Abstract

Chaotic semiconductor lasers offer attractive possibilities to generate random bit sequences at high speed [1]. Semiconductor lasers with their fast internal timescales and inherent noise, allow for large bandwidth dynamics when subjected to external perturbations, such as delayed optical feedback. Consequently, chaotic lasers have enabled the generation of random bits in the Gbit/s range, when used in combination with some sort of postprocessing. Recently, we have experimentally demonstrated that a single-mode semiconductor laser with polarization-rotated feedback represents a robust scheme for random bit generation [2]. Polarization-rotated feedback induces dynamical instabilities characterized by a broad power spectrum and chaotic dynamics of the output signal [3]. Such dynamical conditions are necessary for random bit generation but not sufficient. Here, we investigate in detail the factors that affect the randomness and possible bit rates of a random bit generator based on a chaotic semiconductor laser: dynamical properties of the system, digitization conditions and postprocessing of the original signal. Implementing the proper balance, our random bit generator is demonstrated to have the potential for bit rates up to 480 Gbit/s.

© 2013 IEEE