Loss of Time Delay Signature in Broadband Cascade-Coupled Semiconductor Lasers

Numerical and experimental investigations of time delay concealment and chaos bandwidth enhancement in three semiconductor lasers with a cascade scheme are presented. The cascade system is composed of an external-cavity master laser, a solitary intermediate laser, and a solitary slave laser. The results show that the first two lasers are used for concealing time delay signature, and the last two lasers are used for bandwidth enhancement. For large parameter regions of injection strength and frequency detuning, time delay concealment and bandwidth enhancement of chaotic signals are simultaneously achieved by adopting the simple cascade configuration.