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.

Systems and methods are provided for amplifying optical signals within one of two optical bands, such as C-band and L-band. An optical amplifying device, according to one implementation, may include a shared optical coil configured to propagate an optical signal. The optical amplifying device may further include a first junction configured to separate the shared optical coil into a first-band optical fiber and a second-band optical coil and a pump device configured to amplify the optical signal in the shared optical coil and the second-band optical coil. The first-band optical fiber may be configured to propagate the optical signal when the optical signal resides in a channel of a first plurality of channels within a first optical band. The second-band optical coil may be configured to propagate the optical signal when the optical signal resides in a channel of a second plurality of channels within a second optical band.

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.

Techniques for improving gain equalization in C- and L-band (“C+L”) erbium-doped fiber amplifier (EDFAs) are provided. For example, the C- and L-band amplification sections of a C+L EDFA may be separated and configured in a parallel arrangement or a serial arrangement. For both the parallel and serial arrangements, the C- and L-band amplification sections may share a common gain flattening filter (GFF) or each amplification section may include and employ a separate GFF. Moreover, in some examples, an “interstage” L-band GFF may be located before or upstream of the L-band amplification section such that the L-band optical signal is gain-equalized or flattened prior to the L-band amplification section amplifying the L-band.

The present disclosure generally relates optical amplifier modules. In one form for example, an optical amplifier module includes a booster optical amplifier configured to increase optical power of a first optical signal. The module also includes a preamp optical amplifier configured to increase optical power of a second optical signal and a pump laser optically coupled to the booster optical amplifier and the preamp optical amplifier. The pump laser is configured to provide a booster power to the booster optical amplifier and a preamp power to the preamp optical amplifier, the preamp power is effective to induce a gain in optical power to provide a target optical power of the second optical signal from the preamp optical amplifier, and the booster power is dependent on the preamp power.

Provided are an optical equalizer, a method, and a program which are configured to be capable of flattening a tilt characteristic of a wavelength division multiplexed optical signal with a simple configuration. The optical equalizer includes a detection unit configured to detect a tilt characteristic on the basis of intensities of at least two optical signals among a plurality of optical signals multiplexed into a wavelength division multiplexed optical signal, an optical attenuation unit configured to attenuate an intensity of the wavelength division multiplexed optical signal by an optical attenuation amount, and an optical amplification unit configured to amplify the attenuated wavelength division multiplexed optical signal on the basis of a gain characteristic associated with an intensity of the attenuated wavelength division multiplexed optical signal. In the optical equalizer, the optical attenuation amount is controlled based on the tilt characteristic and the gain characteristic.

The technology of this application relates to the field of communication technologies, and an optical fiber raw material composition, an optical fiber, and an optical fiber product. The optical fiber raw material composition includes components of the following molar percentages: AlF.sub.3 10%-50%, BaF.sub.2 3%-20%, CaF.sub.2 3%-20%, YF.sub.3 1%-15%, SrF.sub.2 3%-20%, MgF.sub.2 3%-20%, and TeO.sub.2 1%-35%. The optical fiber prepared by using the optical fiber raw material composition provided in this disclosure can be used in aspects such as a mid-infrared band transmission optical fiber, an optical fiber amplifier, a fiber laser, and an optical fiber sensor.

A fiber laser apparatus includes: amplification optical fibers including first and second amplification optical fibers, each of which having different amplification characteristics and including a core to which an active element is doped; one or more cooling plates having a first cooling surface that thermally contacts and cools the first amplification optical fiber and a second cooling surface that thermally contacts and cools the second amplification optical fiber; one or more module boxes including a gain module box that houses the amplification optical fibers and the one or more cooling plates; and an enclosure housing the one or module boxes. The first and second cooling surfaces are disposed at different heights in the gain module box. At least a portion of the first cooling surface overlaps at least a portion of the second cooling surface as viewed along a height direction.

Disclosed herein is a method comprising injecting light of a first wavelength λ.sub.1 into a wavelength division multiplexer; injecting light of a second wavelength λ.sub.2 into the wavelength division multiplexer; combining the light of the first wavelength λ.sub.1 and the light of the second wavelength λ.sub.2 in the wavelength division multiplexer to produce light of a third wavelength λ.sub.3; and reflecting the light of the third wavelength λ.sub.3 in a dual-Brillouin peak optical fiber that is in communication with the wavelength divisional multiplexer; wherein the dual-Brillouin peak optical fiber has at least two Brillouin peaks, such that an amplitude A.sub.1 of at least one of said Brillouin peaks is within 50% to 150% of an amplitude A.sub.2 of another Brillouin peak 0.5A2≤A.sub.1≤1.5A.sub.2; wherein the dual-Brillouin peak optical fiber generates a Brillouin dynamic grating that reflects an improved back-reflected Brillouin signal of the combined light.