An optical signal amplification apparatus and a related optical communication device. The apparatus may include a pump light source, a combiner assembly, a doped optical fiber, and an optical filter. The pump light source may be configured to emit a pump beam. The combiner assembly is configured to combine a signal beam and the pump beam and couple a combined beam into the doped optical fiber. The doped optical fiber is configured to amplify the signal beam under excitation by the pump beam. The signal beam includes one or more single-wavelength signals. The optical filter is disposed between two ends of the doped optical fiber and configured to transmit the signal beam and filter out a first beam in the doped optical fiber. The first beam includes a beam of some wavelengths or all wavelengths generated by spontaneous emission in the doped optical fiber.

Examples described herein relate to a receiver training method. To configure a static gain for at least one static gain amplifier and a target amplitude for a dynamic gain amplifier, a dynamic gain adjustment is disabled and the dynamic gain amplifier is configured to apply a predetermined fixed gain to the static gain amplified signal to generate a test signal. Furthermore, an effective static gain magnitude for at least one static gain amplifier and an effective amplitude for the test signal are determined based on a link performance metric. The static gain is set to the effective static gain magnitude, and a target amplitude for the dynamic gain amplifier is set to the effective amplitude. Then, the dynamic gain adjustment may be enabled to maintain an amplitude of a dynamic gain amplified signal at an output of the dynamic gain amplifier at the target amplitude by varying the dynamic gain.

An apparatus includes a substrate, a first patterned layer, and a second patterned layer. The first patterned layer may be coupled to the substrate and may have a first metasurface pattern. The second patterned layer disposed separately from the substrate and the first patterned layer, and may have a second metasurface pattern. Movement of the first patterned layer relative to the second patterned layer may be controllable via control circuitry such that a gap distance of a gap between the first patterned layer and the second patterned layer is changed to cause a transmittance for radiant energy of a selected wavelength passing through the apparatus to change from a first transmittance value to a second transmittance value.

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.

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.

An optical amplifier includes two amplifier stages, a circulator and an output stage. The first amplifier stage amplifies an input optical signal, and provides a first-stage amplified optical signal that is to be outputted via the circulator to the second amplifier stage. The second amplifier stage amplifies the first-stage amplified optical signal, and outputs a second-stage amplified optical signal to the output stage. The output stage outputs a returned optical signal to the second amplifier stage, so that the second amplifier stage amplifies the returned optical signal, and provides a third-stage amplified optical signal that is to be outputted via the circulator and the output stage to serve as an output optical signal.

A slope gain equalizer that corrects a slope of a gain characteristic of an optical signal in a predetermined wavelength bandwidth. An interference filter, which allows insertion losses in a predetermined wavelength region to be inclined in opposite directions between a transmitting direction and a reflecting direction from a short wavelength side to a long wavelength side, is arranged between a dual-core fiber collimator and a single-core fiber collimator facing each other on an optical axis. An optical signal of a predetermined bandwidth inputted from a first or second optical fiber held by the dual-core fiber collimator is reflected by the interference filter and outputted from the second or the first optical fiber. An optical signal inputted from a third optical fiber held by the first optical fiber or the single-core fiber collimator is transmitted through the interference filter and outputted from the third or the first optical fiber.

[Problem] To accommodate single-band signal processing devices in a high-density manner. [Solution] Provided is a system including: a first signal cable; a second signal cable; a third signal cable; a fourth signal cable; a first multi-band signal processing device that processes a first signal input from the first signal cable and outputs a resultant second signal to the second signal cable; a second multi-band signal processing device that processes a third signal input from the third signal cable and outputs a resultant fourth signal to the fourth signal cable; a first joint box that accommodates the first signal cable, the first multi-band signal processing device, the second signal cable, and the fourth signal cable; and a second joint box that accommodates the second signal cable, the third signal cable, the second multi-band signal processing device, and the fourth signal cable.

The present disclosure relates to optical communications, and in particular, to a DWDM remote pumping system for improving an OSNR. The system includes remote pumping gain unit, preamplifier, and gain flattening filter sequentially connected. Remote pumping gain unit and the preamplifier are cascaded one behind the other as a whole amplifier. Gain flattening filter is disposed at the preamplifier's output end. In the system, the remote gain unit and preamplifier which have large impact on the OSNR of the entire system are optimally designed as a whole amplifier. In remote gain unit, gain flattening filter originally disposed between two erbium-doped fiber segments is moved back to preamplifier's output end for significant improvement of gain and noise figures of the remote gain unit while ensuring gain flatness of the entire transmission system, thus effectively improving the entire system's OSNR, improving operation stability and reliability, effectively reducing bit error rate, and facilitating system maintenance.

Example fiber amplifiers and gain adjustment methods for the fiber amplifiers are described. One example fiber amplifier includes a first power amplifier, a wavelength level adjuster, and a controller, where the first power amplifier and the wavelength level adjuster are sequentially connected. The controller includes a first input end and a control output end. The first input end is configured to receive an input optical signal of the fiber amplifier, and the control output end is configured to output a first amplification control signal to the first power amplifier, and output an adjustment control signal to the wavelength level adjuster. The wavelength level adjuster is configured to perform power adjustment on each wavelength based on the adjustment control signal.