Abstract: The present invention provides a laser processing method in which a modified layer is formed inside a workpiece by irradiating the workpiece with a laser beam having such a wavelength as to be transmitted through the workpiece with the focal point of the laser beam positioned inside the workpiece. In the laser processing method, the spectral line width of the laser beam is set equal to or smaller than 10 pm.

Abstract: The present invention provides a laser processing method in which a modified layer is formed inside a workpiece by irradiating the workpiece with a laser beam having such a wavelength as to be transmitted through the workpiece with the focal point of the laser beam positioned inside the workpiece. In the laser processing method, the spectral line width of the laser beam is set equal to or smaller than 10 pm.

Abstract: Two convex lenses (61, 62), each of which has a focal length “f”, and a 90 degree polarization rotator (5) are interposed between solid-state laser elements (21, 22) of a symmetrical resonator having the two solid-state laser elements (21, 22); a space between the two lenses (61, 62) is made shorter than 2f; and distances between the respective lenses (61, 62) and centers of their adjacent solid-state laser elements (21, 22) are set substantially to “f”, to thus achieve a solid-state laser capable of stably performing high power transverse single mode oscillation desirably having power of 100 W or more. There is acquired a wavelength conversion laser that is further provided with a Q switch (3) and a polarization element (4) and that causes an output fundamental wave laser beam to enter nonlinear elements (91, 92) so as to undergo wavelength conversion, thereby producing a high power harmonic laser beam having a high frequency of; desirably, about 100 kHz.

Abstract: Two convex lenses (61, 62), each of which has a focal length “f”, and a 90 degree polarization rotator (5) are interposed between solid-state laser elements (21, 22) of a symmetrical resonator having the two solid-state laser elements (21, 22); a space between the two lenses (61, 62) is made shorter than 2f; and distances between the respective lenses (61, 62) and centers of their adjacent solid-state laser elements (21, 22) are set substantially to “f”, to thus achieve a solid-state laser capable of stably performing high power transverse single mode oscillation desirably having power of 100 W or more. There is acquired a wavelength conversion laser that is further provided with a Q switch (3) and a polarization element (4) and that causes an output fundamental wave laser beam to enter nonlinear elements (91, 92) so as to undergo wavelength conversion, thereby producing a high power harmonic laser beam having a high frequency of; desirably, about 100 kHz.

Abstract: A wavelength conversion laser for generating sum frequency laser beam comprising a laser resonator, a solid-state laser active medium, a second harmonic generation wavelength conversion crystal and a sum frequency generation wavelength conversion crystal, wherein the length of the second harmonic generation wavelength conversion crystal along the optical axis is set to be shorter than that of the sum frequency generation wavelength conversion crystal.

Abstract: In a resonating-type solid-state laser oscillator including a birefringent solid-state element containing a laser active medium and providing a plurality of thermal lenses during excitation and reflecting mirrors arranged oppositely to each other on both sides of the solid-state element so that their optical axes are coincident to each other, a prescribed relationship is given among the refractive index and length of the solid-state element, the radii of curvature of the reflection mirrors, the distances between the reflecting mirrors and the solid-state element and the difference between plural thermal lenses by refringence of the solid-state element so that oscillation areas due to the plurality of thermal lenses are separated from each other.

Abstract: In a resonating-type solid-state laser oscillator including birefringent a solid-state element containing a laser active medium and providing a plurality of thermal lenses during excitation and reflecting mirrors arranged oppositely to each other on both sides of the solid-state element so that their optical axes are coincident to each other, a prescribed relationship is given among the refractive index and length of the solid-state element, the radii of curvature of the reflection mirrors, the distances between the reflecting mirrors and the solid-state element and the difference between 1/f of the plurality of thermal lenses by owing to birefringence of the solid-state element, so that oscillation areas due to the plurality of thermal lenses are separated from each other.

Abstract: An optical transmission device has an graded index optical fiber having a diameter .phi..sub.s of a core of the optical fiber, a refraction index n.sub.0 at a center of the core, and a difference .DELTA.n between refraction indexes of the center of the core and a peripheral section of the core; and an optical fiber incident system having a smallest focussed point at or near an incident side plane in said optical fiber through which the laser beam being introduced, and a diameter .phi..sub.in Of the laser beam at said incident side plane of said optical fiber having a following relationship: 0.5.phi..sub.s .ltoreq..phi..sub.in .ltoreq.2.phi..sub.s, and .phi..sub.s =(.phi..sub.c .phi..sub.0 .theta.(2n.sub.0 .DELTA.n).sup.-1/2).sup.1/2, where a diameter and an opening angle of the laser beam waist are .phi..sub.0 and 2.theta.. A solid state laser device has an graded index optical fiber in which the diameter .phi..sub.in of the laser beam at the optical fiber side having the following relationship: 0.5.phi..sub.

Abstract: A solid state laser apparatus is provided to generate a high quality and high power laser beam, and a laser machining apparatus is provided to perform laser machining by a laser beam generated from the solid state laser apparatus. In the solid state laser apparatus, a laser resonator includes a solid state component cooled in a cylindrical pipe by contacting liquid which is introduced through an inflow opening and discharged through an outflow opening, the solid state component having larger refractive index than that of the liquid, a light source turned ON by a power source to excite the solid state component, and an optical system transmitting light from the light source to the solid state component. Further, a surface roughness of the solid state component is adjusted so as to adjust an excitation distribution in a section of the solid state component.