Abstract
A numerical study is presented in this paper based on semiconductor laser chaos generation which is being used to hide multi-level data signal, i.e., duo-binary message to take the advantage of secure environment & higher data rates at the same time. Duobinary message is generated by using the combination of duobinary precoder, duobinary generator & RZ/NRZ pulse generator. Laser rate equations are used to model chaos generation through semiconductor laser whereas message is made secured by hiding it through chaos masking scheme. Propagation of chaos hiding the multi-format message is studied for long distance communication model. Synchronization between transmitter & receiver is achieved to obtain the acceptable eye-diagrams & quality factor (Q-factor). Q-factor is function of optical signal to noise ratio (OSNR) that gives a qualitative performance of receiver. It provides the minimum SNR to obtain specific bit error rate of signal. A comparison is made with & without deployment of chaos masking scheme on RZ & NRZ duobinary optical system to observe the penalty in terms of Q-factor. In addition, response of amplifier on chaotic signal due to its nonlinearities is investigated by varying the gain of amplifier.