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.

Abstract: There is provided a semiconductor laser pumped solid-state laser device for engine ignition that can stably provide optical energy required for ignition across a wide temperature range. In the semiconductor laser pumped solid-state laser device for engine ignition, a plurality of semiconductor lasers 21, 22, 23, and 24 are used that have locking ranges, a temperature width thereof divided into a plurality of temperature ranges corresponding to a variation width of an ambient temperature, and that have the respective wavelengths falling within an absorption wavelength band of a solid-state laser medium 5 of the solid-state laser device in the temperature width of each locking range, to pump the solid-state laser medium 5 by multiplexing emitted lights from the plurality of semiconductor lasers 21, 22, 23, and 24 using a multiplexing mechanism to irradiate the solid-state laser medium 5.

Abstract: A laser-diode pumped solid-state laser apparatus comprises at least one laser diode producing a pumping laser light, and at least one laser light generator including a monocrystalline substance doped with a dopant element and pumped with the pumping laser light from at least one laser diode, the monocrystalline substance containing the dopant element with a concentration profile such that the dopant element increases a concentration thereof in a direction perpendicular to a laser oscillation direction gently in the form of a slope from a near zero concentration.

Abstract: A laser type ignition device for an internal combustion engine includes a laser oscillator mounted in the internal combustion engine so as to focus its laser beam on an air-fuel mixture supplied into the combustion chamber, a pressure sensor for detecting pressure in the combustion chamber, a power source for the laser oscillator and a control unit for controlling the power source to supply the laser oscillator with the current whose amount changes according to the pressure in the combustion chamber. The power of the laser beam increases as the pressure in the combustion chamber decreases to completely ignite the air-fuel mixture.

Abstract: A laser apparatus 10 includes: a laser medium 11 arranged between a pair of reflecting means 12A and 12B of an optical resonator 12 and adapted to be excited to emit light; a saturable absorber 14 arranged on the optical axis L of the optical resonator 12 between the pair of reflecting means, the transmissivity thereof being adapted to increase with the absorption of emitted light 21 from the laser medium; and an excitation light source unit 13 adapted to output light 22 having a wavelength that excites the laser medium. The saturable absorber 14 is a crystalline body having first to third mutually perpendicular crystallographic axes and is arranged in the optical resonator 12 in such a manner as to have different transmissivities for emitted light in two mutually perpendicular polarization directions.

Abstract: A laser apparatus 10 includes: a laser medium 11 arranged between a pair of reflecting means 12A and 12B of an optical resonator 12 and adapted to be excited to emit light; a saturable absorber 14 arranged on the optical axis L of the optical resonator 12 between the pair of reflecting means, the transmissivity thereof being adapted to increase with the absorption of emitted light 21 from the laser medium; and an excitation light source unit 13 adapted to output light 22 having a wavelength that excites the laser medium. The saturable absorber 14 is a crystalline body having first to third mutually perpendicular crystallographic axes and is arranged in the optical resonator 12 in such a manner as to have different transmissivities for emitted light in two mutually perpendicular polarization directions.

Abstract: A laser-diode pumped solid-state laser apparatus comprises at least one laser diode producing a pumping laser light, and at least one laser light generator including a monocrystalline substance doped with a dopant element and pumped with the pumping laser light from at least one laser diode, the monocrystalline substance containing the dopant element with a concentration profile such that the dopant element increases a concentration thereof in a direction perpendicular to a laser oscillation direction gently in the form of a slope from a near zero concentration.

Abstract: A laser type ignition device for an internal combustion engine includes a laser oscillator mounted in the internal combustion engine so as to focus its laser beam on an air-fuel mixture supplied into the combustion chamber, a pressure sensor for detecting pressure in the combustion chamber, a power source for the laser oscillator and a control unit for controlling the power source to supply the laser oscillator with the current whose amount changes according to the pressure in the combustion chamber. The power of the laser beam increases as the pressure in the combustion chamber decreases to completely ignite the air-fuel mixture.

Abstract: When forming a periodically-poled structure on a nonlinear optical crystal 1 that permits wavelength conversion and/or optical computing, the group velocity matching conditions are determined to synchronize the group velocity of the incident light L1 with that of the outgoing light L2, and the polarization reversal period of the periodically-poled structure is determined to satisfy quasi-phase matching conditions for the aforementioned wavelength conversion and/or optical computing. As a result, the problems associated with wavelength conversion of the pulsed light due to a difference in the group velocity are suppressed.

Abstract: A solid-state laser apparatus includes a solid-state laser medium producing an output laser beam, the solid-state laser medium forming a microchip laser and having opposing end surfaces forming a laser cavity, a semiconductor laser array pumping the solid-state laser medium by a pumping laser beam, the semiconductor laser array injecting the pumping laser beam to the solid-state laser medium from a direction perpendicular to a direction of the output laser beam, the solid-state laser medium and the semiconductor laser array are mounted on a common mounting substrate.

Abstract: The present passively Q-switched laser comprises a condensing optical system for condensing a laser beam emitted from a laser light source onto the surface of the solid-state laser medium. The surface of a solid-state laser medium is disposed off the condensation position of the laser beam produced by the condensing optical system.

Abstract: In the first period from pumping start time T1 to time T2 in a laser light source 1, the power of pumping light L1 outputted from a pumping light source 41 so as to irradiate a laser medium 21 is at value P1 whereas the power of light L2 incident on a saturable absorber 30 after being emitted from the laser medium 21 is at an absorption saturation threshold or lower, which causes a resonator 10 to lower its Q-value, thereby suppressing the laser oscillation. Immediately before time T2, the power of light L2 is slightly lower than the absorption saturation threshold. In the second period subsequent to the first period, the power of light L2 is at value P2 greater than the above-mentioned value P1, whereas the power of light L2 exceeds the absorption saturation threshold, which causes the resonator 10 to increase its Q-value, whereby a mirror 12 outputs pulse laser light L3 to the outside.

Abstract: An optical device which can significantly reduce thermal birefringence effect is provided. In the optical device, depolarization generated by thermally induced birefringence is reduced significantly without making any compensation by using a (110)-cut crystal. Depolarization can be reduced by more than one order in comparison with a (111)-cut crystal.

Abstract: When forming a periodically-poled structure on a nonlinear optical crystal 1 that permits wavelength conversion and/or optical computing, the group velocity matching conditions are determined to synchronize the group velocity of the incident light L1 with that of the outgoing light L2, and the polarization reversal period of the periodically-poled structure is determined to satisfy quasi-phase matching conditions for the aforementioned wavelength conversion and/or optical computing. As a result, the problems associated with wavelength conversion of the pulsed light due to difference in the group velocity are suppressed pulsed light and a preferable element for wavelength conversion and optical computing can be provided.

Abstract: A laser device 1 is provided with: a solid sate laser medium made of GdVO4 or YVO4 to which Nd3+ is added, having first and second surfaces 10A, 10B facing each other; a high reflection film 12 formed on the first surface of the laser medium for reflecting light having a wavelength in a first wavelength range 880±5 nm and in a second wavelength range from 910 nm to 916 nm; a reflecting means 20 placed in a manner where an optical resonator of which the resonance Q-value for light having a wavelength in the second wavelength range is greater than the resonance Q-value for light of every wavelength in a third wavelength range from 1060 nm to 1065 nm is formed together with the high reflection film and the laser medium is positioned within the resonator; and an excitation light source 22 that outputs light having a wavelength in the first wavelength range for exciting the laser medium.

Abstract: A solid-state light source apparatus includes a first excitation laser light source for outputting a laser beam of a first wavelength, a second excitation laser light source for outputting a laser beam of a second wavelength, a difference frequency between the laser beam of the first wavelength and the laser beam of the second wavelength being in a terahertz band, and a semiconductor pseudo phase matching device which is disposed at a place where a first optical axis of the laser beam of the first wavelength overlaps with a second optical axis of the laser beam of the second wavelength, and generates a terahertz beam in a direction coaxial with the first and second optical axes on the basis of irradiation of the laser beams of the first and second wavelengths. Thus, high output and high efficiency terahertz wave generation can be easily and certainly realized while a narrow line width characteristic is maintained.

Abstract: In the first period from pumping start time T1 to time T2 in a laser light source 1, the power of pumping light L1 outputted from a pumping light source 41 so as to irradiate a laser medium 21 is at value P1 whereas the power of light L2 incident on a saturable absorber 30 after being emitted from the laser medium 21 is at an absorption saturation threshold or lower, which causes a resonator 10 to lower its Q-value, thereby suppressing the laser oscillation. Immediately before time T2, the power of light L2 is slightly lower than the absorption saturation threshold. In the second period subsequent to the first period, the power of light L2 is at value P2 greater than the above-mentioned value P1, whereas the power of light L2 exceeds the absorption saturation threshold, which causes the resonator 10 to increase its Q-value, whereby a mirror 12 outputs pulse laser light L3 to the outside.

Abstract: The present passively Q-switched laser comprises a condensing optical system for condensing a laser beam emitted from a laser light source onto the surface of the solid-state laser medium.

Abstract: A solid-state light source apparatus includes a first excitation laser light source for outputting a laser beam of a first wavelength, a second excitation laser light source for outputting a laser beam of a second wavelength, a difference frequency between the laser beam of the first wavelength and the laser beam of the second wavelength being in a terahertz band, and a semiconductor pseudo phase matching device which is disposed at a place where a first optical axis of the laser beam of the first wavelength overlaps with a second optical axis of the laser beam of the second wavelength, and generates a terahertz beam in a direction coaxial with the first and second optical axes on the basis of irradiation of the laser beams of the first and second wavelengths. Thus, high output and high efficiency terahertz wave generation can be easily and certainly realized while a narrow line width characteristic is maintained.