Optimum optical modulation index of laser transmitters in SCM systems

An analysis of the optimum optical modulation index of laser transmitters in SCM systems is presented. Nonlinear distortion arising from overmodulation in a laser-limiter combination is studied. A generalised analysis, based on rectangular signal input power spectral density and broadband transmission, is given for the nonlinear noise spectral density. A computer algorithm is developed to generate the optimum modulation index which maximises the received CNR for SCM transmission.