Theory of shutdown of semiconductor laser source remotely

摘要

We present a new theory that can be applied to predetermine the value of cut-off external optical feedback (EOF) in terms of cut-off external reflectivity r_(cut-off) for a semiconductor laser source subjected to incoherent EOF. r_(cut-off)is defined as the value of external reflectivity around which the turn-on time delay t_(on) of semiconductor laser diode (SLD) will exceed the bit time interval of the injected current pulse and result in shutdown-like/inoperable case. An accurate analytical model of r_(cut-off) is derived and presented in terms of laser cavity parameters, injection current, and biasing ratio. The benefit of this study is that the designer can predetermine the requirements that should be taken into account when considering the SLD in an optical communication system in order to avoid an inoperable case due to incoherent EOF. In addition, the presented theory can be applied to develop an effective method that can be used to control, i.e., shutdown/restart, the laser source remotely. This can be performed by attacking the laser source with incoherent EOF from a distance and tuning the external reflectivity around the value of r_(cut-off.).