an optical data transmission path. A pump port is optically connected to at least one combiner such as a WDM (wavelength division multiplexor) that is placed along the optical transmission path to add in a pump wavelength in the vicinity of the doped fiber. The apparatus, which is preferably completely passive, may be advantageously placed in communication with a remote pump light source such as a pump laser resident on a management node of the network. A second pump port may be added, as well as one or more detector ports to facilitate operation of a remote control processor, which may also be resident in a management node such as an OLT (optical line terminal) in a PON (passive optical network).

Abstract: A third-order Stokes wavelength seed signal at the desired output wavelength of 1240 nm and a zeroth-order Stokes wavelength signal at 1066 nm are input into a Raman amplifier comprised of two Raman resonators in a linear configuration. The first resonator converts the zeroth-order Stokes wavelength signal at 1066 nm into a first-order Stokes wavelength signal at 1118 nm, and also outputs the third-order Stokes wavelength seed signal at 1240 nm. The second resonator then converts the 1118 nm output from the first resonator into a second-order Stokes wavelength signal at 1176 nm, which amplifies the 1240 nm seed signal power level. Each Raman resonator includes a photosensitive Raman fiber communicating with a plurality of high-reflector Bragg gratings. The linewidths of the second and third Stokes orders are controlled by adjusting the resonant bandwidth of the second Raman resonator by offsetting the respective center wavelengths of the high-reflector Bragg gratings.

Abstract: A method includes: selecting an optical pump signal power of a Raman amplifier such that a saturated gain of the Raman amplifier is at a maximum operating level without exceeding a gain threshold above which an optical signal to noise ratio penalty is no longer negligible in the Raman amplifier; selecting an optical signal power for at least one optical communication signal to be transmitted across the optical link to maximise a Q-factor of the optical signal when the Raman amplifier is configured for said maximum operating level of the saturated gain; generating a pump signal power control signal to cause an optical pump signal source of the Raman amplifier to generate an optical pump signal having the selected optical pump signal power; and generating a signal power control signal configured to cause the optical communication signal to be delivered into the optical link at the selected optical signal power.

Abstract: An optical fiber carries optical channels injected into the optical fiber to a Raman amplifier. A controller determines a static tilt associated with the channels in the fiber due to wavelength dependent losses. A photodiode measures a total power of the channels at an output of the Raman amplifier. The controller determines a dynamic tilt associated with channels in the fiber based in part on the measured total power. The dynamic tilt is induced by Stimulated Raman Scattering (SRS) in the fiber and varies as a function of a total power of the signals injected into the fiber. The controller determines a total tilt with which to offset the static and dynamic tilts. The controller sets an amplifier gain tilt applied to the channels equal to the total tilt.

Abstract: A light source emits first incident light to a first polarization-reversed structure. The first polarization-reversed structure then converts the wavelength of the first incident light to emit a higher harmonic wave. A fiber coupler divides the higher harmonic wave output from the first polarization-reversed structure into output light emitted from the light source device and feedback light. The feedback light enters a second polarization-reversed structure. The second polarization-reversed structure then converts the wavelength of the feedback light to emit second incident light. The second incident light has the same wavelength as the first incident light. The second incident light enters a first wavelength converter.

Abstract: A single-pump multi-wavelength lasing semiconductor Raman pump laser comprises a thermoelectric cooler arranged in a shell; a heat transition bearing platform arranged in the thermoelectric cooler; a semiconductor Raman pump laser tube core arranged on the heat transition bearing platform; and a coupling lens group, a thermistor and a backlight detector that are arranged on the heat transition bearing platform respectively. The pump laser tube core, the backlight detector, the thermistor and the thermoelectric cooler are electrically connected to pins outside a laser tube shell. A pump combination apparatus comprises a first signal transmission fiber, a pump signal combiner and a second signal transmission fiber that are sequentially connected to each other. An input terminal of the pump signal combiner is connected to an output terminal of an isolated polarization beam combiner and depolarizer.

Abstract: The present invention relates to a device for monitoring an optical fiber comprising a photo-sensitive device arranged to produce an electric pulse from an optical pulse injected at a first node of the optical fiber, a delay element and a first optical circulator arranged to delay the optical pulse injected at the first node of the optical fiber. Further, the device comprises an optical amplifier arrangement arranged to receive the optical pulse at its input and the produced electric pulse as an operating signal, for producing an amplified optical pulse. Moreover, the device comprises a second optical circulator arranged to receive the amplified optical pulse at a first port and output the amplified optical pulse at a second port connected to a second node of the optical fiber, and to receive an optical signal reflected back from the optical fiber at the second port and outputting the reflected optical signal at a third port.

Abstract: A graphene coated optic-fiber laser is disclosed that includes a doped inner core and an undoped outer core surrounding the doped inner core. A graphene cylinder or capsule surrounds the undoped outer core, thereby forming a cladding layer around the undoped outer core.

Abstract: A Raman amplifier includes: a pump light generator that provides a plurality of pump light beams with different wavelengths for an optical transmission medium; a gain monitor that monitors an average Raman gain in the optical transmission medium; a storage unit that stores ratio information indicating a ratio of power of the plurality of pump light beams for a specified gain characteristic with respect to an average Raman gain in the optical transmission medium; and a controller that controls the power of the plurality of pump light beams based on the average Raman gain monitored by the gain monitor and the ratio information.

Abstract: Systems and methods for achieving eye safety of an optical transceiver are provided. An optical module can be configured to output a first optical signal. A first photodetector can be configured to output a signal indicative of a presence or absence of a second optical signal. A controller can be coupled to the optical module and the first photodetector and can be configured to control the output of the optical module. In response to a determination that an output of the first photodetector indicates the second optical signal is absent, the controller can control the optical module to output the first signal at a decreased average optical power. In response to a determination that an output of the first photodetector indicates the second optical signal is present, the controller can control the optical module to output the first signal at an increased average optical power.

Abstract: A Raman amplifier comprising a gain control unit adapted to control a pump power of an optical pump signal in response to at least one monitored optical feedback signal reflected back from a transmission line fiber connected to said pumped Raman amplifier.

Abstract: An optical signal distribution system is provided herein useful for multiple service operators (MSOs) in providing content data to subscribers, and receiving control and other data from subscribers. The system facilitates the transmission of content data to the subscribers and the control and other data from subscribers substantially in the optical domain. The system includes a head-end configured to transmit the content data via a forward channel optical signal and receive the control data via a composite reverse channel optical signal. The system also includes a signal distribution hub configured to receive and replicate the forward channel optical signal for transmission to optical taps, receive reverse channel optical signals from the optical taps, generate a composite reverse channel optical signal, and transmit the composite reverse channel optical signal. Each optical tap sends and receives the forward and reverse channel optical signals to and from a plurality of subscribers units.

Abstract: A method, a controller, and an optical section include performing an analysis to determine an amount of power offset on any in-service channels in an optical section due to a capacity change with a channel; defining a step size to ensure the capacity change does not exceed an offset limit based on the analysis; performing the capacity change in one or more iterations using the step size to limit the capacity change; and performing an optimization between each of the one or more iterations to adjust amplifier gains in the optical section to compensate for offsets on the in-service channels caused by a previous iteration.

Abstract: A third-order Stokes signal at the desired output wavelength of 1240 nm and a zeroth-order Stokes pump wavelength at 1066 nm are seeded into a Raman amplifier comprised of two nested resonators tuned to the first-order Stokes line at 1118 nm and second-order Stokes line at 1176 nm, respectively. The pump wavelength is first amplified and then sequentially converted into the first and second-order Stokes wavelengths as the light traverses the nested resonators. The desired third-order Stokes output wavelength is then amplified by the second-order Stokes wavelength as it propagates through the outermost resonator. Each Raman resonator includes a photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the various Stokes orders can be controlled through adjusting the resonant bandwidths of the Raman resonators by offsetting, through heating, the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

Abstract: An apparatus for generating a frequency spectrum of an RF signal comprising a gate switch for generating a series of pulses from a laser of wavelength lambda modulated by an input RF signal, a first fiber optical loop for circulating a first percentage of a first pulse of the series of pulses from the gate switch, for a predetermined number of cycles n where each cycle takes time t1, a second fiber optical loop for conducting a second percentage of the first pulse for predetermined number of cycles “k”, where each cycle takes time t2, where t2*k=t1*n, a first switch with a first state for coupling the first pulse from the gate switch to a coupler, the coupler coupling the first pulse into the first fiber optical loop and tapping replicas of the pulse from the first fiber optical loop, and a second state for coupling the second percentage of the first pulse to the coupler to increase intensity of the tapped replica pulses, a processor for correlating the replicas of the pulse with each other to produce a set o

Abstract: The invention can include an optical pulse source for providing optical output pulses, comprising a master oscillator comprising a mode locked fiber oscillator producing optical pulses having an optical pulse frequency; at least one optical fiber amplifier optically coupled to the master oscillator, the at least one optical amplifier including a final optical fiber amplifier; a bulk optic amplifier element optically coupled to the output of the final optical fiber amplifier; a nonlinear optical fiber for nonlinearly producing light, the nonlinear optical fiber optically coupled to the output of the bulk optic amplifier element; an optical pulse compressor optically coupled to the output of the nonlinear optical fiber; and a pulse picker operable to reduce the optical pulse frequency of the optical output pulses to be less than the optical pulse frequency of the optical pulses produced by the master oscillator.

Abstract: Systems and methods are disclosed for shutting down a laser system in an intelligent and flexible manner. An intelligent laser interlock system includes both hardwired components, and intelligent components configured to execute computing instructions. The hardwired components and the intelligent components are configured to shutdown the laser system to one or more alternative shutdown states in response to one or more interlock signals.

Abstract: A high-finesse Fabry-Perot interferometer (FPI) is introduced into a coherent Brillouin RFL configuration to thereby produce a frequency stabilized random laser.

Abstract: A discrete Raman amplifier comprises a Raman gain fiber, an input port into the Raman gain fiber for receiving optical signals to be Raman amplified, and an output port out of the Raman gain fiber for emitting Raman-amplified optical signals. A pump light input provides pump light to the Raman gain fiber at a plurality of wavelengths so as to provide Raman amplification over the selected signal wavelength range. Within both the pump light wavelength range and the selected signal wavelength range, the Raman gain fiber has only positive chromatic dispersion, and the Raman gain fiber has a moderate effective area.

Abstract: An apparatus and method of failure detection in optical amplifier is disclosed. The optical amplifier includes an optical amplifying fiber configured to receive input light so that the input light travels through the optical amplifying fiber, an excitation light generator configured to supply excitation light to the optical amplifying fiber to optically amplify the input light as the input light travels through the optical amplifying fiber, and a processor configured to determine whether a failure has occurred in the optical amplifier, based on a change in power of the excitation light and a change in power of the input light.

Abstract: An object of the present invention is to provide an optical multiplexer and a fiber laser for obtaining high-output light of a single wavelength. The optical multiplexer according to the present invention is provided with input units 11 and 12, a wavelength multiplexing unit 14, a multiplexed light converting unit 15 and an output unit 16. Lights of a plurality of wavelengths ?1 and ?2 are input to the input units 11 and 12, respectively. The wavelength multiplexing unit 14 wavelength-multiplexes the lights of the plurality of wavelengths ?1 and ?2 input from the input units 11 and 12 different for each wavelength to one multiplexed light. By wavelength-multiplexing, it is possible to multiplex without a loss.

Abstract: An amplifying optical fiber includes an inner core, an inner cladding, a depressed trench, and an outer cladding (e.g., an outer optical cladding). Typically, the inner core includes a main matrix (e.g., silica-based) doped with at least one rare earth element. The depressed trench typically has a volume integral V13 of between about ?2200×10?3 ?m2 and ?1600×10?3 ?m2. Exemplary embodiments of the amplifying optical fiber are suitable for use in a compact configuration and high power applications.

Abstract: A transmission device includes an optical amplifier to amplify an optical main signal to be transmitted on an optical transmission path; a first controller to stop output of the optical amplifier and output of an optical monitor signal to be transmitted on the optical transmission path when a failure of the optical transmission path is detected; a second controller to be switched from the first controller and to operate and stop the output of the optical amplifier and the output of the optical monitor signal when the failure of the optical transmission path is detected; an optical monitor signal transceiver to transmit and receive the optical monitor signal including control information; and a switch to switch an operation from the first controller to the second controller, based on information of the failure of the optical transmission path based on the states of transmission and reception of the optical monitor signal.

Abstract: An optical amplifier includes: an optical amplification unit implementing optical amplification on an optical signal input from an input end to output the amplified optical signal from an output end to a device through a transmission line; a branching unit branching light from the output end, where the light contains reflected-light or/and optical feedback; a photo-detector receiving the branched light and detecting optical level of the received light; and a control circuit reducing an amount of optical amplification of the optical amplification unit in case where the detected optical level becomes more than or equal to a first threshold. The control circuit normalizes the amount of optical amplification in case where a variation of the optical level detected by the photo-detector becomes less than or equal to a second threshold, where the variation of the optical level has been brought by the reduction of the amount of optical amplification.

Abstract: An optical amplifier comprising: a pumping light source supplying a pumping light to an optical fiber as an amplification medium; an ASE light power detector detecting an ASE light power including an external ASE power flowing from an upstream side outside an amplification signal band; and a control unit setting a gain within the amplification signal band by using the ASE light power detected by the ASE light power detector outside the amplification signal band. The control unit controls the pumping light source by compensating for an influence of the external ASE power, obtained by measuring a relationship between the gain within the amplification signal band and the ASE light power outside the amplification signal band, to set initially the gain within the amplification signal band.

Abstract: A desired Nth-order Stokes output and corresponding zeroth-order Stokes pump wavelengths are seeded into a Raman amplifier comprised of one or more Raman resonators in series sequentially tuned to the 1st, 2nd, . . . N?1st Stokes orders. The pump wavelength is amplified and sequentially converted to the 1st, 2nd, . . . N?1st order Stokes wavelengths as it propagates through the apparatus. The desired Nth-order Stokes output wavelength is then amplified by the N?1st Stokes order as it propagates through the final resonator tuned to the N?1st Stokes order. Each Raman resonator includes a Raman photosensitive Raman fiber located between a pair of Bragg gratings. The linewidths of the various Stokes orders can be controlled through adjusting the resonant bandwidths of the Raman resonators by offsetting, through heating, the reflectivity bandwidths of each pair of Bragg gratings respectively located in the Raman resonators.

Abstract: An amplifying-apparatus that raman-amplifies light transmitted through an optical-fiber-transmission-path, includes: an inputting-unit that inputs pump light to the optical-fiber-transmission-path; a path-switching-unit that is capable of switching between a first state in which the light transmitted through the optical-fiber-transmission-path is output to a first path and a second state in which the light transmitted through the optical-fiber-transmission-path is output to a second path; a splitting-unit that splits the light output to the second path by the path-switching-unit and outputs resulting first light and second light; and a control-circuit that stores information based on a result of reception of the light output to the first path by putting the path-switching-unit into the first state and then controls power of the pump light on a basis of the stored information and a result of reception of the first light output by the splitting-unit by putting the path-switching-unit into the second state.

Abstract: Narrow line width, high power pulses of optical radiation may be generated by the combination of stimulated emission and stimulated Raman scattering within a rare earth doped optical fibre (24b). The signals of a first (11) and second (13) seed laser sources are coupled into the fiber. The radiation of the pulsed first seed laser source (11) is amplified by stimulated emission of the rare earth ions so that the threshold for stimulated Raman scattering into the mode of the second seed laser source 13 is exceeded, and efficient SRS transfers nearly all the power into the mode seeded by the second seed laser source (13).