We demonstrate robust, high-speed random number generation using interference of the steady-state emission of guaranteed random phases, obtained through gain-switching a semiconductor laser diode. Steady-state emission tolerates large temporal pulse misalignments and therefore significantly improves the interference quality. Using an 8-bit digitizer followed by a finite-impulse response unbiasing algorithm, we achieve random number generation rates of 8 and 20 Gb/s, for laser repetition rates of 1 and 2.5 GHz, respectively, with a +/-20% tolerance in the interferometer differential delay. We also report a generation rate of 80 Gb/s using partially phase-correlated short pulses. In relation to the field of quantum key distribution, our results confirm the gain-switched laser diode as a suitable light source, capable of providing phase-randomized coherent pulses at a clock rate of up to 2.5 GHz.
@article{arxiv.1407.0933,
title = {Robust random number generation using steady-state emission of gain-switched laser diodes},
author = {Z. L. Yuan and M. Lucamarini and J. F. Dynes and B. Frohlich and A. Plews and A. J. Shields},
journal= {arXiv preprint arXiv:1407.0933},
year = {2014}
}