Abstract: A first lens transmits a beam of light having a vertical cross-sectional diameter made closer to a horizontal cross-sectional diameter. The beam of light is emitted from an optical waveguide on a substrate and configured such that the vertical cross-sectional diameter which is the diameter of a vertical cross section along the direction of the thickness of the substrate is greater than the horizontal cross-sectional diameter which is the diameter of a horizontal cross section along the direction of the width of the substrate. A second lens is disposed at a position, at which the vertical cross-sectional diameter and the horizontal cross-sectional diameter coincide with each other, so as to focus the beam of light on the optical fiber. The position is closer to the optical fiber than the first lens along the direction of travel of the beam of light transmitted by the first lens.

Abstract: An optical module connected to an optical fiber for transmitting light includes: a substrate; a ferrule that is formed from a material capable of transmitting therethrough light having a predetermined wavelength, accommodates an end of the optical fiber, and is fixed on the substrate with a fixing agent cured by being irradiated with the light capable of passing through the material; and a semiconductor chip that is disposed on the substrate and modulates light emitted from the end of the optical fiber accommodated in the ferrule.

Abstract: A polarization combiner includes: a base member that includes a body portion, an arm portion extending from the body portion, and a notch portion surrounded with the body portion and the arm portion; a polarization rotating element that is fixed to the arm portion of the base member and that rotates a polarization direction of a first polarized wave; and a polarization combining element that is fixed to the base member so as to face the notch portion of the base member and the polarization rotating element, the polarization combining element combining two polarized waves entering from a surface facing the notch portion and the polarization rotating element, the two polarized waves including the first polarized wave whose polarization direction is rotated by the polarization rotating element and a second polarized wave passing the notch portion.

Abstract: An optical transmitting apparatus includes: a substrate; optical modulators that are arranged in parallel to one another on the substrate and modulate light; waveguides that are formed on the substrate and guide signal light represented by at least one of modulated light beams obtained by the light being modulated by the plurality of optical modulators and monitor light represented by at least another one of the modulated light beams other than the signal light; lenses that collimate the signal light and the monitor light emitted from the waveguides; and a holding member that causes the signal light and the monitor light to be emitted from the lenses in mutually-different directions, by holding the lenses in such a manner that the optical axis of at least one of the lenses is out of alignment in a predetermined direction with the optical axis of at least one of the waveguides.

Abstract: An optical receiver circuit includes a polarization beam splitter configured to split input signal light into two different polarized wave components; two variable optical attenuators configured to respectively adjust attenuation of and output the signal light split by the polarization beam splitter according to polarization state; and a single planar optical waveguide on which the polarization beam splitter and the two variable optical attenuators are disposed.

Abstract: An optical module includes a waveguide substrate including an optical waveguide and electrodes that apply electronic signals to the optical waveguide; a relay substrate disposed adjacent to the waveguide substrate; a terminal substrate disposed adjacent to the waveguide substrate and opposite to the relay substrate across the waveguide substrate; and a carrier substrate on which the waveguide substrate, the relay substrate, and the terminal substrate are mounted. The electrodes have a first interconnect unit from the relay substrate to the terminal substrate via the waveguide substrate and second interconnect units from the first interconnect unit and branching on the terminal substrate. Among the second interconnect units, a first interconnect branch includes a capacitor and a terminal resistor; and a second interconnect branch is connected to an interconnect of the carrier substrate via a bias resistor, passes under the waveguide substrate to a DC electrode for bias-adjusting on the relay substrate.

Abstract: An optical module includes a waveguide substrate having an optical waveguide and electrodes that apply electronic signals to the optical waveguide; a relay substrate disposed adjacently to the waveguide substrate; and a termination substrate disposed sandwiching the waveguide substrate with the relay substrate. The electrodes respectively have a first wiring portion connected from the relay substrate through the waveguide substrate to the termination substrate and a second wiring portion extending from the first wiring portion and branching on the termination substrate. In the second wiring portion, one branched wiring portion has a capacitor and a termination resistor, and another branched wiring portion extends through a bias resistor to a DC electrode on the relay substrate. The second wiring portion is divided into a first group extending in a first direction along the optical waveguide and a second group extending in a direction opposite to the first direction.

Abstract: A circuit device includes a dielectric substrate including a first face and a second face opposite side of the first face; a coplanar line including a first line, a second line and ground electrodes, the first line and the second line being decupled mutually, the ground electrodes formed around the first line and the second line, the first line, the second line and the ground electrodes formed on the first face of the dielectric substrate; a capacitor for connecting the first line and the second line; a termination resistor connecting the second line; a microstrip line formed on the second face of the dielectric substrate; and a conducting portion formed in the dielectric substrate and electrically connecting the first line and the microstrip line.

Abstract: An optical device including (a) a substrate having an electro-optic effect; (b) a modulating optical waveguide formed on a surface layer portion of said substrate and forming an interference optical modulator for modulating input light; (c) an output optical waveguide formed on said surface layer portion of said substrate and connected to a downstream side portion of said modulating optical waveguide; and (d) a branching monitoring section for monitoring branched light of light propagated along said output optical waveguide and emitted from an outgoing end face of said substrate. The output waveguide has a reduced width region in which the waveguide width is reduced.

Abstract: a circuit device includes a dielectric substrate including a first face and a second face opposite side of the first face; a coplanar line including a first line, a second line and ground electrodes, the first line and the second line being decupled mutually, the ground electrodes formed around the first line and the second line, the first line, the second line and the ground electrodes formed on the first face of the dielectric substrate; a capacitor for connecting the first line and the second line; a termination resistor connecting the second line; a microstrip line formed on the second face of the dielectric substrate; and a conducting portion formed in the dielectric substrate and electrically connecting the first line and the microstrip line.

Abstract: An optical device including (a) a substrate having an electro-optic effect; (b) an optical waveguide formed on a surface layer portion of said substrate and including an optical waveguide for performing optical modulation for light inputted to said substrate and an output optical waveguide and a monitoring optical waveguide branched from and connected to a downstream side portion of said modulating optical waveguide, said monitoring optical waveguide guiding light for monitoring optical modulation operation of said modulating optical waveguide; and (c) a reflecting portion being provided on the downstream side of said monitoring optical waveguide for reflecting light propagated along said monitoring optical waveguide, the width of a reflection face of said reflecting portion being substantially equal to the cut-out width of said monitoring optical waveguide.

Abstract: An optical device is disclosed which suppresses a bias shift which is a deviation of a phase relationship between output signal light and monitoring light. The optical device includes a substrate having an electro-optic effect, a modulating optical waveguide formed on a surface layer portion of the substrate and forming an interference optical modulator for modulating input light, and an output optical waveguide and a monitoring optical waveguide each formed on the surface layer portion of the substrate and branched from and connected to a downstream side portion of the modulating optical waveguide. The monitoring optical waveguide guides light for monitoring optical modulation operation of the modulating optical waveguide. The monitoring optical waveguide has a reduced width region which has a reduced waveguide width.

Abstract: An optical device including (a) a substrate having an electro-optic effect; (b) a modulating optical waveguide formed on a surface layer portion of said substrate and forming an interference optical modulator for modulating input light; (c) an output optical waveguide formed on said surface layer portion of said substrate and connected to a downstream side portion of said modulating optical waveguide; and (d) a branching monitoring section for monitoring branched light of light propagated along said output optical waveguide and emitted from an outgoing end face of said substrate. The output waveguide has a reduced width region in which the waveguide width is reduced.

Abstract: An optical device including (a) a substrate having an electro-optic effect; (b) an optical waveguide formed on a surface layer portion of said substrate and including an optical waveguide for performing optical modulation for light inputted to said substrate and an output optical waveguide and a monitoring optical waveguide branched from and connected to a downstream side portion of said modulating optical waveguide, said monitoring optical waveguide guiding light for monitoring optical modulation operation of said modulating optical waveguide; and (c) a reflecting portion being provided on the downstream side of said monitoring optical waveguide for reflecting light propagated along said monitoring optical waveguide, the width of a reflection face of said reflecting portion being substantially equal to the cut-out width of said monitoring optical waveguide.

Abstract: An optical device is disclosed which suppresses a bias shift which is a deviation of a phase relationship between output signal light and monitoring light. The optical device includes a substrate having an electro-optic effect, a modulating optical waveguide formed on a surface layer portion of the substrate and forming an interference optical modulator for modulating input light, and an output optical waveguide and a monitoring optical waveguide each formed on the surface layer portion of the substrate and branched from and connected to a downstream side portion of the modulating optical waveguide. The monitoring optical waveguide guides light for monitoring optical modulation operation of the modulating optical waveguide. The monitoring optical waveguide has a reduced width region which has a reduced waveguide width.

Abstract: An optical modulator of the invention includes a substrate having an optical waveguide and an electric waveguide formed therein, a driving circuit that generates a modulation electric signal, a relay circuit that gives the modulation electric signal to the electric waveguide via an electric filter circuit made of a capacitor and a resistor, and a terminal resistor that terminates the modulation electric signal that has propagated through the electric waveguide. The sum of the impedance of the electric filter circuit and the resistance of the terminal resistor is set to be substantially equal to the impedance of the driving circuit. Also, the resistance of the terminal resistor is set to be substantially equal to the characteristic impedance of the electric waveguide. Then, deterioration of the electric reflection characteristic in a low-frequency region can be restrained even if the frequency characteristic of the optical response is flattened and leveled by application of the electric filter circuit.

Abstract: An optical modulator of the invention includes a substrate having an optical waveguide and an electric waveguide formed therein, a driving circuit that generates a modulation electric signal, a relay circuit that gives the modulation electric signal to the electric waveguide via an electric filter circuit made of a capacitor and a resistor, and a terminal resistor that terminates the modulation electric signal that has propagated through the electric waveguide. The sum of the impedance of the electric filter circuit and the resistance of the terminal resistor is set to be substantially equal to the impedance of the driving circuit. Also, the resistance of the terminal resistor is set to be substantially equal to the characteristic impedance of the electric waveguide. Then, deterioration of the electric reflection characteristic in a low-frequency region can be restrained even if the frequency characteristic of the optical response is flattened and leveled by application of the electric filter circuit.

Abstract: A first optical waveguide, a second optical waveguide, a first electrode, and a second electrode are integrated on a substrate. An optical modulator is provided with a clock signal generator for generating an RZ signal by applying a clock signal to either the first or second electrode, and an NRZ data signal generator for supplying an NRZ data signal to the remaining electrode. Thus, the space required by the optical modulator is reduced while tolerance of the same is improved, thus reducing costs for constructing the optical modulator.

Abstract: The present invention relates to an optical modulator allowing appropriate interaction between signal electrodes and an optical waveguide, only by matching phases at input ends of the signal electrodes. The optical modulator includes an optical waveguide with its center part branched into two at two Y-branch waveguides, forming first and second waveguide arms, a first signal electrode transmitting a first electric signal interacting with first light propagating through the first waveguide arm in a predetermined manner, a second signal electrode transmitting a second electric signal interacting with second light propagating through the second waveguide arm in a predetermined manner, and earthed electrodes, and can match the interacting timing between the first electric signal and the first light to the interacting timing between the second electric signal and the second light, at a first input end supplying the first electric signal and a second input end supplying the second electric signal.

Abstract: The attenuation from connectors to the interaction region of the light signal with the microwave can be reduced, and the bandwidth can be improved in an optical waveguide device, in which a space between strip lines on a ceramic substrate at one end of the strip lines connected to first and second input sections is adapted to be narrower than a space between the strip lines at the other end of the strip lines connected to first and second electric connectors.