Performance evaluation of optically pre-amplified 16-ary PPM systems with Fabry-Pe´rot filters

In this study, we evaluate the end-to-end performance of an optically pre-amplified 16-ary pulse position modulation (PPM) system for the use in free-space optical communication. Simulations were carried out to evaluate the bit-error-ratio (BER) for several scenarios. The results show that the optimum full width half maximum (FWHM) for the Fabry-Pérot filter is twice the bit rate. For the optimum FWHM of the Fabry-Pérot filter with 20 dB extinction ratio, a BER of 10^-4 is achieved at E_b/N₀ of 9.5 dB where E_b is the energy per bit and N₀ is the effective single-sided power spectral density of the noise at the amplifier input. The results also show up to 9.7 dB improvement when compared to the case of on-off keying (OOK) with extinction ratio of 20 dB and an optimum Fabry-Pérot filter with FWHM equal to 0.7 of the bit rate for the same BER of 10^-4.