Investigation of excess noise factor of InGaAs/InP SWIR APDs by direct power method

Avalanche photodiodes (APDs) have been widely used in optical communications, radar imaging and single photon detection fields, etc.. Compared with PIN photodiodes, the internal gain of APDs provide higher sensitivity and signal-to-noise ratio. The APDs gain come from the collision ionization of carriers, which is a random process and causes excess noise in the APDs, therefore, study of the excess noise factor of the detectors is of great significance to the performance improvement of APDs. This paper uses the direct power method to test the excess noise voltage spectral density of the InGaAs/InP APD, uses the source meter to measure the light and dark currents to calculate the gain. The relative intensity noise of the laser and the system impedance are calculated by linear fitting. The effect of measurement temperature and optical power on excess noise factor is investigated and discussed.