Optical digital pulse-position modulation: experimental results for heterodyne detection using suboptimal filtering

Original practical and theoretical results are presented for heterodyne detection of optical digital pulse-position modulation ( = 1.523 µm) employing suboptimal filtering. The measured sensitivity was –62.7 dBm when operating with a 20 ns slot width and 16 data-pulse positions. This represents an improvement of 16.8 dB over an equivalent suboptimal direct detection digital pulse-position modulation system. With –18 dBm of local oscillator power, the sensitivity was within 8.6 dB of the shot-noise limit