OPTICAL TRANSMITTER, AND BIAS VOLTAGE CONTROL METHOD FOR OPTICAL MODULATOR USED THEREFOR

PROBLEM TO BE SOLVED: To easily control a bias voltage even in >=10 GHz band of a driving signal, and to prevent the quality of an optical output signal from being deteriorated due to deterioration in waveform. SOLUTION: This optical transmitter is provided with a Mach-Zehnder type light modulato...

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Hauptverfasser:	KAJIYA SATORU, KOBAYASHI YUKIO, SHIMIZU KATSUHIRO, ISHIDA KAZUYUKI
Format:	Patent
Sprache:	eng
Schlagworte:	DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING ELECTRIC COMMUNICATION TECHNIQUE ELECTRICITY FREQUENCY-CHANGING NON-LINEAR OPTICS OPTICAL ANALOGUE/DIGITAL CONVERTERS OPTICAL LOGIC ELEMENTS OPTICS PHYSICS TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF TRANSMISSION
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Beschreibung
Zusammenfassung:	PROBLEM TO BE SOLVED: To easily control a bias voltage even in >=10 GHz band of a driving signal, and to prevent the quality of an optical output signal from being deteriorated due to deterioration in waveform. SOLUTION: This optical transmitter is provided with a Mach-Zehnder type light modulator 3, a light source 1 for inputting an optical signal of continuous light to the Mach-Zehnder optical modulator 3, a driving circuit 24 for inputting a driving signal to the Mach-Zehnder optical modulator 3, a demultiplexer 4 for taking out a part of the output optical signal, a photodiode 5 for converting the taken-out output optical signal into an electric signal, a band-pass filter 16 for extracting the frequency components of the driving signal contained in this electric signal, an error signal generating circuit 7 for generating an error signal of a bias voltage minimizing a value of the taken-out frequency components, and a bias voltage control circuit 10 for applying a bias voltage summed with this error signal to the Mach-Zehnder optical modulator 3.