Opnext Japan, Inc.

Hitachi, Ltd.

Takeshi Yamashita

Atsushi Hasegawa

Tetsuya Aoki

Hideyuki Kuwano

Osamu Kagaya

Keiichi Yamamoto

Norio Chujo

Hisashi Takamatsu

Katsunori Hirano

Masahiro Hirai

Takayuki Nakao

Hiroyuki Arima

Akio Osaki

Tomoaki Shimotsu

Disclosed is an optical transmission module in which effects of conductive heat from sides of a metal case upon a thermistor are reduced, thereby allowing steady optical beam wavelengths to be obtained over a wide range of temperatures, regardless of the temperature of the usage environment. Specifically, the optical transmission module includes Peltier elements disposed inside a metal case, a metal base disposed upon the Peltier elements, a laser diode substrate disposed upon the metal base, a laser diode disposed upon the laser diode substrate, a thermistor substrate disposed upon the metal base, a thermistor disposed upon the thermistor substrate, and a thermally conductive member, disposed in the vicinity of the thermistor, that has a height greater than the height of the thermistor.

Optical transmitter and optical communications device

An optical transmitter module is described. The optical transmitter module includes a lead pin for electrically connecting the inside and outside of a housing, and a flexible printed circuit board connected to the lead pin. The flexible printed circuit board has a signal pattern and two ground conductor patterns to be connected to an optical modulation element, a laser terminal pattern to be connected to a semiconductor laser, a Peltier terminal pattern to be connected to a Peltier element, and two covering conductive layers in addition to a layer on which such patterns are formed. The covering conductive layers cover all the patterns except for the signal pattern.

Optical transmitter module

In order to solve the problem that since a loop filter constant suitable for asynchronous state cannot be selected in the conventional phase frequency synchronism circuit, it takes a long time to synchronize the input data and the clock signal from the asynchronous state, the present invention is to propose a phase frequency synchronism circuit including a phase comparator for generating a voltage according to the phase difference of the clock signal to the input signal, a frequency comparator for deciding if the frequency of the clock signal is higher or lower than the transmission rate of the input signal and generating a binary signal, a synchronous identifying unit for deciding if the input signal and the clock signal are synchronized in their phases and frequencies, a first switch that receives the output from the phase comparator and is closed and opened when the synchronous identifying unit decides that they are synchronized and not synchronized, respectively, a second switch that receives the output from the frequency comparator and is opened and closed when the synchronous identifying unit decides that they are synchronized and not synchronized, respectively, a loop filter that receives the outputs from the first and second switches, and a voltage controlled oscillator that oscillates on the basis of the output from the loop filter.

Phase frequency synchronism circuitry and optical receiver

A sample & hold type phase detector is used in a CDR IC and, in jitter transfer bandwidth adjustment, VCO output waveforms 90&#xb0; out of phase with each other can be inputted to the phase detector, whereby a jitter transfer bandwidth can be calculated by only the measurement of frequency and of a DC voltage and it is possible to make a jitter transfer bandwidth adjustment in DC test for IC.

Optical modules and methods of making the optical modules

Phase frequency synchronism circuit and optical receiver

An optical receiver circuit comprising: a pre-amplifier for amplifying a signal supplied from a photodetector to output positive and negative signals; first and second peak hold circuits for detecting maximum levels of these positive and negative signals respectively; an offset canceler circuit for compensating the positive signal at the maximum level of the negative signal, for compensating the negative signal at the maximum level of the positive signal, and for then performing differential amplification; and a level shift circuit for replacing an output signal level of the first peak hold circuit with a signal level higher than an actual value for a period of time that light input to the photodetector is in a no-input signal state.

Optical receiver circuit and optical module using same in optical communication system

Growing community of inventors

Yokohama, Japan

Takeshi Yamashita