Abstract: It is an object to provide an optical control device capable of realizing speed matching between a microwave and a light wave or impedance matching of microwaves and of reducing a driving voltage. An optical control device including a thin plate 1 (11) which has an electro-optical effect and has a thickness of 10 ?m or less, an optical waveguide 2 formed in the thin plate, and control electrodes for controlling light passing through the optical waveguide is characterized in that the control electrodes are configured to include a first electrode and a second electrode disposed to interpose the thin plate therebetween, the first electrode has a coplanar type electrode including at least a signal electrode 4 and a ground electrode 5, and the second electrode has at least a ground electrode 54 (55, 56) and is configured to apply an electric field to the optical waveguide in cooperation with the signal electrode of the first electrode.

Abstract: The present invention purposes to provide a THz-wave generator capable of generating a THz-wave stably and efficiently, and particularly, to provide the THz-wave generator which is stable against a frequency shift of a laser source and which can easily vary the frequency of the THz-wave. A THz-wave generator, for inputting a laser beam from a light source unit A including a laser source to a THz-wave generating element D, and generating a THz-wave (fT) from the THz-wave generating element, wherein a light circulating unit including an SSB optical modulator, and wavelength selecting means C are disposed between the laser source A and the THz-wave generating element D, the laser beam is guided into the light circulating unit, a specific wavelength lightwave is selected out of lightwaves having a plurality of wavelengths generated in the light circulating unit by the wavelength selecting means, and the specific wavelength (f0, fn) lightwave is input to the THz-wave generating element.

Abstract: In a THz wave generator for generating a THz wave from a THz wave generating element by inputting a plurality of laser beams having different wavelengths to the THz wave generating element, all of the plurality of laser beams are formed into a pulse beam by the pulse generator and the pulse beam is amplified by a single optical amplifier E to which the laser beams are inputted with polarization planes of the laser beams being controlled, and then the pulse beam is inputted to the THz wave generating element F. Preferably, the plurality of laser beams having different wavelengths are generated by inputting single wavelength beam to a multi wavelength generator from single mode laser light source and by inputting light waves having a plurality of wavelengths generated from the multi wavelength generator to wavelength selecting means.

Abstract: A nested modulator is provided where the circuit arrangement of modifying electrodes including signal electrodes is simplified, and at the same time, the drive voltage can be lowered.

Abstract: A light control element is provided with a thin board having electro-optical effects; an optical waveguide formed on the thin board; and a control electrode for controlling light that passes through the optical waveguide. The light control element performs speed matching between a microwave signal applied to the control electrode and the light, impedance matching of the microwaves, reduction of a driving voltage and high speed operation. In the control electrode of the light control element, a signal electrode and a grounding electrode are arranged on an upper side of the thin board, and on a lower side of the thin board, a second electrode including the grounding electrode is arranged. The second electrode is arranged not to exist below the signal electrode, especially for achieving impedance matching.

Abstract: In a light control element comprising a thin plate having a thickness of 10 [mu]m or less and exhibiting electro optic effect, an optical waveguide formed on the thin plate, and a control electrode for controlling light passing through the optical waveguide, the control electrode includes a first electrode and a second electrode so arranged as to sandwich the thin plate, and the first electrode has a coplanar electrode consisting of a first signal electrode and a ground electrode, while the second electrode has a second signal electrode. Modulation signals having mutually inverted amplitudes are inputted to the first signal electrode of the first electrode and the second signal electrode of the second electrode such that the modulation signals cooperate to apply an electric field to the optical waveguide.

Abstract: A light control element is provided with a thin board having electro-optical effects; an optical waveguide formed on the thin board; and a control electrode for controlling light that passes through the optical waveguide. The light control element performs speed matching between a microwave signal applied to the control electrode and the light, impedance matching of the microwaves, reduction of a driving voltage and high speed operation. In the control electrode of the light control element, a signal electrode and a grounding electrode are arranged on an upper side of the thin board, and on a lower side of the thin board, a second electrode including the grounding electrode is arranged, through a low refractive index layer entirely formed in the length direction of the signal electrode, with a width wider than that of the signal electrode.

Abstract: To provide a light control device which is possible to realize a velocity matching between a microwave and an optical wave or an impedance matching of the microwaves even though a signal path having a high impedance of 70? or more, and is possible to reduce a driving voltage.

Abstract: [Task] To provide the THz wave generator restricting increase in manufacturing cost or large size of the entirety of the apparatus and generating efficiently the several-W THz wave. [Means for Resolution] In a THz wave generator for generating a THz wave from a THz wave generating element by inputting a plurality of laser beams having different wavelengths to the THz wave generating element, at least one laser beam among the plurality of laser beams is formed into a pulse beam by the pulse generator and the pulse beam is amplified by an optical amplifier E and then the pulse beam is inputted to the THz wave generating element F. Preferably, the plurality of laser beams having different wavelengths are generated by inputting single wavelength beam to a multi wavelength generator from single mode laser light source and by inputting light waves having a plurality of wavelengths generated from the multi wavelength generator to wavelength selecting means.

Abstract: It is an object of the invention to realize an optical waveguide device having multiple functions or high performance, to improve the productivity of products, and to provide an optical waveguide device capable of suppressing deterioration of an operating characteristic of the optical waveguide device. An optical waveguide device includes: a thin plate 1 having a thickness of 20 ?m or less; and at least an optical waveguide 2 formed in the thin plate. The thin plate is bonded and fixed to a supporting substrate 5 with an adhesive 4 interposed therebetween, and a film having a higher refractive index than the thin plate and the adhesive is provided on a surface of the thin plate bonded and fixed to the supporting substrate so as to be in contact with or close to at least a part of the optical waveguide. Preferably, the thin plate is formed of a material having a nonlinear optical effect or an electro-optical effect.

Abstract: The purpose of present inventions is to provide an optical control device having a single-mode waveguide in the optical control device having the ridge waveguide, and to stably manufacture and provide the optical control device having the single-mode waveguide with high precision even when the substrate is a thin plate with the thickness of 10 ?m or less. An optical control device having a substrate 1 formed with an optical waveguide, in which the substrate is a thin plate with a thickness of 10 ?m or less, at least a portion of the optical waveguide is configured as a ridge waveguide 21, a trench 20 having a width of 10 ?m or less is formed on both sides of at least portions of the ridge waveguide, and a taper waveguide section (area B) continuously changes a light propagation mode of the waveguide between a single-mode and a multi-mode by continuously changing the width or depth of the trench.

Abstract: The present invention purposes to provide a THz-wave generator capable of generating a THz-wave stably and efficiently, and particularly, to provide the THz-wave generator which is stable against a frequency shift of a laser source and which can easily vary the frequency of the THz-wave. A THz-wave generator, for inputting a laser beam from a light source unit A including a laser source to a THz-wave generating element D, and generating a THz-wave (fT) from the THz-wave generating element, wherein a light circulating unit including an SSB optical modulator, and wavelength selecting means C are disposed between the laser source A and the THz-wave generating element D, the laser beam is guided into the light circulating unit, a specific wavelength lightwave is selected out of lightwaves having a plurality of wavelengths generated in the light circulating unit by the wavelength selecting means, and the specific wavelength (f0, fn) lightwave is input to the THz-wave generating element.

Abstract: An optical modulator capable of efficiently separating radiation light and propagation light from each other or removing the radiation light in the optical modulator to suppress loss of the optical modulator and deterioration of an extinction ratio, including a thin plate of a material having an electrooptic effect and a thickness of 20 ?m or less; an optical waveguide formed in a top surface or a bottom surface of the thin plate; and a modulation electrode formed in the top surface of the thin plate to modulate light which propagates in the optical waveguide, the optical waveguide has an optical junction portion in which a plurality of optical waveguide portions are joined together and, for shielding a portion of radiation light radiated from the optical junction portion, a concave portion or through-hole in the thin plate.

Abstract: A nested modulator is provided where the circuit arrangement of modifying electrodes including signal electrodes is simplified, and at the same time, the drive voltage can be lowered.

Abstract: The present invention offers an optical modulator capable of efficiently transmitting electric signals to an interaction part of a signal electrode with acting on an optical waveguide even when the electric signals are in a high frequency zone, and capable of performing high frequency broad-band operation. The optical modulator comprises a substrate 1 formed of a material having electro-optical effect, an optical waveguide formed on the substrate, and an electrode 3 for modulating the light passing through the optical waveguide.

Abstract: An optical modulator using a thin plate capable of improving an S/N ratio of an output light is provided. The optical modulator including a thin plate 1 having an electrooptic effect and having a thickness of 20 ?m or less, an optical waveguide 4 formed on a top or bottom surface of the thin plate, and a modulation electrode formed on the top surface of the thin plate to modulate light passing through the optical waveguide, wherein a stray light removing member 10 is disposed within the thin plate or in a vicinity of the thin plate.

Abstract: Provided is an optical modulator capable of efficiently separating radiation light and propagation light from each other or removing the radiation light in the optical modulator to suppress loss of the optical modulator and deterioration of an extinction ratio. In the optical modulator including a thin plate made of a material having an electrooptic effect and having a thickness of 20 ?m or less; an optical waveguide formed in a top surface or a bottom surface of the thin plate; and a modulation electrode which is formed in the top surface of the thin plate to modulate light which propagates in the optical waveguide, the optical waveguide has an optical junction portion in which a plurality of optical waveguide portions are joined together and a shielding means for shielding a portion of radiation light radiated from the optical junction portion.

Abstract: A method for generating a carrier residual signal and its device, in which a heterodyne optical signal used in a photometric field or an optical fiber radio communication field can be stably generated with a simplified structure. The device includes an optical modulating unit that includes a light source generating a light wave having a specific wavelength, and an SSB optical modulator. A light wave emitted from the light source enters into the optical modulating unit. A light wave emitted from the optical modulating unit includes a carrier component related to a zero-order Bessel function and a specific signal component related to a specific high-order Bessel function while suppressing signal components other than the specific signal component related to the specific high-order Bessel function, and a ratio of optical intensity between the carrier component and the specific signal component is set substantially to 1.

Abstract: An optical modulator restricted in a photorefractive phenomenon caused by a stray light in an optical modulator, and improved in the quenching ratio characteristics of a signal light. The optical modulator comprises a substrate consisting of a material having an electro-optic effect, an optical waveguide formed on the substrate, and a modulating electrode for allowing an electric field to work on the optical waveguide and changing the phase of light passing through the optical waveguide, characterized in that stray light removing means are provided on the surface of the substrate.

Abstract: The present invention provides a highly-integrated and compact optical element and further provides an optical element having various functions such as lower driving voltage, chirping suppression and polarization-independency. The optical element has a substrate 1 formed of a material having an electrooptic effect, a plurality of optical waveguides formed on the substrate, and a modulating electrode for applying electric field into the optical waveguides, and is characterized in that the modulating electrode has at least two branching and confluence lines on the same line for applying the same modulating signal into different optical waveguides.