A laser device includes: a laser unit that outputs laser light; an output end that launches the laser light; a first fusion splice portion; and a second fusion splice portion. In each of the first fusion splice portion and the second fusion splice portion, two multi-mode fibers are fusion-spliced. Each of the two multi-mode fibers include a core through which the laser light propagates and a cladding that surrounds the core. The first fusion splice portion is disposed closer to the laser unit than is the second fusion splice portion. At least a part of the core in the first fusion splice portion contains a dopant that is the same type as a dopant contained in the cladding in the first fusion splice portion for decreasing a refractive index.

Provided is a laser device in which: a laser medium doped with ytterbium emits light upon absorption of excitation light; the light emitted by the laser medium is amplified to obtain output light; and the output light is outputted in the form of a plurality of pulses. In the laser device, a spatial filter is disposed in the optical path of the light emitted by the laser medium or is disposed in the optical path of the output light outputted from an optical resonator, the spatial filter being configured to filter out a portion of the light or of the output light around the optical axis.

A resonator for coherent oscillator matterwaves (COMW) includes a cavity bound by reflectors. The reflectors are fields of light blue-detuned with respect to an energy-level transition of the rubidium 87 (.sup.87Rb) atoms that constitute the COMW. One of the reflectors is partially transmissive to that COMW can enter and exit the resonator. The COMW resonator can be used to stabilize a COMW oscillator much as an optical resonator can stabilize a laser.

A laser processing method of performing laser processing on a transparent material that is transparent to ultraviolet light by using a laser processing system includes: performing relative positioning of a transfer position of a transfer image and the transparent material in an optical axis direction of a pulse laser beam so that the transfer position is set at a position inside the transparent material at a predetermined depth ΔZsf from a surface of the transparent material in the optical axis direction; and irradiating the transparent material with the pulse laser beam having a pulse width of 1 ns to 100 ns inclusive and a beam diameter of 10 μm to 150 μm inclusive at the transfer position.

A laser machining apparatus includes an output ratio control unit that changes an output ratio between a first laser beam and a second laser beam having different propagation characteristics; a superimposing optical system that multiplexes the first laser beam and the second laser beam; an optical fiber in which beam propagation characteristics of a combined laser beam at an exit varies depending on the output ratio, the combined laser beam being a laser beam obtained by combination of the first laser beam and the second laser beam; and a condensing optical system that performs machining of a workpiece by concentrating, on the workpiece, the beam emitted from the optical fiber.

The invention relates to a laser beam device for generating an effective laser beam and an illuminating laser beam, having a coupling element for coupling the illuminating laser beam into a beam path of the effective laser beam. The laser beam device is characterized in that the coupling element has a first sub-region and a second sub-region that is different from the first sub-region, and the effective laser beam, the illuminating laser beam and the coupling element are arranged relative to one another such that the effective laser beam is directed onto the first sub-region and the illuminating laser beam is directed onto the second sub-region, the first sub-region being transparent to the effective laser beam and the second sub-region being designed to reflect the illuminating laser beam in parallel with the effective laser beam.

A system for generating extreme ultraviolet light, in which a target material inside a chamber is irradiated with a laser beam to be turned into plasma, includes a first laser apparatus configured to output a first laser beam, a second laser apparatus configured to output a pedestal and a second laser beam, and a controller connected to the first and second laser apparatuses and configured to cause the first laser beam to be outputted first, the pedestal to be outputted after the first laser beam, and the second laser beam having higher energy than the pedestal to be outputted after the pedestal.

An optical assembly is for polarizing a laser beam. The optical assembly has a plurality of plate-shaped optical elements having a beam entry surface and a beam exit surface, and a holder configured to joint fix the plate-shaped optical elements. At least three spacers are arranged between each two adjacent ones of the plate-shaped optical elements. Each of the spacers is configured to provide punctiform contact with the respective beam exit surface of a first plate-shaped optical element, of the plate-shaped optical elements, and to provide punctiform contact with the respective beam entry surface of a second adjacent plate-shaped optical element, of the plate-shaped optical elements.

Apparatus for producing a multiplicity of photons having quantum-entangled single-photon states is provided. The single photon includes two quantum-entangled degrees of freedom, and the apparatus includes a source apparatus of the multiplicity of photons having quantum-entangled single-photon states including first- and second-generation stages. The first stage includes a first element having a source generating a multiplicity of photons, the first element selects a first degree of freedom of two degrees of freedom of the single photon, which includes only one pair of values, and a second element that selects a second degree of freedom of two degrees of freedom of the single photon. The second degree of freedom includes only one pair of values, the second stage: generates a coherent superposition of the two degrees of freedom of the single photon; selects one value of a first and a second of said two degrees of freedom.

The present invention discloses a grating enhanced distributed vibration demodulation system based on three-pulse shearing interference, comprising: a laser device, a pulse optical modulator, a three-pulse generation polarization-maintaining structure, a first erbium-doped fiber amplifier, a first optical circulator, a fiber grating array, a second erbium-doped fiber amplifier, a second optical circulator, a three-in-three optical coupler, a first Faraday rotator mirror, a second Faraday rotator mirror, and a four-channel data acquisition card, On the basis of a distributed fiber grating vibration sensing system, three-pulse dislocation interference and three-in-three optical coupler digital phase demodulation technologies are adopted, XX and XY pulses are utilized to complement interference visibility, and demodulation is performed by selecting a better path, so that polarization fading resistance and interference signal high visibility in the distributed fiber grating vibration sensing system are realized.