An optical communication system includes an optical transmitter and one or more processors. The optical transmitter is configured to output an optical signal, and includes an average-power-limited optical amplifier, such as an erbium-doped fiber amplifier (EDFA). The one or more processors are configured to receive optical signal data related to a received power for a communication link from a remote communication system and determine that the optical signal data is likely to fall below a minimum received power within a time interval. In response to the determination, the one or more processors are configured to determine a duty cycle of the optical transmitter based on a minimum on-cycle length and a predicted EDFA output power and operate the optical transmitter using the determined duty cycle to transmit an on-cycle power that is no less than the minimum required receiver power for error-free operation of the communication link.

Disclosed are a system and a method for configuring an optical transmission system. A process may include arranging a first ruggedized repeater on or in a first object or structure. A second ruggedized repeater may be arranged on or in a second object or structure different from the first object or structure. A third ruggedized repeater may be arranged on or in a third object or structure different from the first and second objects or structures, wherein: (i) a first distance between the first ruggedized repeater and the second ruggedized repeater and (ii) a second distance between the second ruggedized repeater and the third ruggedized repeater are equal or nearly equal and based on signal loss.

A controller for a front-exciting Raman-amplifier that amplifies an optical signal transmitted from one end of an optical fiber to other end by inputting an excitation light to the one end, the controller includes a memory, and a processor coupled to the memory and configured to acquire communication-related information regarding communication of the optical signal in the optical fiber, when the acquired communication-related information does not indicate the communication of the optical signal, set a Raman gain of the front-exciting Raman amplifier based on a first light intensity of an amplified spontaneous scattered light of the excitation light, and when the acquired communication-related information indicates the communication of the optical signal, set the Raman gain based on a second light intensity of the optical signal output from the optical fiber.

Provided herein is a wavelength/bandwidth tunable optical filter capable of flexibly tuning a wavelength and bandwidth, the wavelength/bandwidth tunable optical filter including an optical circulator configured to receive a WDM (Wavelength-Division-Multiplexing) optical signal from an optical cable; and a plurality of wavelength-tunable optical filters configured to receive the WDM optical signal via the optical circulator, wherein the plurality of wavelength-tunable optical filters reflect wavelengths of different bandwidths from one another.

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 remote optically pumped amplifier in a multi-span optical communications link. A backwards Raman pump module performs backwards Raman amplification in an optical communications span that contains the remote optically pumped amplifier. A residual amount of backwards Raman pump power is then used to power the remote optically pumped amplifier. The remote optically pumped amplifier may be located 40 to 120 kilometers in optical distance from the backwards Raman pump module such that at least three milliwatts of residual Raman pump power is received by the remote optically pumped amplifier. The Raman pump module may be a multi-pump Raman pump module. A controller controls pump power provided by at least one of the pumps of the backwards Raman pump module, so as to at least partially compensate for optical signal strength versus wavelength variation introduced by the remote optically pumped amplifier and the backwards Raman pump module.

Disclosed are an optical signal outputting device and method, and a storage medium. The device includes a pump laser, first fiber grating and target fiber grating connected seriatim, the pump laser being configured to emit a first optical signal to the first fiber grating upon receiving a target waveband optical signal transmission instruction, and convert a second waveband optical signal into a target waveband optical signal by resonance upon receiving an optical signal adjusting instruction, then output the same; the first fiber grating being configured to filter the first optical signal to obtain a first waveband optical signal and send it to the target fiber grating; and the target fiber grating being configured to filter the first waveband optical signal to obtain a second waveband optical signal and the target waveband optical signal to use one of them to deliver the optical signal adjusting instruction to the pump laser.

A method for realizing precise gain control for a hybrid fibre amplifier, and a hybrid fibre amplifier, in which by an erbium-doped fibre amplifier firstly outputting a constant power, a comparable source signal optical power is provided for a raman fibre amplifier of a next stage. A feedback for the gain control may be formed by comparing a source signal optical power calculated after starting pumping of the Raman fibre amplifier and a source signal optical power detected after pumping stops, thereby greatly improving gain control precision of the Raman fibre amplifier. Moreover, the erbium-doped fibre amplifier parts of all the hybrid fibre amplifiers may simultaneously output a constant optical power, and the Raman amplifier parts of all the hybrid fibre amplifiers may simultaneously start calibration, so that the time for starting operation of the entire system may be improved greatly.

A method for performing optical constellation conversion, according to which each received symbol from a constellation of input symbols is optically split into M components and each component is multiplied by a first predetermined different complex weighing factor, to achieve M firstly weighted components with different amplitudes. Then a nonlinear processor optically performs a nonlinear transform on each M firstly weighted components, so as to obtain M outputs which are linearly independent, Finally, a linear processor optically performs a linear transform to obtain a new converted constellation by optically multiplying, in the complex plane, each of the M outputs by a second predetermined different complex weighing factor, to achieve M secondly weighted components and then summing the M secondly weighted components.

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. The hybrid fiber amplifier and method of adjusting gain and gain slope thereof are applicable to technical field of optical communications.