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.

A fiber applied to an optical amplifier, where the fiber includes a rare earth-doped core and a cladding. The core includes a gain equalization unit. The core is configured to separately amplify optical signals of all wavelengths in a received multiplexing wave. The gain equalization unit is configured to equalize gains of the optical signals of all the wavelengths, such that gains of optical signals that are of all the wavelengths and that are transmitted from an egress port of the fiber all fall within a preset range, The gain of the optical signal of each wavelength in the optical signals of all the wavelengths is determined based on a ratio of power of an amplified optical signal to power of the unamplified optical signal.

Described herein are photonic integrated circuits (PICs) comprising a semiconductor optical amplifier (SOA) to output a signal comprising a plurality of wavelengths, a sensor to detect data associated with a power value of each wavelength of the output signal of the SOA, a filter to filter power values of one or more of the wavelengths of the output signal of the SOA, and control circuitry to control the filter to reduce a difference between a pre-determined power value of each filtered wavelength of the output signal of the SOA and the detected power value of each filtered wavelength of the output signal of the SOA.

A Raman fiber laser includes a pump light source, a reflective end mirror, a wavelength division multiplexer, a Raman gain fiber, and an output end mirror. The output end mirror is an ultra-low reflectance fiber Bragg grating. The reflective end mirror is connected to a reflective end of the wavelength division multiplexer. The pump light source is connected to an input end of the wavelength division multiplexer. One end of the Raman gain fiber is connected to a common end of the wavelength division multiplexer, and the other end of the Raman gain fiber is connected to the ultra-low reflectance fiber Bragg grating. The laser of the present invention can reduce loss of laser light at the reflective end mirror, thereby increasing laser light optical conversion efficiency and output power, and simultaneously achieving high time domain stability and extremely low coherence.

Disclosed are a control method and an optical fiber amplifier. The optical fiber amplifier is configured to execute the control method. The method comprises: initially correcting a target gain on the basis of a first compensation gain to obtain an initially corrected target gain; when the actual power of the pump laser reaches target power determined on the basis of the initially corrected target gain obtaining, on the basis of a first signal optical power and a second signal optical power, a second compensation gain and a first compensation slope through calculation; correcting the initially corrected target gain again according to the second compensation gain to obtain a corrected target gain; and correcting a target slope according to the first compensation slope to obtain a corrected target slope. This solution can provide high precision control for the gain and the slope of the optical fiber amplifier.

A multi-stage thulium-doped (Tm-doped) fiber amplifiers (TDFA) is based on the use of single-clad Tm-doped optical fiber and includes a wavelength conditioning element to compensate for the nonuniform spectral response of the initial stage(s) prior to providing power boosting in the output stage. The wavelength conditioning element, which may comprise a gain shaping filter, exhibits a wavelength-dependent response that flattens the gain profile and output power distribution of the amplified signal prior to reaching the output stage of the multi-stage TDFA. The inclusion of the wavelength conditioning element allows the operating bandwidth of the amplifier to be extended so as to encompass a large portion of the eye-safe 2 μm wavelength region.

A system and method for communicating supervisory information between amplifier nodes in an optical communication network utilizes modulation of an included pump source to superimpose the supervisory information on through-transmitted customer signals (or ASE associated with the amplifier if no customer traffic is present). The supervisory information (which may include monitoring messages, provisioning data, protocol updates, and the like) is utilized as an input to an included modulator, which then forms a drive signal for the pump controller. In a preferred embodiment, binary FSK modulation is used.

An optical fiber filter includes a fiber core, inner cladding, and outer cladding. A refractive index of the fiber core, a refractive index of the inner cladding, and a refractive index of the outer cladding progressively decrease in sequence. The fiber core is configured to transmit at least two mutually different first optical signal modes, the inner cladding is configured to transmit at least two mutually different second optical signal modes, and at least one fiber grating is etched on the fiber core. At least part of optical power of a target first optical signal mode is coupled to only a target second optical signal mode at the fiber grating. The target first optical signal mode is one of the at least two first optical signal modes, and the target second optical signal mode is one of the at least two second optical signal modes.

A fixed input current is provided to a pump laser of an optical pumping block. Further, a first tuning temperature is provided to the pump laser while providing the fixed input current. The first tuning temperature is based on a target band of a pumping beam and causes the pump laser to generate a light beam having a first frequency band that is dictated by the first tuning temperature and the fixed input current. Further, a second tuning temperature is provided to a temperature dependent optical reflector configured to receive the light beam. The second tuning temperature is based on the target band of the pumping beam and causes the optical reflector to reflect light of the light beam that is within a second frequency band that corresponds to the target frequency band. The reflected light beam is emitted into a transmission optical medium configured to carry an optical signal.

A gain adjuster, a gain adjustment method, and an optical line terminal are provided, to separately adjust a gain of a to-be-adjusted optical signal. The gain adjuster includes a light spot conversion component and a gain medium that are sequentially coupled. The gain adjuster further includes a pump laser. The light spot conversion component is configured to adjust light spot sizes of at least some optical signals in received optical signals to output a first optical signal transmitted in space. The pump laser is configured to excite the gain medium. The gain medium is configured to adjust a gain of the first optical signal to output a second optical signal.