| 摘要 |
PROBLEM TO BE SOLVED: To set the multiplication factor of a ternary APD(GaInAs avalanche photodiode) so as to be an optimal value. SOLUTION: A temperature detecting circuit 8 detects the temperature of a ternary APD1. An ROM9 stores a relationship between the reverse bias voltage and multiplication factor of the ternary APD1 for each temperature. A reverse bias applying circuit 7 applies a reverse bias voltage decided by a reverse bias control circuit 6 to the ternary APD1. The reverse bias control circuit 6 reads the relationship between the reverse bias voltage and multiplication factor corresponding to the temperature of the ternary APD1 detected by a temperature detecting circuit 8 from the ROM9, and decides the reverse bias voltage of the ternary APD1 based on this relationship and the light receiving power of the ternary APD1 and an amplification peak value detected by a peak detecting circuit 5. |
