Laser amplifier apparatus 100 includes gain medium 10 for receiving seed pulse(s) 2 and pump pulse(s) 3 and for emitting laser pulse(s) 1, resonator device 20 including gain medium and resonator mirrors spanning resonator beam path 25 with multi-pass geometry, coupler arrangement 30 for coupling seed pulse(s) and pump pulse(s) to resonator device and coupling output laser pulse(s) out of resonator device, and gain medium cooling device 40A. Resonator mirrors include first and second telescope mirrors 21, 22 with mutual distance and common focal section therebetween and defining optical axis z of resonator device, and first and second groups of end mirrors 23, 24 between mirrors 21 and 22 for forming path 25, wherein end mirrors are on ring-shaped section surrounding optical axis z, and resonator are arranged such that emitting sections of the gain medium are imaged in themselves. A method of amplifying laser pulses is also described.

An additive manufacturing system having multiple components includes a high power laser to form a laser beam. A beam dump with a fluid chamber having at least one laser transparent window into which the laser beam is directed is provided. A heat exchanger is connected to the fluid chamber, with the heat exchanger acting to provide useful energy to at least one of the multiple components of the additive manufacturing system. An absorbing fluid can be circulated through both the fluid chamber and the heat exchanger.

An optical illumination device (10) includes: a laser light source (1); microlens arrays (2, 3) through which light emitted from the laser light source (1) passes; a moving mechanism (5) that moves the microlens arrays (2, 3) without changing an optical length from the laser light source (1); and a Fourier lens (4) through which light passing through the microlens arrays (2, 3) passes.

Provided herein are wearable laser devices that provide an intuitive visual indication of a fixed radius around the wearer. Some embodiments include optical detectors that detect when two or more persons are in proximity with one another. The wearable laser devices may be used in a variety of applications, including, but not limited to, infection control, sports and entertainment.

An optical fiber includes: a center core; an inner ring layer, located outside of the center core in a radial direction, that has a refractive index lower than a refractive index of the center core; an outer core, located outside of the inner ring layer in the radial direction, that has a refractive index higher than the refractive index of the inner ring layer; and an outer ring layer, located outside of the outer core in the radial direction, that has a refractive index lower than the refractive index of the outer core. A relative refractive index difference Δ.sub.CF between the center core and the inner ring layer varies along a longitudinal direction such that the relative refractive index difference Δ.sub.CF at a location along the longitudinal direction is smaller than a relative refractive index difference Δ.sub.PF between the outer core and the outer ring layer.

The present disclosure provides a method for aligning a master oscillator power amplifier (MOPA) system. The method includes ramping up a pumping power input into a laser amplifier chain of the MOPA system until the pumping power input reaches an operational pumping power input level; adjusting a seed laser power output of a seed laser of the MOPA system until the seed laser power output is at a first level below an operational seed laser power output level; and performing a first optical alignment process to the MOPA system while the pumping power input is at the operational pumping power input level, the seed laser power output is at the first level, and the MOPA system reaches a steady operational thermal state.

An optical fiber fuse protection device includes an upstream optical fiber disposed on an upstream side, a downstream optical fiber disposed on a downstream side, and a wall interposed between a part of the upstream optical fiber and a part of the downstream optical fiber. The downstream optical fiber is fusion-spliced to the upstream optical fiber and is made of a single optical fiber or a plurality of optical fibers fusion-spliced to each other.

An apparatus for combining a plurality of coherent laser beams includes a splitting device configured to split an input laser beam into the plurality of coherent laser beams, a plurality of phase setting devices configured to adjust a respective phase of one of the plurality of coherent laser beams, and a beam combining device configured to combine the plurality of coherent laser beams, which emanate from a plurality of grid positions of a grid arrangement. The beam combining device includes a microlens arrangement having at least two microlens arrays. The apparatus further includes a controller configured to adjust a respective phase of a respective one of the plurality of coherent laser beams and/or vary a respective phase of a respective one of the plurality of coherent laser beams.

Reduction or elimination of negative consequences of reflected stray light from lens surfaces is achieved by propagating a laser beam through an eccentric pupil that excludes the optical axis of the system, which is rotationally symmetric. In such systems, stray light reflections eventually are focused onto the unique optical axis of the system, in either a real or virtual focal region. By using an eccentric pupil, all damage due to focusing of the stray light lies outside of the beam. These focal regions can, e.g., be physically blocked to eliminate beam paths that lead to optical damage, re-pulse beams and parasitic lasing.

A laser system for the generation of ultrashort optical pulses of light including an oscillator emitting low power and negatively chirped optical pulses with a spectral bandwidth W1, a dispersive connecting segment to maintain the sign of the chirp of the pulses of the oscillator, an optical amplifier for amplifying the optical light pulses and a negative group velocity dispersion segment for compensating phase contributions of the whole propagation process. During the propagation from the output of the oscillator to the end of the optical amplifier, the chirp of the light pulses will change once from negative to positive chirp. After a final compression stage ultrashort optical pulses can be generated.