Abstract: Provided is a high-speed optical transmission-reception apparatus including a digital-signal processing circuit and optical modulation and optical reception modules, in which a flexible printed circuit is used as a high-frequency interface for the optical modulation and optical reception modules, a mechanism for connecting the high-frequency line pattern to the flexible printed circuit is provided on a package substrate of the digital-signal processing circuit, and the package substrate and the optical modulation and optical reception modules are connected by the flexible printed circuit.

Abstract: Provided is a high-speed optical transmission-reception apparatus including a digital-signal processing circuit and optical modulation and optical reception modules, in which a flexible printed circuit is used as a high-frequency interface for the optical modulation and optical reception modules, a mechanism for connecting the high-frequency line pattern to the flexible printed circuit is provided on a package substrate of the digital-signal processing circuit, and the package substrate and the optical modulation and optical reception modules are connected by the flexible printed circuit.

Abstract: A semiconductor Mach-Zehnder optical modulator includes input-side lead-out lines, phase modulation electrode lines, and electrodes that apply modulation signals propagating through the phase modulation electrode lines to waveguides, respectively. The semiconductor Mach-Zehnder optical modulator further includes a conductive layer between a substrate and the waveguides, a plurality of first wiring layers connected to the conductive layer, and a second wiring layer that connects an electrode pad and the plurality of first wiring layers.

Abstract: Phase modulation electrode lines of a semiconductor Mach-Zehnder optical modulator are formed along waveguides. Output-side lead lines are bent in a direction crossing the extending direction of the waveguides in the plane of a dielectric layer and are connected to terminal resistors. The output-side lead lines are formed in a predetermined width corresponding to a desired impedance and make the width narrower than the predetermined width only in the bent portions and portions where the output-side lead lines crosses the waveguides.

Abstract: A novel configuration of an optical modulator is disclosed. The optical modulator includes: an input-side coupler that splits input light; an output-side coupler that couples a first optical path and a second optical path branched from the input-side coupler; a differential optical phase modulation unit that modulates phases of respective optical waves of the first optical path and the second optical path with a periodic signal having a frequency fc; and a first IQ modulation unit arranged on the first optical path and a second IQ modulation unit arranged on the second optical path. The circuit configuration is simplified while achieving a bandwidth extension equivalent to that of an optical modulator by an optical time interleaving function of the related art, and size and loss reduction of the entire optical modulation circuit, relaxation of requirements of design and manufacturing processes, and cost reduction are achieved.

Abstract: An integrated optical device capable of easily connecting waveguides and achieving stable optical coupling is provided. In the integrated optical device in which an optical circuit that is provided on a substrate that does not transmit light from an ultraviolet range to a visible range and performs optical signal processing and an optical function element made of a material that does not transmit light in the ranges are butt-connected, in the optical circuit, a butt coupling holding substrate that transmits light in the ranges is mounted in a groove that reaches a connection end face where an input/output waveguide is formed, the connection end face of the optical circuit and an end face of the butt coupling holding substrate are processed to be flush with each other, and the optical circuit and the optical function element are fixed by a UV curing adhesive filling the connection end face.

Abstract: Provided is an IQ optical modulator including a nest-type MZ optical waveguide having optical modulation regions of I channel and Q channel End portions of an input optical waveguide and an output optical waveguide of the IQ optical modulator are located on a same edge face of a chip of the IQ optical modulator, an optical cross waveguide is included in which an optical waveguide between a first optical combiner and a second optical combiner of the nest-type MZ optical waveguide and the input optical waveguide cross each other, a first optical divider is provided between the I-channel optical modulation region and the Q-channel optical modulation region, and a light propagation direction in the first optical divider and a light propagation direction in the optical modulation regions are opposite to each other.

Abstract: In the adjustment method of optical coupling for an optical integrated circuit according to the present disclosure, the optimal adjustment position of optical coupling is determined on the basis of, for example, a sum of a plurality of photocurrents at electrodes on arm waveguides respectively formed on the plurality of MZIs in the polarization-multiplexing IQ modulator. According to the maximum value of the sum of the plurality of photocurrents, the light condensing spot position is adjusted to the center position of the end face core of the optical waveguide of the integrated chip. Typically, the light condensing spot position is adjusted to the center of the end face core by displacing the two input lenses.

Abstract: In the adjustment method of optical coupling for an optical integrated circuit according to the present disclosure, the optimal adjustment position of optical coupling is determined on the basis of, for example, a sum of a plurality of photocurrents at electrodes on arm waveguides respectively formed on the plurality of MZIs in the polarization-multiplexing IQ modulator. According to the maximum value of the sum of the plurality of photocurrents, the light condensing spot position is adjusted to the center position of the end face core of the optical waveguide of the integrated chip. Typically, the light condensing spot position is adjusted to the center of the end face core by displacing the two input lenses.

Abstract: A semiconductor optical modulator in which a radio frequency (RF) line which is disposed parallel to an optical waveguide and is a differential configuration for transmitting an RF modulation signal, a connecting pad which is formed in the same direction continuously with the RF line, and a termination resistor which has two rectangular resistors for differentially terminating the RF modulation signal from the connecting pad are linearly disposed, and terminated on-chip, and the RF line which forms a differential pair immediately after passing through the termination resistor is short-circuited.

Abstract: A semiconductor IQ optical modulator in which a phase modulation unit is configured by a differential capacitively loaded traveling-wave electrode structure based on an SS line configuration, phase modulation units of adjacent channels are spaced apart from each other by 400 ?m or more, a distance between main signal lines of the capacitance loading type structure is 60 ?m or less, a DC phase adjustment electrode and a PAD are provided between an I side phase modulation unit and a Q side phase modulation unit, the DC phase adjustment electrode is spaced apart by at least 80 ?m or more from a signal line of the phase adjustment unit, and a crosstalk characteristic between the adjacent channels is ?30 dB or less in a required frequency band.

Abstract: Provided is a high-speed optical transmission-reception apparatus including a digital-signal processing circuit and optical modulation and optical reception modules, in which a flexible printed circuit is used as a high-frequency interface for the optical modulation and optical reception modules, a mechanism for connecting the high-frequency line pattern to the flexible printed circuit is provided on a package substrate of the digital-signal processing circuit, and the package substrate and the optical modulation and optical reception modules are connected by the flexible printed circuit.

Abstract: Provided is an IQ optical modulator including a nest-type MZ optical waveguide having optical modulation regions of I channel and Q channel End portions of an input optical waveguide and an output optical waveguide of the IQ optical modulator are located on a same edge face of a chip of the IQ optical modulator, an optical cross waveguide is included in which an optical waveguide between a first optical combiner and a second optical combiner of the nest-type MZ optical waveguide and the input optical waveguide cross each other, a first optical divider is provided between the I-channel optical modulation region and the Q-channel optical modulation region, and a light propagation direction in the first optical divider and a light propagation direction in the optical modulation regions are opposite to each other.

Abstract: A semiconductor Mach-Zehnder optical modulator includes input-side lead-out lines, phase modulation electrode lines, and electrodes that apply modulation signals propagating through the phase modulation electrode lines to waveguides, respectively. The semiconductor Mach-Zehnder optical modulator further includes a conductive layer between a substrate and the waveguides, a plurality of first wiring layers connected to the conductive layer, and a second wiring layer that connects an electrode pad and the plurality of first wiring layers.

Abstract: In a semiconductor light modulator having a multiple quantum well structure, a light spot size converter element provided in a light input/output section is easily and accurately manufactured. At least one layer of a compound semiconductor layer containing a P element is inserted into a desired position in the multiple quantum well structure containing an Al element. This layer is smaller than a band gap of a compound semiconductor used in a bather layer of the multiple quantum well.

Abstract: Provided is an optical modulator having an optical modulation high frequency line through which a high frequency electrical signal can be efficiently input to an optical modulation region and which is in a broadband. High frequency lines of an optical modulator, that is, an input high frequency line, an optical modulation high frequency line, and an output high frequency line have a line configuration in which each of the input high frequency line and the output high frequency line is divided into a plurality of segments, and adjacent segments of the plurality of the segments have different characteristic impedances and propagation constants. The input high frequency line and the output high frequency line may be implemented by changing a width or a thickness of a signal electrode formed on a dielectric forming a micro-strip line between adjacent segments.

Abstract: A Mach-Zehnder modulator is enabled to perform high-speed modulation operation by reducing RF loss of a high-frequency wiring formed on an optical waveguide without deteriorating optical characteristics of branching and multiplexing optical circuits.

Abstract: Phase modulation electrode lines of a semiconductor Mach-Zehnder optical modulator are formed along waveguides. Output-side lead lines are bent in a direction crossing the extending direction of the waveguides in the plane of a dielectric layer and are connected to terminal resistors. The output-side lead lines are formed in a predetermined width corresponding to a desired impedance and make the width narrower than the predetermined width only in the bent portions and portions where the output-side lead lines crosses the waveguides.

Abstract: The present invention provides a highly reliable, high-speed, and low-loss semiconductor optical modulation element that protects a pin junction structure in a modulation region against reverse voltage ESD by configuring an additional capacity having a thyristor structure between a plurality of feeding pad electrodes. An n-type contact layer, an n-type cladding layer, a non-doped core/cladding layer, a p-type cladding layer, and a p-type contact layer are sequentially laminated on the substrate surface. A Mach-Zehnder interferometric waveguide and a plurality of feeding pad installation sections are formed by dry etching. The n-type contact layer and the n-type cladding layer are removed except for a modulation region of the Mach-Zehnder interferometric waveguide and a feeding region in which the feeding pad installation sections are formed so that the modulation region and the semiconductor of the lower part of the feeding region are electrically isolated from each other.

Abstract: The present invention provides a highly reliable, high-speed, and low-loss semiconductor optical modulation element that protects a pin junction structure in a modulation region against reverse voltage ESD by configuring an additional capacity having a thyristor structure between a plurality of feeding pad electrodes. An n-type contact layer, an n-type cladding layer, a non-doped core/cladding layer, a p-type cladding layer, and a p-type contact layer are sequentially laminated on the substrate surface. A Mach-Zehnder interferometric waveguide and a plurality of feeding pad installation sections are formed by dry etching. The n-type contact layer and the n-type cladding layer are removed except for a modulation region of the Mach-Zehnder interferometric waveguide and a feeding region in which the feeding pad installation sections are formed so that the modulation region and the semiconductor of the lower part of the feeding region are electrically isolated from each other.