Abstract: The systems and methods directed towards a reconfigurable optical add-drop multiplexer (ROADM). The ROADM comprising: i) a plurality of line cards, wherein each one of the plurality of line cards is configured to receive a plurality of wavelength channels from an optical link in an optical network; ii) a plurality of add/drop cards, wherein each one of the plurality of add/drop cards includes a primary path and a secondary path; and iii) a controller configured to: a) select a set of wavelength channels from the plurality of wavelength channels, b) determine if there is any contention between the set of wavelength channels, c) direct a first subset of wavelength channels from the set of wavelength channels that do not have contentions to the primary path, and d) direct a second subset of wavelength channels from the set of wavelength channels that have contentions to the secondary path.

Abstract: Methods and apparatus for providing spectrally beam-combined fiber-based transmitters and/or receivers for laser communications, LiDAR, and similar devices. A transmitter can include a launch array configured to spatially position each output beam of pulsed lasers, a transform optical component to correct deflection of the output beams of the pulsed lasers from the launch array, and a dispersive optical element to combine beams from the transform optical element and generate a spectrally combined beam. A receiver can include spectral comb filters to spectrally discriminate multi-wavelength detected signals from background illumination.

Abstract: An optical network management device (100) which assigns a path from a transmitting node to a receiving node in an optical network system including a multi-core optical fiber, includes at least one processor, the processor being configured to carry out: a core extraction process of extracting a core constituting the path; and a path assignment process of selecting, in accordance with an attribute of the path, a wavelength to which the path is to be assigned, the multi-core optical fiber having an optical amplifier attached thereto, the optical amplifier having an amplification gain that is larger in a first wavelength region than in a second wavelength region, the path assignment process including preferentially assigning, to the first wavelength region, the path having a specific attribute.

Abstract: Optical line amplifiers with on-board controllers and supervisory devices for controlling optical line amplifiers are provided for controlling bootstrap or power-up procedures when optical line amplifiers are initially installed in an optical communication network. The controllers may include non-transitory computer-readable medium configured to store computer logic having instructions that, when executed, cause one or more processing devices to block an input to one or more gain units of the line amplifier and cause the line amplifier to operate in an Amplified Spontaneous Emission (ASE) mode. In response to a detection of a valid power level of the line amplifier, the instructions can further cause the one or more processing devices to switch the line amplifier from the ASE mode to a regular mode and unblock the input to the one or more gain units of the line amplifier to allow operation of the line amplifier in the regular operating mode.

Abstract: An apparatus for mitigating polarization dependent loss (PDL) in an optical signal-to-noise ratio (OSNR) of a modulated optical signal is disclosed. The apparatus may comprise a spectrum analyzer to measure an optical power spectrum of a modulated optical signal. The apparatus may also comprise a measuring unit to select a first portion of the modulated optical signal and a second portion of the modulated optical signal, where each of the first and second portions of the modulated optical signals may include an independent noise distribution indicative of PDL, and measure a time-varying parameter of the first and second portions. The apparatus may also include a signal processor to PDL in an OSNR by transforming any elliptical polarization associated with the independent noise distribution into a ball polarization, determining a correlation between time-varying parameters of the first and second portions, and calculating a PDL mitigated OSNR.

Abstract: To reduce bad connections of a BGA optical module as an optical fiber interface during mounting by reflowing. An optical module includes: a substrate to which an optical fiber is connected and fixed and on which an electronic circuit, an optical circuit or the like is formed; a ball grid array provided on one face of the substrate as an electrical interface used when the optical module is mounted on a mounting substrate; a lid having a thermal conductivity provided on another face of the substrate; and a fiber routing mechanism provided in contact with the lid, the fiber routing mechanism having a thermal conductivity and shaped to enable the optical fiber to be wound around the fiber routing mechanism.

Abstract: A multi-stage thulium-doped (Tm-doped) fiber amplifiers (TDFA) is based on the use of single-clad Tm-doped optical fiber and includes a wavelength conditioning element to compensate for the nonuniform spectral response of the initial stage(s) prior to providing power boosting in the output stage. The wavelength conditioning element, which may comprise a gain shaping filter, exhibits a wavelength-dependent response that flattens the gain profile and output power distribution of the amplified signal prior to reaching the output stage of the multi-stage TDFA. The inclusion of the wavelength conditioning element allows the operating bandwidth of the amplifier to be extended so as to encompass a large portion of the eye-safe 2 ?m wavelength region.

Abstract: The present invention is to provide a backscattered light amplification device, an optical pulse test apparatus, a backscattered light amplification method, and an optical pulse test method for amplifying a desired propagation mode of Rayleigh backscattered light with a desired gain by stimulated Raman scattering in a fiber under test having the plurality of propagation modes. The backscattered light amplification device according to the present invention is configured to control individually power, incident timing, and pulse width of a pump pulse for each propagation mode when the pump pulse is incident in a plurality of propagation modes after the probe pulse is input to the fiber under test in any propagation mode.

Abstract: A method for establishing a data model and an apparatus, where a network element may create an optical signal group that includes optical signals with different wavelengths. After selecting a first optical signal group and obtaining first data of the first optical signal group, the network element may reflect, based on a first model established based on the first data of the first optical signal group, a noise coefficient and a gain that are obtained after an optical signal in the optical signal group of different wavelength combinations passes through the network element.

Abstract: The present invention provides a method for converting the topological charge of an orbital angular momentum mode of light to an opposite topological charge by applying the light to a spool of optical fiber having a bend radius R and length L. The length of the fiber used to form the spool is defined by ½ the bend-induced 2? walk-off length Ll,mb(2?). The length of the fiber L and the bend radius R of the spool may be adjusted to account for an ellipticity-induced 2? walk-off length Ll,m3(2?). Using the proportionality rules, Ll,mb(2?)?R2l and Ll,m3(2?)???l adjustments to account for ellipticity induced 2? walk-off length Ll,me(2?), or to account for a change in the bend radius ?R of the spool can be easily determined.

Abstract: Automatic optical link calibration systems and methods include an optical node with an Optical Add-Drop Multiplexer (OADM) multiplexer including a channel holder source; an optical amplifier connected to the OADM multiplexer and to a fiber span; an Optical Channel Monitor (OCM) configured to monitor optical spectrum before and after the optical amplifier; and a controller configured to obtain data associated with the fiber span including measurements from the OCM, determine settings of the channel holder source needed to meet a target launch power profile for the fiber span, and configure the channel holder source based on the determined settings.

Abstract: A reflection reduction device includes an optical fiber (104) configured for optical sensing and having an end portion. A tip portion (102) is coupled to the end portion. The tip portion includes a length dimension (d) and is index matched to the optical fiber. The tip portion is further configured to include an absorption length to absorb and scatter light within the length dimension, and a surface (S) opposite the end portion is configured to reduce back reflections.

Abstract: A fiber-based optical amplifying system for use with a multi-wavelength input optical signal operating over a predetermined bandwidth is specifically configured to eliminate the need for a separate gain-flattening filter, improving the power conversion efficiency (PCE) of the system. Both a distributed Raman amplifier (DRA) and an erbium-doped fiber amplifier (EDFA) are used, where the DRA component is configured to use a pump beam with at a power level no greater than 200 mW. The EDFA is configured to exhibit a gain profile the complements that of the DRA, while also providing amplification that is no less than 10dB at any wavelength within the system bandwidth. With these parameters, the combination of the DRA and EDFA is able to maintain an output gain deviation of less than about 2 dB.

Abstract: A polarization-dependent loss (PDL) determining method includes obtaining two groups of optical powers within first duration, selecting at least one group of target optical powers that satisfy a same power constraint from the two groups of optical powers, where each group of target optical powers includes a first target power and a second target power from the two groups of optical powers, and determining a PDL of the optical device based on the at least one group of target optical powers.

Abstract: This application provides a sending device, a receiving device, an optical transmission system, and an optical power control method. The sending device includes a multiplexing unit and an optical power adjustment unit. The multiplexing unit is configured to send at least two communication optical waves to a fiber channel, and is further configured to send or receive at least two detection optical waves through the fiber channel. The optical power adjustment unit is configured to: obtain a power control instruction, where the power control instruction is generated according to power change information between the at least two detection optical waves. The optical power adjustment unit is further configured to perform optical power amplification and/or attenuation on at least one communication optical wave in the at least two communication optical waves according to the power control instruction.

Abstract: Embodiments discussed herein refer to LiDAR systems and methods that enable substantially instantaneous power and frequency control over fiber lasers. The systems and methods can simultaneously control seed laser power and frequency and pump power and frequency to maintain relative constant ratios among each other to maintain a relatively constant excited state ion density of the fiber laser over time.

Abstract: An optical amplifier of the present disclosure includes an optical resonator that includes an amplification fiber capable of amplifying signal light having one or more propagation modes and resonates at least one propagation mode of the signal light amplified by the amplification fiber; an excitation light source that outputs excitation light for exciting the amplification fiber; and a multiplexer that multiplexes the signal light and the excitation light, in which the optical resonator includes a gain clamp setting unit which sets gain clamp for at least one propagation mode out of a plurality of propagation modes resonating in the optical resonator.

Abstract: Systems and methods for performing data transfer between first and second electrical devices are provided. One method may include electrically coupling the first electrical device to a first electrical-optical (E-O) device via a first plurality of electrical lanes, electrically coupling the second electrical device to a second E-O device via a second plurality of electrical lanes, optically coupling the first and second E-O devices via a plurality of optical lanes, and transferring data therebetween via a first optical lane. The method may include monitoring one or more parameters associated with an optical transmitter of the first optical lane, and comparing each parameter to a respective threshold. Responsive to the comparison, the method includes commencing transfer of data between the first and second E-O devices via a second optical lane, and terminating transfer of the data between the first and second E-O devices via the first optical lane.

Abstract: The de-multiplexing unit 2 de-multiplexes an inputted optical wavelength multiplexed signal into a first optical wavelength multiplexed signal having a first wavelength band and a second optical wavelength multiplexed signal having a second wavelength band in a longer wavelength band than the first wavelength band. The first optical amplifier 3 amplifies the first optical wavelength multiplexed signal. The second optical amplifier 4 amplifies the second optical wavelength multiplexed signal. The multiplexer 5 multiplexes the amplified first optical wavelength multiplexed signal and the amplified second optical wavelength multiplexed signal and outputs the multiplexed signal to a Raman amplifier 6. The first optical amplifier 3 adjusts the amplification rate of the first optical wavelength multiplexed signal so that the intensity of light in the second wavelength band is compensated for by the Raman effect in the Raman amplifier 6.

Abstract: An amplification optical fiber includes: a core; an inner cladding having a refractive index lower than a refractive index of the core, wherein an active element pumped by pumping light is entirely doped to the core, and a relative effective refractive index difference of light in an LP01 mode is greater than or equal to 0.05% and a relative effective refractive index difference of light in an LP21 mode is less than 0.05% in light propagating through the core.

Abstract: An optical transmission system includes: a terminal station device that transmits a wavelength multiplexed optical signal resulting from multiplexing an optical signal and dummy light; and an optical add-drop multiplexer that receives respective wavelength multiplexed optical signals transmitted from a plurality of the terminal station devices and performs add-drop processing on the wavelength multiplexed optical signals. The dummy light has a wavelength arrangement in which adjacent wavelengths are arranged with equal spacing, and the wavelength arrangement of the dummy light differs between the terminal station devices.

Abstract: An optical receiver can implement a transimpedance amplifier (TIA) to process received light using a closed loop optical pre-amplification. The optical receiver can use an average input value of the TIA to control an semiconductor optical amplifier (SOA) or pre-amplification as received average signal varies. The optical receiver can include a gain controller for the TIA that can measure the TIA swing to adjust the gain of the SOA to pre-amplify received light in a closed loop control configuration.

Abstract: The disclosed systems, structures, and methods are directed to an optical communication comprising a first wavelength division multiplexer (WDM) configured to receive WDM signals, the first WDM is further configured to split the received WDM signals into C band WDM signals and L band WDM signals, a C band amplifier configured and an L band amplifier configured to amplify the C band WDM signals and L band WDM signals respectively and compute a fast total instantaneous powers Ptot-CBand(t) and Ptot-LBand(t) on a fast time scale, a slow per channel power detector configured to extract slow per channel powers P(?1), P(?2) . . . P(?n) on a slow time scale, a Stimulated Raman Scattering (SRS) estimator configured to estimate an SRS induced gain change in the WDM signals, and a second WDM configured to combine and transmit the amplified C band WDM signals and L band WDM signals over optical cables.

Abstract: A free space optical communication system transmits and receives optical signals in a colorless manner using an optical circulator. The system installs the optical circulator with a single mode (SM) fiber at port 1, a double clad (DC) fiber at port 2, and a multimode (MM) fiber at port 3. The system injects a first optical signal into a core of the SM fiber. The system then routes the first optical signal at port 1, using the optical circulator, into a SM core of the DC fiber via Port 2. Further, the system injects a second optical signal into a first cladding of the DC fiber. The system then routes the second optical signal at port 2, using the optical circulator, into the MM fiber via Port 3.

Abstract: Methods and systems for relaying an optical image using a cascade arrangement of tilted, concave mirrors are presented. An exemplary optical relay system includes a cascade arrangement of four mirrors each having concave, spherical surface figures. The first and third mirrors are configured to focus collimated wavefronts and the second and fourth mirrors re-collimate diverging wavefronts reflected from the first and third mirrors. Each mirror is tilted such that wavefronts located in the local field plane and local pupil plane of each mirror are physically separated. The magnitude and direction of each tilt angle are arranged such that off-axis aberrations introduced by each individual mirrors are largely compensated by the other mirrors. Such an optical relay system is employed to relay images of the pupil plane of a metrology system that is configured to perform accurate measurements of semiconductor structures and materials over a broad range of illumination wavelengths.

Abstract: A high-resolution single-chip spectrometer is disclosed. Embodiments of the present invention are analogous to Fourier-transform spectrometers; however, embodiments of the present invention have no moving parts. An illustrative embodiment is a spectrometer having a nested plurality of Mach-Zehnder interferometers (MZIs), where all MZIs share at least one surface-waveguide section in each of its sample and reference arms. The light signals in the sample and reference arms are tapped at a series of discrete locations along their length via electro-optically-controlled directional couplers, which are separated by uniform-length waveguide portions in each arm, but where the uniform lengths are different in the sample and reference arms providing a different path-length difference for the arms of each MZI. The tapped light from the sample and reference arms is recombined at a low-loss beam combiner to generate a distribution of optical power as a function of time-delay difference in the arms.

Abstract: An optical fiber laser device generates laser light by using an optical amplifying fiber as an amplification medium in a laser oscillator and includes: an optical outputting fiber configured to emit laser light to an outside; a return-light-attenuating portion configured to perform an attenuation process to return light propagating through at least the optical outputting fiber in a reverse direction of the laser light; a thermal conversion unit provided at the return-light-attenuating portion and configured to convert the return light into heat; a temperature-monitoring device configured to measure an increase in a temperature, of the return-light-attenuating portion, caused by the heat converted by the thermal conversion unit; and a control unit configured to decrease or stop an output of the laser light when the temperature measured by the temperature-monitoring device becomes a predetermined threshold temperature or higher.

Abstract: This disclosure discloses a method of creating a three-dimensional image of a sample using snapshot optical tomography. The method includes generating a plurality of beams incident on the sample simultaneously, acquiring a field image at a plane not conjugate to the sample plane using off-axis digital holography, extracting amplitude data and phase data for the field image, restoring the sharpness by backpropagating the field image using the extracted amplitude and phase data, acquiring a background image, extracting amplitude data and phase data for the background image, and reconstructing a three-dimensional image of the sample with the backpropagated field image and the background image. The method also includes arranging more than one imaging chains to remove the missing angle artefacts in optical tomography. Also disclosed are systems for performing the method.

Abstract: An apparatus includes an optical amplifier configured to receive an input optical signal and generate an amplified output optical signal. The optical amplifier includes multiple amplifier stages including at least a first amplifier stage and a second amplifier stage. The apparatus also includes a gain clamp configured to accumulate optical power from the first amplifier stage after an optical power level of the input optical signal drops and provide a first portion of the accumulated optical power to the first amplifier stage to clamp a gain applied by the first amplifier stage. The gain clamp is also configured to provide a second portion of the accumulated optical power to the second amplifier stage to adjust a gain applied by the second amplifier stage. The second amplifier stage is configured to amplify the second portion of the accumulated optical power.

Abstract: In a case where a variation in reflection resistance among fiber lasers occurs, a reflection resistance of a fiber laser system as a whole is restored by reducing the variation while maintaining an output power of the fiber laser system as a whole. The fiber laser system includes a control section (C) configured to increase a proportion of a backward excitation power (PBi) in a fiber laser (FLi) so that fiber lasers (FL1 through FLn) less vary in reflection resistance.

Abstract: Method and systems for characterizing an optical signal propagating along a communication link are disclosed. The signal includes a data-carrying signal contribution, modulated at a symbol frequency, and a noise contribution. The method includes measuring an optical power spectrum of the signal, which includes a data-carrying signal spectrum component and a noise spectrum component. The method also includes determining a measured spectral correlation function within pairs of spectral components of the signal as a function of center frequency of the pairs, the spectral components in each pair being spectrally separated from each other by the symbol frequency. The method further includes obtaining a solution for the data-carrying signal spectrum component based on the measured optical power spectrum, such that a calculated spectral correlation function based on the solution matches the measured spectral correlation function.

Abstract: A method and a device are provided for monitoring OSNR system margin in optical networks which relies on the relationship that exists between the OSNR value and the ESNR value.

Abstract: A polishing apparatus capable of accurately measuring a film thickness by regulating a quantity of light illuminating a wafer is disclosed. The polishing apparatus includes: a light source; an illuminating fiber having distal ends arranged at different locations in the polishing table; and a light-receiving fiber having distal ends arranged at the different locations in the polishing table. The illuminating fiber includes a first illuminating fiber and a second illuminating fiber. A first dimmer is attached to the first illuminating fiber and the second illuminating fiber, and a second dimmer is attached to at least one of the first illuminating fiber and the second illuminating fiber.

Abstract: Methods, devices, and systems for amplifying laser pulses having different wavelengths in a drive laser assembly for an extreme ultraviolet (EUV) radiation generating device are provided. The drive laser assembly includes a radiation source configured to generate a first laser pulse having a first wavelength and a second laser pulse having a second wavelength, and an amplifier assembly having at least one optical amplifier for amplifying the first laser pulse and the second laser pulse. The amplifier assembly has at least one wavelength-selective optical element configured to attenuate the first laser pulse at the first wavelength more strongly than the second laser pulse at the second wavelength.

Abstract: Embodiments provide a light source having a coherent light generator arrangement configured to generate at least one output light, and a waveguide arrangement optically coupled to the coherent light generator arrangement, the waveguide arrangement including at least one first resonator element and at least one second resonator element arranged in different orientations, wherein the waveguide arrangement is configured to interact with the at least one output light to cause the at least one first resonator element and the at least one second resonator element to emit respective first and second optical signals to co-operatively interact with each other to generate an output optical signal, and wherein the light source is configured to change a polarization characteristic of the output optical signal in response to at least one electrical signal applied to the light source to vary at least one of respective magnitudes of the first and second optical signals relative to each other.

Abstract: An optical transmission device includes: a first optical amplifier, a WSS (wavelength selective switch), a second optical amplifier and a controller. The first optical amplifier amplifies a received WDM (wavelength division multiplexed) optical signal. The WSS controls optical powers of respective channels multiplexed in the WDM optical signal that is amplified by the first optical amplifier. The second optical amplifier amplifies the WDM optical signal output from the WSS. The controller controls a gain of the first optical amplifier based on initial setting information. The controller corrects the gain of the first optical amplifier such that an average optical power of a plurality of channels multiplexed in the WDM optical signal that is amplified by the first optical amplifier approaches a target level after a specified period of time has elapsed from when the gain of the first optical amplifier is controlled based on the initial setting information.

Abstract: A method and a device are provided for monitoring OSNR system margin in optical networks which relies on the relationship that exists between the OSNR value and the ESNR value.

Abstract: An apparatus is provided that includes an optical noise generator and a noise combiner. The noise generator is configured to produce an optical signal having a noise channel. The noise combiner is configured to combine an optical data channel with the noise channel received at one or more add ports to produce an optical output signal. A controller is configured to operate the noise generator or the noise combiner to provide a variable bandwidth of added noise combined with the optical data channel.

Abstract: An optical communication device and related method are provided for reducing power variations among wavelength division multiplexing (WDM) signals. The device includes a dynamic gain equalizer (DGE) coupled to an optical communication path carrying WDM optical signals. The DGE is controlled in response to signals generated by an optical channel monitor (OCM). The OCM monitors signals coming into the DGE and monitors the signals leaving the DGE to thus monitor the WDM spectrum for optical signal power variations and adjust the DGE to reduce the signal power variations.

Abstract: A distributed Automatic Power Optimization (APO) system and method are provided. The distributed APO system includes: one or more APO modules and a network management system. The one or more APO modules belong to one or more pre-divided APO links. Each APO module in the one or more APO modules belongs to only one APO link. The APO module is configured to, when the APO link to which the APO module belongs is triggered to perform power regulation, regulate a power attenuation or a gain between the two adjacent stations corresponding to the APO module and report a regulation result. The network management system is configured to, when learning that all of one or more APO modules in one APO link are successful in regulation, if there is a next APO link of the APO link, trigger the next APO link of the APO link to perform power regulation.

Abstract: A method is described in which a loss of spectrum in an optical signal having an optical signal spectrum is detected. The optical signal is transmitted from a first node to a second node. In response to detecting the loss of spectrum in the optical signal, at least one idler carrier without data imposed is supplied into the optical signal spectrum transmitted from the first node to the second node, the optical signal spectrum encompassing a frequency band including a plurality of optical channels, the idler carrier being amplified stimulated emission light having a frequency corresponding to a first optical channel of the plurality of optical channels.

Abstract: An optical gain fiber for use in high power (e.g., greater than 500 W pump power) is proposed that is configured to exhibit a minimum bend radius such that the bend loss for the propagating LP01 mode is greater than about 0.03 dB/m. It has been discovered that this bend radius criteria, which is less stringent than that typically suggested in the art (e.g., bend loss less than about 0.03 dB/m), meets the modal stability requirements at high power operation, since the increase in operating temperature of the fiber laser or amplifier has been found to somewhat relax the bend radius requirement (which was heretofore only measured at “room temperature”, not “operating temperature”). Modal stability is defined in terms of a reduced presence of unwanted higher-order modes (such as the LP11 mode) in the amplified output signal.

Abstract: An optical receiver includes a demultiplexer configured to demultiplex, for each channel, optical signals input through a plurality of channels, a photoelectric converter having a number of light receivers corresponding to the plurality of channels, the photoelectric converter being configured to convert an optical signal into an electric signal for each channel, a monitor circuit configured to monitor, for each channel, an amplitude characteristic of the optical signal converted into the electric signal by the photoelectric converter, and a control circuit configured to control, based on a monitored result of the monitor circuit, a bias voltage to be applied to the light receiver such that an amount of variability in the amplitude characteristic between the channels is minimum or falls within a predetermined range.

Abstract: A subscriber device includes a demultiplexer configured to demultiplex input wavelength-multiplexed light into a plurality of light signals for each wavelength, a plurality of light receivers configured to receive each of the plurality of light signals obtained through demultiplexing by the demultiplexer and to convert the light signals into electrical signals, a plurality of limiting amplifiers configured to amplify each of the plurality of electrical signals output from the plurality of light receivers, and a plurality of signal selection units configured to select a plurality of signals to be received from among a plurality of amplified signals output from the plurality of limiting amplifiers.

Abstract: Aspects of an optical communications network are described that include two or more optical fibers arranged to allow communication in the same direction. The optical network includes a first optical amplifier coupled to the first optical fiber, a second optical amplifier coupled to the second optical fiber, a first optical pump to provide optical power to the first optical fiber, and a second pump to provide optical power to both the first and the second optical fibers. By sharing the second pump between the first and the second optical fibers, a need to deploy additional pumps is alleviated. Scaling of the optical network to include additional optical fibers provides further cost savings by allowing more pumps to be shared among the multiple optical fibers.

Abstract: In one embodiment, an optical amplifier includes a first pump laser diode and a second pump laser diode. The first pump laser diode is configured to produce pump light that includes a first amount of optical power at a first wavelength, and the second pump laser diode is configured to produce pump light that includes a second amount of optical power at a second wavelength different from the first wavelength. The optical amplifier also includes an optical gain fiber configured to receive the pump light from the first and second pump laser diodes and provide optical gain for an optical signal propagating through the optical gain fiber. The optical amplifier further includes a controller configured to adjust the first amount of optical power produced by the first pump laser diode and the second amount of optical power produced by the second pump laser diode.

Abstract: An optical fiber apparatus and a method of recovering radiation-induced-attenuation (RIA) onto a rare-earth-doped optical fiber under irradiation are provided in this disclosure. A light source is coupled to a rare-earth doped optical fiber. The light source emits a combination of mode locked pulsed light and non-mode locked quasi-continuous-wave light. The mode locked pulsed light are used to recover RIA onto the rare-earth doped optical fiber in real time, and the non-mode locked light are used to pump the rare-earth doped optical fiber as a gain medium. Each pulsed duration of the mode locked pulsed light is much shorter than operation duration of the non-mode locked light, such that an instantaneous power of the mode locked pulsed light exceeds a saturated pumping power required for the rare-earth doped optical fiber, so as to effectively elevate the core temperature of rare-earth doped fiber to achieve a confined photo-annealed recovery of RIA onto rare-earth doped fibers.

Abstract: Provided is a method of measuring a phase noise of a repetition rate of a femtosecond laser including generating a combined signal using a first wavelength element and a second wavelength element of an optical pulse train generated by the femtosecond laser, which is mode-locked, guiding the combined signal to a first path and a second path, allowing a signal of the second path to interfere with the signal of the first path, and outputting an interfering combined signal, dividing the interfering combined signal into a first interference signal and a second interference signal, converting the interference signals to radio frequency signals, and detecting a baseband signal including a frequency noise of the repetition rate from the radio frequency signals using a mixer.

Abstract: Implementing a laser into a system that uses a remote powered combiner or an aggregating combiner (AC) with one or more in-range contributing combiners may provide power to the downstream contributing combiners (CC). The power may be provided on the same fiber that downstream signals and the upstream signals traverse.

Abstract: An amplifier receives an optical signal including a number of labeled channels via a fiber. The amplifier determines a count of the labeled channels and a spectral distribution of the labeled channels. The amplifier adjusts a parameter of the amplifier based on the count of the labeled channels and the spectral distribution of the labeled channels. The amplifier amplifies the optical signal at an adjusted output gain resulting from adjusting the parameter of the amplifier.