Chaos masking properties of a cascaded laser injection scheme

In this paper, we investigate the effect of chaos-pass filtering in a cascaded laser injection scheme. To enable secure transmission, a message is masked within the chaotic carrier generated through optical injection between a tunable laser and a transmitter (DFB) laser. The generated chaotic signal is then synchronized with the receiver laser with a high correlation quality of up to 97%. High-quality recovery of the masked message is achieved for modulation frequencies up to 6 GHz with a BER<5%. The encryption laser scheme does not rely on optical feedback and therefore does not require the suppression of the chaos time-delay signature to guarantee the concealment.