Low noise optical receiver using Si APD

Time of flight laser range finding, scanning video imaging and deep space communications are three applications requiring very low noise optical receivers in order to achieve detection of fast and weak optical signal. Avalanche photodiode is the detector of choice for its high quantum efficiency, compact size and reduced electronics complexity. Optimal operating condition in terms of gain and temperature is the key to maximize the signal to noise ratio. This paper describes the model and the measured performance of a hybrid optical receiver using a TE cooled Silicon Avalanche Photodiode. Receiver performance in terms of responsivity and NEP will be presented as a function of temperature, signal power and APD Gain. A NEP of only 5fW/sqrt(Hz) has been obtained with a bandwidth of 200MHz in linear mode at a wavelength of 1060nm.