A broadband optical amplifier for operation in the 2 μm visible wavelength band is based upon a single-clad Tm-doped fiber amplifier (TDFA). A compact pump source uses a combination of low-power laser diode with a fiber laser to provide a multi-watt pump beam without needing to include thermal management and/or pump wavelength stability components. The broadband optical amplifier is therefore able to be relatively compact device with fiber coupled output powers of >0.5 W CW, high small signal gain, low noise figure, and large OSNR, important for use as a versatile wideband preamplifier or power booster amplifier.

A broadband optical amplifier for operation in the 2 μm visible wavelength band is based upon a single-clad Ho-doped fiber amplifier (HDFA). A compact pump source uses a combination of discrete laser diode with a fiber laser (which may be a dual-stage fiber laser) to create a pump output beam at a wavelength associated with creating gain in the presence of Ho ions (an exemplary pump wavelength being 1940 nm). The broadband optical amplifier may take the form of a single stage amplifier or a multi-stage amplifier, and may utilize a co-propagating pump and/or a counter-propagating pump arrangement.

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.

The technology of this application relates to an optical component constituting a fiber amplifier, a fiber amplifier, and a manufacturing method. The optical component is connected to a gain fiber by using a first fiber, or the optical component is directly connected to the gain fiber. The optical component is connected to one or more second optical components in the fiber amplifier by using a second fiber, and/or the optical component inputs an optical signal or outputs an optical signal amplified by the gain fiber by using the second fiber. Softening temperatures and/or refractive indexes of the first fiber and the second fiber are different, or softening temperatures and/or refractive indexes of the second fiber and the gain fiber are different.

An objective of the present invention is to provide an amplification fiber having a cladding excitation configuration that improves amplification efficiency and an optical amplifier. An amplification fiber (10) according to the present invention is a multi-core amplification fiber having, from one end (E1) to the other end (EE), a plurality of cores (11b) in a cladding (11a), and a total distance from the one end (E1) to the other end (EE) in which rare earth ions are doped differs depending on the types of cores (11b). The cores (11b) are preferably disposed such that the cores of the same type are not adjacent to each other. By arranging the types of the cores in this manner, requirements for inter-core crosstalk can be mitigated since the bands of signal light in the adjacent cores are different. As a result, a density of cladding excitation light can be increased by shortening the inter-core distance, and thus the amplification efficiency can be improved.

A laser system includes a signal source configured to generate input pulses, a diffraction grating module configured to stretch and split the input pulses into a plurality of spectral channels, a set of phase control devices, each phase control device being configured for spectral phase control of a respective spectral channel of the plurality of spectral channels, a power amplifier array of amplifier modules, each amplifier module of the power amplifier array being configured to amplify a respective spectral channel of the plurality of spectral channels, a spectral combiner configured to spectrally combine the plurality of spectral channels via diffraction grating-based pulse compression, and a feedback controller coupled to the spectral combiner to provide feedback to the set of phase control devices for pulse shaping.

A femtosecond laser source according to an embodiment of the present invention includes: a pulse generator that converts a continuous wave laser into an optical pulse train; a burst generator that separates the optical pulse train into a plurality of burst pulses; a pulse amplification and spectral broadening unit that expands the spectrum by amplifying a plurality of burst pulses; and a pulse compressor that compresses a plurality of amplified burst pulses to generate a femtosecond laser with a pulse width of 1 picosecond (10.sup.−12 s) or less.

An optically amplified repeater system includes optical transmission paths, a multi-channel optical amplifier, one or more Raman amplification pumping light sources, and a wavelength multiplexer. The multi-channel optical amplifier includes K simultaneous pumping light sources, N optical amplification media, and one or more optical couplers, and simultaneously amplifies, with the K simultaneous pumping light sources, light intensities of optical signals that pass through the N optical amplification media and propagate through the optical transmission paths. Light intensities of the wavelength band of the optical signals is Raman amplified by the Raman amplification pumping light. A light intensity of the Raman amplification pumping light output from the one or more Raman amplification pumping light sources is determined in accordance with characteristic differences between the optical signals passing through the optical transmission paths.

An optical repeater is a C+L-band repeater inserted between a first transmission path fiber and a second transmission path fiber. The optical repeater includes: a first optical fiber amplifier inserted in a first line, for amplifying a C-band signal; a second optical fiber amplifier inserted in a second line, for amplifying an L-band signal; a third optical fiber amplifier inserted in a third line, for amplifying a C-band signal; a fourth optical fiber amplifier inserted in a fourth line, for amplifying an L-band signal; and a first loopback means provided between an input to the first optical fiber amplifier or an output from the first optical fiber amplifier and an input to the third optical fiber amplifier or an output from the third optical fiber amplifier.