Loss of time-delay signature in a ring of three unidirectionally coupled semiconductor lasers

A ring of three unidirectionally coupled semiconductor lasers(RTUC-SLs) is used to generate broadband chaos with no pronounced time-delay(TD) signature. Using the autocorrelation function and permutation entropy as the TD measures, we demonstrate that under suitable coupling strength, the loss of the TD signature of the lasers in the RTUC-SL configuration is achieved both for the intensity and the phase. These findings should prove valuable for developing high-quality optical chaos for potential applications, such as chaos-based communications and random number generation.