Abstract: A first electro-optic crystal substrate and a second electro-optic crystal substrate are provided as an electro-optic crystal substrate. The first electro-optic crystal substrate comprises a first periodic polarization reversal structure in which first polarization pairs, in each of which the directions of polarization in response to electric fields are opposite to each other, are arranged in a first period along a first arrangement direction which is orthogonal or inclined with respect to the direction of propagation, and light passes through the first periodic polarization reversal structure.

Abstract: A first electro-optic crystal substrate and a second electro-optic crystal substrate are provided as an electro-optic crystal substrate. The first electro-optic crystal substrate comprises a first periodic polarization reversal structure in which first polarization pairs, in each of which the directions of polarization in response to electric fields are opposite to each other, are arranged in a first period along a first arrangement direction which is orthogonal or inclined with respect to the direction of propagation, and light passes through the first periodic polarization reversal structure.

Abstract: The ferroelectric substrate 11 of ferroelectric crystals, while being supported by the support plate 14 which is thicker than the ferroelectric substrate 11, is integrated with the support plate 14 by letting the junction 13 mediate between one major surface S1A of the ferroelectric substrate 11 and one major surface S1B of the support plate 14, and therefore, it is possible through the flat surface polishing to perform thinning of the ferroelectric substrate 11, namely, the ferroelectric crystals, and as a result, it is possible to obtain the thin periodically poled structure. By the voltage application method, the domain inverted region is formed in the ferroelectric substrate 11 which is made thin.

Abstract: As a spatial light modulator 35 is disposed between a wavelength conversion part 315 and an exit surface 311b in a ferroelectric crystal substrate 31, only zeroth-order light which is at a particular wavelength is guided to a substrate while laser light from the wavelength conversion part 315 is being modulated, whereby a pattern corresponding to LSI data is drawn. Further, the spatial light modulator 35 is disposed together with the wavelength conversion parts 314 and 315 inside the ferroelectric crystal substrate 31.

Abstract: As a spatial light modulator 35 is disposed between a wavelength conversion part 315 and an exit surface 311b in a ferroelectric crystal substrate 31, only zeroth-order light which is at a particular wavelength is guided to a substrate while laser light from the wavelength conversion part 315 is being modulated, whereby a pattern corresponding to LSI data is drawn. Further, the spatial light modulator 35 is disposed together with the wavelength conversion parts 314 and 315 inside the ferroelectric crystal substrate 31.

Abstract: In an optical modulator, a first electrode portion having a plurality of first electrodes is provided on the upper surface of a base part having a periodically-poled structure and a second electrode portion is provided on the lower surface thereof, and voltage is applied in one direction between the first electrode portion and the second electrode portion, to thereby cause a periodic change of the refractive index in a polarization-part array direction in the periodically-poled structure and diffract light which enters the base part. This allows reduction in the voltage applied between the first electrode portion and the second electrode portion, and it is thereby possible to form a desired electric field inside the periodically-poled structure while achieving a high-density channel arrangement. By reducing the voltage, the rate of the optical modulation performed by the optical modulator can be increased.

Abstract: The ferroelectric substrate 11 of ferroelectric crystals, while being supported by the support plate 14 which is thicker than the ferroelectric substrate 11, is integrated with the support plate 14 by letting the junction 13 mediate between one major surface S1A of the ferroelectric substrate 11 and one major surface S1B of the support plate 14, and therefore, it is possible through the flat surface polishing to perform thinning of the ferroelectric substrate 11, namely, the ferroelectric crystals, and as a result, it is possible to obtain the thin periodically poled structure. By the voltage application method, the domain inverted region is formed in the ferroelectric substrate 11 which is made thin.

Abstract: In an optical modulator, a first electrode portion having a plurality of first electrodes is provided on the upper surface of a base part having a periodically-poled structure and a second electrode portion is provided on the lower surface thereof, and voltage is applied in one direction between the first electrode portion and the second electrode portion, to thereby cause a periodic change of the refractive index in a polarization-part array direction in the periodically-poled structure and diffract light which enters the base part. This allows reduction in the voltage applied between the first electrode portion and the second electrode portion, and it is thereby possible to form a desired electric field inside the periodically-poled structure while achieving a high-density channel arrangement. By reducing the voltage, the rate of the optical modulation performed by the optical modulator can be increased.

Abstract: A pickup apparatus for a magneto-optical recording medium comprises a waveguide for receiving a light beam reflected by a magneto-optical recording medium, and first and second focusing grating couplers disposed side by side on the waveguide for introducing the reflected light beam into the waveguide in a TE or TM guided mode and converging the thus guided optical waves at two positions spaced from each other. First and second photodetectors are mounted on the waveguide for detecting the optical waves converged by the first and second focusing grating couplers. Tracking error and focusing error are detected based on the outputs of the first and second photodetectors, and recorded signals are detected based on the output of the first photodetector and/or the output of the second photodetector. In another embodiment, three focusing grating couplers are disposed on two waveguides.

Abstract: An optical pickup apparatus comprises an optical waveguide disposed to receive a light beam reflected by an optical recording medium, first and second focusing grating couplers disposed side by side on the optical waveguide for coupling the reflected light beam into the optical waveguide and converging the optical wave guided through the optical waveguide to positions spaced from each other, and first and second photodetectors secured to the optical waveguide for respectively detecting the optical waves converged by the first and second focusing grating couplers so that reading out of recorded information, detection of tracking error and detection of focusing error can be effected.

Abstract: A pickup apparatus for a magneto-optical recording medium comprises the first and second waveguides lying one upon the other for receiving a light beam reflected by a magneto-optical recording medium, and first and second focusing grating couplers disposed on the first waveguide for introducing the reflected light beam into the first waveguide in the same guided mode. A third focusing grating coupler is disposed for introducing the reflected light beam into the second waveguide in a different guided mode. First, second and third photodetectors are secured to the first or second waveguide for detecting the optical waves converged by the first, second and third focusing grating couplers. Tracking error and focusing error are detected based on the outputs of the first and second photodetectors, and recorded signals are detected based on a difference between the output of the first and/or second photodetector and an output of the third photodetector.

Abstract: An optical IC-type head assembly for recording and for reading information on an optical disc, comprising a substrate, a light guiding layer comprising a dielectric thin film formed monolithically on the substrate, a laser oscillator for injecting the laser beam into the light guiding layer, a grating coupler for converging the laser beam on the optical disc, and a photo detector for receiving the beam reflected by the optical disc and coming out of the grating coupler. In one embodiment the substrate is made of material having cleavability. One side surface of the light guiding layer receiving the laser beam is a break surface formed by cleaving the substrate along the cleavage plane. The photo detector is disposed at the break surface of the light guiding layer. The substrate is preferably made of single crystal material.

Abstract: A pickup apparatus for a magneto-optical recording medium comprises an optical waveguide for receiving a light beam reflected by a magneto-optical recording medium, and first and second focusing grating couplers disposed side by side on the optical waveguide for introducing the reflected light beam into the optical waveguide by exciting the same guided mode, and converging the guided optical waves. A third focusing grating coupler is disposed for introducing the reflected light beam into the optical waveguide in a different guided mode and converging the guided optical wave. First, second and third photodetectors are secured to the optical waveguide for respectively detecting the optical waves converged by the first, second and third focusing grating couplers.

Abstract: A light beam scanning read-out apparatus and a light beam scanning recording apparatus comprise an optical system for converting light guided inside of an optical waveguide into collimated optical wave, a device for generating surface acoustic waves which deflect the guided optical wave, a drive circuit for operating the surface acoustic wave generating device so that the frequency of the surface acoustic waves changes continuously, and a focusing grating coupler for converging the guided and deflected optical wave at a space outside of the optical waveguide. The read-out apparatus further comprises a sub-scanning device for moving a read-out original exposed to the converted light with respect to the optical waveguide, and a photodetector for detecting light obtained from the read-out original.

Abstract: An optical IC-type head assembly for recording and for reading information on an optical disc, comprising a substrate, a light guiding layer comprising a dielectric thin film formed monolithically on the substrate, a laser oscillator for injecting the laser beam into the light guiding layer, a grating coupler for converging the laser beam on the optical disc, and a photo detector for receiving the beam reflected by the optical disc and coming out of the grating coupler. In one embodiment the substrate is made of material having cleavability. One side surface of the light guiding layer receiving the laser beam is a break surface formed by cleaving the substrate along the cleavage plane. The photo detector is disposed at the break surface of the light guiding layer. The substrate is preferably made of single crystal material.