Analysis of dicode pulse position modulation using a PINFET receiver and a slightly/highly dispersive optical channel

PINFET receivers have been considered for use in digital pulse position modulation (PPM) links, where they can give sensitivities far greater than that achievable with pulse code modulation (PCM). However, digital PPM suffers from a very large bandwidth expansion factor, resulting in line rates that can be prohibitively high. An alternative is dicode PPM and the paper is concerned with the use of a PINFET receiver and a noise-whitened matched filter in such a scheme. With this particular implementation, the line rate is four times that of the PCM, making it a viable alternative to digital PPM. The original analysis presented predicts that such a system can give a sensitivity of -59.51 dBm when operating with high fibre bandwidth and 155.52 Mbit/s PCM data. The impact of intersymbol interference is also studied and it is shown that the system can offer a sensitivity of -53.33 dBm at a bandwidth of 1.5 times the PCM bit-rate. These sensitivities should be compared with a predicted PCM sensitivity of -51.95 dBm when operating in a high-bandwidth link.