Wideband Chaos With Time-Delay Concealment in Vertical-Cavity Surface-Emitting Lasers With Optical Feedback and Injection

Both the time-delay signature and the bandwidth of chaos have been investigated in four schemes of chaos generation in vertical-cavity surface-emitting lasers (VCSELs). The results show that suppression of the TD signature and the enhanced bandwidth of chaos can be obtained simultaneously in two schemes - a chaotic beam unidirectionally injected into a CW VCSEL and a CW VCSEL mutually coupled to a chaotic VCSEL. However, suppression of the TD signature and the enhanced chaos bandwidth cannot be achieved simultaneously in two other schemes - a CW optical beam unidirectionally injected into a chaotic VCSEL and two mutually coupled CW VCSELs.