Frequency upconversion of infrared signals via molecular optomechanical cavities

TL;DR

This paper investigates noise and efficiency in molecular optomechanical cavities for infrared to visible frequency upconversion, highlighting regimes with high conversion efficiency and minimal added noise.

Contribution

It analyzes the noise characteristics and conversion efficiency in molecular optomechanical cavities, extending previous work on signal amplification mechanisms.

Findings

Anti-Stokes sideband has higher efficiency in red-detuned regime.

Stokes sideband dominates and amplifies IR in blue-detuned regime.

Added noise approaches the quantum limit when amplifying signals.

Abstract

Molecular optomechanical cavities have recently emerged as a promising platform for frequency upconversion, enabling the quantum coherent conversion of infrared signal into the visible range. In a recent work [F. Zou et al., Phys. Rev. Lett. 132, 153602 (2024)], we proposed an amplification mechanism that can enhance the intensity of the upconverted infrared signals by a factor of 1000 or more within such a cavity under the ideal case without any noise. In this work, we employ the power spectrum method to investigate the noise added to the upconverted signal in a molecular optomechanical cavity along with the conversion efficiency from infrared signal into visible range. In the red-detuned regime, the anti-Stokes sideband achieves superior conversion efficiency relative to the Stokes sideband. Conversely, the Stokes sideband dominates under the blue-detuned condition, which amplifies the infrared signal. We further demonstrate the dependence of the added noise on the coupling strength and decay rates of the system. In particular, we find that when the infrared signal is amplified, the added noise approaches the quantum limit of one quantum.