# Realization of a high power optical trapping setup free from thermal lensing effects

## TL;DR

This paper characterizes thermal lensing effects in high power laser setups for cold atom trapping and proposes a passive scheme to eliminate these effects, enhancing beam stability and quality.

## Contribution

It identifies the main source of thermal lensing in such setups and introduces a simple passive method to mitigate it, improving optical trapping performance.

## Key findings

- Thermal lensing is mainly caused by the TeO2 crystal in the AOM.
- The passive scheme effectively suppresses thermal lensing effects.
- The setup maintains high beam quality at high power levels.

## Abstract

Transmission of high power laser beams through partially absorbing materials modifies the light propagation via a thermally-induced effect known as thermal lensing. This may cause changes in the beam waist position and degrade the beam quality. Here we characterize the effect of thermal lensing associated with the different elements typically employed in an optical trapping setup for cold atoms experiments. We find that the only relevant thermal lens is represented by the $TeO_2$ crystal of the acousto-optic modulator exploited to adjust the laser power on the atomic sample. We then devise a simple and totally passive scheme that enables to realize an inexpensive optical trapping apparatus essentially free from thermal lensing effects.