Abstract: A saturable absorber (SA) is constructed using a fiber taper embedded in a carbon nanotube/polymer composite. A fiber taper is made by heating and pulling a small part of standard optical fiber. At the taper's waist light is guided by the glass-air interface, with an evanescent field protruding out of the taper. Carbon nanotubes mixed with an appropriate polymer host material are then wrapped around the fiber taper to interact with the evanescent field. Saturable absorption is possible due to the unique optical properties of the carbon nanotubes. The device can be used in mode-locked lasers where it initiates and stabilizes the pulses circulating around the laser cavity. The SA can be used in various laser cavities, and can enable different pulse evolutions such as solitons, self-similar pulses and dissipative solitons. Other applications include but are not limited to optical switching, pulse cleanup and pulse compression.

Abstract: Included are a semiconductor device unit in which a semiconductor optical amplifier and a first semiconductor photo detector being configured to monitor a part of an input light input to the semiconductor optical amplifier or a part of an output light output from the semiconductor optical amplifier are integrated on a mutually same substrate, and a passive waveguide unit connected to the semiconductor device unit and in which a first passive waveguide being configured to cause the input light to be input to the semiconductor optical amplifier or to cause the output light to be output from the semiconductor optical amplifier and a second passive waveguide branching from the first passive waveguide and being configured to cause a part of the input light or a part of the output light to be input to the first semiconductor photo detector are provided on a mutually same substrate.

Abstract: A pumping unit supplies pumping light to a fiber connecting medium; a light monitoring unit detects light power of multiple-wavelength light; and a control unit controls the pumping light based on light power detected by the light monitoring unit and connecting medium information indicating optical characteristics in the connecting medium. The connecting medium information includes information indicating a fiber type of the fiber connecting medium, information indicating a length of the fiber connecting medium, an average fiber loss coefficient of the fiber connecting medium and an intra-station loss value.

Abstract: The present invention relates to a method of amplification based on spatio-temporal frequency drift for a pulse laser comprising a so-called CPA (Chirped Pulse Amplification) frequency-shift amplifying chain, the various spectral components spatially spread. The various components separately amplified.

Abstract: A method is provided for dispersion compensation of an optical signal communicated in an optical network. The method may include receiving an optical signal comprising a plurality of channels. The method may further include filtering at least one channel from the plurality of channels. The method may also include analyzing the at least one channel of the plurality of channels to measure optical dispersion in the at least one channel. The method may additionally include compensating for optical dispersion based on the measured dispersion.

Abstract: An optical demultiplexer (13, 30) for wavelength division multiplex WDM optical radiation comprising a plurality of wavelength channels (Ch1 . . . Ch16) spaced over a wavelength spectrum said demultiplexer being for separating the WDM radiation into individual wavelength channels is described. The demultiplexer comprises a first demultiplexer (12) for dividing the W-DM radiation into a plurality of sub-bands (Ch1 . . . Ch4, Ch5 . . . Ch8, Ch9 . . . Ch12, Ch13 . . .

Abstract: In an embodiment, a power selective optical filter device includes an input polarizer for selectively transmitting an input signal. The device includes a wave-plate structure positioned to receive the input signal, which includes at least one substantially zero-order, zero-wave plate. The zero-order, zero-wave plate is configured to alter a polarization state of the input signal passing in a manner that depends on the power of the input signal. The zero-order, zero-wave plate includes an entry and exit wave plate each having a fast axis, with the fast axes oriented substantially perpendicular to each other. Each entry wave plate is oriented relative to a transmission axis of the input polarizer at a respective angle. An output polarizer is positioned to receive a signal output from the wave-plate structure and selectively transmits the signal based on the polarization state.

Abstract: An optical amplifier apparatus for amplifying a wavelength division signal light includes a detector for detecting an inputted wavelength division signal light, a dispersion compensator for compensating for a dispersion of the inputted wavelength division signal light, an optical amplifier for amplifying the inputted wavelength division signal light after compensation by stimulated emission of an optical gain medium including a rare-earth element, a propagation delay detector for detecting a propagation delay time of the wavelength division signal light between the detector and the optical amplifier, and a controller for controlling the gain of the optical amplifier on the basis of the propagation delay time such that the change of the gain of the optical amplifier is adjusted by the propagation delay time.

Abstract: The distributed Raman amplifier monitors an OSNR of each channel in a WDM light which has been propagated through a transmission path to be Raman amplified, and thereafter, is amplified by an optical amplifier in an optical repeating node; judges whether a monitor value of the OSNR is larger or smaller than a previously set target value thereof; and feedback controls a driving state of a pumping light source which supplies a Raman pumping light to the transmission path, based on the judgment result. The optical communication system comprises the above distributed Raman amplifier in each repeating span thereof, and performs a pumping light control of the distributed Raman amplifier corresponding to the repeating span selected based on the OSNR in each distributed Raman amplifier and the monitor result of span loss. As a result, it becomes possible to effectively improve the OSNR of each channel in the WDM light, and also, to reduce the power consumption.

Abstract: An optical amplifying device includes a semiconductor laser that outputs a pump light having a power according to a provided drive current; a rare-earth-doped amplifying medium that amplifies an input light by the pump light output from the semiconductor laser; and a detector that detects, in the power of the pump light, a fluctuation faster than a response speed of a gain of the amplifying medium with respect to the power of the pump light. The optical amplifying device varies the drive current provided to the semiconductor laser based on the fluctuation detected by the detector.

Abstract: An object of the present invention is to provide an optical fiber amplifier capable of suppressing oscillation of ASE. The optical fiber amplifier includes a second amplifier fiber 30 doped with a rare earth element; a second pumping source 26 that supplies pump light to the second amplifier fiber 30; a storage unit 40 for storing a relationship between oscillation threshold pump power and temperature of the second amplifier fiber 30, the oscillation threshold pump power being power of the pump light which causes oscillation of ASE in a different wavelength range from a signal wavelength range produced by the second amplifier fiber 30; and a temperature controller 38 for controlling the temperature of the second amplifier fiber 30 so that the oscillation threshold pump power is higher than the power of the pump light outputted by the second pumping source 26, by referring to the relationship stored in the storage unit 40.

Abstract: A signal detection method used in an optical receiver apparatus detects the variation of an optical input level from the presence or absence of a clock signal and appropriately controls a dispersion compensator, thereby enabling the presence or absence of an input signal to be correctly determined. The signal detection method includes: detecting the level of input light of an optical amplifier, storing the level of the detected input light, comparing the level of the stored previous input light with the level of current input light, detecting the level variation of the input light by the comparison to detect the state change of the presence or absence of an optical signal, performing a dispersion compensation on the input light, and extracting a clock from an optical input. When the level variation of the input light is detected, the presence or absence of the optical signal of the input light is determined from the presence or absence of the clock signal.

Abstract: The present disclosure relates to streamlining optical module and/or subassembly development, manufacturing, and testing through introducing a memory component within a module and/or subassembly that is utilized with a host module for system calibration and/or configuration. In an exemplary embodiment, the present invention can streamline optical amplifier (EDFA) module and/or subassembly development, manufacturing, and testing. The present invention includes an optical module/sub-assembly without control circuitry, i.e. a “dumb module”, but with a memory that is used to load relevant data from a supplier. This data is utilized to calibrate, test, and configure the optical module/sub-assembly in a host module. The host module includes control circuitry to access this memory in the optical module/sub-assembly and to calibrate, test, configure, and control the optical module/sub-assembly.

Abstract: A method and apparatus for suppression of four-wave mixing using polarization control with a high power polarization maintaining fiber amplifier system. The apparatus includes a master oscillator (MO) that generates a beam; a polarization controller that receives the beam from the MO and transmits the beam with a desired polarization; a pre-amplifier that receives the beam from the polarization controller, pre-amplifies the beam, and transmits the beam; a high power fiber amplifier that receives the beam from the pre-amplifier, amplifies the beam, and transmits an output beam; and a polarization detector that detects the polarization of the output beam. The polarization detector transmits feedback to the polarization controller to ensure that the output beam components aligned with the principal birefringent axes of the high power fiber amplifier have approximately equal power.

Abstract: According to an aspect of an embodiment, an apparatus includes an optical branching unit for branching an input signal light in four directions, a polarization component extraction unit extracting four polarization components having mutually different polarization parameters from lights branched in four directions by the optical branching unit, and a determination unit determining input/non-input of the signal light based on the four polarization components extracted by the polarization component extraction unit.

Abstract: An optical signal processing device includes a waveform width widening unit configured to widen a waveform width of an optical signal; and an optical limiter circuit, to which the optical signal the waveform width of which is widened is input, configured to suppress an intensity of the optical signal in a region where an input intensity and an output intensity are not proportional.

Abstract: A gain equalizer for compensation a variation of intensity among a plurality of optical signals each including a different wavelength in a wavelength multiplexed optical signal includes an input part for receiving the wavelength multiplexed optical signal, an outputting part and a gain equalizing unit for repeatedly giving a loss to the wavelength multiplexed optical signal received by the input part, and for outputting the wavelength multiplexed optical signal to the outputting part. Here, the loss is set for each wavelength and is smaller than a loss characteristic required for compensation the variation of intensity.

Abstract: A light output control apparatus, includes: an excitation light source that outputs excitation light; an excitation light guiding unit that guides the excitation light to an optical amplifying medium for transmitting a signal light; and a loss causing unit that includes an optical transmission medium located between the excitation light source and the excitation light guiding unit, and changes a radius of curvature of the optical transmission medium.

Abstract: A system and method for optimizing the selection of ghost channels to mitigate the effects of polarization hole burning in a node of an optical communication system including identifying an optical communication channel in the node for use as a ghost channel, identifying a first set of degrees carrying the optical communication channel within the node, identifying a second set of degrees within the first set of degrees, the second set containing the degrees with the optical communication channel being a valid channel, identifying a third set of degrees within the first set of degrees, the third set containing degrees with the optical communication channel being sufficiently powerful, and selecting a first degree to source the ghost channel from the first set of degrees based at least on the second set of degrees and the third set of degrees.

Abstract: The invention relates to a light source apparatus having a structure for effectively suppressing a negative effect due to a nonlinear effect generated in propagation of an amplifying light, and realizing a stable operation. In the light source apparatus, light amplified in an optical amplifier fiber is emitted to the outside of the apparatus through an optical output fiber whose one end is connected to an output connecter. At this time, a part of Raman scattered light, generated in the optical output fiber, propagates toward an pumping light source through the optical amplifier fiber from the optical output fiber. An optical component having an insertion loss spectrum that attenuates the Raman scattered light but allows pumping light or light to be amplified to transmit therethrough, is provided on a propagation path of the Raman scattered light, due to the light component, the intensity of the Roman scattered light reaching the pumping light source is effectively reduced.

Abstract: In an optical amplifier, an input light is supplied to one end of an optical fiber connected to an output port, and the power of a light in an opposite direction which is input to the output port from the one end of the optical fiber, is measured, thereby obtaining a stimulated Brillouin scattering (SBS) occurrence threshold in the optical fiber based on the measurement result. Then, using the SBS occurrence threshold, a relation between the input light power and an occurrence amount of the self phase modulation (SPM) or the like in the optical fiber is obtained to be reflected on a control of the optical amplifier, so that an occurrence of the SPM or the like in the optical fiber is suppressed. As a result, it becomes possible to accurately measure, with a simple configuration, the nonlinear optical properties of the optical fiber actually connected to the output port of the optical amplifier, so that the optical S/N ratio degradation due to a nonlinear optical effect can be effectively suppressed.

Abstract: An optical system having an input surface configured to receive an input optical signal having a polarization, and a polarization changer comprising the input surface and configured to generate two orthogonal polarization components from the input optical signal. The polarization changer also changes a direction of the polarization of the input optical signal in a controlled manner while maintaining coherence of the two orthogonal polarization components in order to reduce stimulated Brillion scattering.

Abstract: An optical amplifier of the present invention includes: an optical amplifier circuit that amplifies input signal light and outputs the amplified light as output signal light; a first monitor for monitoring the presence or absence of the input signal light; and a control circuit that, when receiving a shutdown control signal, controls the optical amplifier circuit such that a shutdown control speed for reducing a level of the output signal light to zero differs according to the presence or absence of the input signal light.

Abstract: A method for laser safety protection in an optical communication system includes: a downstream station detecting whether an identification signal loaded by an upstream station on a main optical channel in a direction from the upstream station to the downstream station, exist on the main optical channel; if the identification signal is not detected, the downstream station executing a scheduled safety protection procedure. Methods for loading an identification signal on a main optical channel in an optical communication system and an optical amplifier of laser safety protection, which implement loading the identification signal by controlling the change of pump light of optical amplifier or the wave motion of signal light of main optical channel, are also provided. The solution makes it possible to reliably detect a fiber failure when RAMAN amplifiers or remotely-pumped amplifiers exist, thereby implementing laser safety protection.

Abstract: A MO-PA type optical amplifier is provided which includes an oscillator and an amplifier including a fiber for optical amplification, including: a reflected-light wavelength conversion fiber which is provided on an optical path between the oscillator and the amplifier and which converts a wavelength of reflected-light traveling toward the oscillator due to Stimulated Raman Scattering; and a filter which is provided on the optical path between the oscillator and the amplifier and which eliminates the wavelength-converted light.

Abstract: An optical amplifier includes a first amplification medium to receive light obtained by combining signal light input into an input port and the excitation light generated by a light source; a second amplification medium disposed between the first amplification medium and an output port; a loss medium to receive the signal light separated from light output from the first amplification medium; a variable optical attenuator that is disposed on a path that bypasses the loss medium, and to receive the excitation light separated from the light output from the first amplification medium; a first photodetector to detect power of light separated from the signal light transmitted from the second amplification medium; and a controller to control the amount of attenuation for the variable optical attenuator or output power of the light source so that signal light power per wavelength of the signal light becomes closer to a target value.

Abstract: Embodiments of the present invention provide an array of semiconductor optical amplifiers, within a photonic integrated circuit (hereinafter, “PIC”), that apply a gain to one or more optical bands within a WDM signal. According to various embodiments of the invention this array of SOAs can function as both an amplifier and a ROADM by adjusting the gain characteristics of one or more of the SOAs within the array. A band within the WDM signal may be blocked by adjusting the SOA, corresponding to the particular band, to attenuate the band below a threshold.

Abstract: The invention describes techniques for the control of the spatial as well as spectral beam quality of multi-mode fiber amplification of high peak power pulses as well as using such a configuration to replace the present diode-pumped, Neodynium based sources. Perfect spatial beam-quality can be ensured by exciting the fundamental mode in the multi-mode fibers with appropriate mode-matching optics and techniques. The loss of spatial beam-quality in the multi-mode fibers along the fiber length can be minimized by using multi-mode fibers with large cladding diameters. Near diffraction-limited coherent multi-mode amplifiers can be conveniently cladding pumped, allowing for the generation of high average power. Moreover, the polarization state in the multi-mode fiber amplifiers can be preserved by implementing multi-mode fibers with stress producing regions or elliptical fiber cores These lasers find application as a general replacement of Nd: based lasers, especially Nd:YAG lasers.

Abstract: The present disclosure relates to streamlining optical module and/or subassembly development, manufacturing, and testing through introducing a memory component within a module and/or subassembly that is utilized with a host module for system calibration and/or configuration. In an exemplary embodiment, the present invention can streamline optical amplifier (EDFA) module and/or subassembly development, manufacturing, and testing. The present invention includes an optical module/sub-assembly without control circuitry, i.e. a “dumb module”, but with a memory that is used to load relevant data from a supplier. This data is utilized to calibrate, test, and configure the optical module/sub-assembly in a host module. The host module includes control circuitry to access this memory in the optical module/sub-assembly and to calibrate, test, configure, and control the optical module/sub-assembly.

Abstract: A system for optical communication including an optical amplifier card configured to receive a plurality of pump laser modules. The optical amplifier card includes a receptacle configured to receive the pump laser module, a connector configured to couple the pump laser module to the optical amplifier card, a monitor configured to measure at least the optical output power of the pump laser module, and a pump combiner communicatively coupled to the monitor. The pump combiner is configured to receive a signal from the monitor indicating a drop in the output power of a first pump laser module below a threshold level, and, in response to the signal, switch the optical amplifier card from using the optical power of the first pump laser module to using the optical power of a second pump laser module without substantially affecting normal operation of the optical amplifier card.

Abstract: An optical amplifier includes a semiconductor optical amplifier which has a gain that changes in accordance with a wavelength of input light and which generates a noise light power having different levels in accordance with a drive current, a detector that detects an optical power branched from output light of the semiconductor optical amplifier, and a controller that controls supply of the drive current based on the optical power such that an output light power of the semiconductor amplifier is a sum of a target signal light power and the noise light power.

Abstract: An optical direct amplifier lowers the power consumption with a simple structure at a low cost. This amplifier includes an optical amplification medium (e.g., optical fiber) that carries out an optical amplification function in response to optical excitation by an exciting light source (e.g., semiconductor laser); a temperature controller for controlling the temperature of the amplification medium; a heat radiating member for radiating the heat generated by the light source; and a heat transmission regulator (e.g., Peltier module) for allowing the heat to flow into the amplification medium from the light source and for preventing the heat from flowing into the light source from the amplification medium. The amplification medium is heated by application of the heat generated by the light source by way of the heat radiating member and the heat transmission regulator.

Abstract: An optical amplifier has a pump and an “anti-pump” for reducing a variation of the amplifier gain with the input optical power. The wavelength of “anti-pump” light is longer than the wavelength of the optical signal being amplified, so that the optical signal serves as a pump for the “anti-pump” light, whereby an optical loss variation with the signal power at the signal wavelength is created, which reduces optical gain variation with the signal power. To compensate for gain loss due to the anti-pump light, two and three stages of amplification can be used.

Abstract: Systems and methods are disclosed for compensating for impairments caused by a semiconductor optical amplifier (SOA). One such method comprises receiving an optical signal which has been distorted in the physical domain by an SOA, and propagating the distorted optical signal backward in the electronic domain in a corresponding virtual SOA.

Abstract: According to an optical surge suppressive type optical amplifier in the present invention, for a WDM optical amplifier having a multi-stages amplification configuration in which a plurality of optical amplifying means is connected in series, an optical amplifying medium capable of causing a homogeneous up-conversion (HUC) phenomenon is applied to the optical amplifying means on the signal light output side, so that an optical surge is suppressed utilizing the degradation of gain efficiency by the HUC caused at the time when the input power is decreased. Further, for a one wave optical amplifier, an optical amplifying medium capable of causing a pair induced quenching (PIQ) phenomenon is applied to the optical amplifying means on the signal light input side, so that the optical surge is suppressed utilizing the degradation of output power efficiency by the PIQ caused at the time when the input power is increased.

Abstract: Provided is an all-optical gain-clamped fiber amplifier, comprising transmission and isolation means for periodically transmitting an optical signal or reflecting amplified spontaneous emission (ASE) back to a gain medium. The transmission and isolation means can be embodied by an optical interleaver or a number of optical fiber Bragg gratings. Accordingly, an optical signal can be amplified across the entire C-band, and an ASE reflector-based gain-clamped fiber amplifier having a wider dynamic range than conventional amplifiers can be implemented.

Abstract: A fiber amplifier suitable for high power, narrow linewidth applications exhibits suppression of stimulated Brillouin scattering (SBS) by segmenting the fiber amplifier into separate portions that exhibit different Brillouin center frequencies. By changing the center frequencies in adjoining segments of the fiber amplifier, the backward-propagating Stokes signal is essentially blocked, and SBS is suppressed. In a preferred embodiment the segmentation is added to the terminating portion of the fiber amplifier. Various techniques, including temperature modifications, can be used to impart the desired center frequency shift.

Abstract: An automated optical transport system is provided which provides for automatic discovery of system components, automatic inventory of system components, automatic topology detection, automatic provisioning of channels, and automatic characterization and tuning of system components and fiber. The invention provides automation capability through inclusion of management card capabilities at each station which communicates through a reverse propagating service channel. Dynamic and propagation direction independent segments are provided in conjunction with a token-based scheme to repeatedly tune, update and monitor the transport system.

Abstract: An optical amplifying device includes a first optical amplifier for amplifying signal light; a second optical amplifier serially connected with the first optical amplifier; an optical device for compensating deterioration of the signal light, the optical device arranged between the first optical amplifier and the second optical amplifier; a variable optical attenuator for attenuating the signal light, the variable optical attenuator arranged between the first optical amplifier and the second optical amplifier; a first automatic level controller for detecting a second amplifier output power and for controlling driving status of the second amplifier in a predetermined output power level; and a first automatic gain controller for detecting an input power of the second optical amplifier and an output power of the second optical amplifier, and for controlling an optical attenuation value of the variable optical attenuator.

Abstract: In an optical transmission system according to one aspect of the present invention, for transmitting a WDM light from a transmission station to a reception station, utilizing a Raman amplifier, the Raman amplifier comprises: an optical amplification medium; a pumping light source generating a plurality of pumping lights having wavelengths different from each other; an optical device introducing the plurality of pumping lights to the optical amplification medium; and control means for controlling the pumping light source, the transmission station sends out a plurality of reference lights having wavelengths at which respective Raman gain obtained by the plurality of pumping lights reach peaks or wavelengths close to the above wavelengths, and the control means controls the plurality of pumping lights based on the optical powers of the plurality of reference lights. Thus, it becomes possible to accurately manage the optical power balance of the WDM light and the optical power of the entire WDM light.

Abstract: By using a wavelength routing, a single optical amplifier can have the function of a boost amplifier and the function of a preamplifier. Moreover, by attenuating a transmission signal in advance, it is possible to adjust a gain difference required in the boost amplifier and the preamplifier.

Abstract: An automated optical transport system is provided which provides for automatic discovery of system components, automatic inventory of system components, automatic topology detection, automatic provisioning of channels, and automatic characterization and tuning of system components and fiber. The invention provides automation capability through inclusion of management card capabilities at each station which communicates through a reverse propagating service channel. Dynamic and propagation direction independent segments are provided in conjunction with a token-based scheme to repeatedly tune, update and monitor the transport system.

Abstract: In an optical amplifier of the present invention, an input light is supplied to one end of an optical fiber connected to an output port, and the power of a light in an opposite direction which is input to the output port from the one end of the optical fiber, is measured, thereby obtaining a stimulated Brillouin scattering (SBS) occurrence threshold in the optical fiber based on the measurement result. Then, using the SBS occurrence threshold, a relation been the input light power and an occurrence amount of the self phase modulation (SPM) or the like in the optical fiber is obtained to be reflected on a control of the optical amplifier, so that an occurrence of the SPM or the like in the optical fiber is suppressed.

Abstract: A WDM system includes a plurality of P to P WDM systems connected for wavelength-multiplexing optical signals of a plurality of wavelengths, transmitting them to a transmission path, transmitting wavelength-division multiplexed light while performing amplification by using optical AMP in the transmission path, and subjecting the wavelength-division multiplexed light to wavelength isolation at the reception side. An OSC which is a monitoring control signal such as a normal optical signal is used closely within one P to P WDM system. However, by transmitting and receiving the OSC between a plurality of P to P WDM systems, it is possible to solve a problem at the system rise. Moreover, since accumulative OSNR data is transmitted up to the P to P WDM system of the final stage, it is possible to detect an accurate OSNR value and a leak ASE light quantity at the end side.

Abstract: An optical amplifier of the present invention comprises: an optical amplifying circuit which amplifies a signal light; an optical reflection medium which is disposed on an optical fiber connected to the optical amplifying circuit and is capable of reflecting a noise light which exists in a predetermined wavelength range outside a signal band, among noise lights generated in said optical amplifying circuit, to radiate the reflected noise light to the outside of a core of the optical fiber; a light receiver which receives the noise light reflected to be radiated to the outside of the core of the optical fiber by the optical reflection medium, to detect the power of the noise light; and a computation circuit which computes the total power of the noise lights generated in the optical amplifying circuit based on the detection result of the light receiver.

Abstract: A method of managing gain tilt in an optical transmission segment including providing an optical transmission segment having a plurality of fiber optic cable spans and a plurality of repeaters coupled to the fiber optic cable spans. Gain tilt in the optical transmission segment is monitored. If negative gain tilt is accumulated at a repeater location in the transmission segment, the repeater at the repeater location is replaced with a higher gain repeater having a higher nominal gain value than the nominal gain value of the repeater being replaced.

Abstract: An apparatus for compensating for pixel distortion while reproducing hologram data includes an extraction unit, a determination and calculation unit, a table, and a compensation unit. The extraction unit extracts a reproduced data image from a reproduced image frame including the reproduced data image and borders. The determination and calculation unit determines position values of edges of the extracted reproduced data image, and calculates average magnification error values of pixels within line data from position values of start and end point pixels thereof, which are based on the determined position values of the edges. The table stores misalignment compensation values for the pixels within the line data, wherein the misalignment compensation values correspond to predetermined references for average magnification error values.

Abstract: Provided is a fiber ring laser capable of obtaining a back-up laser light and standard light having a wavelength continuously tuned in a single mode with equal spacing of 12.5 GHz, 25 GHz, 50 GHz or 100 GHz recommended by ITU-T Recommendation G. 692 & G. 694.1 in a C-band and an L-band using a fiber tunable etalon filter, an air gap etalon filter and a saturable absorber in an optical fiber laser resonator having a serial ring shape using a C-band optical amplifier and an L-band optical amplifier. The fiber ring laser can generate laser light having a wavelength tuned by more than 70 nm, excellent output power flatness and a source spontaneous emission ratio of more than 70 dB in 361 channels with equal spacing of 25 GHz by applying a bias voltage to a voltage-operated piezoelectric element of a tunable etalon filter. A single longitudinal mode operation of the fiber ring laser can be obtained by using a saturable absorber serving as a narrow-bandwidth filter.

Abstract: The invention relates to an apparatus for dynamically controlling the gain of an optically pumped optical amplifier, and the optical amplifier including such apparatus, which utilizes a multiplying digital to analog converter to implement a digitally adjustable analog feed forward control of a source of pump radiation of the optical amplifier.

Abstract: An electronic circuit for controlling a laser system consisting of a pulse source and high power fiber amplifier is disclosed. The circuit is used to control the gain of the high power fiber amplifier system so that the amplified output pulses have predetermined pulse energy as the pulse width and repetition rate of the oscillator are varied. This includes keeping the pulse energy constant when the pulse train is turned on. The circuitry is also used to control the temperature of the high power fiber amplifier pump diode such that the wavelength of the pump diode is held at the optimum absorption wavelength of the fiber amplifier as the diode current is varied. The circuitry also provides a means of protecting the high power fiber amplifier from damage due to a loss of signal from the pulse source or from a pulse-source signal of insufficient injection energy.