Chaotic lightwave generation by semiconductor lasers and its application to dynamical optical memories and novel optical communications

摘要

Abstract: We demonstrate a simple method for controlling thenonlinear oscillations by only using a semiconductorlaser and photo detectors. The nonlinearity necessaryfor exhibiting period- doubling bifurcations andchaotic phenomenon was realized by appropriatelysuperposing the threshold characteristics ofsemiconductor lasers on the saturation characteristicsof photodiodes in their electric current vs. lightintensity properties. An electro-optical NDFS(nonlinear delayed feedback system) has been composedby making use of this nonlinearity. A low-pass filterwas inserted into this NDFS as an electric feedbackelement, which gave variety to the behavior of thenonlinear oscillations. With this system, multi-stableoscillations and chaotic transitions with variouspatterns have been observed. In this scheme, an opticaldynamical memory function has been demonstrated toperform binary data writing. In addition, we haveapplied an external light input to the NDFS, forexample, some sinusoidal wave modulations with acousticfrequencies. If the external input light effects to theoscillation waveform are to be reproducibly derived,new application to a waveform recognition system andcryptography will be expected. !6