| 摘要 |
PROBLEM TO BE SOLVED: To provide a control circuit which can hod a degree of optical modulation constant as well as light output as to the analog modulation of a laser diode. SOLUTION: The light output and temperature of the laser diode(LD) 32 are controlled by a light output control (APC) circuit 34 and a temperature control (ATC) circuit 35 to control the light output to a constant value. An RF control circuit 33 detects an LD bias current from the APC circuit 34 and adjusts the gain of an RF amplifier 31 with its variation quantity. Consequently, an error between bias currents generated by the ATC circuit 34 ATC circuit 35 is corrected by varying the RF input level by the RF control circuit 33 to hold the optical modulation degree constant. |
