Abstract: Highly-qualified crystals are grown with good yield under an optimal temperature condition by controlling the axial temperature distribution in the vicinity of the seed crystal locally. In an apparatus for producing crystals to grow crystals wherein a seed crystal 14 is placed in a crucible 11 which is retained in a furnace, raw materials 12 filled in the crucible 11 are heated and liquefied, and a raw material 12 slowly cooled in the crucible 11 from below upward, the apparatus including a temperature controller for controlling temperature to cool or heat the vicinity of the seed crystal 14 locally. The temperature controller controls the temperature by a hollow constructed cap 17 mounted outside the portion of crucible 11 and regulates refrigerant flow running through the hollow portion.

Abstract: A variable focusing lens is provided that can change the focal length at a high speed. The variable focusing lens includes: a single crystal electrooptic material having inversion symmetry; a first anode formed on a first surface of the electrooptic material; a second cathode provided to have an interval to the first anode; and a first cathode and a second anode that are formed on a second surface opposed to the first surface and that are formed at positions opposed to the first anode and the second cathode. An optical axis is set so that, when light enters through a third face orthogonal to the first surface, light exists through a fourth surface opposed to the third face. A voltage applied between the first and the second pair of electrodes is changed to thereby change the focal point of light emitted from the fourth surface of the electrooptic material.

Abstract: A variable focusing lens is provided that can change the focal length at a high speed. The variable focusing lens includes: a single crystal electrooptic material having inversion symmetry; a first anode formed on a first surface of the electrooptic material; a second cathode provided to have an interval to the first anode; and a first cathode and a second anode that are formed on a second surface opposed to the first surface and that are formed at positions opposed to the first anode and the second cathode. An optical axis is set so that, when light enters through a third face orthogonal to the first surface, light exists through a fourth surface opposed to the third face. A voltage applied between the first and the second pair of electrodes is changed to thereby change the focal point of light emitted from the fourth surface of the electrooptic material.

Abstract: To provide a variable-focal length lens capable of altering its focal length at high speed. The variable-focal length lens has an electrooptic material and electrodes formed on an incident surface of light and on an exit surface of the light of the electrooptic material. An optical axis is set so that the light is inputted into a gap where the electrodes of the incident surface are not formed and is outputted from a gap where the electrodes of the exit surface are not formed. A focus of the light that is transmitted through the electrooptic material becomes variable by varying an applied voltage between the electrodes of the incident surface and the electrodes of the exit surface.

Abstract: The present invention relates to an electric field sensor including: a light source (1); an electro optic crystal (7) which is applied with an electric field based on a signal under test, in which a birefringent index changes according to the electric field, and which changes a polarization state of light incident from the light source according to the birefringent index and emits the light; and a detector (9, 17, 19, 21) that detects an electric signal according to the change of the polarization state of the light emitted from the electro optic crystal (7). Further, the electric field sensor includes: a signal electrode (11) for applying the electric field based on the signal under test to the electro optic crystal (7); a counter electrode (12) that forms a pair with the signal electrode (11); and an auxiliary electrode (61) that is electrically connected to the counter electrode (12), and that forms a capacitance with ground.

Abstract: To provide a variable-focal length lens capable of altering its focal length at high speed. The variable-focal length lens has an electrooptic material and electrodes formed on an incident surface of light and on an exit surface of the light of the electrooptic material. An optical axis is set so that the light is inputted into a gap where the electrodes of the incident surface are not formed and is outputted from a gap where the electrodes of the exit surface are not formed. A focus of the light that is transmitted through the electrooptic material becomes variable by varying an applied voltage between the electrodes of the incident surface and the electrodes of the exit surface.

Abstract: An optical medium having a high refractive index without anisotropy and a wide transmission wavelength is obtained. The cubic crystal material is ??O3, where ? is at least one of K, Ba, Sr, Ca, and ? is at least one of Ta, Ti. Optimally, the cubic crystal material is KTa1-xNbxO3, where composition x is 0?x?0.35. This composition enables to raise refractive index while its phase transition temperature is below a room temperature.

Abstract: A method and an apparatus for producing crystals wherein crystal quality can be kept and a crystal composition is uniformed from a growth early stage to a growth last stage are provided. In an apparatus for producing crystals wherein the crystals 13 are grown from a liquefying raw material 12 in a crucible retained in a furnace and slowly cooling the raw material 12 in the crucible 11 from below upward, the apparatus comprises a raw material supply apparatus 18 which supplies a resupply raw material, and a reflection plate 20 placed above the crucible 11, which liquefies the resupply raw material 19 supplied from the raw material supply apparatus 18 and drops it as a liquid into the crucible.

Abstract: The present invention provides an optical switch, an optical modulator, and a wavelength variable filter each of which has a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch according to the present invention includes a 3-dB coupler (16) placed on an input, a 3-dB coupler (17) placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section (18) that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-yO3 (0<x<1, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.

Abstract: A method and an apparatus for producing crystals wherein crystal quality can be kept and a crystal composition is uniformed from a growth early stage to a growth last stage are provided. In an apparatus for producing crystals wherein the crystals 13 are grown from a liquefying raw material 12 in a crucible retained in a furnace and slowly cooling the raw material 12 in the crucible 11 from below upward, the apparatus comprises a raw material supply apparatus 18 which supplies a resupply raw material, and a reflection plate 20 placed above the crucible 11, which liquefies the resupply raw material 19 supplied from the raw material supply apparatus 18 and drops it as a liquid into the crucible.

Abstract: An optical switch, an optical modulator, and a wavelength variable filter each have a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch includes a 3-dB coupler placed on an output, a 3-dB coupler placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-yO3 (0<x<1, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.

Abstract: The invention provides an optical waveguide material whose refractive index can be tailored without changing the ratio of Ta and Nb. An optical waveguide of this invention comprising an under-clad layer 1 and a core 2 that is formed on the under-clad layer 1 and has a higher refractive index than that of the under-clad layer 1 is shown. For example, KTN (KTa1-xNbxO3) is used as the core 2, and a material that is obtained by substituting at least one element selected from the group consisting of Zr, Hf, and Sn for a portion of one element of the constituent elements of KTN and has the same perovskite type crystal structure as KTN is used as the clad. The refractive index of KTN can be reduced considerably, and this controllability widens the degree of freedom in the design of optical waveguide devices.

Abstract: An optical switch, an optical modulator, and a wavelength variable filter each have a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch includes a 3-dB coupler placed on an output, a 3-dB coupler placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-yO3 (0<x<1, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.

Abstract: An optical switch, an optical modulator, and a wavelength variable filter each have a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch includes a 3-dB coupler placed on an output, a 3-dB coupler placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-yO3 (0<x<1, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.

Abstract: An optical switch, an optical modulator, and a wavelength variable filter each have a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch includes a 3-dB coupler placed on an output, a 3-dB coupler placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-yO3 (0<x<1, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.

Abstract: Highly-qualified crystals are grown with good yield under an optimal temperature condition by controlling the axial temperature distribution in the vicinity of the seed crystal locally. In an apparatus for producing crystals to grow crystals wherein a seed crystal 14 is placed in a crucible 11 which is retained in a furnace, raw materials 12 filled in the crucible 11 are heated and liquefied, and a raw material 12 slowly cooled in the crucible 11 from below upward, the apparatus including a temperature controller for controlling temperature to cool or heat the vicinity of the seed crystal 14 locally. The temperature controller controls the temperature by a hollow constructed cap 17 mounted outside the portion of crucible 11 and regulates refrigerant flow running through the hollow portion.

Abstract: An optical medium having a high refractive index without anisotropy and a wide transmission wavelength is obtained. The cubic crystal material is ??O3, where ? is at least one of K, Ba, Sr, Ca, and ? is at least one of Ta, Ti. Optimally, the cubic crystal material is KTa1-xNbxO3, where composition x is 0?x?0.35. This composition enables to raise refractive index while its phase transition temperature is below a room temperature.

Abstract: An optical switch, an optical modulator, and a wavelength variable filter each have a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch includes a 3-dB coupler placed on an output, a 3-dB coupler placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-xO3 (0<x<1, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.

Abstract: An optical switch, an optical modulator, and a wavelength variable filter each have a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch includes a 3-dB coupler placed on an output, a 3-dB coupler placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-yO3 (0<x<2, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.

Abstract: The present invention provides an optical switch, an optical modulator, and a wavelength variable filter each of which has a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch according to the present invention includes a 3-dB coupler (16) placed on an output, a 3-dB coupler (17) placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section (18) that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaxNb1-xO3 (0<x<1) and KxLi1-xTayNb1-yO3 (0<x<1, 0<y<1), or KTaxNb1-xO3 or KxLi1-xTayNb1-yO3.