Fast, low-loss all-optical phase modulation in warm rubidium vapour

TL;DR

This paper demonstrates a fast, low-loss optical phase modulator using warm rubidium vapor, achieving high bandwidth and low loss simultaneously, which is promising for quantum and classical photonic technologies.

Contribution

The authors present a novel all-optical phase modulation technique in rubidium vapor that combines high speed and low loss, overcoming limitations of existing modulators.

Findings

Achieved 100 MHz bandwidth for phase modulation.

Realized 83% transmission with significant phase shift.

Demonstrated potential for scalable quantum and classical photonic applications.

Abstract

Low-loss high-speed switches are an integral component of future photonic quantum technologies, with applications in state generation, multiplexing, and the implementation of quantum gates. Phase modulation is one method of achieving this switching, but existing optical phase modulators either achieve high bandwidth or low loss, but not both. We demonstrate fast ($100\,\mathrm{MHz}$ bandwidth), low-loss ($83\pm2\%$ transmission) phase shifting ($\Delta\phi = (0.90\pm0.05)\pi$) in a signal field, induced by a control field, and mediated by the two-photon $5S_{1/2} \rightarrow{} 5P_{3/2} \rightarrow{} 5D_{5/2}$ transition in $^{87}\text{Rb}$ vapour. We discuss routes to enhance both performance and scalability for application to a range of quantum and classical technologies.