Abstract: A optical modulator with reduced with a reduced amount of ripple is provided. A Mach-Zehnder optical modulator includes a phase modulation unit including optical waveguides having a PN junction structure and traveling wave electrodes, and a dummy phase modulation unit including portions of the traveling wave electrodes, the portions being obtained by forming the respective traveling wave electrodes longer than the phase modulation unit in the light propagation direction of the phase modulation unit, and optical waveguides having the same PN junction structure as that of the optical waveguides of the phase modulation unit and not connected to the optical waveguides of the phase modulation unit.

Abstract: In an integrated optoelectronic module according to the present disclosure, a heat dissipation path for an electric integrated circuit (IC) for signal processing, which consumes a relatively large amount of power, and a heat dissipation path for an electric IC for driving an optical circuit are separated from each other. The electric IC for driving an optical circuit is mounted on a connection surface of a photonic IC in the state in which a connection surface of the electric IC for driving an optical circuit faces the connection surface of the photonic IC. The electric IC for driving an optical circuit is housed in a depressed portion formed at a portion in a substrate on a connection surface side coupled to a photonic IC. The bottom portion of the depressed portion is thermally coupled to a non-connection surface of the electric IC for driving an optical circuit.

Abstract: A COSA as an optical communication component that can prevent energy radiated in a package from causing performance degradation includes a DC block capacitor that is mounted on an upper surface of the package and located at a position different from those of a SiP chip and an optical modulator driver IC to cut off a DC signal included in a RF signal to be transmitted to the IC and a lid provided over an upper portion of the package. A separation projecting portion of the lid projecting toward an upper surface of the package separately defines a region where the capacitor is present and a region where the SiP chip and the IC are present. The separation projecting portion is connected to GND of the package, and the lid is at a GND potential.

Abstract: To reduce bad connections of a BGA optical module as an optical fiber interface during mounting by reflowing. An optical module includes: a substrate to which an optical fiber is connected and fixed and on which an electronic circuit, an optical circuit or the like is formed; a ball grid array provided on one face of the substrate as an electrical interface used when the optical module is mounted on a mounting substrate; a lid having a thermal conductivity provided on another face of the substrate; and a fiber routing mechanism provided in contact with the lid, the fiber routing mechanism having a thermal conductivity and shaped to enable the optical fiber to be wound around the fiber routing mechanism.

Abstract: An optical circuit of the present disclosure shares at least a part of an electrical path including phase variable means between neighboring optical interference circuits, or configures an electrical path so as to straddle neighboring optical interference circuits, thereby performing electrical or thermal feedback. The optical circuit includes a mechanism using the electrical or thermal feedback for cancelling components of thermal crosstalk from one optical interference circuit to another neighboring optical interference circuit. The optical circuit of the present disclosure has a resistor element that shares electrical paths including respective phase variable means between the neighboring optical interference circuits. The optical circuit changes the phase change amount by the phase variable means in the neighboring optical interference circuit, in such a way as to cancel the thermal crosstalk components by the resistor element.

Abstract: In a pipe structure in which an optical fiber passes, miniaturization of the optical module in the longitudinal direction of the optical fiber is prevented. In the optical module according to the present invention, a holding structure of the optical fiber necessary to adopt the pipe structure is moved to a cover extension unit of the package. The optical fiber is adhered and fixed to the cover extension unit protruding from the cover body unit of the package to ensure protection of the optical fiber, and the optical waveguide chip is disposed to be closer to an inner wall of a side surface of the package. By disposing the optical waveguide chip to be close to the inner wall of the package as much as possible and reducing the mounting area in the package to the utmost, it is possible to realize miniaturization of the entire optical module.

Abstract: Provided is an optical transmitter having improved frequency characteristics by controlling the band by using components constituting the optical transmitter. An optical transmitter including an optical modulator that includes a traveling-wave electrode and a terminating resistor, and an optical modulator driver configured to drive the optical modulator, in which a characteristic impedance of a transmission line connecting the optical modulator driver and the optical modulator is 20% or more higher than a characteristic impedance of the optical modulator, and an electrical length of the transmission line is 1/20 or more and ½ or less of a wavelength corresponding to a 3 dB band frequency of an electrical signal driving the optical modulator.

Abstract: A optical modulator with reduced with a reduced amount of ripple is provided. A Mach-Zehnder optical modulator includes a phase modulation unit including optical waveguides having a PN junction structure and traveling wave electrodes, and a dummy phase modulation unit including portions of the traveling wave electrodes, the portions being obtained by forming the respective traveling wave electrodes longer than the phase modulation unit in the light propagation direction of the phase modulation unit, and optical waveguides having the same PN junction structure as that of the optical waveguides of the phase modulation unit and not connected to the optical waveguides of the phase modulation unit.

Abstract: An optical modulator is provided that is capable of preventing a short circuit at a step such as an annealing step in a manufacturing process, thereby improving the manufacturing yield.

Abstract: Provided is an optical transmitter having improved frequency characteristics by controlling the band by using components constituting the optical transmitter. An optical transmitter including an optical modulator that includes a traveling-wave electrode and a terminating resistor, and an optical modulator driver configured to drive the optical modulator, in which a characteristic impedance of a transmission line connecting the optical modulator driver and the optical modulator is 20% or more higher than a characteristic impedance of the optical modulator, and an electrical length of the transmission line is 1/20 or more and ½ or less of a wavelength corresponding to a 3 dB band frequency of an electrical signal driving the optical modulator.

Abstract: To reduce bad connections of a BGA optical module as an optical fiber interface during mounting by reflowing. An optical module includes: a substrate to which an optical fiber is connected and fixed and on which an electronic circuit, an optical circuit or the like is formed; a ball grid array provided on one face of the substrate as an electrical interface used when the optical module is mounted on a mounting substrate; a lid having a thermal conductivity provided on another face of the substrate; and a fiber routing mechanism provided in contact with the lid, the fiber routing mechanism having a thermal conductivity and shaped to enable the optical fiber to be wound around the fiber routing mechanism.

Abstract: An optical modulator is provided that is capable of preventing a short circuit at a step such as an annealing step in a manufacturing process, thereby improving the manufacturing yield.

Abstract: The MZ type optical modulator of the invention includes: a Si optical modulator including an input optical waveguide, two arm waveguides branching and guiding light input from the input optical waveguide, an output optical waveguide combining the light guided through the two arm waveguides and outputting the combined light, two signal electrodes for applying radio frequency signals that are arranged in parallel to the two arm waveguides respectively, and a DC electrode for applying a bias voltage that is provided between the two signal electrodes; and at least one ground electrode arranged in parallel to the two signal electrodes.

Abstract: In a dual electrode Si optical modulator having a CPW electrode structure according to a related art, a phase difference of return currents propagating through two ground electrodes degrades the modulation frequency characteristic. To prevent this degradation, the modulator length has been shortened to terminate signal propagation before occurrence of a phase difference. However, a short modulator length would reduce an electric field applied to the optical waveguide, thus lowering the modulation efficiency. An optical modulator according to the present invention includes a bridge wiring that connects two ground electrodes, disposed between an RF electrode and an optical waveguide inside a substrate. The bridge wiring equalizes the potential between the two ground electrodes of the CPW, thereby eliminating a phase difference of return currents induced by a radio-frequency electrical signal to the RF electrode and propagating through the two ground electrodes.

Abstract: In a dual electrode Si optical modulator having a CPW electrode structure according to a related art, a phase difference of return currents propagating through two ground electrodes degrades the modulation frequency characteristic. To prevent this degradation, the modulator length has been shortened to terminate signal propagation before occurrence of a phase difference. However, a short modulator length would reduce an electric field applied to the optical waveguide, thus lowering the modulation efficiency. An optical modulator according to the present invention includes a bridge wiring that connects two ground electrodes, disposed between an RF electrode and an optical waveguide inside a substrate. The bridge wiring equalizes the potential between the two ground electrodes of the CPW, thereby eliminating a phase difference of return currents induced by a radio-frequency electrical signal to the RF electrode and propagating through the two ground electrodes.

Abstract: A germanium photodetector which reduces a dark current without degradation of a photocurrent includes: a silicon substrate; a lower clad layer formed on the silicon substrate; a core layer formed on the lower clad layer; a p-type silicon slab formed in a part of the core layer and doped with a p-type impurity ion; p++ silicon electrode sections that are highly-doped with a p-type impurity and act as an electrode; and germanium layers which absorb light. The germanium photodetector further includes an upper clad layer, an n-type germanium region doped with an n-type impurity above the germanium layer, and an electrode. According to the present invention, two germanium layers are provided on the p-type silicon slab so as to miniaturize the area of the surface of the individual germanium layer in contact with the p-type silicon slab, so that the dark current due to threading dislocation can be reduced.

Abstract: An optical module that is connectable to an optical fiber array and that can be packaged in a high density. Two package modules are mounted on a board, and optical waveguides in a Si photonic lightwave circuit mounted on the package module are connected to an optical fiber array fixed to an optical fiber block. Moreover, output end surfaces of the optical waveguides in the Si photonic lightwave circuit are perpendicular to a mount surface of the package module. The optical waveguides in the Si photonic lightwave circuit may be tilted at an appropriate angle with respect to a direction perpendicular to a right end surface. Moreover, the optical fiber block fixes optical fibers with the optical fibers tilted with respect to a direction perpendicular to an end surface connected to the Si photonic lightwave circuit.

Abstract: An optical receiver is configured so as to be as less susceptible to noise as possible even in the case where high noise occurs inside an optical transceiver. The optical receiver includes a connection part that connects two photodiodes (PDs) constituting a dual photodiode and a transimpedance amplifier (TIA), wherein signal lines from the dual photodiode are surrounded by a conductor pattern that is not connected to each of the signal lines for each channel, and the conductor pattern is connected to a ground pattern on the transimpedance amplifier or a power source pattern for the PDs.

Abstract: An optical module which is connectable to an optical fiber array and which can be packaged in a high density. Two 30 mm square package modules are mounted on a board, and optical waveguides in a 20 mm square Si photonic lightwave circuit mounted on the package module are connected to an optical fiber array fixed to an optical fiber block (15×10 mm). Moreover, output end surfaces of the optical waveguides in the Si photonic lightwave circuit are perpendicular to a mount surface of the package module. In the embodiment, the optical waveguides in the Si photonic lightwave circuit are tilted at an appropriate angle, for example, 20 degrees with respect to a direction perpendicular to a right end surface. Moreover, the optical fiber block fixes optical fibers with the optical fibers tilted at 20 degrees with respect to a direction perpendicular to an end surface connected to the Si photonic lightwave circuit.

Abstract: An optical receiver is configured so as to be as less susceptible to noise as possible even in the case where high noise occurs inside an optical transceiver. The optical receiver includes a connection part that connects two photodiodes (PDs) constituting a dual photodiode and a transimpedance amplifier (TIA), wherein signal lines from the dual photodiode are surrounded by a conductor pattern that is not connected to each of the signal lines for each channel, and the conductor pattern is connected to a ground pattern on the transimpedance amplifier or a power source pattern for the PDs.