Opnext Japan, Inc.

Hitachi, Ltd.

Other

Shigeru Tokita

Hiroo Matsue

Atsushi Hasegawa

Yoichi Honzawa

Takahiro Hamagishi

Osamu Yamada

Fumihide Maeda

Tomonao Kikuchi

Mitsuo Akashi

Tarou Tonoduka

Antony Cleitus

Isamu Yoshida

Kazumi Kawamoto

Hiroaki Furuichi

Naohiko Baba

Katsumi Kuroguchi

Shigenobu Maruyama

Tadashi Hatano

Yasunori Iwafuji

Toshikazu Ohtake

Tomokazu Tanaka

Cleitus Antony

Masazumi Noguchi

Akira Kuwahara

Tooru Yoshida

Sunil Sharma

Katsumi Saito

Hiroshi Ibe

Tsutomu Kuroiwa

Katsuya Ohno

Hideki Satoh

Katsuya Oono

Toshikazu c/o Hitachi Comm Systmes Inc Ohtake

Provided is an optical transmission circuit capable of realizing a high-quality optical signal waveform with low power consumption. An optical transmission circuit () includes: a laser diode (); a modulator () for supplying a differential modulation current to an anode terminal and a cathode terminal of the laser diode () through transmission lines (to); a current source () for supplying a forward bias current to the laser diode (); and a magnetic sheet (wave absorber) () disposed so as to cover at least a part of the transmission lines (and). An impedance of the laser diode () is lower than characteristic impedances of the transmission lines (to) which are formed so that the characteristic impedances thereof are matched to an output impedance of the modulator ().

Optical transmission circuit

The invention provides a heat radiating structure which reduces a mechanical stress applied to an electronic part mounted on a printed circuit board including a semiconductor package. The heat radiating structure is constructed by a semiconductor package mounted on a printed circuit board, a thermal conduction sheet arranged on an upper surface of the semiconductor package, and a metal case provided with a heat radiating fin for receiving a heat transmitted form the thermal conduction sheet so as to discharge to an atmospheric air, and the metal case is provided with a concavo-convex structure in a contact portion with the thermal conduction sheet.

Semiconductor device

An optical transmission module mounted pluggably to a cage having an opening. The optical transmission module comprises a gasket on at least a part of an outer periphery of the module. The gasket is deformed depending on temperature change. The gasket is deformed according to temperature rise in a direction toward an inner wall of the cage to push the inner wall and deformed according to temperature drop in an opposite direction to the direction.

Optical transmission module, optical transmission apparatus, and structure for fixing member

A master station includes a group of circuits for performing an optimization method. In such a system, the optimization is achieved by adjusting the pull-up resistance and by setting the best possible clock frequency to ensure that data/clock high and low voltage levels are within predetermined specifications. An optimization procedure is performed in a calibration phase invoked by a user or a system whenever a change is introduced to the system, such as addition or deletion of slave stations, a change of data/clock lines, or a change that may affect on the electrical and timing characteristics of the two-wire communication system.

Bidirectional communication system and calibrator

A reader/writer is provided which is capable of speedily recognizing a correspondence between one end and the other end of a fiber-optic cable when a plurality of fiber-optic cables is laid. The reader/writer according to the present invention reads, on receiving through the fiber-optic cable a signal that is an instruction to read data from a RF tag mounted to an end of the fiber-optic cable, data from the RF tag through radio communication, and transmits the read data through the fiber-optic cable. Also, on receiving through the fiber-optic cable a signal that is an instruction to write data into the RF tag and a signal indicating the write data, the reader/writer writes the write instruction and the write data into the RF tag through radio communication.

Reader/writer, optical transceiver module, and cable system

The present invention is related to an optical communication module for transmitting high frequency signals (e.g., 10 Gbit/s and higher data rates) between an optical element and an external circuit. In an illustrative embodiment, the optical communication module includes signal transmission lines and ground lines formed on a ceramic substrate, a flexible wiring board, and a printed circuit board. The widths of the signal lines and the ground lines vary, as well as the spacing between the signal and ground lines. This facilitates characteristic impedance matching among the signal lines to within about 50&#x3a9;.

Optical communication module

Optical transmission equipment with more than one power supply which can, when turning on the power supplies, set predetermined function of a signal processing circuit after a predetermined time period after the last turn-on of the power supply and can enable the operation of a drive circuit of the light emitting device after an additional predetermined time period.

Optoelectronic transceiver with power voltage supply detection

An optical transmission system includes a current source for outputting a drive current, a semiconductor laser for converting the drive current into a stimulated emission light and producing the same, a drive circuit for converting a transmission data signal into a modulation control signal and outputting the same, an optical modulator for receiving the stimulated emission light and a shading control signal for interrupting light emission and producing and outputting transmission signal light by changing an amount of transmission of the stimulated emission light according to the shading control signal, and a shading element for receiving the transmission signal light and a shading control signal for interrupting light emission and interrupting the transmission of the transmission signal light according to the shading control signal whereby an optical signal having wrong optical wavelength is rapidly prevented.

Optical transmission device and optical transmission system using the same

An optical transmission module includes a housing with a heat radiating fin and a receptacle for being connected to an external optical fiber. The module also includes a coaxial can stem for mounting an optical element and a ceramic printed circuit board. The signal transmission lines are provided on one side of the board, and heat from the coaxial can package is radiated from the radiating fin.

Optical transmission module

An optical transmitter for use in an optical transmitting system based on PDS (Passive Double Star) technology, does not erroneously output an optical signal when the optical transmitter is powered on/off. The optical transmitter has a current sourcefor outputting a drive current having a magnitude corresponding to an input control signal, a Laser diode (LD) for generating an optical output signal based on the received drive current, a modulatorfor controlling the supply and cutoff of the drive current to the Laser diode (LD), a source voltage detectorfor monitoring a source voltage to detect whether the source voltage is lower than a predetermined voltage, and a switch circuitfor outputting a control signal to the current sourceto stop the supply of the drive current when the source voltage is determined to be lower than the predetermined voltage.

Optical transmitter and optical transmitting apparatus using the same

An optical transmitter receiver module and an apparatus incorporating the same module are provided, which realizes the reduction of power consumption and the enlargement of the operating temperature range. As an example, an optical transmitter module is provided which comprises a light emitting element to generate a light signal, a signal processing circuit to transmit an electrical signal to the light emitting element and a voltage regulating circuit to lower a power voltage so as to supply the signal processing circuit with a constant voltage, wherein the module is further provided with a current regulating circuit to shunt a part of a current to be supplied into the voltage regulating circuit from a power source so as to generate a control current and a temperature controller to receive the control current so as to control a temperature of the light emitting element, wherein the module is further provided with a temperature detector to detect the temperature of the light emitting element and a temperature controlling circuit to control the control current according to an electrical signal output by the temperature detector.

Optical transmission module with light element temperature control

In the initial state, any wavelength variation of the output signal light with a change of the current injected into the laser is monitored with a wavelength meter, the quantity of wavelength variation is fed back to the wavelength compensation circuit, a compensation voltage for maintaining the wavelength in the initial stage is figured out, and that voltage is recorded into a memory element or the like. A configuration to add this compensation voltage to a comparator makes it possible to compensate for fluctuations of the characteristics of the optical splitter, wavelength filter and light receiving elements and thereby to obtain a stable optical wavelength. By constantly monitoring the injected current applied to the laser when the optical transmitter is in operation and giving a compensation voltage matching the current variation to the comparator, stabilization of the optical wavelength can be realized. By simulating in the initial state the operation of the laser after deterioration and providing in advance a compensation voltage for suppressing wavelength fluctuations, wavelength fluctuations after deterioration can be restrained.

Optical wavelength stabilization circuit, optical transmitter and optical transmission system

An optical transmitter comprises a modulator for generating a modulated current in accordance with a modulation control signal, a light emitting element driven by the modulated current from the modulator to emit light in accordance with the modulated current, a first current source for supplying the modulator with a driving current, a first temperature detector for detecting an operating temperature of the modulator to output a signal indicative of a detected operating temperature of the modulator, and an amplifier for receiving a data signal to supply the modulator with the modulation control signal based on the data signal. The amplifier has a first modulation control signal controller for controlling a changing amount per unit time of the modulation control signal at rising and falling times in accordance with an output signal of the temperature detector.

Optical transmission method and optical transmitter with temperature compensation function

An optical transmitter for use in an optical transmitting system based on PDS (Passive Double Star) technology, does not erroneously output an optical signal when the optical transmitter is powered on/off. The optical transmitter has a current source for outputting a drive current having a magnitude corresponding to an input control signal, a Laser diode (LD) for generating an optical output signal based on the received drive current, a modulator for controlling the supply and cutoff of the drive current to the Laser diode (LD), a source voltage detector for monitoring a source voltage to detect whether the source voltage is lower than a predetermined voltage, and a switch circuit for outputting a control signal to the current source to stop the supply of the drive current when the source voltage is determined to be lower than the predetermined voltage.

Growing community of inventors

Yokohama, Japan

Shigeru Tokita