| 摘要 |
<P>PROBLEM TO BE SOLVED: To enable long-distance transmission of an optical signal by promptly performing rise from a shutdown state to output of a desired optical power. <P>SOLUTION: At restart of an optical fiber after restoration of a failure, a driving current of excited LD (laser diode) is supplied by using an ACC (automatic current control) circuit and optical output is promptly raised by targeting an optical output power P1 in an area 1. Since the optical level of P1 is determined by the driving current to be supplied to the excited LD, its current value is preset. Next, constant control of the optical output power P1 is performed in an area 2, output of the excited LD is changed by targeting an optical output power P2 after fixed time T3 from the restart (an area 3 (between T3 and T4)), next, the ACC circuit is switched to the AGC (automatic gain control) circuit, the AGC circuit is made to execute gain control to a light from the excited LD, constant control of the optical output power P2 is performed, and the optical output is promptly raised. <P>COPYRIGHT: (C)2004,JPO |
