An interference system and an interference method

摘要

A master laser outputs a sequence of phase-randomised optical pulses, which serve as pulse injection seeding for a slave laser and cause the slave laser to also output a sequence of phase-randomised optical pulses. The lasers are preferably gain-switched lasers. The jitter of the pulses output by the slave laser is less than the jitter of the pulses output by the master laser. This reduction in jitter is achieved by synchronising the periodic electrical driving signals of the master and slave lasers such that light from the master laser is in the cavity of the slave laser before the slave laser gain modulation is raised above the lasing threshold. One slave light pulse is generated during each period of time when a master light pulse is received. The output from the slave laser is input to an interference system, such as an interferometer or beam combiner, which may form part of a random number generator (RNG) (Fig. 9) or a quantum key distribution (QKD) system (e.g. Figs. 10 and 13).