Abstract: A semiconductor light emission device includes a semiconductor light amplifier, a mirror which reflects light emanating from an end face of the semiconductor light amplifier to return to the end face of the semiconductor light amplifier and a wavelength selector which is inserted into the optical path of the light. The wavelength selector is a Lyot filter, an etalon or a combination of a Lyot filter and an etalon.

Abstract: An etalon is disposed in a resonator of a laser to make the laser oscillate in a single longitudinal mode. Opposite end faces of the etalon through which light travels are provided with coating by ion-assisted deposition to prevent output fluctuations of the laser due to changes in environmental moisture and/or aging of the laser. Preferably the coating is of HfO.sub.2 and SiO.sub.2. In accordance with a second aspect of the present invention, there is provided a single longitudinal mode laser comprising a resonator and an etalon which is disposed in the resonator to make the laser oscillate in a single longitudinal mode, wherein the improvement comprises that opposite end faces of the etalon through which light travels are provided with coating by ion-assisted deposition. Further, the resonator may be contained in an airtight casing.

Abstract: A laser-diode-pumped solid state laser includes a Fabry-Perot resonator having a pair of resonator mirrors. A holder is provided with a pair of mirror mounting portions respectively having mirror mounting surfaces which are spaced from each other in the direction of the optical axis of the resonator and extend to intersect the optical axis of the resonator, and with connecting portion which is formed integrally with the mirror mounting portions to connect the mirror mounting portions. The resonator mirrors are fixed to the mirror mounting portions with their light transmissive end faces bonded to the mirror mounting surfaces of the holder.

Abstract: In a radiation image information read apparatus, a stimulable phosphor sheet, on which radiation image information has been stored, is scanned with stimulating rays, and light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected by a photodetector and converted into an electric image signal bearing thereon the radiation image information. A solid laser crystal which emits a laser beam having a wavelength of .lambda.2 pumped by a laser beam at a wavelength of .lambda.1 from a laser diode is combined with a nonlinear optical crystal which converts the laser beam at .lambda.2 to a laser beam at .lambda.3 within the stimulating wavelength range of the stimulable phosphor sheet, is employed as a source of the stimulating light. A filter which cuts the laser beam at .lambda.3 and transmits light emitted from the stimulable phosphor sheet, is disposed between the stimulable phosphor sheet and the photodetector.

Abstract: A method for fabricating domain reversals in predetermined periods without the occurrence of localized variations in refractive index. Localized areas of a unipolarized ferroelectric material which is made of an LiNbO.sub.3 substrate, or the like, and possesses a nonlinear optical effect are exposed to electron beams in a predetermined pattern, so that domain reversals are defined. Thereafter, this ferroelectric material is subjected to a heat treatment at a temperature below the Curie temperature of the ferroelectric material.

Abstract: A wavelength-conversion solid-state laser capable of generating a ultraviolet laser beam with high efficiency. The wavelength-conversion solid-state laser is made up of a phonon-based solid-state laser crystal, a semiconductor laser which emanates pump light to pump the phonon-based solid-state laser crystal, a laser resonator, a wavelength selection element which selects an oscillation wavelength, and a nonlinear optical crystal which generates a sum frequency of a solid-state laser beam, whose wavelength is selected by the wavelength-selection element, and the pump light. The phonon-based solid-state laser crystal is pumped with pump light emitted from the semiconductor laser, as a result of which a solid-state laser beam is emitted. A sum frequency of the solid-state laser beam and the pump beam is produced by enabling them to pass through the nonlinear optical crystal.

Abstract: In a solid state laser, a solid state laser medium is pumped with a pumping source. A wavelength selector element is disposed in a laser resonator and a twisting element makes a mode of an oscillating beam a twisted mode in the laser resonator.

Abstract: In an optical wavelength converting apparatus, a fundamental wave impinges upon a crystal of a nonlinear optical material, the type II of phase matching between the fundamental wave and its second harmonic is effected, and the second harmonic of the fundamental wave is thereby radiated out of the optical wavelength converting apparatus. Two crystals constituted of the same material are employed as the crystal. The two crystals have equal lengths and are located in orientations such that corresponding optic axes may be shifted 90.degree. from each other. The optical wavelength converting apparatus yields the second harmonic having the maximum possible output power and yet can be kept small in size and low in cost.

Abstract: In an optical wavelength converting apparatus, a fundamental wave impinges upon a crystal of a nonlinear optical material, the type II of phase matching between the fundamental wave and its second harmonic is effected, and the second harmonic of the fundamental wave is thereby radiated out of the optical wavelength converting apparatus. Two crystals constituted of the same material are employed as the crystal. The two crystals have equal lengths and are located in orientations such that corresponding optic axes may be shifted 90.degree. from each other. The optical wavelength converting apparatus yields the second harmonic having the maximum possible output power and yet can be kept small in size and low in cost.

Abstract: A single-longitudinal-mode laser comprises a laser medium, an etalon, and a resonator. The etalon is located in the resonator in a state such that two light passage end faces of the etalon, which are parallel to each other, may make a predetermined angle with respect to a resonator axis. The longitudinal mode of the etalon coincides with a gain peak wavelength of the laser medium. The single-longitudinal-mode laser is free from the problems in that the threshold value of the pumping power for the oscillation of the laser becomes large, in that the output power of the laser becomes low, in that the profile of the radiated beam becomes distorted, and in that the single longitudinal mode characteristics become bad.

Abstract: A solid-state laser is made up of a solid-state laser crystal, a pump source for pumping the laser crystal, a resonator, an etalon disposed in the resonator for selecting an oscillation wavelength, and a nonlinear optical crystal disposed in the resonator for converting the wavelength of the solid-state laser beam. A wedge-shaped optical member, with two light-transmission end faces being not parallel to each other, is disposed in the resonator. A resonator mode is set to a mode, where the maximum output of a solid-state laser beam is obtained with respect to a resonator temperature in the vicinity of a temperature at which the maximum efficiency of wavelength conversion of the nonlinear optical crystal is obtained, by fixing the wedge-shaped optical member at an optimum position. A wedge-shaped nonlinear optical member may be used both as the nonlinear optical crystal and the wedge-shaped optical member, or a wedge-shaped etalon may be used both as the etalon and the wedge-shaped optical member.

Abstract: A laser diode pumped solid laser comprises an optical module comprising a laser diode, a solid laser crystal, which is excited by a laser beam produced by the laser diode, and a resonator. An electronic cooling device has a cooling surface, on which the optical module is placed, and a heat radiating surface. An inner case housing houses the optical module therein on the cooling surface of the electronic cooling device. An outer case housing houses the inner case housing and the electronic cooling device therein and supports the electronic cooling device via its heat radiating surface. A temperature sensor detects the temperature in the region inside of the inner case housing. A control circuit controls the electronic cooling device in accordance with an output of the temperature sensor and thereby keeps the temperature in the region inside of the inner case housing at a predetermined target value.

Abstract: An optical wavelength converting apparatus comprises a fundamental wave source, which produces a laser beam serving as a fundamental wave, and an optical wavelength converting device, which is provided with an optical waveguide constituted of a nonlinear optical material. The optical wavelength converting device converts a wavelength of the laser beam impinging upon and guided through the optical waveguide. The optical waveguide is provided with a plurality of periodic domain-inverted structures, which effect phase matching between the laser beam and wavelength-converted waves. Reflection of the fundamental wave or wavelength-converted waves from end faces of the optical wavelength converting device is thereby minimized, and a plurality of wavelength-converted waves having high intensities are obtained in a state combined with one another.

Abstract: In an optical wavelength converting apparatus, a fundamental wave impinges upon a crystal of a nonlinear optical material, the type II of phase matching between the fundamental wave and its second harmonic is effected, and the second harmonic of the fundamental wave is thereby radiated out of the optical wavelength converting apparatus. Two crystals constituted of the same material are employed as the crystal. The two crystals have equal lengths and are located in orientations such that corresponding optic axes may be shifted 90.degree. from each other. The optical wavelength converting apparatus yields the second harmonic having the maximum possible output power and yet can be kept small in size and low in cost.

Abstract: A method for fabricating an optical wavelength converter element which has a high optical damage threshold value, and is capable of achieving a high wavelength conversion efficiency without involving propagation losses caused by the reflection and scattering of a fundamental wave and a wavelength-converted wave. Domain reversals periodically arranged are formed on a substrate made of a LiNbO.sub.3 crystal which acts as a ferroelectric substance possessing a nonlinear optical effect. Thereafter, an ITO thin film made of a transparent electrically conductive material is deposited on a surface of the substrate extending in the direction of the arrangement of the domain reversals, that is, "y" and "z" surfaces.

Abstract: An image is formed in a color photosensitive material through scanning exposure by using at least one semiconductor laser excited solid laser including a semiconductor laser, a non-linear optical element and means for controlling the temperature thereof as a light source for producing a laser beam. The laser beam is modulated by an external modulator in accordance with the image to be formed. Among the combinations of photosensitive layers and laser beams, at least two laser beam light sources are such that a laser beam has a wavelength falling within .+-.20 nm from the maximum wavelength in the spectral sensitivity distribution of the corresponding photosensitive layer. Each photosensitive layer has a spectral sensitivity distribution with a peak width of up to 40 nm.

Abstract: In a laser diode pumped solid state laser, a primary solid state laser medium containing a rare earth metal is pumped by a semiconductor laser, and the wavelength of a laser beam having been obtained from the solid state laser oscillation is converted by a nonlinear optical material into a different wavelength. A solid state laser medium for injection locking is located between the primary solid state laser medium and the semiconductor laser. The solid state laser medium for injection locking is pumped by the semiconductor laser and produces a laser beam for injection locking through solid state laser oscillation in a single longitudinal mode, such that the laser beam for injection locking may impinge upon the primary solid state laser medium.

Abstract: A laser-diode-pumped solid-state laser includes a solid-state laser rod which is doped with a rare-earth material such as neodium and has a wavelength converting function and a semiconductor laser which pumps the solid-state laser rod. Opposite end faces of the solid-state laser rod are formed into resonator mirrors, and a wavelength-converted wave such as a second harmonic of the laser beam oscillated by the solid-state laser rod or a sum frequency wave of a laser beam oscillated by the solid-state laser rod and a semiconductor laser beam emitted by a semiconductor laser is extracted.

Abstract: In an optical wavelength converting apparatus, a fundamental wave impinges upon a crystal of a nonlinear optical material, the type II of phase matching between the fundamental wave and its second harmonic is effected, and the second harmonic of the fundamental wave is thereby radiated out of the optical wavelength converting apparatus. Two crystals constituted of the same material are employed as the crystal. The two crystals have equal lengths and are located in orientations such that corresponding optic axes may be shifted 90.degree. from each other. The optical wavelength converting apparatus yields the second harmonic having the maximum possible output power and yet can be kept small in size and low in cost.

Abstract: A laser diode pumped solid laser comprises a solid laser medium, to which a rare earth metal has been added, a semiconductor laser, which produces a laser beam for pumping the solid laser medium, and a condensing lens, which causes the laser beam to converge in the solid laser medium. The condensing lens is located such that an optical axis of the condensing lens may deviate in the width direction of a semiconductor laser active layer from a center of irradiation area of the semiconductor laser. The amount of light returning to the semiconductor laser is thereby reduced markedly, and good stability in the output power of the laser diode pumped solid laser is obtained. A nonlinear optical material for converting the wavelength of a laser beam, which has been produced by the solid laser medium, into a different wavelength may be located in a solid laser resonator.