Abstract
Experimental studies on operational characteristics of two kinds of avalanche photodiodes (Si-APD and Ge-APD) have been carried out for weak signal detection in the visible and infrared regions. To achieve high sensitivity, it is necessary to operate the APD at liquid nitrogen temperature. At this temperature, the dark current can be reduced considerably (Id≅10-14∼10-15A). Hence, a linearity between the optical input intensity and the photocurrent was obtained in the range from about 10-6 to 10-14W. This results in an APD used for analog optical sensor with a wide dynamic range.
