Aspects of Two-photon Absorption of Squeezed Light: the CW limit

TL;DR

This paper provides a theoretical analysis of two-photon absorption of squeezed light in continuous-wave regimes, highlighting conditions for enhancement and the dominance of one-photon absorption under typical experimental parameters.

Contribution

It develops a general theoretical approach for two-photon absorption with squeezed light, considering both resonant and off-resonant conditions, and analyzes enhancement effects in different regimes.

Findings

Two-photon absorption can be enhanced by squeezed light bandwidth and photon bunching.

One-photon absorption remains dominant in the parameter space where two-photon enhancement occurs.

The analysis applies to both narrowband and broadband photon pair scenarios.

Abstract

We present a theoretical analysis of two-photon absorption of classical and squeezed light valid when one-photon absorption to an intermediate state is either resonant or far-detuned from resonance, and in both the low and high intensity regimes. In this paper we concentrate on continuous-wave excitation, although the approach we develop is more general. We calculate the energy removed from an incident field for typical experimental parameters and consider the limiting cases when the photon pairs are narrowband or broadband compared to the molecular linewidths. We find an enhancement of the two-photon absorption due to resonant contributions from the large squeezed light bandwidth and due to photon bunching in the low intensity regime. However, in both cases, for the parameters we choose, the one-photon absorption is the dominant process in the region of parameter space where a large enhancement of the two-photon absorption is possible.