Prospects for very deep space optical communication using photon-counting links

An investigation is conducted regarding the feasibility to use an optical communication system in connection with space missions involving a study of stars and, possibly, planetary systems in the vicinity of the solar system. A possible candidate for the considered kind of mission would be Barnard's Star, at six light years distance. Pierce et al. (1981), have shown that the capacity of a photon-counting link in the presence of thermal noise at low temperature is essentially the same as for microwave. The conducted investigation assumes the employment of a pulse position modulation scheme limited by technology to approximately 1,000,000 positions. The use of an optical communication system similar to the considered type is found to be very likely for the contemplated kind of space mission.