| 摘要 |
PURPOSE:To remove influence of a dark current with respect to a temperature change and to stabilize an optical output by providing a second photoelectric converter connected to a current/voltage converter and a negative power source and applied by a reverse bias voltage, and supplying only a photocurrent to the converter. CONSTITUTION:Sum of a photocurrent 15 and a dark current ID1 flows to a current/voltage converter 5 as a detected current of a monitored light as indicated by a solid line A. On the other hand, a photoelectric converter 7 generates only a dark current ID2, and the current flows from the converter 5 as indicated by a one-dotted chain line B. Here, if a photoelectric converter 4 is formed of the same material as that of the converter 7, the dark currents ID1 and ID2 have the same amplitude. Accordingly, since the currents ID1 and ID2 flow in opposite directions in the converter 5, they cancel each other, and only a photocurrent IS flows in the converter 5. Therefore, an optical output can be constant irrespective of temperature change around a semiconductor laser. |
