Abstract: A laser diode is configured with a substrate delimited by opposite AR and HR reflectors and a gain region. The gain region bridges the portions of the respective AR and HR reflectors and is configured with a main resonant cavity and at least one side resonant cavity. The main resonant cavity spans between the portions of the respective reflectors, and at least one additional resonant cavity extends adjacent to the main resonator cavity. The gain region is configured so that stimulated emission is generated only the main resonant cavity. Accordingly, the laser diode is operative to radiate a high-power output beam emitted through the portion of the AR reflector which is dimensioned to shape the output beam with the desired near-field.

Abstract: Optical apparatus, comprising an optical fiber having a wavelength of operation, the optical fiber comprising an inner core, the inner core supporting a fundamental mode and at least first and second higher order modes (HOMs) at the wavelength of operation; a first ring-shaped core region spaced from and disposed about the inner core; a second ring-shaped core region spaced from and disposed about the ring-shaped core region; and wherein the optical fiber is configured and arranged such that the first HOM optically interacts with the first ring-shaped core region and the second HOM optically interacts with the second ring-shaped core region.

Abstract: Optical fiber apparatus having a wavelength of operation, that comprises an optical fiber including a core comprising an active material for providing light having the operating wavelength responsive to the optical apparatus receiving pump optical energy having a pump wavelength; a cladding disposed about the core; at least one region spaced from the core; and wherein the optical fiber is configured and arranged such that at the wavelength of operation the optical fiber can propagate a plurality of modes and wherein the optical fiber comprises a fundamental mode that is primarily a mode of the core and at least one higher order mode (HOM) that is a mixed mode of a selected mode of the core and of a selected mode of the at least one region.

Abstract: An optical fiber apparatus having a wavelength of operatic comprises an optical fiber comprising a core; a pump cladding disposed about the core for receiving pump optical energy having a pump wavelength; and a second cladding disposed about for tending to confine pump optical energy to the pump cladding. The core can comprise a rare earth material for providing optical energy having the wavelength of operation responsive to the optical fiber receiving the pump optical energy, and the fiber can further comprise at least one ring core spaced from the core, the ring core defined by inner and outer diameters and comprising the cross sectional area therebetween. The ring core can comprise an absorbing material for absorbing optical energy having the wavelength of operation.

Abstract: A powerful fiber laser system is configured with at least one filtering element capable of preventing a backreflected Raman component of the main signal from propagating along the upstream stretch of the system. The filtering element includes a slanted fiber grating, one or more cladding formations disposed in a cladding of fiber and having a refractive index greater than that one of the cladding, but lower than a refractive index of the core, and/or a combination of two spaced apart single mode fibers and a low mode fiber spliced to the opposing ends of the respective SM fibers.

Abstract: A monolithic fiber is configured with a double bottleneck-shaped multimode (MM) core capable of supporting substantially only a fundamental mode at a given wavelength and having opposite end regions, frustoconically shaped transformer regions, which run inwards from the respective end regions, and a central uniformly dimensioned region, which bridges the transformer regions. The MM core has a refractive step-index profile which is configured with a centrally positioned dip having a variable width along the length of the fiber. The width of the dip is relatively small at the end regions of the MM core so as to support only the fundamental mode with a Gaussian profile. As the dip becomes larger along the input transformer region, it gradually shapes the Gaussian profile into the ring profile of the fundamental mode, which is guided along the central region of the MM core.

Abstract: A high power single mode fiber laser system is configured with an active fiber including coextending multimode core (MM) and cladding around the MM core. The MM core is doped with one or more ions selected from rare earth and transitional metals and has a bottleneck cross in accordance with one aspect of the disclosure. The bottleneck cross-section includes a relatively small uniformly dimensioned input end region, a frustoconical region and a relatively large uniformly dimensioned amplifying region. The refractive step index of the MM core is configured with a central dip shaped and dimensioned along the input region so as not to disturb a Gaussian field profile of fundamental mode, gradually transform the Gaussian field profile into the ring profile of the fundamental mode and support the latter along the amplifying region.

Abstract: A laser assembly is configured with a frequency conversion laser head operative to shift a fundamental frequency of input light to the desired frequency of an output light. The frequency conversion laser head includes a dump means operative to guide an unconverted output light at the fundamental frequency outside the case of the frequency conversion laser head. The dump means is configured with a guide optics operative to couple the output light at the fundamental frequency to a fiber terminating outside the case of the frequency conversion laser head.

Abstract: A system for recording multiple volume Bragg gratings (VBGs) in a photo thermo-refractive material is configured to implement a method which provides for irradiating the material by a coherent light through a phase mask. The system has a plurality of actuators operative to displace the light source, phase mask and material relative to one another so as to mass produce multiple units of the material each having one or more uniformly configured VBGs.

Abstract: A dynamic compensator for a fiber optic cable having a jacket which is centered along a longitudinal axis, an elongated buffer tube surrounded by the jacket, and an elongated fiber surrounded by the buffer tube and dimensioned to move radially inwards and outwards within the buffer tube. The dynamic compensator includes a cable holder configured to receive and loop a portion of the fiber optic cable so that when the jacket elongates, the fiber extending along the loop is displaced radially inwards so as to release stresses upon end portions of the fiber, and when the jacket shrinks, the fiber is displaced radially outward to increase stresses upon the end portions of the fiber.

Abstract: A dynamic compensator for a fiber optic cable having a jacket which is centered along a longitudinal axis, an elongated buffer tube surrounded by the jacket, and an elongated fiber surrounded by the buffer tube and dimensioned to move radially inwards and outwards within the buffer tube. The dynamic compensator includes a cable holder configured to receive and loop a portion of the fiber optic cable so that when the jacket elongates, the fiber extending along the loop is displaced radially inwards so as to release stresses upon end portions of the fiber, and when the jacket shrinks, the fiber is displaced radially outward to increase stresses upon the end portions of the fiber.

Abstract: A powerful fiber laser system is configured with at least one large-area multi-clad rare-earth doped fiber, which is configured with a MM core capable of propagating a single mode laser emission at a first wavelength, and with at least one pumping assembly capable of generating an optical pump output at a wavelength shorter than the first wavelength of the rare-earth doped fiber. The pumping assembly has a plurality SM fiber lasers coupled to a SM-MM combiner which is operative to lunch the pump output into the cladding of the rare-earth doped fiber so that the powerful fiber laser system is operative to deliver a power of up to 20 kW.

Abstract: A method of producing a large mode area optical preform includes selecting a preexisting rod and at least one preexisting outer tube. The rod and tube are selected so that a difference between respective indices of refraction is uniform and lies within the desired range, and a ratio between respective rod and tube diameters is within the desired range after the rod is inserted into the tube and both are thermally treated. The predetermined ranges are selected to provide mass production of a large mode area fiber with the desired physical and geometrical characteristics.

Abstract: A laser system for effective injection seeding is configured with a master oscillator lasing a narrowband seed radiation which is characterized by a single longitudinal master mode injected into a slave oscillator so that the latter generates a broadband slave radiation with a dominant slave mode and side slave modes. The slave radiation is coupled into an input of a SM fiber laser amplifier operative to output an amplified radiation with the spectra which is substantially as narrow as the spectra of the slave radiation.

Abstract: A powerful fiber laser system is configured with at least one filtering element capable of preventing a backreflected Raman component of the main signal from propagating along the upstream stretch of the system. The filtering element includes a slanted fiber grating, one or more cladding formations disposed in a cladding of fiber and having a refractive index greater than that one of the cladding, but lower than a refractive index of the core, and/or a combination of two spaced apart single mode fibers and a low mode fiber spliced to the opposing ends of the respective SM fibers.

Abstract: A powerful fiber laser system is configured with at least one large-area multi-clad rare-earth doped fiber, which is configured with a MM core capable of propagating a single mode laser emission at a first wavelength, and with at least one pumping assembly capable of generating an optical pump output at a wavelength shorter than the first wavelength of the rare-earth doped fiber. The pumping assembly has a plurality SM fiber lasers coupled to a SM-MM combiner which is operative to lunch the pump output into the cladding of the rare-earth doped fiber so that the powerful fiber laser system is operative to deliver a power of up to 20 kW.

Abstract: A powerful fiber laser system is configured with at least one large-area multi-clad rare-earth doped fiber, which is configured with a MM core capable of propagating a single mode laser emission at a first wavelength, and with at least one pumping assembly capable of generating an optical pump output at a wavelength shorter than the first wavelength of the rare-earth doped fiber. The pumping assembly has a plurality SM fiber lasers coupled to a SM-MM combiner which is operative to lunch the pump output into the cladding of the rare-earth doped fiber so that the powerful fiber laser system is operative to deliver a power of up to 20 kW.

Abstract: A powerful fiber laser system is configured with at least one large-area multi-clad rare-earth doped fiber, which is configured with a MM core capable of propagating a single mode laser emission at a first wavelength, and with at least one pumping assembly capable of generating an optical pump output at a wavelength shorter than the first wavelength of the rare-earth doped fiber. The pumping assembly has a plurality SM fiber lasers coupled to a SM-MM combiner which is operative to lunch the pump output into the cladding of the rare-earth doped fiber so that the powerful fiber laser system is operative to deliver a power of up to 20 kW.

Abstract: A single-mode fiber laser includes a single mode holding, large mode area optical fiber assembly having a large mode area core, a first cladding and a second cladding. The optical fiber assembly has several unique sections including a gain section having a ytterbium-doped core, first and second reflective sections including fiber Bragg gratings that define a lasing cavity, and an absorptive section also having a ytterbium-doped core, the absorptive section having an output end coupled to an input end of said first reflective section. A broad area, multi-mode diode pump source is configured to pump multi-mode light into a tapered input section and cladding-pump the gain section. The gain section absorbs the multi-mode pump light and emits single-mode light. The absorptive section absorbs emissions at the operating wavelength and prevents operating emissions from reflecting back into said pump source.

Abstract: A large mode area optical fiber includes a large diameter core (d1 up to 60 ?m), and a first cladding (diameter d2) wherein the difference between refractive index (n1) in the core and the first cladding (n2) is very small (?n<0.002), thus providing a very low numerical aperture core (NA1 between 0.02 and 0.06). The preferred ratio of d2/d1<2. The fiber further has a second cladding, preferably a layer of air holes, having a very low refractive index n3 as compared to the core and first cladding such that the first cladding has a relatively high numerical aperture (NA2>0.4) (n3 is preferably less than 1.3). The small change in refractive index between the core and inner cladding combined with a large change in refractive index between the first cladding and second cladding provides a significantly improved single mode holding waveguide.