Design of an Opto-Electronic Receiver for Deep-Space Optical Design of an Opto-Electronic Receiver for Deep-Space Optical Communications

An 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, and margin), delivered power, pulse width, background signal, telescope quality, and atmospheric effects. Meeting these requirements becomes challenging as mission range and demand for link capacity increase. In this article, the detector’s characteristics (e.g., quantum efficiency, noise, gain, and diameter) are designed to address these various requirements. The dependence of the receiver’s sensitivity on background noise power and on the characteristics of the avalanche photodiode detector (APD) is analyzed. The improvement in optoelectronic receiver sensitivity is quantified for improvements in APD quantum efficiency, ionization factor, and bulk dark current. It is also found that, as the background signal increases, the improvement in 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 link requirement of a pulse-position-modulated (M = 256) 30-kb/s data-rate (with a bit-error rate of 10−5). Improvements to the APD detector are also studied to describe a design that would achieve over 50-kb/s data rates for a Mars–Earth optical communication link.