Random Number Generation Using Semiconductor Laser Dynamics

Description

Random number sequence generation has long been an important research problem in science and engineering. Random numbers are required in applications such as numerical simulation and encryption. While true random number generation has to rely on physical non-deterministic entropy sources, pseudo-random number generation is founded on well-designed algorithms using true random numbers as seeds. Over the years, chaotic systems have been suggested as an attractive candidate for random number generation. Owning to their well-known sensitivity to initial conditions, chaotic systems can amplify very small ever-present fluctuations in producing random numbers. Such approach has been undertaken using different chaotic circuits, both analogue and digital, for low-speed applications. For high-speed applications, chaotic dynamics of wide bandwidth deemed necessary. Recently, semiconductor lasers in chaotic dynamics were investigated for high-speed random number generation. Due to the short photon and electron lifetimes of semiconductor lasers, random numbers were generated at rates on the order of gigabits per second. In order to obtain optical chaos, proper perturbations to the lasers are always required. While all related works employed optical feedback for perturbation, the possibility of using different kinds of perturbations remains unexplored. In this proposed work, we intend to investigate the dynamics of optically injected semiconductor lasers for random number generation. Optical injection is known for its effect of bandwidth enhancement, lack of time-delay signature, and flexibility in design, which are advantageous properties for random number generation. Enhancement of bandwidth allows increase of data rate. The absence of time-delay signature relaxes the stringent requirement on the sampling rate. The flexibility in varying the injection parameters enables convenient optimization for randomness. As a result, the quality of the random sequences generated from optically injected semiconductor lasers has to be investigated. Possibilities of fully utilizing the chaotic bandwidth and alleviation on high-speed electronics will be explored. Moreover, in order to tailor the chaotic signals, variations on the optical injection will be employed. Configurations with modulated injection, cascaded injection, and injection with distributed feedback will be considered. In addition, feasibility of synchronizing chaotic oscillations for secure distribution of random number sequences will be explored. Success of the system will enable simultaneous secure chaos communication together with random number distribution. The results will lead to an extra level of security in chaos communication. The overall outcome of the proposed work is expected to generate novel and interesting applications using optically injected semiconductor lasers.