| 摘要 |
PROBLEM TO BE SOLVED: To provide an intermediate frequency stabilization control method in an optical transmission system in which the level fluctuations and intermediate frequency errors of an output signal are small and which requires short time up to an end and executes a cold start. SOLUTION: This optical signal transmission system mixes output light of a laser 2 for modulation and output light of a local laser 1, then obtains an intermediate frequency signal by performing photoelectric conversion through a light receiving device 8. In such cases, the set temperature of the laser 2 is swept at a fixed speed, and when the direction of a change in the output voltage of a frequency discriminator 10, to which the intermediate frequency is inputted, is a predetermined direction and also when the output voltage is within a predetermined range, the sweeping is stopped, and after that, bias current control and temperature control of the laser 2 are simultaneously performed so as to maintain the intermediate frequency constant. |
