Design of the opto-electronic receiver for deep space optical communications

The opto-electronic receiver (detector and pre-amplifier) necessary to meet the demands of high capacity deep space missions is designed for a Mars-Earth optical communication link. The receiver requirements are driven by link performance (data rate, bit-error rate, margin), delivered power, pulse width, background signal, telescope quality, and atmospheric effects. Meeting these requirements becomes more challenging as the mission range and the demand for link capacity increases. In this article, the detector's characteristics (e.g. quantum efficiency, noise, gain, and diameter) are designed to address these various requirements. The receiver sensitivity's dependence on the background noise power and on the APD detector's characteristics is analyzed. The improvement in opto-electronic receiver sensitivity is quantified for improvements in APD quantum efficiency, ionization factor, and hulk dark current. It is also found that as the background signal increases the improvement on the receiver sensitivity from an improved detector is diminished due to the quantum noise limit. An opto-electronic receiver is designed based on a Silicon APD to meet the mission requirement of a PPM (M=256) 30 kbps data rate (BER of 10(-5)) link. Improvements to the APD detector are also studied to describe a design that would achieve over 50 kbps data rates for a Mars-Earth optical communication link.