An EDFA may include an input photodiode configured to generate a control signal based on an input signal. The EDFA may include a blind stage configured to generate an amplified signal based on the control signal and the input signal. The EDFA may include a non-blind stage configured to generate an output signal based on the amplified signal within the blind stage, the control signal, and a feedback signal. The EDFA may include a filter configured to generate a filtered signal based on the output signal. The EDFA may include an output photodiode configured to generate the feedback signal based on the filtered signal. The EDFA may include an alarm device. A signal within the non-blind stage may be generated based on the feedback signal and the control signal. The alarm device may be configured to generate an alarm signal when the signal exceeds a threshold value.

A smart spool is configured to be optically coupled between a pumping light source and optical point-loss sources in an optical fiber transmission line. The smart spool comprises a probe signal transmitter that transmits an optical probe signal into the transmission line. An optical detector receives probe signals scattered in the transmission line. A loss-measuring device is coupled to the optical detector and operable to measure aggregate losses in the transmission line and report the aggregate losses to a network manager. The spool comprises a fiber of sufficient length to offset the aggregated losses to enable a distributed Raman amplifier to pump the transmission line. The smart spool prevents the distributed Raman amplifier from shutting down and allows the distributed Raman amplifier to achieve entitled gain by pumping the fiber in the spool.

A MOPA laser system that includes a seed laser configured to output pulsed laser light, an amplifier configured to receive and amplify the pulsed laser light emitted by the seed laser; and a pump laser configured to deliver a pump laser beam to both the seed laser and the amplifier and a variable attenuator configured to eliminate missing Q-switched pulses.

An optical amplifier includes at least two stages of optical amplifier systems, an optical switch, a dynamic gain equalizer (DGE), and a control circuit. An input end of the optical switch is separately coupled to an output end of a first-stage optical amplifier system and an output end of a second-stage optical amplifier system, and an output end of the optical switch is separately coupled to an input end of the second-stage optical amplifier system and an input end of the DGE. The optical switch is configured to set at least two gain modes of the optical amplifier. The control circuit is configured to adjust an attenuation spectrum of the DGE based on the at least two gain modes set by the optical switch. The DGE is configured to perform, based on an adjusted attenuation spectrum, power attenuation processing on signals of different wavelengths in a received optical signal.

A fiber laser amplifier system including a non-linear fiber amplifier receiving a seed beam and a pump beam, where the amplifier amplifies the seed beam using the pump beam to provide an output beam having a carrier spectrum. A beam sampler samples off a sample beam from the output beam, a filter receives the sample beam and filters out the carrier spectrum from the sample beam, a photodetector detects beam power of the filtered sample beam and provides a beam power signal, and a controller receives the beam power signal, where the controller controls one or more of an FM drive signal, an AM drive signal and a pump beam to change seed beam FM modulation, seed beam AM modulation and/or pump power in a manner that reduces the beam power of the filtered sample beam and thus beam power outside of the carrier spectrum.

A spectral beam combining (SBC) fiber laser amplifier system including a beam shaper array assembly and a beam source that provides a plurality of beams having a low fill factor profile. The assembly includes an input beam shaper array having a plurality of input cells positioned adjacent to each other that are shaped to cause the beams to expand as they propagates away from the input array to be converted from the low fill factor profile to a high fill factor profile and be tapered to a lower value at a perimeter of each input array cell. The assembly further includes an output beam shaper array having a plurality of output cells positioned adjacent to each other that are shaped to cause the beams to stop expanding so that the output array provides a plurality of adjacent beams with minimal overlap and a minimal gap between the beams.

A system comprising a recirculating loop configured to store an electromagnetic wave signal, the recirculating loop comprising a transmission medium and a plurality of transceivers configured to introduce the electromagnetic wave signal into the transmission medium and retrieve the electromagnetic wave signal from the transmission medium, and a signal conditioning system comprising a plurality of signal conditioners coupled to the transmission medium, the plurality of signal conditioners configured to amplify or regenerate the electromagnetic wave signal traveling in the transmission medium, one or more pump laser sources, wherein at least one of the one or more pump laser sources is configured to provide a pump laser beam to at least two of the plurality of signal conditioners, and one or more control circuits for controlling the plurality of signal conditioners, wherein at least one of the one or more control circuits is configured to control and monitor at least two of the plurality of signal conditioners, is disclosed.

A method of controlling an optical transmitter includes steps of amplifying, by an EDFA, a main signal output from an optical modulator, attenuating and outputting, by a VOA, the main signal amplified and output by the EDFA, and maintaining an output power of the main signal output from the VOA at a predetermined value, suspending the phase modulation in the optical modulator to output continuous wave light from the optical modulator, disabling feedback control of the VOA that is performed by the VOA controller and maintaining a constant control signal of the VOA, disabling feedback control of a pump laser that is performed by a pump laser controller, and controlling the pump laser to modulate an intensity of the excitation light and generate an auxiliary signal having a cycle longer than a cycle of the main signal.

An apparatus for automatic amplifier gain setting of an optical amplifier, said apparatus comprising an optical channel counter, OCC, unit configured to detect a number of channels present in an optical transmission spectrum; a determination unit configured to determine an average power per channel calculated by dividing a measured total power of a signal input and/or signal output of the optical amplifier by the number of channels detected by said optical channel counter, OCC, unit and a gain adjustment unit configured to adjust the amplifier gain of said optical amplifier automatically depending on a calculated power difference between a predetermined desired power per channel and the determined average power per channel provided by said determination unit.

The present invention provides an optical amplifier and a control method therefor, with which it is possible to stably control an optical amplifier that uses a multicore optical fiber. The optical amplifier uses, in a gain medium, a multicore optical fiber having a plurality of cores, and comprises: an input-light power monitor that monitors the optical power of input light to the plurality of cores of the multicore optical fiber; an output-light power monitor that monitors the optical power of medium-passed output light from the plurality of cores that has passed through the multicore optical fiber; a crosstalk monitor that monitors the amount of inter-core crosstalk among the plurality of cores; and a controller that controls the pump-light power of pump light superimposed on the input light to the plurality of cores on the basis of the monitored optical power of input light, the monitored optical power of output light, and the monitored amount of inter-core crosstalk.