Performance evaluation of optically pre-amplified PPM systems

An original analysis is presented for an optical fiber n-ary pulse position modulation (PPM) system employing optical preamplification. The theoretical results, from calculations performed at a bit-rate of 622 Mbit/s and a wavelength of 1.53 μm, demonstrate that the PPM system offers a 7.5 dB sensitivity benefit in comparison with an equivalent PCM system. Furthermore the results illustrate that optically preamplified PPM offers sensitivities significantly better than the fundamental limit of an optically preamplified PCM system and in fact approaches that of coherent detection.