Nippon Telegraph and Telephone Corporation

Kiyofumi Kikuchi

Ken Tsuzuki

Hiroshi Fukuda

Shin Kamei

Yuriko Kawamura

Shunichi Soma

Yusuke Nasu

Makoto Jizodo

Takashi Saida

Takashi Goh

Kotaro Takeda

Shuichiro Asakawa

Toshihiro Ito

Masayuki Takahashi

Hiroshi Takahashi

Takashi Yamada

Hiroshi Yamazaki

Yuichiro Ikuma

Yoshiho Maeda

Toshihiro Itoh

Mikitaka Itoh

Mitsuo Usui

Tatsuro Hiraki

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.

Opto-electronic integrated module

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.

Optical circuit with common ground configuration for resistors and thermo-optic phase shifters

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.

Optical module

Provided is a photodetector which can be manufactured in a standard process of a mass-produced CMOS foundry. The photodetector includes a silicon (Si) substrate; a lower clad layer; a core layer including a waveguide layer configured to guide signal light, and including a first Si slab doped with first conductive impurity ions and a second Si slab doped with second conductive impurity ions; a germanium (Ge) layer configured to absorb light and including a Ge region doped with the first conductive impurity ions; an upper clad layer; and electrodes respectively connected to the first and second Si slabs and the Ge region. A region of the core layer sandwiched between the first Si slab and the second Si slab operates as an amplification layer.

Photodetector

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.

Optical modulator

An object is to easily convey by suction an optical module equipped with optical fibers having ends coupled to optical receptacles and mount the optical module on a substrate. An optical module according to the present invention includes an optical device to which optical fibers having ends coupled to optical receptacles are optically coupled and also includes a carrier composed of a substrate and adhesive layers formed on the upper and lower surfaces of the substrate. The optical device is bonded on the adhesive layer formed on the lower surface of the substrate. Part of the optical fibers and the optical receptacles are bonded on the adhesive layer formed on the surface of the substrate.

An optical module with optical fibers is intended to be able to be easily sucked and conveyed, and mounted on another substrate. An optical module of the present disclosure includes an optical device to which optical fibers are optically connected; and a carrier including a substrate and an adhesive layer formed at a surface of the substrate, and a part of the optical device and a part of the optical fibers are adhesively fixed on a surface of the adhesive layer. The optical device may include ball grid array shaped electrodes. The carrier may be provided with a plurality of holes.

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.

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 &#xbd; or less of a wavelength corresponding to a 3 dB band frequency of an electrical signal driving the optical modulator.

Optical transmitter

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.

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.

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.

Optical receiver

A coherent optical mixer circuit is provided that can measure a phase error without requiring a step of cutting away a delay circuit. Odd-numbered or even-numbered two of four inputs of an 4-input-and-4-output multimode interference circuit are connected to an input mechanism. The four outputs of the multimode interference circuit are all connected to an output mechanism to the exterior. Other two inputs of the multimode interference circuit are connected to two monitor waveguides. One of the monitor waveguide is longer than the other to configure a light delay circuit. The monitor waveguides constituting the light delay circuit are connected to the respective outputs of a 2-branched light splitter. The 2-branched light splitter has an input connected to a monitor light input mechanism from the exterior via a monitor input waveguide.

Coherent optical mixer circuit

An optical module that suppresses crosstalk between high-frequency transmission lines includes at least one set of: an optical port; an optical processing circuit optically connected to the optical port; an electro-optical transducer optically connected to the optical processing circuit; two or more high-frequency transmission lines connected to the electro-optical transducer; and electrical ports connected to the high-frequency transmission lines, and includes a conductive cover block which is provided above the high-frequency transmission lines so as to at least partly cover the high-frequency transmission lines and which is grounded.

A one chip-integrated digital coherent polarization multiplexing optical transmission and reception circuit with optimal optical power distribution between sending and receiving is provided by using an optical power splitter having a branching ratio of a lower asymmetry property so that the unbalanced loss depending on the polarization path can be compensated. A polarization multiplexing optical transmission and reception circuit includes a polarization multiplexing optical transmission circuit, including: the first optical power splitter for branching the optical power of continuous light outputted from a light source; one polarization optical modulation circuit at the side of a path having a higher loss connected to one output of the first optical power splitter; the second optical power splitter connected to the other output of the first optical power splitter; and the other polarization optical modulation circuit connected to one output of the second optical power splitter.

Growing community of inventors

Atsugi, Japan

Kiyofumi Kikuchi