Deeply-trapped molecules in self-nanostructured gas-phase material

TL;DR

This paper introduces a novel laser-trapping method for molecules using self-structured high-pressure molecular hydrogen in photonic fibers, achieving ultra-narrow spectral lines and complex nonlinear optical phenomena.

Contribution

It presents a new trapping technique based on self-optical nanostructuring in a hollow-core fiber, enabling trapping of fast molecules and sub-Doppler spectroscopy.

Findings

Molecules with speeds up to 1800 m/s are trapped.

Achieved sub-recoil linewidth of 14 kHz in Raman spectrum.

Observed complex nonlinear optical effects like Mollow triplet and four-wave mixing.

Abstract

Since the advent of atom laser-cooling, trapping or cooling natural molecules has been a long standing and challenging goal. Here, we demonstrate a method for laser-trapping molecules that is radically novel in its configuration, in its underlined physical dynamics and in its outcomes. It is based on self-optically spatially-nanostructured high pressure molecular hydrogen confined in hollow-core photonic-crystal-fibre. An accelerating molecular-lattice is formed by a periodic potential associated with Raman saturation except for a 1-dimentional array of nanometer wide and strongly-localizing sections. In these sections, molecules with a speed of as large as 1800 m/s are trapped, and stimulated Raman scattering in the Lamb-Dicke regime occurs to generate high power forward and backward-Stokes continuous-wave laser with sideband-resolved sub-Doppler emission spectrum. The spectrum exhibits a central line with a sub-recoil linewidth of as low as 14 kHz, more than 5 orders-of-magnitude narrower than in conventional Raman scattering, and sidebands comprising Mollow triplet, molecular motional-sidebands and four-wave-mixing.