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.

An amplified hollow-core fiber (HCF) optical transmission system for low latency communications. The optical transmission system comprises a low-latency amplified HCF cable. The low-latency amplified HCF cable comprises multiple HCF segments (or HCF spans). Between consecutive HCF segments, the system comprises low-latency remote optically pumped amplifiers (ROPAs). Each ROPA comprises a gain fiber, a wavelength division multiplexing (WDM) coupler, and an optical isolator. Preferably, the ROPAs are integrated into the HCF cable. Each ROPA is pumped by a remote optical pump source, which provides pump light to the gain fiber. The gain fiber receives an optical transmission signal from the HCF. The WDM coupler combines the pump light with the optical transmission signal, thereby allowing the gain fiber to amplify the optical transmission signal to an amplified transmission signal. The amplified signal is transmitted to another HCF segment through the optical isolator.

A fiber structure includes a covering part, the covering part having an optical fiber strand and a coating covering the optical fiber strand; a strand exposed part adjacent to the covering part, the strand exposed part including an exposed optical fiber strand, and a sealing part covering a boundary between the covering part and the strand exposed part. The sealing part including a fluororesin having a structure represented by formula (1):

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where R represents a divalent organic fluorine compound group, and n represents an integer of 1 or more.

A photonic lantern couples light from several fibers or fiber cores into one or more fibers or fiber cores. Photonic lanterns are often used to combine several lower-power beams into a single higher-power beam. They can also be used to couple light from multi-core fibers into single-mode, multi-mode, or other multi-core fibers. By modulating the phases of the input beams, the light can be switched from output to output—for example, between output cores of a multi-core output fiber. If desired, the beams can also be amplified using an active fiber in or coupled to the photonic lantern. A first photonic lantern couples signal light and pump light into the core and cladding, respectively, of an active multi-mode or multi-core fiber. And the active multi-mode or multi-core fiber couples amplified signal light into output fiber(s) via a second photonic lantern.

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 may include a core in which core-guided light generated by one or more light sources propagates along a length of the at least one optical fiber, one or more claddings, surrounding the core, to guide cladding-guided light generated by the one or more light sources along the length of the at least one optical fiber, and a reflector structure machined into the at least one optical fiber. The reflector structure may include multiple angled facets arranged at one or more respective angles relative to an axis of the optical fiber to reflect at least a portion of the core-guided light and/or the cladding-guided light passing through the optical fiber.

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.

A thermoelectric device and method of use thereof are provided for cooling and powering a laser device. The thermoelectric device comprises a first side, a second side, and a plurality of thermoelectric elements disposed therebetween. The thermoelectric device engages a photodiode array of the laser device, such that when heat is generated by the photodiode array, the thermoelectric device passively cools the photodiode array by receiving the heat and converts the heat generated to electricity to power the laser device.

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.

The present invention benefits from the determination that pre-selected spectral bandwidths that avoid the spectrum of an electronic transition of a metal/alloy vapor allow for welds substantially free from detritus that may discolor the weld. Accordingly, the present invention provides analytical methods, welding methods and fiber lasers configured to provide high quality metal/alloy welds.