| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical transmitter in which a duty factor of modulated light output signals is stabilized. <P>SOLUTION: The optical transmitter is provided with a light source with a modulator modulating optical signals on the basis of an information code, a modulator driving circuit driving the modulator and a control circuit controlling the light source, the modulator and the modulator driving circuit. Electrical characteristics, optical characteristics and temperature characteristics of the light source, the modulator and the modulator driving circuit are measured beforehand, the characteristics by the measurement are recorded in a storage device inside the optical transmitter, and by electrically computing the recorded characteristics and an external environment change obtained by a means for observing the change of the external environment of the optical transmitter, the optimum control conditions of the light source, the modulator and the modulator driving circuit are derived and modulated optical signal output is controlled. In the control, for signals driving the modulator, the signals of an opposite phase are grounded at a terminating resistor, then passed through a low-pass filter and converted to DC voltage signals, the signals are defined as duty factor monitoring signals and the duty factor of driving signals impressed to the modulator is controlled so as not to be changed by a secular change and the external environment change. <P>COPYRIGHT: (C)2003,JPO |
