| 摘要 |
PURPOSE: To fixedly maintain light output in a level in response to the number of multiple signals when a wave-length multiplexing light signal is amplified by changing the light output level of a light amplifier according to the number of multiple signals of the wave-length multiplexing light signal. CONSTITUTION: Light output branched off by a turnout 28 is converted to electric signals showing the levels of component light of respective wave lengths by a WDM filter 29 and light receiving elements 301 -30N, and voltage corresponding to multiple signal information is generated by an addition circuit 41. A level conversion circuit 42 converts level of the voltage corresponding to the multiple signal information so as to generate reference voltage. A light output control circuit 25 compares the output voltage detecting output level from a light receiving element 8 with the reference voltage, controls a transistor 43 according to error voltage, and generates driving voltage against excitation LD 2. Hereby the excitation LD generates an excited light of which intensity is controlled, and as a result the signal light output is always fixedly maintained on the level in response to the number of multiple signals. |
