Opnext Japan, Inc.

Mitsuo Akashi

Shigeru Tokita

Naohiko Baba

Yoichi Honzawa

Hirofumi Nakagawa

Yasuhiro Yamada

Tomonao Kikuchi

Tetsuya Aoki

Akihiro Hayami

Hiroki Irie

Fumitoshi Goto

Raju Kankipati

Hideki Satoh

Hironori Saitoh

Sunil Sharma

A relation between a light input power monitor value of an optical transmission signal before passing through a fiber and an input signal amplitude monitor value is recorded in advance in a storage device. Next, actual optical-transmission-waveform is inputted into an optical receiver module, and then comparisons between a light input power monitor value and an input signal amplitude monitor value, and respective monitor values in the case without having the waveform distortion as described above are performed in an operation device to calculate a waveform distortion value. According to the waveform distortion level calculated herein, an optimum threshold value and an optimum phase adjusting value, at which receiver sensitivity is maximized, are calculated in the operation device to control a threshold-value adjusting circuit and a phase-value adjusting circuit, thereby a threshold value and a phase value that are optimum for an input distortion level can be established.

Optical receiver module and optical receiver module system

The printed circuit board with the respective components of the optical transmitter-receiver mounted thereon is split into several parts, the fixing position of which respective parts with regard to the housing is set according to the standardized size of the respective components and which respective parts are interconnected through an electric connector and so forth, which makes the height of the transmitter-receiver lower. The split circuit boards are overlapped such that they make no contact with one another so as to enlarge the area of the circuit boards or practically increase the packaging area of the respective components, which realizes the structural compactness of the optical transmitter-receiver. The packaging side of the respective components is selected in an arbitrary manner according to the cooling direction of the respective ICs, which allows such direction to be oriented to the side of the heat sinks so as to enhance cooling behavior. When deteriorated parts are found, only the circuit board with such parts mounted is removed for repair or replacement, resulting in improving productivity and reducing production cost.

Optical communication device, optical transmitter, optical transmitter-receiver, and optical transmission system

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

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

Two sets of a high speed differential amplifier and a low speed differential amplifier are prepared, and frequency response speeds of these high speed/low speed differential amplifiers are different from each other. Both an oscillating frequency and a frequency modulation sensitivity of a ring oscillator type voltage-controlled oscillator circuit can be separately set by adding two outputs of these differential amplifiers to each other and by varying the selection ratio of these high speed/low speed differential amplifiers in a linear manner. Thus, the setting ranges for the oscillating frequency and the frequency modulation sensitivity are enlarged. At this time, since a summation of currents flowing through the high speed/low speed differential amplifiers is continuously made constant, the oscillating frequency depending characteristic of the output amplitude of the VCO circuit can be canceled. Furthermore, since control signals are supplied in a differential structure, increasing of jitter components caused by the common mode noise can be suppressed.

Optical receiver module optical transmitter module phase-locked loop circuit voltage-controlled oscillator and frequency response controllable amplifier

Growing community of inventors

Yokohama, Japan

Mitsuo Akashi