Post-processing-free 400 Gb/s true random number generation using optical heterodyne chaos

Abstract

True or physical random number generation (RNG) is vital to supply keys for information security. Chaotic laser has proven to be a promising physical entropy source for high-speed RNG. Unfortunately, some defects of laser chaos such as sharp spectrum, time-delay signature and asymmetrical amplitude distribution, limit the generation speed and lead to requirement of complicated post processing. Here, we report a RNG method by using the optical heterodyne of two chaotic optical-feedback semiconductor lasers as entropy source. The optical heterodyne chaos has a flat spectrum, symmetric amplitude distribution, and has no time-delay signature; these merits can improve the RNG speed and reduce post-processing requirements. In experiments, we generate a flat-spectrum chaos with a 3-dB bandwidth of 16GHz. Using 8-bit analog-digital conversion at a sampling rate of 80Gb/s, we experimentally find that the random numbers directly extracted from the 5 least significant bits (LSBs) can pass the NIST randomness test without help of any post-processing method. That is, 400-Gb/s (5×80Gb/s) physical random number generation is achieved without post processing.