Abstract: The invention relates to pulsed optical sources formed of a source of seed optical radiation, a pulsed optical amplifier for pulsing the seed optical radiation, and an output optical port for outputting a pulsed optical signal produced by the pulsed optical amplifier. An optically isolating element such as an optical circulator is provided in the optical path between the optical seed source and the pulsed optical amplifier.

Abstract: The invention provides fiber-optic light sources such as cladding-pumped master oscillator—power amplifier (MOPA) systems which use double-clad optical fibers (DCF). The inner cladding of the first DCF used in the master oscillator section has a circular cross-section in order to enable the formation of low loss optical splices in the integrated MOPA structure. The inner cladding of the second DCF in the output amplifier section has a shaped non-circular cross-section in order to enhance the absorption of the pump light in the doped core of the second DCF.

Abstract: A beam-stabilized laser system using optical frequency conversion in a nonlinear optical crystal is disclosed. An optimal phase-matching angle in the crystal depends on both wavelength and temperature. If the crystal temperature changes, the optimal phase-matching direction will change as well. A different wavelength can be selected so that the optimal phase-matching occurs along the original beam path and returns the output beam to the original direction. Thus, a central wavelength of the laser beam illuminating the nonlinear optical crystal can be slightly adjusted to compensate for the pointing drift. Since the illuminating wavelength can normally be tuned much faster than the crystal temperature, a more agile and responsive pointing stabilization can be achieved.

Abstract: An optical delivery waveguide for a material laser processing system includes a small lens at an output end of the delivery waveguide, transforming laser beam divergence inside the waveguide into a spot size after the lens. By varying the input convergence angle and/or launch angle of the laser beam launched into the waveguide, the output spot size can be continuously varied, thus enabling a continuous and real-time laser spot size adjustment on the workpiece, without having to replace the delivery waveguide or a process head. A divergence of the laser beam can also be adjusted dynamically and in concert with the spot size.

Abstract: A very large more area active double clad optical waveguide doped with Nd3+ at a concentration of at least 0.1% by weight can be used to effectively amplify light at a wavelength of between 1050 nm and 1120 nm. At a doping concentration sufficient to provide a net optical absorption of at least 3 dB/m for the pump light at the wavelength of 795 to 815 nm or 883 to 887 nm, Nd3+ operates under much lower inversion levels than Yb3+. Due to the lower inversion levels, the Nd3+ doped waveguide is subject to reduced pump bleaching or photodarkening.

Abstract: The invention relates to a laser system including a nonlinear crystal having a first length portion and a second length portion. The nonlinear crystal disposed to receive input light from the laser for converting the input light into frequency converted light; wherein the nonlinear crystal is configured so that the first length portion of the nonlinear crystal is phase matching for the input light and the frequency converted light, and the second length portion of the nonlinear crystal is phase mismatching for the input light and the frequency converted light. Phase mismatching means may include a temperature controlling board, a clamp, or electrodes.

Abstract: The invention relates to a laser system including a nonlinear crystal having a first length portion and a second length portion. The nonlinear crystal disposed to receive input light from the laser for converting the input light into frequency converted light; wherein the nonlinear crystal is configured so that the first length portion of the nonlinear crystal is phase matching for the input light and the frequency converted light, and the second length portion of the nonlinear crystal is phase mismatching for the input light and the frequency converted light. Phase mismatching means may include a temperature controlling board, a clamp, or electrodes.

Abstract: The invention relates to pulsed optical sources formed of a source of seed optical radiation, a pulsed optical amplifier for pulsing the seed optical radiation, and an output optical port for outputting a pulsed optical signal produced by the pulsed optical amplifier. An optically isolating element such as an optical circulator is provided in the optical path between the optical seed source and the pulsed optical amplifier.

Abstract: An optical fiber holding device is disclosed having an optical fiber held therein. The device has a base with a spiral channel in an upper surface holding and housing the optical fiber. The channel has a first location where the fiber enters leading to a plurality of turnings for holding the optical fiber wrapped therearound at another end a second location where the fiber exits the channel wherein the bend radius of the optical fiber housed within the spiral channel is at least 2 cm. The dimensions are such that housing forms a heat sink allowing heat within the fiber to dissipate within the base. The spiral channel is preferably designed to keep the fiber within the channel and to prevent it from inadvertently springing out spring tension of the bent fiber holds the fiber within the groove or channel.

Abstract: A waveguide retroreflector consists of an end cap with curved output surface attached to a waveguide such as optical fiber. The radius of curvature of the output surface of the end cap matches the length of the end cap so as to retro-reflect a substantial portion of radiation exiting the waveguide, back into the waveguide. A method of fabricating the waveguide retroreflector includes steps of splicing an end cap to a waveguide, heating the free flat surface of the end cap, so that surface tension changes the shape of the end cap to a convex shape due to surface tension, monitoring amount of light reflected off the surface being heated, and stopping applying the heat when the amount of the reflected light approaches a maximum value.

Abstract: An expanded-beam all-glass retroreflector for a fiber laser cavity. The retroreflector consists of a section of a tapered double-clad fiber for beam expansion, e.g. a tapered section of the laser fiber itself, or a piece of coreless fiber spliced to the laser fiber, and a reflective surface for reflection of the expanded beam back into laser cavity through the tapered fiber section.

Abstract: A waveguide retroreflector consists of an end cap with curved output surface attached to a waveguide such as optical fiber. The radius of curvature of the output surface of the end cap matches the length of the end cap so as to retro-reflect a substantial portion of radiation exiting the waveguide, back into the waveguide. A method of fabricating the waveguide retroreflector includes steps of splicing an end cap to a waveguide, heating the free flat surface of the end cap, so that surface tension changes the shape of the end cap to a convex shape due to surface tension, monitoring amount of light reflected off the surface being heated, and stopping applying the heat when the amount of the reflected light approaches a maximum value.

Abstract: An optical fiber holding device is disclosed having an optical fiber held therein. The device has a base with a spiral channel in an upper surface holding and housing the optical fiber. The channel has a first location where the fiber enters leading to a plurality of turnings for holding the optical fiber wrapped therearound at another end a second location where the fiber exits the channel wherein the bend radius of the optical fiber housed within the spiral channel is at least 2 cm. The dimensions are such that housing forms a heat sink allowing heat within the fiber to dissipate within the base. The spiral channel is preferably designed to keep the fiber within the channel and to prevent it from inadvertently springing out spring tension of the bent fiber holds the fiber within the groove or channel.

Abstract: The invention relates to a conventional broad-area laser having a single-mode output through the phenomenon of multimode interference (MMI) in step-index waveguides. Another aspect of the present invention relates to a very robust multi-mode compound cavity laser design that is fully defined by the geometry and the refractive index profile of the MMI region, which is quite insensitive to slight macro-scale refractive index variations due to manufacturing variation or temperature. As the self-imaging position shifts linearly in the refractive index, the confocal beam parameter can be made relatively long.

Abstract: An optical fiber structure for use in gain applications which comprises a core, selectively doped with an active gain species, and an inner cladding surrounding the core, where the inner cladding serves the purpose of receiving multimode pump energy from an external power source, confining this energy, and transferring the energy into the core by means of repeated interactions between the energy and the active dopant within the core as the pump energy propagates along the length of the fiber structure. The cross-sectional shape of the inner cladding is in the form of a non-rectangular, convex polygon so that the propagating pump energy is induced to form an essentially uniform radiation field in which the various radiation modes comprising the pump energy are isotropically distributed.

Abstract: A high-power optical fiber device comprising a pump source of light-emitting facets, optical means for collimating and converging the array, an optical beam rotator for transforming the array by rotating individual light emissions, and an optical fiber structure having a core surrounded by an inner cladding for transferring pump energy into the core, the inner cladding having a cross-sectional shape in the form of a convex polygon.