Optimization of a laser communications system using electrooptic modulation

An analysis is made of the optimum carrier-to-noise ratio (CNR) that can be obtained from a laser communications system using external polarization electrooptic modulation and avalanche diode detection. The analysis is not restricted to low-modulation index but covers the range up to the maximum possible modulation. Alternate definitions of modulation index are given in terms of communication concepts. Finally, some practical uses of the results are discussed.