Abstract: An optical path control apparatus includes a first substrate. A second substrate is movably provided for the first substrate. A mirror section is provided on the second substrate. A driving section moves the second substrate such that a first optical path of input light to the mirror section is optically connected to one of a plurality of second optical paths.

Abstract: There is disclosed a method of inspecting an optical waveguide substrate for optical conduction at an increased inspecting rate and also inspecting an optical waveguid—e substrate for cross-talk. According to the disclosed method, a laser beam is applied from a laser beam scanning optical system to one end face of an optical waveguide of an optical waveguide substrate which is an object to be inspected, and the laser beam emitted from the other end of the optical waveguide is detected by a CCD camera, which output detected result data. A light spot position confirming device compares the detected result data with stored data.

Abstract: A method for a method including the steps of: irradiating ultra short pulse laser rays having a pulse width not more than 30 pico-seconds to at least one of a core section and a clad section of an optical wave-guide device to modify a refractive index of the core section and the clad section.

Abstract: Nonlinear optical crystal of beta-BaB2O4 is available for generating optical harmonics of incident laser light, and an absorption spectrum shifter, a heat sink and a walk-off angle compensator are selectively provided for the non-linear optical crystal for increasing the efficiency of generating the optical harmonics.

Abstract: A laser wavelength conversion method and device for making the converted beam shape and the energy distribution point symmetrical which is suitable for high precision manufacturing and machining. First and second wavelength conversion devices are adjusted such that the phase matching orientations which give the minimum angular tolerances are orthogonal with each other. Fundamental wave is focused by focusing lens, and then incident on first device and second device, and is ejected as the cross shaped beam made of two orthogonal ellipses of the second harmonic waves. First device and second device are unified in order to eliminate the angular adjustment thereof for improving the working efficiency.

Abstract: An electro-acoustic transducer is attached to a block of optical material, and forms an acoustic standing wave in the block; the acoustic standing wave periodically changes the refractive index of the optical material, and forms high refractive index portions alternated with low refractive index portions; and the high refractive index portions serve as optical wave guides, and the electro-acoustic transducer easily produces the optical wave guide in the block.

Abstract: In the case of device for wavelength-converting an incoming ordinary ray with a wavelength of 532 nm to an extraordinary ray with a wavelength of 266, the incoming plane to which an ordinary ray is input is formed so as to have a first Brewster's angle to the ordinary ray. Moreover, the outgoing plane of the device from which an extraordinary ray is emitted is formed so as to have a second Brewster's angle to an extraordinary ray. The incoming and outgoing planes of the wavelength conversion device are formed by considering the deflection directions of ordinary and extraordinary rays.

Abstract: In growing a single crystal of .beta.-BaB.sub.2 O.sub.4 from a melt of BaB.sub.2 O.sub.4 by the Czochralski method, crushed single crystal particles of either .beta.-BaB.sub.2 O.sub.4 or .alpha.-BaB.sub.2 O.sub.4 are used as the starting material of the melt. The primary advantage of using the crushed single crystal particles resides in that transformation of a polycrystal initially nucleated on a platinum rod, which is brought into contact with the melt in place of a seed crystal, to single crystal can be accomplished in a greatly shortened time. In consequnce, high quality single crystals are obtained at good yield.

Abstract: Disclosed is a frequency conversion device fabricated in a phase matching angle in which laser damage scarcely occurs, in order to increase the damage threshold value of the device, thus providing a greater harmonic output than a conventional device. This device also has an improved reliability. The angle where the laser damage threshold value is large is measured with light permitted to enter along X, Y and Z axes of the crystal in vertical and horizontal polarization, so that the frequency conversion device can be fabricated in the phase matching angle in which the laser threshold value becomes maximum.