Abstract: A fiber block is configured with a fiber block including a Nd-doped active fiber and a pump-light delivery fiber which has a stretch extending along the active fiber in a side-to-side configuration so as to lunch pump light into the Nd-doped core of the active fiber. The core of the active fiber is surrounded by at least one or more claddings which, like the core, have a double bottleneck cross-section with a relatively large-area central region and relatively small input and output regions. The pump light delivery fiber is structured to have a substantially dumbbell cross-section with a relatively small-area central region coextending with the central region of the active fibers. The active fiber is dimensioned so that the overall length of the active fiber is configured to provide for the maximal amplification of the laser signal in a 900 nm range while limiting amplification in the 1060 nm range to the preset threshold.

Abstract: The present invention is a method and system for reducing contamination in the resulting plasma of a weld produced by a fiber laser. The invention establishes the fiber laser in an optimal configuration for applying a high density beam to a weld material that eliminates spectral interference. The beam is applied in a narrow bandwidth of 1064 nm+/?0.5 nm in one operative condition using an inert shielding gas, preferably argon, in a cross-flow or controlled environment around the welding region to prevent contamination of the plasma forming in the weld region. The method is optimized by determining and avoiding the emission spectrum for the fiber laser and the cover gas or gasses as well as any particular excitation spectra for the weld material. The system can utilize a single laser input, or can utilize multiple lasers joined by coupling means and utilizing a switch to select one or more of the fiber lasers.

Abstract: A fiber block is configured with a fiber block including a Nd-doped active fiber and a pump-light delivery fiber which has a stretch extending along the active fiber in a side-to-side configuration so as to lunch pump light into the Nd-doped core of the active fiber. The core of the active fiber is surrounded by at least one or more claddings which, like the core, have a double bottleneck cross-section with a relatively large-area central region and relatively small input and output regions. The pump light delivery fiber is structured to have a substantially dumbbell cross-section with a relatively small-area central region coextending with the central region of the active fibers. The active fiber is dimensioned so that the overall length of the active fiber is configured to provide for the maximal amplification of the laser signal in a 900 nm range while limiting amplification in the 1060 nm range to the preset threshold.

Abstract: A fiber laser system is configured with a nonlinear resonator cavity which includes a plurality of mirrors. One of the mirrors is a piezoelectric mirror capable of being displaced between multiple positions in response to a control signal generated by a digital controller. The generation of the control signal is caused by mismatch between a fundamental frequency, imputed into the resonant cavity and further split by a nonlinear crystal into resonant and harmonic frequencies, and the resonant frequency. The positions of the piezoelectric mirror and time interval the piezoelectric mirror may occupy these position are controlled so that the output radiation at the harmonic may be periodically interrupted which results in a pulsed output radiation.

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 monolithic fiber has a double bottleneck-shaped core configured with opposite uniformly configured end regions, frustoconical transformer regions which run inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The core is configured as a multimode core or single-mode core and capable of guiding a single transverse mode between the end regions without splice losses.

Abstract: A fiber laser system is configured with a nonlinear resonator cavity which includes a plurality of mirrors. One of the mirrors is a piezoelectric mirror capable of being displaced between multiple positions in response to a control signal generated by a digital controller. The generation of the control signal is caused by mismatch between a fundamental frequency, imputed into the resonant cavity and further split by a nonlinear crystal into resonant and harmonic frequencies, and the resonant frequency. The positions of the piezoelectric mirror and time interval the piezoelectric mirror may occupy these position are controlled so that the output radiation at the harmonic may be periodically interrupted which results in a pulsed output radiation.

Abstract: The present disclosure is a system for the protection of a fiber within a laser system. The system has a water-cooled housing supporting a termination block, which is operative to shield a protective layer of a delivery fiber from back-reflected beams of light. The termination block is manufactured from quartz and is frustconical in configuration and fuseable to the delivery fiber. The delivery fiber has a polymeric protective layer with an acceptance end and a delivery end, and passes through a washer contained within the housing; the washer has a dielectric reflective coating. The system has at least one terminal block connector which further comprises a cone termination block, a reflector, and a set of light guards. The cone termination block is spliced to an output end of the delivery fiber and produces an angle ? so as to reduce propagation of back-reflected light. The reflector is positioned so as to block additional back-reflected light from the protective layer of the delivery fiber.

Abstract: A high power single mode fiber laser system has a monolithic active fiber configured with a double bottleneck-shaped multimode (MM) core which is capable of supporting substantially only a fundamental mode at a given wavelength. The core has opposite uniformly configured end regions, frustoconical transformer regions running inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The MM core is configured with a refractive step-index profile which includes a continuous dip configured to shape an intensity field of the fundamental mode from a Gaussian or dome-shaped field profile to a two-peak-shaped profile and back to the Gaussian filed profile.

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 in 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: A monolithic fiber has a double bottleneck-shaped core configured with opposite uniformly configured end regions, frustoconical transformer regions which run inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The core is configured as a multimode core or single-mode core and capable of guiding a single transverse mode between the end regions without splice losses.

Abstract: A high power single mode fiber laser system has a monolithic active fiber configured with a double bottleneck-shaped multimode (MM) core which is capable of supporting substantially only a fundamental mode at a given wavelength. The core has opposite uniformly configured end regions, frustoconical transformer regions running inwards from the respective end regions, and a central uniformly-dimensioned region which bridges the transformer regions. The MM core is configured with a refractive step-index profile which includes a continuous dip configured to shape an intensity field of the fundamental mode from a Gaussian or dome-shaped field profile to a two-peak-shaped profile and back to the Gaussian filed profile.

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: 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: 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 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: An optical fiber apparatus having a wavelength of operation 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: The present disclosure is a system for the protection of a fiber within a laser system. The system has a water-cooled housing supporting a termination block, which is operative to shield a protective layer of a delivery fiber from back-reflected beams of light. The termination block is manufactured from quartz and is frustconical in configuration and fuseable to the delivery fiber. The delivery fiber has a polymeric protective layer with an acceptance end and a delivery end, and passes through a washer contained within the housing; the washer has a dielectric reflective coating. The system has at least one terminal block connector which further comprises a cone termination block, a reflector, and a set of light guards. The cone termination block is spliced to an output end of the delivery fiber and produces an angle ? so as to reduce propagation of back-reflected light. The reflector is positioned so as to block additional back-reflected light from the protective layer of the delivery fiber.

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 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.