Abstract: Both of multi-mode laser beam 8A and excitation beam 34A for amplification are imputed to an amplification gain medium 62 in a relationship in which their optical axes match each other and an effective beam diameter of the excitation beam for amplification is smaller than an effective beam diameter of the multi-mode laser beam. As a result, laser beam of a part of modes progressing in a radiation range of the excitation beam 34A for amplification is selectively amplified. Laser beam 40A subjected to mode cleaning is thereby outputted.

Abstract: Provided is a passive Q-switch laser device possessing a power density controller (15) making power density of excitation light from an excitation light source (14) equal to or greater than power density so that delay time required for reaching oscillation after start of excitation of a laser gain medium (12) becomes equal to or shorter than a laser upper energy level lifetime of the laser gain medium (12).

Abstract: A technique which is suitable in joining an end surface of a laser medium to a transparent heat sink for maintaining thermal resistance therebetween low and avoiding large thermal stress from acting on the laser medium is to be provided. An end coat is provided on the end surface of the laser medium, a same-material layer constituted of a same material as the heat sink is provided on a surface of the end coat, a surface of the same-material layer and an end surface of the heat sink are activated in a substantially vacuum environment, and those activated surfaces are bonded in the substantially vacuum environment. A laser apparatus having low thermal resistance between the laser medium and the heat sink and high transparency at a joint interface therebetween, and no large thermal stress acting on the laser medium is thereby obtained.

Abstract: A translucent in-vivo indwelling device with a translucent region including a rare earth doped fluorapatite.

Abstract: Provided is a passive Q-switch laser device possessing a power density controller (15) making power density of excitation light from an excitation light source (14) equal to or greater than power density so that delay time required for reaching oscillation after start of excitation of a laser gain medium (12) becomes equal to or shorter than a laser upper energy level lifetime of the laser gain medium (12).

Abstract: A laser ignition device capable of achieving stable ignition, preventing deterioration of a semiconductor laser element is provided, by suppressing the intensity of oscillated light leakage leaking towards semiconductor laser side from the laser resonator with a simple configuration. A laser ignition device 7 includes an excitation light source 1 emitting coherent excitation light LPMP, an optical element 2 transmitting excitation light LPMP, a laser resonator 3 oscillating oscillated light having high energy density by being irradiated with excitation light LPMP, and condensing means 6 condensing the oscillated light LPLS oscillated by the laser resonator 3. Moreover, the laser ignition device 7 is provided with a light-transmissive-reflective film 5 disposed between the excitation light source 1 and the laser resonator 3. The light-transmissive-reflective is film 5 permeating the excitation light LPMP having short wavelength and reflecting oscillated light leakage LLEAK having long wavelength.

Abstract: Upon producing a transparent polycrystalline material, a suspension liquid (or slurry 1) is prepared, the suspension liquid being made by dispersing a raw-material powder in a solution, the raw-material powder including optically anisotropic single-crystalline particles to which a rare-earth element is added. A formed body is obtained from the suspension liquid by means of carrying out slip casting in a space with a magnetic field applied. On this occasion, while doing a temperature control so that the single-crystalline particles demonstrate predetermined magnetic anisotropy, one of static magnetic fields and rotary magnetic fields is selected in compliance with a direction of an axis of easy magnetization in the single-crystalline particles, and is then applied to them. A transparent polycrystalline material is obtained by sintering the formed body, the transparent polycrystalline material having a polycrystalline structure whose crystal orientation is controlled.

Abstract: When an excitation light is entered in a laser medium including a doped (containing rare earth element) YAG, the vicinity of the excitation light entry face is locally heated which generates a birefringence, causing degradation of linear polarization of emitted laser. To avoid such a phenomenon, it was necessary to make the excitation light pulsed and slow down the repetition rate of the pulse. In this device, an undoped YAG is bonded to a excitation light entry face of the laser medium made of a doped YAG. By arranging the YAG <100> axis so as to extend along the optical axis of the laser oscillation system, a linearly polarized pulse laser can be obtained.

Abstract: Provided is a method for manufacturing a translucent polycrystalline material with optical properties continuously varying in the material. A slurry including single crystal grains that are acted upon by a force when placed in a magnetic field is immobilized in a gradient magnetic field with a spatially varying magnetic flux density and then sintered. For example, where a slurry including single crystal grains of YAG doped with Er and single crystal grains of YAG undoped with a rare earth material is immobilized in the gradient magnetic field, the region with a strong magnetic field becomes a laser oscillation region that is rich in Er-doped YAG, whereas the region with a weak magnetic field becomes a translucent region rich in YAG undoped with a rare earth material. A polycrystalline material having a core with laser oscillations and a guide surrounding the core are obtained at once.

Abstract: When an excitation light is entered in a laser medium including a doped (containing rare earth element) YAG, the vicinity of the excitation light entry face is locally heated which generates a birefringence, causing degradation of linear polarization of emitted laser. To avoid such a phenomenon, it was necessary to make the excitation light pulsed and slow down the repetition rate of the pulse. In this device, an undoped YAG is bonded to a excitation light entry face of the laser medium made of a doped YAG By arranging the YAG <100> axis so as to extend along the optical axis of the laser oscillation system, a linearly polarized pulse laser can be obtained.

Abstract: To provide a passive Q-switch-type solid laser apparatus for outputting a high peak-power pulse laser whose pulse energy is large and pulse-time width is small. A passive Q-switch-type solid laser apparatus has: two reflection elements for forming an oscillator; a solid gain medium being disposed between the two reflection elements; a saturable absorber being disposed between the two reflection elements; an excitation device for exciting the solid gain medium; and a cross section control device for making at least one of a stimulated emission cross section of the solid gain medium and an absorption cross section of the saturable absorber closer to another one of them; and the cross section control device is equipped with at least one or both of a temperature control device for retaining the solid gain medium at a predetermined temperature and an oscillatory-wavelength control device for fixating an oscillatory wavelength at a predetermined wavelength.

Abstract: Provided is an external resonance-type laser device with high wavelength conversion efficiency in which a nonlinear optical crystal is disposed outside of a resonator. The laser device includes a laser generation device configured to generate high-intensity laser light, a nonlinear optical crystal on which the high-intensity laser light generated by the laser generation device is incident and which is configured to generate a second harmonic wave light, and a different-element-fluxless-grown nonlinear optical crystal on which the second harmonic wave light generated by the nonlinear optical crystal is incident and which is configured to generate a fourth harmonic wave light. In the laser device, the different-element-fluxless-grown nonlinear optical crystal is not damaged even when high-intensity laser light of 100 MW/cm2 or more is incident.

Abstract: A solid laser apparatus which includes: two reflection elements for forming an oscillator; a plate-shaped gain medium being disposed between the two reflection elements, thereby augmenting a stimulated emission light in a thickness-wise direction; a doughnut- or deformed-doughnut-type planar waveguide being disposed so as to make an inner peripheral face thereof come in contact with an outer peripheral face of the plate-shaped gain medium; and a plurality of excited-light sources being directed in five or more directions, the excited-light sources being coupled to an outer peripheral face of the doughnut- or deformed-doughnut-type planar waveguide so as to make excited lights propagate from the outer peripheral face of the doughnut- or deformed-doughnut-type planar waveguide to the plate-shaped gain medium.

Abstract: A solid laser apparatus which includes: two reflection elements for forming an oscillator; a plate-shaped gain medium being disposed between the two reflection elements, thereby augmenting a stimulated emission light in a thickness-wise direction; a doughnut- or deformed-doughnut-type planar waveguide being disposed so as to make an inner peripheral face thereof come in contact with an outer peripheral face of the plate-shaped gain medium; and a plurality of excited-light sources being directed in five or more directions, the excited-light sources being coupled to an outer peripheral face of the doughnut- or deformed-doughnut-type planar waveguide so as to make excited lights propagate from the outer peripheral face of the doughnut- or deformed-doughnut-type planar waveguide to the plate-shaped gain medium.

Abstract: To provide a passive Q-switch-type solid laser apparatus for outputting a high peak-power pulse laser whose pulse energy is large and pulse-time width is small. A passive Q-switch-type solid laser apparatus has: two reflection elements for forming an oscillator; a solid gain medium being disposed between the two reflection elements; a saturable absorber being disposed between the two reflection elements; an excitation device for exciting the solid gain medium; and a cross section control device for making at least one of a stimulated emission cross section of the solid gain medium and an absorption cross section of the saturable absorber closer to another one of them; and the cross section control device is equipped with at least one or both of a temperature control device for retaining the solid gain medium at a predetermined temperature and an oscillatory-wavelength control device for fixating an oscillatory wavelength at a predetermined wavelength.

Abstract: Provided is a method for manufacturing a translucent polycrystalline material with optical properties continuously varying in the material. A slurry including single crystal grains that are acted upon by a force when placed in a magnetic field is immobilized in a gradient magnetic field with a spatially varying magnetic flux density and then sintered. For example, where a slurry including single crystal grains of YAG doped with Er and single crystal grains of YAG undoped with a rare earth material is immobilized in the gradient magnetic field, the region with a strong magnetic field becomes a laser oscillation region that is rich in Er-doped YAG, whereas the region with a weak magnetic field becomes a translucent region rich in YAG undoped with a rare earth material. A polycrystalline material having a core with laser oscillations and a guide surrounding the core are obtained at once.

Abstract: Upon producing a transparent polycrystalline material, a suspension liquid (or slurry 1) is prepared, the suspension liquid being made by dispersing a raw-material powder in a solution, the raw-material powder including optically anisotropic single-crystalline particles to which a rare-earth element is added. A formed body is obtained from the suspension liquid by means of carrying out slip casting in a space with a magnetic field applied. On this occasion, while doing a temperature control so that the single-crystalline particles demonstrate predetermined magnetic anisotropy, one of static magnetic fields and rotary magnetic fields is selected in compliance with a direction of an axis of easy magnetization in the single-crystalline particles, and is then applied to them. A transparent polycrystalline material is obtained by sintering the formed body, the transparent polycrystalline material having a polycrystalline structure whose crystal orientation is controlled.

Abstract: A laser ignition system that is mounted on an internal combustion engine and that condenses a laser beam oscillated from a laser oscillator into an engine combustion chamber by using a condenser lens to generate a flame kernel with high energy and to perform ignition includes at least a highly-refractive optical element that refracts optical axes OPX1 to OPXn of plural laser beams oscillated from plural semiconductor lasers 5-1 to 5-n through a resonator to change traveling directions of the laser beams and a condenser device that condenses the laser beams refracted by the highly-refractive optical element on plural positions FP1 to FPn in the engine combustion chamber.

Abstract: Upon producing a transparent polycrystalline material, a suspension liquid (or slurry 1) is prepared, the suspension liquid being made by dispersing a raw-material powder in a solution, the raw-material powder including optically anisotropic single-crystalline particles to which a rare-earth element is added. A formed body is obtained from the suspension liquid by means of carrying out slip casting in a space with a magnetic field applied. On this occasion, while doing a temperature control so that the single-crystalline particles demonstrate predetermined magnetic anisotropy, one of static magnetic fields and rotary magnetic fields is selected in compliance with a direction of an axis of easy magnetization in the single-crystalline particles, and is then applied to them. A transparent polycrystalline material is obtained by sintering the formed body, the transparent polycrystalline material having a polycrystalline structure whose crystal orientation is controlled.

Abstract: A compact semiconductor laser pumped solid-state laser device is provided that can suppress unnecessary parasitic oscillation in a microchip and efficiently extract energy.