# Parametric wave mixing enhanced by velocity insensitive two-photon excitation in Rb vapour

## TL;DR

This paper explores how cell orientation and velocity-insensitive two-photon excitation enhance parametric wave mixing in rubidium vapor, leading to increased efficiency and distinct mid-IR emissions.

## Contribution

It demonstrates the significant impact of cell orientation and velocity-insensitive two-photon excitation on wave mixing efficiency and spectral characteristics in Rb vapor.

## Key findings

- Cell orientation affects intensity and spectral features of generated fields.
- Velocity-insensitive two-photon excitation enhances coherent light generation.
- Distinct mid-IR fields can be produced simultaneously via different excitation pathways.

## Abstract

We demonstrate how the orientation of the Rb cell can significantly affect the intensity and spectral characteristics of both the frequency up- and down-converted fields generated by nonlinear processes in Rb vapour. The efficiency of parametric wave mixing in Rb vapour excited to the 5D5/2 level by two-colour resonant laser light can be significantly increased by seeding the excitation region with coherent and directional radiation at 5.23 um that is resonant with the population inverted 5D5/2-6P3/2 transition. It has been shown that the process of velocity insensitive two-photon excitation is central to understanding the observed coherent blue and mid-IR light enhancements and that the velocity insensitive and velocity selective two-photon excitations could produce two co-existing but spectrally and spatially distinguishable mid-IR fields at 5.23 um.

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Source: https://tomesphere.com/paper/1701.06015