Fast and low noise optical receiver using Si APD for Cloud-Aerosol LIDAR

摘要

A Fast and Low-noise Optical Receiver using a Silicon Avalanche Photodiode with an internal gain of 100 connected to a Broadband Preamplifier Circuit was developed. The optical receiver and the receiving optics form the detection channel of a Cloud-Aerosol Lidar Remote Sensing System used to measure profiles of aerosol and cloud backscatter at the near-infrared wavelength of 1064 nm. While a 10 Hz repetition rate solid state pulsed Nd:YAG laser emitting at 1.06 μm and the emission optics form the transmission channel. The preamplifier circuit with a 300 MHz bandwidth and a gain of 10 is capable of accommodating laser pulses of 10 ns full width at half maximum. The preamplifier matches 50 Ω impedances at the input and the output sides. The input matching is used to reduce the Johnson noise and hence a much better sensitivity was achieved. The output matching was useful when this preamplifier is to be connected to other instrumentation requiring 50 Ω impedance matching or to be interfaced in cascade to increase the overall gain of the detection chain. These 50 Ω impedances at the input and output sides, also allows using the preamplifier coupled with a photodiode at the input in the detection of fast signals without distortion or integration. A low noise level at the preamplifier circuit input of only 1.6 nV/Hz~(1/2) and a very good linearity from 1 KHz to 280 MHz were achieved, allowing the transmission of the backscattered signal to the acquisition system without distortion. In addition, the experimental characterization of the optical receiver coupled with the receiving optics showed good detection performance of the lidar detection channel: A low Noise Equivalent Power of 50 pW/Hz~(1/2) and a high Signal-to-Noise Ratio of 2 were achieved. Furthermore, the maximal range of the lidar remote sensing system was estimated.