Role of linewidth enhancement factor on time-delay signature concealment of chaos in mutually-coupled semiconductor ring lasers
The time-delay signature (TDS) properties in chaotic semiconductor ring lasers (SRLs) with mutual injection are investigated numerically. The TDS is quantified via auto-correlation function. We numerically investigate the influence of linewidth enhancement factor α on the TDS. The results show that the TDS can be efficiently concealed when the linewidth enhancement factor of SRLs is large enough, and much larger ranges of operation parameters can be continuously adjusted. Hence, for practical applications, by simply choosing mutually-coupled SRLs with larger linewidth factors, four sets of widely tunable chaos with TDS concealment can be simultaneously achieved, which is highly desirable for high speed random number generation and optical chaotic encryption system based on chaotic SRLs.