An optical component includes: a first fiber having a first end and a second end; a second fiber having a third end and a fourth end; a third fiber having a fifth end and a sixth end; a first coating layer that covers the cladding of the second fiber and has a higher refractive index than that of the cladding of the second fiber; and a first high refractive index layer that covers part of an outer peripheral surface and an end face of the second fiber. The first high refractive index layer has a higher refractive index than that of the cladding of the second fiber. The outer diameter of the cladding of the first fiber is smaller than that of the cladding of the second fiber. The outer diameter of the cladding of the third fiber is smaller than that of the cladding of the second fiber.

A fiber laser apparatus includes a fiber laser oscillator that performs laser oscillation with laser light from at least one laser diode module, and includes a loop-shaped optical fiber formed with: a combiner in which at least two input side optical fibers are connected to one output side optical fiber that includes one output end; and an optical fiber for connection of both ends in which the output end of the output side optical fiber is connected to the input end of any one of the input side optical fibers, the optical fiber for connection of both ends including a light leakage means formed such that at least one of values among a numerical aperture, a core diameter and a mode field diameter of the optical fiber for connection of both ends is gradually reduced from a side which is connected to the output end toward a side which is connected to the input end.

Described herein are isolated ring cavities that have refractive and heat-generating components physically separated and mechanically held by flexure mounts that are adapted to function in combination with the physically separated structure to moderate the thermal expansion effects of the heat generated by the refractive and other heat-generating elements (e.g., gain element) of the optical cavity. The flexure mounts may be configured as thinned portions of connective elements, reducing the effects of thermal expansion of the baseplate and allowing a thermal isolation from the baseplate. Multiple flexure mounts may be arranged to minimize further the effects of thermal expansion of the baseplate.

A system for frequency conversion of laser pump radiation includes an optical element for frequency conversion of lasers or laser beams with power scalability. The element has a nonlinear birefringent, thin plate crystal. A pump beam generates frequency-shifted radiation. Phase or quasi-phase matching conditions are in the crystal between beams. Frontside and backside of the crystal have high-reflective and partially-reflective coatings, obtaining intensity enhancement of the pump and frequency-converted radiation, and maintaining relative phase delay between beams, maximizing conversion efficiency. The crystal contacts a heat sink through the high-reflective coating, minimizing temperature inhomogeneity in the crystal. Intrinsic longitudinal heat flow provides power scalability. The element, used intra-cavity, acts as a wavelength-selective component forcing laser operation on resonance of the element, maximizing frequency conversion. The wavelength selectivity allows single-frequency operation of high-power lasers with intra-cavity frequency conversion.

In one aspect, a transparent heat exchanger includes a first transparent substrate optically attached to a heat source, one or more fins to transfer heat from the heat source, the one or more fins comprising transparent material and further comprising one of a manifold coupled to the first transparent substrate or a facesheet coupled to the first transparent material.

An electro-optical crystal-mounted apparatus includes a compactly configured mounting sub-assembly, and a compactly configured position adjustment sub-assembly onto which the mounting sub-assembly is mounted. The mounting sub-assembly includes a mount including a thermally conductive and electrically insulating material, an electro-optical crystal housed within a cavity of the mount, and a layer of electrically conductive material disposed on at least a portion of the mount. The mounting sub-assembly further includes a crystal sub-assembly oven mounted to, and at least partially enclosing the mount, and a heater thermally coupled to the crystal sub-assembly oven. An electrical wire electrically is coupled to the layer of electrically conductive material. The position adjustment sub-assembly positions the electro-optical crystal with respect to a laser beam configured to pass through the electro-optical crystal, and includes at least one tilt/tip adjuster for adjusting at least one of a tip and a tilt of the electro-optical crystal.

A fiber amplifier system including an optical component responsive to a seed beam and causing amplitude modulation that creates a non-uniform spectral transmission having peaks and nulls, and an actuator operable to shift the spectral transmission. The system further includes a fiber amplifier responsive to the seed beam and generating an amplified output beam and a beam sampler responsive to the output beam that provides a sample beam. A detector detects power fluctuations in the sample beam caused by the amplitude modulation, and generates a control metric identifying a magnitude of the fluctuations. A controller uses the control metric to control the actuator to cause it to make adjustments to the seed beam or to the optical component to cause the spectral transmission caused by the optical component to shift so that the peaks or nulls of the spectral transmission align with a center frequency of the seed beam.

A fiber laser apparatus includes a fiber laser oscillator that performs laser oscillation with laser light from at least one laser diode module, and includes a loop-shaped optical fiber formed with: a combiner in which at least two input side optical fibers are connected to one output side optical fiber that includes one output end; and an optical fiber for connection of both ends in which the output end of the output side optical fiber is connected to the input end of any one of the input side optical fibers, the optical fiber for connection of both ends including a light leakage means formed such that at least one of values among a numerical aperture, a core diameter and a mode field diameter of the optical fiber for connection of both ends is gradually reduced from a side which is connected to the output end toward a side which is connected to the input end.

A Raman Laser device having an nth Stokes shifted output the device including: a laser pump input; a lasing cavity having feedback elements at each end; and a diamond Raman active gain medium within the cavity, exhibiting first and higher Stokes emissions when subjected to pumping by the laser pump input; wherein the feedback elements feeding back the pump input, and 1st Stokes output from the gain medium, and a gain portion of the higher Stokes outputs, with a transmitting portion of the nth Stokes output being the output of the device.

In one aspect, a transparent heat exchanger includes a first transparent substrate optically attached to a heat source, one or more fins to transfer heat from the heat source, the one or more fins comprising transparent material and further comprising one of a manifold coupled to the first transparent substrate or a facesheet coupled to the first transparent material.