A mirrorless spinwave resonator

TL;DR

This paper introduces a mirrorless atomic spinwave system that mimics optical cavities, allowing dynamic tuning of resonance properties with a compact setup, potentially revolutionizing optical device design.

Contribution

It demonstrates how atomic spinwaves can replicate cavity-like resonances without physical mirrors, with tunable parameters and comparable performance to large optical cavities.

Findings

Effective FSR of 83 kHz achieved in a 20 cm cell

Dynamic control of resonance parameters demonstrated

Spinwave system mimics optical cavity behavior

Abstract

Optical resonance is central to a wide range of optical devices and techniques. In an optical cavity, the round-trip length and mirror reflectivity can be chosen to optimize the circulating optical power, linewidth, and free-spectral range (FSR) for a given application. In this paper we show how an atomic spinwave system, with no physical mirrors, can behave in a manner that is analogous to an optical cavity. We demonstrate this similarity by characterising the build-up and decay of the resonance in the time domain, and measuring the effective optical linewidth and FSR in the frequency domain. Our spinwave is generated in a 20 cm long Rb gas cell, yet it facilitates an effective FSR of 83 kHz, which would require a round-trip path of 3.6 km in a free-space optical cavity. Furthermore, the spinwave coupling is controllable enabling dynamic tuning of the effective cavity parameters.