Opnext Japan, Inc.

Hitachi, Ltd.

Tetsuya Aoki

Atsushi Hasegawa

Takeshi Yamashita

Hiroshi Yamamoto

Keiichi Yamamoto

Norio Chujo

Michihide Sasada

Katsunori Hirano

Takayuki Nakao

Kenji Yoshimoto

Mitsuo Akashi

Akio Osaki

Tomoaki Shimotsu

Hirofumi Nakagawa

Koichiro Tonehira

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

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

To provide economical high-speed optical communications through an optical module a silicon substrate with a ball lens and semiconductor luminescence element mounted thereon, and a laser driver IC are provided. A silicon subassembly includes a silicon substrate with a pyramidal cavity etched into the substrate near its edge. A ball lens is precision-mounted in the pyramidal cavity by bonding it at multiple points. This provides a high-strength connection and a small, inexpensive silicon substrate. Also provided on the silicon substrate is a semiconductor luminescence element and a slit on the opposite side of the ball lens. The slit enables collimated light emitted from the ball lens to be optically coupled without being blocked or reflected by the substrate. The semiconductor luminescence element and its laser driver IC are placed in close proximity to each other, and ribbon wires are kept short (approximately 300 &mgr;m) to reduce signal line impedance mismatch for high-speed transmission.

Optical module and optical transceiver

Phase frequency synchronism circuit and optical receiver

Growing community of inventors

Yokohama, Japan

Tetsuya Aoki