Robust random number generation using steady-state emission of gain-switched laser diodes

TL;DR

This paper presents a method for high-speed, robust random number generation using gain-switched laser diodes with steady-state emission, achieving rates up to 80 Gb/s and demonstrating tolerance to misalignments, suitable for quantum key distribution.

Contribution

It introduces a robust, high-speed random number generator based on steady-state emission of gain-switched laser diodes, improving interference quality and tolerance to misalignments.

Findings

Achieved random number rates of 8, 20, and 80 Gb/s.

Demonstrated tolerance to +/-20% in interferometer delay.

Confirmed suitability of gain-switched lasers for quantum key distribution.

Abstract

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.