Fujitsu Corporation

Akihiko Hayashi

Yasunori Nagakubo

Makoto Miyoshi

Takashi Tsuda

Kazuya Sasaki

Sadao Ibukuro

Norio Nagase

Shinichi Aoki

Keisuke Imai

Tomoyuki Otsuka

Hirokazu Osada

Shinichiro Sano

Kensuke Matsui

A module is configured to be attached to a cage. A handle is rotatable about a rotation shaft between an accommodated position where the module is mounted to the cage and a withdrawal position where the module can be withdrawn from the cage. A resiliently-bendable tongue piece performs engagement and disengagement between the module and the cage. A notch portion is provided to the tongue piece. A press portion is provided to the handle on a circumference having a center located on the rotation shaft of the handle, the press portion configured to contact with the notch portion when the handle is at the accommodated position. A cam rotatable with the handle so as to resiliently bend the tongue piece.

Module having a handle to be operated to attach the module to a cage

A light source device has a continous wave (CW) light source for emitting first direct current (DC) light, a level converter for converting optical electric power of the first DC light into second DC light and outputting the second DC light, and a mixer for mixing an optical main signal having a constant extinction ratio with the second DC light.

Light source device

The invention relates to a modulation controlling circuit for supplying a modulating signal to an external modulator that outputs a modulated optical signal, while setting a proper operating point in the external modulator. The external modulator that operates in cooperation with the modulation controlling circuit of the invention enables high-quality modulation at a wide bit rate range. Therefore, in an optical transmission system or a measuring instrument to which the invention is applied, the characteristics and the performance are improved and the operation is made stable without loss of advantages of the external modulator.

Modulation controlling circuit

The present invention relates to A drive circuit can stabilize a bias voltage of an optical modulator to realize long distance transmission by preventing degradation of waveform, even if there is a dispersion on a characteristic of an electro-absorption modulator according to temperature and a secular change. The drive circuit supplies a driving voltage to an electro-absorption modulator which adsorbs a carrier light, depending on the driving voltage and outputting an intensity-modulated signal, and a peak value detector for detecting a peak value of a voltage at an anode of the electro-absorption modulator, and a bias current supplying circuit for supplying a bias current to control the driving voltage according to a difference between the peak value detected by the peak value detector and a predetermined value.

Drive circuit for electro-absorption modulator and optical transmitter

In a light transmitter comprises an automatic bias control circuit which automatically controls a bias for an external modulator, a part of a light output/input signal of the external modulator is branched to detect an electrical monitor signal and a gain control signal is generated in inverse proportion to the level of the monitor signal to control the gain of the automatic bias control circuit.

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Yokohama, Japan

Akihiko Hayashi