Coherent anti-Stokes Raman Scattering Lidar Using Slow Light: A Theoretical Study

TL;DR

This theoretical study proposes enhancing backward CARS signals using slow light via EIT, potentially leading to more sensitive CARS lidar systems with high pulse energy lasers and large telescopes.

Contribution

It introduces a novel scheme to significantly boost backward CARS signals by employing slow light through EIT, with applications in advanced lidar technology.

Findings

Backward CARS emission can be greatly enhanced using slow light.

A CARS lidar with high sensitivity is feasible with large aperture telescopes and high-energy lasers.

The scheme is applicable to O2 and N2 detection in atmospheric sensing.

Abstract

We theoretically investigate a scheme in which backward coherent anti-Stokes Raman scattering (CARS) is significantly enhanced by using slow light. Specifically, we reduce the group velocity of the Stokes excitation pulse by introducing a coupling laser that causes electromagnetically induced transparency (EIT). When the Stokes pulse has a spatial length shorter than the CARS wavelength, the backward CARS emission is significantly enhanced. We also investigated the possibility of applying this scheme as a CARS lidar with O2 or N2 as the EIT medium. We found that if nanosecond laser with large pulse energy (>1 J) and a telescope with large aperture (~10 m) are equipped in the lidar system, a CARS lidar could become much more sensitive than a spontaneous Raman lidar.