Tunable ultranarrow linewidth of cavity induced by interacting dark resonances

TL;DR

This paper proposes a method to achieve a tunable, ultranarrow linewidth in a cavity using double-dark resonances in a four-level atomic medium, enabling precise control of transmission properties.

Contribution

It introduces a novel scheme utilizing double-dark resonances to significantly narrow cavity linewidths and allows tunability through control field adjustments.

Findings

Linewidth can be narrowed by an order compared to single-dark-resonance systems.

Ultranarrow transmission peaks are tunable via control field parameters.

Steep dispersion from double-dark resonances enhances cavity transmission features.

Abstract

A scheme for getting a tunable ultranarrow linewidth of a cavity due to an embedded four-level atomic medium with double-dark resonances is proposed. It is shown that the steep dispersion induced by double-dark resonances in the transparency window leads to the ultranarrow transmission peak. Compared with the case of a single-dark-resonance system, the linewidth can be narrowed even by one order under proper conditions. Furthermore, the position of the ultranarrow peak can be engineered by varying the intensity and detuning of the control field.