Novel laser intersatellite communication system employing optically preamplified PPM receivers

An original scheme for the utilisation of optically preamplified (EDFA) PPM receivers in intersatellite laser communications is presented. In order to facilitate high bit rate operation an analysis is presented for a PPM system employing threshold detection. When operating at the STM-1 bit rate of 155 Mbit/s and using conservative parameters the authors´ model demonstrates a possible receiver sensitivity of 13.5 photons/bit (at a BER of 10^-6) in the presence of background noise, thus indicating the impressive potential of the proposed receiver formation for use in satellite communications. The authors further demonstrate that their threshold detection PPM scheme can obtain receiver sensitivities up to 12.3 dB-better than an equivalent EDFA OOK NRZ satellite receiver, for which new results are also presented. Furthermore the results indicate that the PPM system may perform at sensitivities beyond the fundamental optically preamplified OOK NRZ limit of 27.3 photons/bit