| 摘要 |
PURPOSE:To keep an optical output to a prescribed value without causing a hit on an optical communication pulse by keeping the sum of reference inputs of a bias control circuit of a duplicated semiconductor laser drive circuit to a prescribed value and changing inverse proportionally the inputs. CONSTITUTION:A signal inputted to a switch circuit 2 is converted into a signal S2b proportional to a signal Sc and a signal S2a inversely proportional to the signal Sc by changing the switch control signal Sc to 0-100%. The value of (S2a+S2b) is constant however, in this case. Since the signals S2a, S2b are reference signals of a bias current IB, optical outputs SL7, SL70 of the semiconductor lasers 7, 20 are proportional to the amplitude, synthesized at a synthesizer 3 and the value of (SL7+SL70) is kept almost constant. |
