Phase-Randomized Laser Pulse Generation at 10 GHz for Quantum Photonic Applications

TL;DR

This paper introduces a method to generate phase-randomized laser pulses at 10 GHz by combining an external spontaneous emission source with gain-switching lasers, enhancing quantum photonic applications like secure communication.

Contribution

The authors demonstrate a novel approach that overcomes phase correlation limitations at high repetition rates, enabling truly random phase generation at 10 GHz.

Findings

Effectively removes interpulse phase correlations

Restores phase randomization at 10 GHz

Enhances quantum key distribution and random number generation

Abstract

Gain-switching laser diodes is a well-established technique for generating optical pulses with random phases, where the quantum randomness arises naturally from spontaneous emission. However, the maximum switching rate is limited by phase diffusion: at high repetition rates, residual photons in the cavity seed subsequent pulses, leading to phase correlations, which degrade randomness. We present a method to overcome this limitation by employing an external source of spontaneous emission in conjunction with the laser. Our results show that this approach effectively removes interpulse phase correlations and restores phase randomization at repetition rates as high as 10 GHz. This technique opens new opportunities for high-rate quantum key distribution and quantum random number generation.