Abstract: A small-sized, highly efficient optical amplifier having a PLZT optical waveguide layer to which a rare earth element is added, and a method for manufacturing the same are provided. Disclosed is an optical amplifier including an optical waveguide layer, the optical waveguide layer including Pb1-xLax(ZryTi1-y)1-x/4 O3 (PLZT: 0<x<0.3, 0<y<1.0), being doped with Yb (ytterbium) in an amount of from 0.2 mol % to 11.0 mol %, and being a single crystal film formed by solid-phase epitaxial growth.

Abstract: An optical amplifier including an optical waveguide layer (for example channel-shaped optical waveguide layer) including Pb1?xLax(ZryTi1?y)1?x/4O3(PLZT: 0<x<0.3, 0<y<1.0) doped with a rare earth element at an amount of 0.2 mol % to 11.0 mol %, the optical waveguide layer (for example channel-shaped optical waveguide layer) being formed as a single crystal film by solid-phase epitaxial growth.

Abstract: The invention provides an optical switch including a substrate which has conductivity or semiconductivity, an optical waveguide layer which is formed on the substrate, and a control electrode which is formed on the optical waveguide layer. The optical waveguide layer includes an incident-side channel waveguide to which a light signal is incident and plural outgoing-side channel waveguides branched from the incident-side channel waveguide. The control electrode forms a reflection plane reflecting the incident light signal near a crossover portion of the plural outgoing-side channel waveguides by applying voltage to the optical waveguide layer with the substrate to control a refractive index of the optical waveguide layer, and switches propagation paths of the light signal.

Abstract: An optical amplifier including an optical waveguide layer (for example channel-shaped optical waveguide layer) including Pb1-xLax(ZryTi1-y)1-x/4 O3 (PLZT: 0<x<0.3, 0<y<1.0) doped with a rare earth element at an amount of 0.2 mol % to 11.0 mol %, the optical waveguide layer (for example channel-shaped optical waveguide layer) being formed as a single crystal film by solid-phase epitaxial growth.

Abstract: The invention provides an optical switch including a substrate which has conductivity or semiconductivity, an optical waveguide layer which is formed on the substrate, and a control electrode which is formed on the optical waveguide layer. The optical waveguide layer includes an incident-side channel waveguide to which a light signal is incident and plural outgoing-side channel waveguides branched from the incident-side channel waveguide. The control electrode forms a reflection plane reflecting the incident light signal near a crossover portion of the plural outgoing-side channel waveguides by applying voltage to the optical waveguide layer with the substrate to control a refractive index of the optical waveguide layer, and switches propagation paths of the light signal.

Abstract: The invention provides an optical switch including a substrate which has conductivity or semiconductivity, an optical waveguide layer which is formed on the substrate, and a control electrode which is formed on the optical waveguide layer. The optical waveguide layer includes an incident-side channel waveguide to which a light signal is incident and plural outgoing-side channel waveguides branched from the incident-side channel waveguide. The control electrode forms a reflection plane reflecting the incident light signal near a crossover portion of the plural outgoing-side channel waveguides by applying voltage to the optical waveguide layer with the substrate to control a refractive index of the optical waveguide layer, and switches propagation paths of the light signal.

Abstract: An optical waveguide element capable of being coupled with optical fibers at high coupling efficiency is to be provided. Also an optical waveguide element manufacturing method permitting accurate production of such optical waveguide elements is to be provided. The optical waveguide element is provided with a buffer layer formed over a monocrystalline substrate and an optical waveguide layer formed over the buffer layer, and a recess is formed in the buffer layer along the lengthwise direction of the monocrystalline substrate. The optical waveguide layer is provided to fit into this recess to form a channel optical waveguide. Over the upper face of the optical waveguide layer on the light incidence side and the light emission side, a cladding layer whose refractive index is smaller than that of the optical waveguide layer and whose thickness increases towards the end face(s) in a flared shape is provided in the same width as that of the monocrystalline substrate.

Abstract: A ridge type channel optical waveguide is formed in an optical waveguide layer. A cladding layer having a refractive index smaller than that of the optical waveguide layer and having a width substantially the same as that of the channel optical waveguide and having a thickness which increases in a tapered manner toward an end surface, is formed above both of a light entering end portion and a light exiting end portion of the channel optical waveguide. By the cladding layer, a mode field diameter in a direction orthogonal to a substrate surface can be enlarged, and a coupling loss with an optical fiber can be greatly reduced. Further, loss due to mode mismatching can be prevented by a light confining effect.

Abstract: An optical waveguide element capable of being coupled with optical fibers at high coupling efficiency is to be provided. Also an optical waveguide element manufacturing method permitting accurate production of such optical waveguide elements is to be provided. The optical waveguide element is provided with a buffer layer formed over a monocrystalline substrate and an optical waveguide layer formed over the buffer layer, and a recess is formed in the buffer layer along the lengthwise direction of the monocrystalline substrate. The optical waveguide layer is provided to fit into this recess to form a channel optical waveguide. Over the upper face of the optical waveguide layer on the light incidence side and the light emission side, a cladding layer whose refractive index is smaller than that of the optical waveguide layer and whose thickness increases towards the end face(s) in a flared shape is provided in the same width as that of the monocrystalline substrate.

Abstract: An optical waveguide element capable of being coupled with optical fibers at high coupling efficiency is to be provided. Also an optical waveguide element manufacturing method permitting accurate production of such optical waveguide elements is to be provided. The optical waveguide element is provided with a buffer layer formed over a monocrystalline substrate and an optical waveguide layer formed over the buffer layer, and a recess is formed in the buffer layer along the lengthwise direction of the monocrystalline substrate. The optical waveguide layer is provided to fit into this recess to form a channel optical waveguide. Over the upper face of the optical waveguide layer on the light incidence side and the light emission side, a cladding layer whose refractive index is smaller than that of the optical waveguide layer and whose thickness increases towards the end face(s) in a flared shape is provided in the same width as that of the monocrystalline substrate.

Abstract: A buffer layer and an optical waveguide layer are formed on a single crystal substrate. A ridge type channel optical waveguide is formed at the optical waveguide layer along a longitudinal direction of the single crystal substrate. A cladding layer having a refractive index smaller than that of the optical waveguide layer and having a width substantially the same as that of the channel optical waveguide and having a thickness which increases in a tapered manner toward an end surface, is formed above both of a light entering end portion and a light exiting end portion of the channel optical waveguide. By the cladding layer, a mode field diameter in a direction orthogonal to a substrate surface can be enlarged, and a coupling loss with an optical fiber can be greatly reduced. Further, loss due to mode mismatching can be prevented by a light confining effect.

Abstract: An optical device assures high speed drive, excellent temperature stability, low drive voltage and small crosstalk and insertion loss. The optical device includes a single crystal substrate which is used as a conductive or semiconductive lower electrode, an epitaxial buffer layer consisting of an oxide provided on the single crystal substrate, an epitaxial optical waveguide layer with an oxide ferroelectric material having an electro-optic effect which is provided on the buffer layer and which has a channel optical waveguide of which an optical path is switched when a voltage is applied to the branching portion between an optical path for incident light and an optical path for outgoing light, and a couple of upper electrodes for applying a voltage to the branching portion of the channel optical waveguide.

Abstract: The present invention uses a single substrate to provide a small-size optical waveguide element that requires no optical axis adjustments, can be driven at a low voltage, is excellent in light utilization efficiency, and can rapidly two-dimensionally deflect a light beam. A right-triangle upper electrode and a rectangular transparent upper electrode are formed on top of a thin-film optical waveguide formed on a conductive substrate to serve as a lower electrode, and an emission right-angled prism is secured on top of the transparent upper electrode. A voltage is applied between the upper electrode and the conductive substrate, and between the transparent upper electrode and the conductive substrate. A horizontal deflection is performed upon application of a voltage to the upper electrode and a vertical deflection is performed upon application of a voltage to the transparent upper electrode.

Abstract: In an optical waveguide device, a laser beam is collected to an end face of a channel waveguide, and introduced into a PLZT thin film optical waveguide. The incident laser beam, when emitted from the channel waveguide, diverges in the PLZT waveguide, permeates a thin film lens and is collimated into 0.4 Mm size. When a high frequency voltage is not applied to a comb Al electrode, the laser beam is collected after penetrating through the second thin film and emitted from the end face through the channel waveguide to form an emission beam. When the high frequency voltage is applied to the comb Al electrode, a diffraction grating is formed by an acousto-optic effect, and the laser beam is deflected. The deflected laser beam, when penetrating through the second thin film lens, is collected and emitted from the end face through the channel waveguide in adjacent with the above-described channel waveguide to form a deflected emission beam.

Abstract: An optical waveguide element capable of being coupled with optical fibers at high coupling efficiency is to be provided. Also an optical waveguide element manufacturing method permitting accurate production of such optical waveguide elements is to be provided. The optical waveguide element is provided with a buffer layer formed over a monocrystalline substrate and an optical waveguide layer formed over the buffer layer, and a recess is formed in the buffer layer along the lengthwise direction of the monocrystalline substrate. The optical waveguide layer is provided to fit into this recess to form a channel optical waveguide. Over the upper face of the optical waveguide layer on the light incidence side and the light emission side, a cladding layer whose refractive index is smaller than that of the optical waveguide layer and whose thickness increases towards the end face(s) in a flared shape is provided in the same width as that of the monocrystalline substrate.

Abstract: The invention intends to provides an optical waveguide device having a structure that satisfies the low drive voltage characteristic and the low propagation loss characteristic at the same time. The optical waveguide device contains a conductive or semiconductive lower electrode, an epitaxial or single orientational buffer layer provided on the lower electrode, an epitaxial or single orientational optical waveguide provided on the buffer layer, and an upper electrode of a conductive thin film or a semiconductive thin film, provided on the optical waveguide. The optical waveguide device is able to modulate, switch, or deflect incident light beams guided into the optical waveguide by applying a voltage between the upper electrode and the lower electrode.

Abstract: An optical scanning device for deflecting a plurality of light beams is disclosed. The device includes a plurality of deflection means for deflecting each of the plurality of light beams. The means are formed in a thin film waveguide, and distributes a refractive index of the waveguide by an electro-optic effect according to input signals to cause diffraction due to the distributed refractive index, thereby deflecting a plurality of light beams.

Abstract: An oxide thin film comprising an oxide represented by ABO.sub.3, wherein A comprises at least one element selected from the group consisting of the groups IA, IIA, IIIA, IVB and VB of the periodic table, and B comprises at least one element selected from the group consisting of the groups IVA and VA of the periodic table, wherein said oxide thin film has a mixed structure in which crystal grains are dispersed in an amorphous phase or an ultrafine grain phase. The oxide thin film is prepared by preparing an organic solvent solution (1) of a metal alkoxide compound of A and a metal alkoxide compound of B; adding water, or water and a catalyst to the organic solvent solution (1) to prepare a solution (2); mixing the organic solvent solution (1) and the solution (2) to prepare a mixed solution; coating the mixed solution on a substrate to form a thin film; and subjecting the thin film to heat treatment.

Abstract: The present invention is to provide a production method of a ferroelectric thin film element comprising an epitaxial ferroelectric thin film having stable composition control, an optical smoothness of the surface, and a high crystallization. In the production method, carrying out a first solid phase epitaxial growth process where a first organometallic compound is applied on the single-crystalline substrate and heated to form a ferroelectric buffer layer on a single-crystalline substrate, having a composition different from the substrate with a film thickness of 1 nm to 40 nm; carrying out at least once a second solid phase epitaxial growth process where a second organometallic compound is applied on the ferroelectric buffer layer formed in the above process and heated to form a ferroelectric single layer thin film with a film thickness of 10 nm or more, and being thicker than the ferroelectric buffer layer.

Abstract: An oriented ferroelectric thin film element, which comprises a single-crystal substrate having thereon (a) a first epitaxial or oriented ferroelectric thin film prepared by a gas phase growth method and (b) a second epitaxial or oriented ferroelectric thin film prepared by application of a coating solution of an organic metal compound to the first ferroelectric thin film followed by heating the coated material. The oriented ferroelectric thin film element has a smooth surface and is useful as an optical guide element, light modulation element, etc. The second ferroelectric thin film can be formed by repeating the process of application of a coating solution of an organic metal compound followed by heating the coated material several times. The present invention also discloses a process for preparing the oriented ferroelectric thin film element.