Abstract: Disclosed is an optical fiber-based divergence-limiting device for limiting divergence from a first maximum divergence of input light to a second maximum divergence of output light, in which the second maximum divergence is less than the first maximum divergence.

Abstract: Disclosed are embodiments for multi-band pumping of a doped fiber source. The doped fiber source has a first absorption band and a second absorption band that is different from the first absorption band. In some embodiments, a first laser pump generates a first pump power in a first pump band corresponding to the first absorption band that is generated. A second laser pump generates a second pump power in a second pump band corresponding to the second absorption band. The second pump band is different from the first pump band. The first and second pump power is simultaneously applied to the doped fiber source.

Abstract: Some embodiments may include a fiber laser including two or more input fibers and an output fiber to deliver a beam to a workpiece, the fiber laser comprising. The fiber laser may include a combiner having ends and a length, wherein the combiner is arranged to release, from its length, a portion of back-reflected light received from the output fiber at an output end of the ends from the combiner, the combiner including: a capillary tube to enclose part of the two or more input fibers at an input end of the ends of the combiner, the capillary tube having ends and a length located between the ends of the capillary tube; and a cladding light stripper (CLS) defined by part of the length of the capillary tube, wherein the CLS provides the release of the portion of the back-reflected light. Other embodiments may be disclosed and/or claimed.

Abstract: A method of processing by controlling one or more beam characteristics of an optical beam may include: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP and one or more confinement regions; modifying the one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; confining the modified one or more beam characteristics of the optical beam within the one or more confinement regions of the second length of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP may differ from the second RIP.

Abstract: A fiber connector, comprising a housing comprising a region extending in a lengthwise direction an optical fiber disposed in the region, a first portion of the optical fiber comprising an inner core, a cladding layer surrounding the core, and a first outer polymer layer surrounding the cladding layer and a second portion of the optical fiber comprising the inner core, the cladding layer surrounding the core and a second outer polymer layer that is different from the first polymer layer.

Abstract: Systems and methods for temporal amplitude modulation of an optical beam. An exemplary system may include a birefringent fiber positioned between two polarizers, or between a polarized input light source and an output polarizer. Light may enter the birefringent fiber as linearly polarized. Depending on birefringence and orientation of the birefringent fiber, the polarization state changes as the light propagates through the birefringent fiber. This changed polarization state then enters the output polarizer, for which transmission is a function of the polarization state and the relative orientation of the polarization axis. The polarization state emerging from the birefringent fiber may be changed by modulating the fiber birefringence, for example through application of an external stress. Net transmittance of the system may be varied according to a magnitude of an external force (e.g., pressure) to some or all of the birefringent fiber.

Abstract: Disclosed are techniques for generating a laser output beam having a functionally homogenized intensity distribution. According to some embodiments, a population of few modes in a multi-mode confinement core is excited by application of a low-moded source beam to the multi-mode confinement core, such that the population exhibit an unstable intensity distribution. The unstable intensity distribution is functionally homogenized by providing one or both of modulation of phase displacement in the multi-mode confinement core and variation of launch conditions of the low-moded source beam into the multi-mode confinement core.

Abstract: A laser assembly comprising a multi-clad fiber optically coupled to a light source configured to emit optical radiation at a first wavelength and a protective element disposed between the light source and the multi-clad fiber so as to prevent a portion of backward-propagating optical radiation at a second wavelength from coupling into the light source.

Abstract: Signal combined optical fiber devices, systems, and methods for reducing signal spectrum pumping of Raman spectrum. Power of a Raman component in an output of a signal combined fiber laser system may be reduced by diversifying peak signal wavelengths across a plurality of signal generation and/or amplification modules that are input into a signal combiner. In some examples, fiber laser oscillators that are to have their output signals combined to reach a desired cumulative system output power are tuned to output signal bands of sufficiently different wavelengths that signal from separate ones of the oscillators do not collectively pump a single Raman band. With the combined signal component comprising different peak signal wavelengths, the Raman component of combined output may have multiple peak wavelengths and significantly lower power than in systems where signals of substantially the same signal peak wavelength are combined.

Abstract: Optical fiber devices, systems, and methods for separating Raman spectrum from signal spectrum. Once separated, the Raman spectrum may be suppressed (e.g., as a result of a reduction in gain from the signal spectrum, and/or through dissipation of the Raman spectrum energy), while the signal spectrum may be propagated in one or more guided modes of a fiber system. In some embodiments, a fiber system may include a chirped fiber Bragg grating (CFBG) or a long period fiber grating (LPFG), each configured to couple a core propagation mode into a cladding propagation mode with an efficiency that is higher for Raman spectrum than for signal spectrum. A fiber system further may include a cladding light stripper (CLS) configured to preferentially remove cladding modes containing the Raman component.

Abstract: Apparatus include a first optical fiber including a core situated to propagate a signal beam at a signal wavelength and an unwanted stimulated Raman scattering (SRS) beam at an SRS wavelength associated with the signal wavelength, and a fiber Bragg grating (FBG) situated in a core of a second optical fiber optically coupled to the core of the first optical fiber, the FBG having a selected grating reflectivity associated with the SRS wavelength and being situated to reflect the SRS beam back along the core of the second optical fiber and to reduce a damage associated with propagation of the SRS beam to power sensitive laser system components optically coupled to the second optical fiber. Methods are also disclosed.

Abstract: Fiber laser devices, systems, and methods for reducing Raman spectrum in emissions from a resonant cavity. A fiber laser oscillator that is to generate an optical beam may include a Raman reflecting output coupler that strongly reflects a Raman component pumped within the resonant cavity, and partially reflects a signal component to sustain the oscillator and emit a signal that has a reduced Raman component. A Raman filtering output coupler may comprise a superstructure fiber grating, and such a grating may be chirped or otherwise designed to have a desired bandwidth.

Abstract: Optical fiber devices, systems, and methods for coupling Raman spectrum out of an optical fiber selectively over a signal spectrum, which may be propagated in one or more guided modes of a fiber system. A fiber system may include a chirped fiber Bragg grating (CFBG) or a long period fiber grating (LPFG), each to unguide Raman light propagating in a core propagation mode of a fiber completely out of the fiber (through any surrounding cladding layer(s)) selectively over signal spectrum which is to remain in a guided mode of the fiber.

Abstract: Optical fiber devices, systems, and methods for separating Raman spectrum from signal spectrum Raman spectrum may be suppressed as a result of a reduction in gain and/or through dissipation while the signal spectrum may Raman Components In be propagated in one or more guided modes of a fiber system. A fiber system may Length include a propagation mode coupler to couple a first guided mode into a second guided mode with an efficiency that varies as a function of wavelength of the propagated light. Mode coupling efficiency may be higher for Raman spectrum, and lower for signal spectrum so that Raman spectrum associated with a fundamental mode is preferentially coupled into a higher-order mode. A fiber system may include a mode filter operable to discriminate between first and second guided modes. Within the filter, guiding of the first mode may be superior to that of the second mode with Raman spectrum preferentially rejected.

Abstract: Beam combining optical systems include a fiber beam combiner having multiple inputs to which output fibers of laser diode sources are spliced. Cladding light stripping regions are situated at the splices and include exposed portions of fiber claddings that are at least partially encapsulated with an optical adhesive or a polymer. A beam combiner fiber that is optically downstream of a laser source has an exposed cladding secured to a thermally conductive support with a polymer or other material that is index matched to the exposed cladding. This construction permits attenuation of cladding light propagating toward a beam combiner from a splice.

Abstract: An optical apparatus includes one or more pump sources situated to provide laser pump light, and a gain fiber optically coupled to the one or more pump sources, the gain fiber including an actively doped core situated to produce an output beam, an inner cladding and outer cladding surrounding the doped core and situated to propagate pump light, and a polymer cladding surrounding the outer cladding and situated to guide a selected portion of the pump light coupled into the inner and outer claddings of the gain fiber. Methods of pumping a fiber sources include generating pump light from one or more pump sources, coupling the pump light into a glass inner cladding and a glass outer cladding of a gain fiber of the fiber source such that a portion of the pump light is guided by a polymer cladding surrounding the glass outer cladding, and generating a single-mode output beam from the gain fiber.

Abstract: A method of processing by controlling one or more beam characteristics of an optical beam may include: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP and one or more confinement regions; modifying the one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; confining the modified one or more beam characteristics of the optical beam within the one or more confinement regions of the second length of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP may differ from the second RIP.

Abstract: Beam combining optical systems include a fiber beam combiner having multiple inputs to which output fibers of laser diode sources are spliced. Cladding light stripping regions are situated at the splices, and include exposed portions of fiber claddings that are at least partially encapsulated with an optical adhesive or a polymer. A beam combiner fiber that is optically downstream of a laser source has an exposed cladding secured to a thermally conductive support with a polymer or other material that is index matched to the exposed cladding. This construction permits attenuation of cladding light propagating toward a beam combiner from a splice.

Abstract: An apparatus includes an optical gain fiber having a core, a cladding surrounding the core, the core and cladding defining an optical gain fiber numerical aperture, and a multimode fiber having a core with a larger radius than a radius of the optical gain fiber core, a cladding surrounding the core, the core and cladding of the multimode fiber defining a multimode fiber stable numerical aperture that is larger than the optical gain fiber numerical aperture, the multimode fiber being optically coupled to the optical gain fiber so as to receive an optical beam propagating in the optical gain fiber and to stably propagate the received optical beam in the multimode fiber core with low optical loss associated with the optical coupling.

Abstract: An example apparatus includes an optical fiber including a core and cladding, the core being situated to propagate an optical beam along a propagation axis associated with the core, and at least one fiber Bragg grating (FBG) situated in the core of the optical fiber, the fiber Bragg grating including a plurality of periodically spaced grating portions situated with respect to the propagation axis so that light associated with Raman scattering is directed out of the core so as to reduce the generation of optical gain associated with stimulated Raman scattering (SRS).