Principles of Direct Detection Optical Communication

Abstract

This paper describes principles of direct detection laser communications link design. As background, it reviews the status of communication systems operating at McDonnell Douglas. It summarizes key modulation techniques, describing how they have been implemented at data rates up to one gigabit per second (Gbps) and how minor component changes can support eight Gbps. The paper describes, in detail, methods for calculating performance of important direct detection modulation schemes: pulse gated, pulse polarization, and pulse delayed binary modulations; pulse quaternary modulation; and pulse interval modulation. It also compares results of these calculations with measurements. Finally, it presents an example of end-to-end communications link analysis.