Optomechanical cavity without a Stokes side-band

TL;DR

This paper theoretically demonstrates perfect frequency conversion in an optomechanical cavity without generating a Stokes side-band, achieved at a specific coupling strength independent of cavity type, enabling selective anti-Stokes mode generation.

Contribution

It introduces a novel condition in weak-coupling optomechanics where the Stokes side-band vanishes, allowing pure anti-Stokes frequency conversion without additional filtering.

Findings

Stokes side-band can be completely suppressed at a specific coupling strength.

Anti-Stokes mode remains with a narrow spectral bandwidth of hundreds of Hz.

Suppression of Stokes mode is independent of cavity configuration.

Abstract

We investigate a theoretical demonstration of perfect frequency conversion in an optomechanical system in the weak coupling regime without a Stokes side-band. An optomechanical cavity illuminated by a weak probe field generates two side-modes, differentiating from the original signal by a phonon frequency. We report the presence of a special combination of parameters in the weak-coupling regime, where Stokes side-mode vanishes exactly. Only the anti-Stokes mode is observed with a few hundreds Hz spectral bandwidth of the probe field. Emergence of this special point is totally unrelated with the electromagnetically induced transparency (EIT) condition, where absorption (dip) cancellation is limited with the damping rate of the mechanical oscillator. Emergence is independent of the cavity type, i.e. single or double-sided, and takes place only for a single value of the effective coupling strength constant which is specific to the system parameters. At a specific effective coupling strength between the mirror and the cavity field, which can be tunable via the coupling field, only the anti-Stokes band is generated. At that specific coupling there appears no Stokes field. Hence, a filter, to eliminate the Stokes field, does not necessitate.