Abstract: An optical modulator includes a substrate that is formed of a material having an electro-optic effect, an optical waveguide 2 that is formed on the substrate 1, the optical waveguide 2 having at least an input waveguide 21 leading the optical wave input to the optical modulator, branch waveguides 23, 24, 27, and 28 branching from the input waveguide, and an output waveguide 30 coupling the branch waveguides and leading the optical wave to the outside of the optical modulator, modulation electrodes 61 and 62 that are formed on the substrate to modulate an optical wave propagating on the waveguide, modulation means 25 and 26 that are provided at apart of the branch waveguides to modulate the optical wave propagating on the branch waveguide, where at least a part of the modulation electrodes is provided, polarization plane selection means 4 that is provided at a part of the optical waveguide up to a part where the branch waveguides are coupled, and controls the polarization plane of the optical wave modulated by

Abstract: The waveguide-type polarizer includes: a Z-cut lithium niobate substrate; an optical waveguide having a ridge structure and formed on the substrate; a low refractive index film formed with a thickness satisfying 0?n·t/??0.3742 (where n is a refractive index, t (?m) is the thickness of the film, and ? (?m) is the wavelength of a light wave) on the side of the ridge structure; and a high refractive index film formed with a thickness satisfying 0.089?n·/? on the low refractive index film. The width of the ridge structure is a ridge width where the distribution of ordinary light of the light waves propagated through the optical waveguide changes and the distribution of extraordinary light of the light waves does not change, the angle of the ridge structure is less than 90°, and the waveguide-type polarizer has a function of transmitting extraordinary light.

Abstract: Provided is an optical modulator wherein frequency characteristics in a high frequency band are further improved and temperature drift phenomenon is more suppressed. The optical modulator is provided with a substrate (1) having electro-optical effects; an optical waveguide (2) formed on the substrate; and a modulation electrode on the substrate. The modulation electrode is composed of a signal electrode for controlling an optical wave guided in the optical waveguide, and ground electrodes (4, 5). A high frequency modulation signal introducing path or a terminator is bonded to at least one of end sections (31, 32) of the signal electrode by bonding (81-86). Dummy electrode sections (131-186) are arranged on the side opposite to the end section of the bonded signal electrode, by having a waveguide path in between.

Abstract: An optical waveguide device includes: a substrate having an electro-optical effect; an optical waveguide formed on the substrate; and a control electrode for applying an electric field to the optical waveguide. The optical waveguide device has the following characteristics. A thickness of the substrate is 30 ?m or less. The control electrode has a signal electrode and a ground electrode. A low-permittivity layer is formed at least on a surface portion of the signal electrode in contact with the substrate.

Abstract: A method of adjusting the optical axis of an optical waveguide element which can improve a manufacturing yield of the optical waveguide element, an alignment yield between the optical waveguide element and an input waveguide means, etc. and can equalize the branch ratio in a Y-branch waveguide; and an optical waveguide element which can be made compact and also inhibited from complication in structure by using this method. The optical waveguide element (5) formed on a substrate comprises at least a linear waveguide (6) and a Y-branch waveguide (7) branched from the linear waveguide.

Abstract: In order to provide an optical modulator capable of suppressing generation of mode mismatching light in the Y-multiplexer in the MZ-type waveguide or mixing of the mode mismatching light with the radiation-mode light or the output light, and separately extracting output light and radiation-mode light, there is provided an optical modulator having a Mach-Zehnder type waveguide on a surface of a dielectric substrate, wherein a waveguide after multiplexing in a Y-multiplexer in an output side of the Mach-Zehnder type waveguide is a multiple mode waveguide 2, a subsidiary output waveguide as a high-order mode waveguide 2 is connected to a portion where the multiple mode waveguide is changed to a main output waveguide 3 as a single mode waveguide, and the multiple mode waveguide 2 has a length equal to or longer than 150 ?m.

Abstract: An optical waveguide device includes: a substrate having an electro-optical effect; an optical waveguide section formed on the substrate; and a plurality of modulating electrodes for modulating optical waves propagating in the optical waveguide section. The optical waveguide section branches into two parts in the propagating direction of the optical waves, thus forming the two main optical waveguides, and each of the main optical waveguides branches into two parts in the propagating direction of the optical waves, thus forming the two sub optical waveguides. The two main optical waveguides constitute a main Mach-Zehnder type optical waveguide, and the two sub optical waveguides are incorporated into the main Mach-Zehnder type optical waveguide to constitute a sub Mach-Zehnder type optical waveguide. A heat conduction suppressing zone is defined on a portion of the substrate disposed between two opposite sub Mach-Zehnder type optical waveguides.

Abstract: An optical modulator is provided which suppresses a radiation mode of a microwave generated in a connection substrate or a termination substrate from entering a signal electrode of the optical modulator and suppresses modulation properties from being degraded. The optical modulator includes an optical modulation element (1) having a substrate with an electro-optic effect, an optical waveguide formed on the substrate, and a modulating electrode (or a signal electrode (2)) for modulating light passing through the optical waveguide; and a connection substrate (4), arranged outside the substrate, for supplying the optical modulation element with a microwave signal operating the optical modulation element. A signal input terminal (22) and a signal output terminal (23) are formed on the connection substrate (20).

Abstract: The waveguide-type polarizer includes: a Z-cut lithium niobate substrate; an optical waveguide having a ridge structure and formed on the substrate; a low refractive index film formed with a thickness satisfying 0?n·t/??0.3742 (where n is a refractive index, t (?m) is the thickness of the film, and ? (?m) is the wavelength of a light wave) on the side of the ridge structure; and a high refractive index film formed with a thickness satisfying 0.089?n·/? on the low refractive index film. The width of the ridge structure is a ridge width where the distribution of ordinary light of the light waves propagated through the optical waveguide changes and the distribution of extraordinary light of the light waves does not change, the angle of the ridge structure is less than 90°, and the waveguide-type polarizer has a function of transmitting extraordinary light.

Abstract: The present invention is directed to provide a light modulation device capable of not only restricting the faint light propagating in the adhesive layer from being re-incident on the thin substrate but also increasing an adhesive strength of the thin substrate and the supplementing plate. The invention is characterized in a light modulation device having a thin substrate 1 made of material with an electro-optical effect and with a thickness of below 20 ?m; an optical waveguide 2 formed on a surface of the thin substrate or the other surface thereof; and a modulation electrode 3 formed on the surface of the thin substrate and for modulating light passing through the optical waveguide, comprising: a supplementing plate 5 adapted to be bonded to the thin substrate via an adhesive layer 4, wherein a bonding surface of the supplementing plate is formed as a rough surface 10 relative to a bonding surface of the thin substrate.

Abstract: An optical modulator suppresses a radiation mode of a microwave generated in a connection substrate or termination substrate from entering a signal electrode of the optical modulator and suppresses modulation properties from being degraded. The optical modulator includes an optical modulation element (1) having a substrate with an electro-optic effect, an optical waveguide formed on the substrate, and a modulating electrode (or a signal electrode (2)) for modulating light passing through the optical waveguide; and a connection substrate (4), arranged outside the substrate, for supplying the optical modulation element with a microwave signal operating the optical modulation element. A signal input terminal (22) and a signal output terminal (23) are formed on the connection substrate (20).

Abstract: Provided is an optical waveguide element module which suppresses reflection of a modulation signal and attenuation of a modulation signal, even when an impedance of a modulation electrode of an optical waveguide element and an impedance of a transmission line for inputting the modulation signal from the external of the optical waveguide element are different from each other. The optical waveguide clement module is provided with an optical waveguide element, which has a substrate (1) composed of a material having electro-optical effects, an optical waveguide (2) formed on the substrate, and a modulation electrode (3) which modules optical waves propagating in the optical waveguide; a connector (8), wherein an external signal line which inputs the modulation signal to the modulation electrode is connected to the modulation electrode; and a relay line which connects the connector and the modulation electrode and is formed on a relay substrate (7).

Abstract: An optical modulator suppresses a radiation mode of a microwave generated in a connection substrate or termination substrate from entering a signal electrode of the optical modulator and suppresses modulation properties from being degraded. The optical modulator includes an optical modulation element (1) having a substrate with an electro-optic effect, an optical waveguide formed on the substrate, and a modulating electrode (or a signal electrode (2)) for modulating light passing through the optical waveguide; and a connection substrate (4), arranged outside the substrate, for supplying the optical modulation element with a microwave signal operating the optical modulation element. A signal input terminal (22) and a signal output terminal (23) are formed on the connection substrate (20).

Abstract: Disclosed is an optical waveguide element module in which a filter circuit including a capacitor is provided on a line through which a modulation signal is input to a modulating electrode of an optical waveguide element and which is capable of preventing the deterioration of an electric signal in the filter circuit or the occurrence of a resonance phenomenon within the frequency range used and obtaining flat electrical/optical response frequency characteristics in a wide band of more than several tens of gigahertz, even though a single-layer capacitor is used as the capacitor.

Abstract: Provided is an optical modulator wherein frequency characteristics in a high frequency band are further improved and temperature drift phenomenon is more suppressed. The optical modulator is provided with a substrate (1) having electro-optical effects; an optical waveguide (2) formed on the substrate; and a modulation electrode on the substrate. The modulation electrode is composed of a signal electrode for controlling an optical wave guided in the optical waveguide, and ground electrodes (4, 5). A high frequency modulation signal introducing path or a terminator is bonded to at least one of end sections (31, 32) of the signal electrode by bonding (81-86). Dummy electrode sections (131-186) are arranged on the side opposite to the end section of the bonded signal electrode, by having a waveguide path in between.

Abstract: An optical modulator includes a substrate that is formed of a material having an electro-optic effect, an optical waveguide 2 that is formed on the substrate 1, the optical waveguide 2 having at least an input waveguide 21 leading the optical wave input to the optical modulator, branch waveguides 23, 24, 27, and 28 branching from the input waveguide, and an output waveguide 30 coupling the branch waveguides and leading the optical wave to the outside of the optical modulator, modulation electrodes 61 and 62 that are formed on the substrate to modulate an optical wave propagating on the waveguide, modulation means 25 and 26 that are provided at apart of the branch waveguides to modulate the optical wave propagating on the branch waveguide, where at least a part of the modulation electrodes is provided, polarization plane selection means 4 that is provided at apart of the optical waveguide up to a part where the branch waveguides are coupled, and controls the polarization plane of the optical wave modulated by

Abstract: It is an object of the invention to provide an optical modulator in which a connection substrate or a terminal substrate is disposed outside an optical modulation element and which can maintain at a proper voltage amplitude value a modulation signal applied to an optical modulation element. An optical modulator includes: a substrate having electro-optic effect; an optical waveguide formed on the substrate; an optical modulation element 1 having a modulation electrode (which includes a signal electrode 2) for modulating light passing through the optical waveguide; and a connection substrate 20 disposed outside the substrate to supply a modulation signal for driving the optical modulation element to the optical modulation element.

Abstract: An optical waveguide type device employing an X-cut substrate having an electro-optical effect is provided in which the modulation efficiency due to an electric field formed by control electrodes is improved. The optical waveguide type device includes: an X-cut substrate having an electro-optical effect; an optical waveguide formed on the substrate; and a control electrode controlling an optical wave propagating in the optical waveguide and including a signal electrode and a ground electrode. Here, the bottom surface of at least one of the signal electrode and the ground electrode disposed to interpose the optical waveguide therebetween is lower (by a height difference d) than the top surface on which the optical waveguide is formed.

Abstract: An optical waveguide type modulator with a decreased driving voltage and an improved return loss of a driving signal is provided which includes an optical waveguide having a Mach-Zehnder type optical waveguide portion and a signal electrode and a ground electrode modulating an optical wave guided in the optical waveguide. The signal electrode is arranged along at least one of two branched waveguides and Y-branched portions of the Mach-Zehnder type optical waveguide portion and along a part of one Y-branched portion connected to the one branched waveguide. Outside the part of one Y-branched portion, the signal electrode is drawn across a symmetric axis of the Mach-Zehnder type optical waveguide portion with a gap from the one Y-branched portion, and is drawn so as not to extend along the other Y-branched portion connected to the one branched waveguide and so as not to extend across the symmetric axis with a gap from the one branched waveguide.

Abstract: An optical waveguide device includes: a substrate having an electro-optical effect; an optical waveguide section formed on the substrate; and a plurality of modulating electrodes for modulating optical waves propagating in the optical waveguide section. The optical waveguide section branches into two parts in the propagating direction of the optical waves, thus forming the two main optical waveguides, and each of the main optical waveguides branches into two parts in the propagating direction of the optical waves, thus forming the two sub optical waveguides. The two main optical waveguides constitute a main Mach-Zehnder type optical waveguide, and the two sub optical waveguides are incorporated into the main Mach-Zehnder type optical waveguide to constitute a sub Mach-Zehnder type optical waveguide. A heat conduction suppressing zone is defined on a portion of the substrate disposed between two opposite sub Mach-Zehnder type optical waveguides.