The present disclosure relates to a technical field of optical communication, and provides a method and an apparatus for determining maximum gain of Raman fiber amplifier. Wherein the method includes obtaining transmission performance parameters of a current optical fiber transmission line; respectively obtaining impact factors A.sub.1, A.sub.2, A.sub.4 according to a distance between a joint and a pump source, a fiber loss coefficient, and a fiber length included in the transmission performance parameters; calculating a joint loss value Att.sub.Aeff according to a distance between a joint and a pump source, a fiber loss coefficient, and looking up impact factor A.sub.3 according to Att.sub.Aeff; determining an actual maximum gain which may actually be achieved by the Raman fiber amplifier according to A.sub.1, A.sub.2, A.sub.3, A.sub.4. The actual maximum gain obtained in the present disclosure is the maximum gain that may be achieved over all input power ranges, and the original signal in system is kept to operate at a fixed gain, such that a gain locking effect is realized, and fluctuation of existing transmission signal power caused by signal change in transmission fiber link is avoided.

The embodiments of the present invention disclose a method and an apparatus for determining a gain of a Raman optical amplifier and a Raman optical amplifier. The method includes: acquiring present gain parameter information of a Raman optical amplifier; and determining a present gain of a monitoring channel of the Raman optical amplifier according to the present gain parameter information and a correspondence between a gain of the monitoring channel of the Raman optical amplifier and gain parameter information. According to the method and apparatus for determining a gain of a Raman optical amplifier and the Raman optical amplifier that are in embodiments of the present invention, a present gain of a monitoring channel can be accurately determined; therefore, a gain spectrum of the Raman optical amplifier can be accurately monitored, and the gain of the Raman optical amplifier can be accurately adjusted to a target gain.

A method and a device is provided driving an optical laser diode (710, 711) during operation in an optical communication network, by determining a laser transfer function (741, 742) during operation of the laser diode (710, 711) and providing a control signal (750, 749) for driving the laser diode (710, 711) according to the laser transfer function (741, 742). Further, a method for driving a first and a second optical laser diode during operation in an optical communication network is provided. Furthermore, an optical amplifier and a communication system is suggested.

The optical amplifier, which amplifies wavelength multiplexed signal light, comprises: a multi-core optical fiber which includes cladding and a first core and a second core disposed in the cladding, and which is doped with rare-earth ions; an excitation light source for supplying excitation light to the cladding of the multi-core optical fiber; and a wavelength demultiplexing means for separating the wavelength bands of the wavelength multiplexed signal light that has propagated through the first core. The signal light of a relatively long wavelength band among a plurality of wavelength bands separated by the wavelength demultiplexing means is caused to propagate through the second core, and is then multiplexed with the signal light of a relatively short wavelength band among the plurality of wavelength bands separated by the wavelength demultiplexing means, and the resultant multiplexed signal light is output.

An amplifier operable with an electric drive signal can amplify signal light having a signal wavelength. A laser diode has an active section with input and output facets. The facets are in optical communication with the signal light and are configured to pass the signal light through the laser diode. The active section is configured to generate pump light in response to injection of the electrical drive signal into the active section. The pump light has a pump wavelength different from the signal wavelength. A doped fiber doped with an active dopant is in optical communication with the signal light and is in optical communication with at least a portion of the pump light from the laser diode. The pump wavelength of the pump light is configured to interact with the active dopant of the fiber and thereby amplify the signal light.

A system includes a master oscillator configured to generate a first optical beam and a beam controller configured to modify the first optical beam. The system also includes a PWG amplifier configured to receive the modified first optical beam and generate a second optical beam having a higher power than the first optical beam. The second optical beam has a power of at least about ten kilowatts. The PWG amplifier includes a single laser gain medium configured to generate the second optical beam. The system further includes a feedback loop configured to control the master oscillator, PWG amplifier, and beam controller. The feedback loop includes a laser controller. The laser controller may be configured to process wavefront information or power in bucket information associated with the second optical beam to control an adaptive optic or perform a back-propagation algorithm to provide wavefront correction at an output of the PWG amplifier.

An amplifier includes a first monitor configured to measure first optical power including first signal light and ASS light of a first wavelength band propagated through the amplification medium, and a processor configured to calculate the first ASS light power corresponding to the first excitation light power, based on the determined first model formula, calculate the second ASS light power corresponding to the second excitation light power, based on the determined second model formula, calculate the first signal light power by subtracting the calculated first ASS light power and second ASS light power from the first optical power measured by the first monitor, and calculate a difference between the calculated first signal light power and first target signal light power, and controll a first excitation light source or a second excitation light source to adjust the first excitation light power or the second excitation light power based on the difference.

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 is connected to the wavelength level adjuster. The controller includes a first input end and a control output end. The first input end is configured to receive an input optical signal, 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 in a separate manner based on the adjustment control signal.

An optical amplifying device according to the present invention includes: an optical propagation path including an optical amplifier for amplifying input light; an excitation light source for generating excitation light to excite the optical amplifier; first and second optical receivers detect the power of the input light in the optical propagation path before being amplified by the optical amplifier and the power of the light in the optical propagation path after being amplified by the optical amplifier; a third optical receiver for detecting the power of light having a traveling direction opposite to that of the input light amplified by the optical amplifier, in the optical propagation path; and a control unit for controlling the excitation light source on the basis of the light power detected by the first optical receiver, the light power detected by the second optical receiver, and the light power detected by the third optical receiver. This optical amplifying device can prevent a light surge without providing dummy light and without causing a service interruption.

It is necessary to reduce the power consumption of a plurality of optical amplifiers when there is a difference in the required pumping power between the plurality of optical amplifiers; therefore, an optical amplifying apparatus according to an exemplary aspect of the invention includes a plurality of optical amplifying means for amplifying a plurality of optical signals, each of the plurality of optical amplifying means including a gain medium; a plurality of laser light generating means for generating a plurality of laser beams; at least one optical coupling means for coupling the plurality of laser beams variably in accordance with a coupling factor and outputting a plurality of excitation light beams, each of the plurality of excitation light beams exciting the gain medium; and controlling means for controlling the coupling factor and an output power of each of the plurality of laser light generating means.