Oki Electric Industry Co., Ltd.

Fuji Jukogyo Kabushiki Kaisha

Toyo Microsystems Corporation

Hideaki Satoh

Kazuo Tanaka

Fujio Matsui

Mitsunori Ishii

Yukihiro Ozeki

Mikihiro Suzuki

Atsushi Horio

A communication bufferof a node has a plurality of storage areas for storing transmission data of other nodes. The plurality of nodes receive data transmitted by the token passing communication method and store the received data to the storage area corresponding to the transmission originator by a micro-sequencer. The node specified as a transmission destination informs a receiving acknowledgment.

Multiplex communication method, the device and the system thereof

An optical transmitter includes a light source emitting input light; and a modulator modulating the input light in accordance with an input electric signal to generate an optical transmission signal. The transmitter also includes a monitor which detects frequency fluctuation of the optical transmission signal. The modulator is controlled so as to optimize the amount of frequency fluctuation of the optical transmission signal.

Optical transmitter and optical communication system using the same

An optical signal receiver producing an output signal from a received optical signal also generates two complementary signals from the output signal, integrates the two complementary signals, and takes the difference between the two integrated signals. The difference signal is used to control a bias current supplied to the input terminal of an amplifier that generates the output signal signal. Alternatively, the difference signal controls the gain of the amplifier. Output distortion is thereby corrected without requiring external adjustments.

Adjustable-free optical signal receiver

A differentiating circuit and a clock generating circuit that do not include unwanted frequency components in a differentiated signal. An inverted signal of an NRZ (Non Return Zero) data signal is delayed by a fixed time in a delay circuit and added to a non inverted signal to generate a differentiated signal. A clock signal is generated by driving a resonator using a rectified signal produced by full wave rectifying the differentiated signal. At this time, resonant components arising due to impedance mismatching are removed by providing a LPF.

Differentiating circuit and clock generator circuit using the

An optical transmitter has a Mach-Zehnder modulator, and a feedback loop that controls the bias voltage supplied to the modulator according to the insertion loss of the modulator, to compensate for DC drift in the attenuation characteristic of the modulator. The feedback loop can be switched to provide negative feedback on either the positive or negative slope of the attenuation characteristic. Switching the slope switches the polarity of the chirp generated by the modulator, enabling positive or negative chirp to be selected, whichever produces the least dispersion penalty. Since switching the slope also switches the polarity of the modulated signal, an optical transmission system using this optical transmitter has an additional circuit that selectively inverts the transmitted or received signal.

Optical transmitter and optical transmission system with switchable

An LN (Lithium Niobate) modulator outputs light Po modulated using a modulation voltage Vm. An inputted light signal average level monitor is arranged at the input of the LN modulator. Further, an outputted light signal average level monitor is arranged at the output of the LN modulator. A negative feedback circuit controls the feeding back of a bias voltage applied to the modulator from the average level of the input signal and the average level of the output signal. Further, a bias voltage limiter performs control in such a manner that the center of the voltage limiting range for the bias voltage becomes the optimum operating point. This bias voltage limiter has: a voltage limiter for limiting the operating output range of an op-amp to be a prescribed voltage range; an integrator for applying an offset voltage to and shifting the limiting voltage of the voltage limiter; and a difference monitor for monitoring the difference between a modulation voltage Vm and an offset voltage .increment.V. The integrator generates an offset voltage based on shift information monitored by the difference monitor, with this offset voltage being provided to the voltage limiter. The voltage limiter then shifts the voltage control range in response to the provided offset voltage.

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Tokyo, Japan

Hideaki Satoh