Abstract: An optical semiconductor apparatus includes at least two upper and lower light waveguides. The waveguides are formed in a direction of semiconductor layers layered on a substrate and have a predetermined coupling degree therebetween. At least one semiconductor laser and at least one photodetector are respectively arranged in any one of the light waveguides. A grating may be formed in or in the vicinity of any one of the light waveguides to attain a wavelength-sensitivity in the coupling between the upper and lower light waveguides. The coupling degree may be controlled by a voltage applied to a part of the waveguides. An incident light entering one of the waveguides can be coupled to a local oscillation light emitted from the semiconductor laser to generate a beat signal therebetween. The beat signal can be detected by the photodetector.

Abstract: An optical device comprises a substrate, a first guiding layer having a guided mode provided on the substrate, a second guiding layer laminated with the first guiding layer on the substrate, the second guiding layer having a guided mode different from that of the first guiding layer, and a diffraction grating provided on an area where the first and second guiding layers have their guided modes overlapping, the diffraction grating serving to couple the light on the specific range of wavelengths that propagate through the first guiding layer, with the second layer, wherein the diffraction grating comprises a high refractive index region and a low refractive index region disposed periodically in the propagation direction of light, the ratio of the high refractive index region to the low refractive index region occupied in one period changing gradually in the propagation direction of light.

Abstract: There is provided a display device in a viewfinder, including a diffraction grating whose shape is determined at an interface between first and second materials, at least one of the first and second materials being adapted to have a variable refractive index for light reflected by an object to be photographed, and control means for changing the refractive index of the first and/or second materials, wherein the control means causes the light from the object to substantially pass through the diffraction grating in a first state and causes the diffraction grating to partially diffract the light from the object to display a pattern in a second state.

Abstract: This specification discloses an integrated type optical node comprising a substrate, a channel light waveguide formed on the substrate for connecting the transmission lines of an optical information system, an amplifying portion provided on the light waveguide for amplifying a light propagated through the waveguide, and a light branching-off portion provided on the light waveguide for coupling a light transmitter and/or a light receiver to the transmission lines. The specification also discloses an optical information system using such optical node.

Abstract: In a multi-wavelength light detecting and/or emitting apparatus, there are provided of a first unit of a first directional coupler having a grating for an optical coupling function and a photodetector having a photoelectric conversion function and a second unit of a second directional coupler having a grating for an optical coupling function and a semiconductor laser, and a common light waveguide extending parallel with the unit in a light propagating direction. The first directional coupler and the photodetector are serially arranged in the light propagating direction and parallel with the common light waveguide, and the second directional coupler and the semiconductor laser are serially arranged in the light propagating direction and parallel with the common light waveguide. When there are formed a plurality of the first units and the gratings have different pitches, wavelength multiplexed light signals can be simultaneously detected per each wavelength with an equal detection performance.

Abstract: This specification discloses an integrated type optical node comprising a substrate, a channel light waveguide formed on the substrate for connecting the transmission lines of an optical information system, an amplifying portion provided on the light waveguide for amplifying a light propagated through the waveguide, and a light branching-off portion provided on the light waveguide for coupling a light transmitter and/or a light receiver to the transmission lines. The specification also discloses an optical information system using such optical node.

Abstract: The present invention relates to optical apparatus such as a photosensor, a semiconductor laser, an optical amplifier in which a wavelength selective photocoupler is used so as to couple two waveguides through a diffraction grating.

Abstract: A semiconductor laser element capable of changing an oscillation wavelength over a wide range without increasing a threshold current is disclosed. A wavelength selective filter capable of changing a selected wavelength over a wide range is also disclosed. The semiconductor laser element has a substrate and a laser resonator formed on the substrate by stacking semiconductor layers including an active layer and an optical waveguide layer of a superlattice structure. The resonator includes a first reflection portion, an active portion, a phase adjustment portion and second reflection portion which are juxtaposed in a resonance direction. Diffraction gratings are formed in the optical guide layer of the first and second reflection portions. Electrodes are independently formed in the active portion, the phase adjustment portion and the first and second reflection portions. Further, a method for driving the semiconductor laser is disclosed.

Abstract: An optical modulation element characterized in that a two-dimensional phase type diffraction gratings, whose refractive index changes for each predetermined period along two different directions in a predetermined plane, is adopted, and a changing state of the refractive index is controlled to change characteristics of the diffraction grating, so that a diffraction phenomenon of light incident on the element is controlled.

Abstract: The present invention relates to optical apparatus such as a photosensor, a semiconductor laser, an optical amplifier in which a wavelength selective photocoupler is used so as to couple two waveguides through a diffraction grating.

Abstract: An optical modulator includes a substrate, a first waveguide layer formed on the substrate, a second waveguide layer stacked together with the first waveguide layer in a direction of a thickness thereof on the substrate, the second waveguide layer having a waveguide mode different from that of the first waveguide layer, a diffraction grating formed in a region where the waveguide modes of the first and second waveguide layers overlap each other, and an electrode. When the electrical signal is applied through the electrode, the wavelength of the light coupled by the diffraction grating is changed, and light output from the second waveguide layer is modulated in accordance with the electrical signal. A method of modulating light using the above optical modulator is also disclosed.

Abstract: This specification discloses an integrated type optical node comprising a substrate, a channel light waveguide formed on the substrate for connecting the transmission lines of an optical information system, an amplifying portion provided on the light waveguide for amplifying a light propagated through the waveguide, and a light branching-off portion provided on the light waveguide for coupling a light transmitter and/or a light receiver to the transmission lines. The specification also discloses an optical information system using such optical node.

Abstract: A wavelength selective filter capable of changing a selected wavelength over a wide range, andd a method for driving such a filter. The wavelength selective filter has a substrate and an optical waveguide layer including a superlattice structure on the substrate. The optical waveguide layer includes a reflection portion and an optical waveguide portion which are juxtaposed in a light propagation direction. A diffraction grating is formed in the reflection portion of the optical waveguide layer, and an electrode is formed in the reflection portion for applying voltage.

Abstract: A functional optical element has at least one diffraction grating in which first and second elements are alternately arranged. At least one of the first and second elements comprises an optically anisotropic substance and the adjacent elements are substantially different from each other. This diffraction grating is so disposed that the arrayed surface of the diffraction grating is located in the path of the incident light beam. The functional optical device is characterized in that an incident light beam having an arbitrary polarization characteristic is functioned as a plurality of light beams which are polarized in the different directions, so that at least part of the incident light beam is subjected to the diffraction effect. The optical condition of at least one of the first and second elements may be varied by a control device.

Abstract: A nonlinear optical element comprises a nonlinear medium having photoconductivity and an electrooptical effect, a pair of electrodes, arranged on two side surfaces of said nonlinear medium, for applying an electric field to the medium, for serving as reflection mirrors forming an optical resonator, and a pair of insulating layers formed between the nonlinear medium and the electrodes. A predetermined DC voltage is supplied to the electrodes, and the nonlinear medium is irradiated with a light having a variable intensity. Thus, the reflectance and transmittance of the optical element is non-linearly varied in accordance with the intensity of the incident light. Also disclosed is a method for activating such a nonlinear optical element.

Abstract: An optical analog-digital converter comprises a nonlinear optical element having a threshold value for the intensity of an input light and producing a first and a second output light from the input light with the threshold value as a reference. The optical element produces a first output light of intensity corresponding to a digital signal meaning the digital 0 and a second output light of intensity proportional to the input light intensity when the intensity of the input light is smaller than the threshold value, and produces a first output light of an intensity corresponding to a digital signal meaning the digit 1 and a second output light of intensity equal to the input light intensity minus the threshold value when the intensity of the input light is greater than the threshold value.

Abstract: A display element includes a substrate and a display pattern formed on the substrate, the display pattern including a diffraction grating. The width in the direction perpendicular to the grating lines of the diffraction grating of the display pattern is selected so as to prevent re-diffraction of the light diffracted by the one diffraction grating. An observation apparatus includes the afore-said display element, but the display pattern has a first diffraction grating structure and a second diffraction grating structure. An illuminating system and an observation system are added so as to allow for observation of the display pattern. The direction of the grating lines of the first diffraction grating structure differs from that of the grating lines of the second diffraction grating structure, thereby preventing the occurrence of a rainbow-like image.

Abstract: An optical modulation device for effecting optical modulation by controlling the diffraction phenomenon of light, which not only consumes a small amouhnt of the driving energy employed, such as a electric power, but which is also capable of improvements in reliability.

Abstract: A liquid crystal light modulation device conprises a pair of substrates at least one of which is transparent, a diffraction grating formed between or on at least one of the substrates, a liquid crystal arranged between fine grooves of the diffraction grating, and control means for changing the orientation of the liquid crystal which has been oriented in a predetermined state by the grooves of the diffraction grating.

Abstract: A single image is exposed a plurality of times on a solid state image sensor. Charges induced in each exposure and distributed accordingly are added upon shifting the charge positions in the image sensor and are extracted as electrical signals. The multiple exposures may be made at locations on the sensor which are shifted slightly from each to other, or charges from one exposure may be shifted before a later exposure.