High-energy transient gas pinholes via saturated absorption

TL;DR

This paper introduces a gas-based spatial filter using saturated absorption in ozone to replace solid pinholes, effectively cleaning ultraviolet laser beam profiles with high energy transmission.

Contribution

It demonstrates a novel gas-based spatial filtering method using saturated absorption, offering an alignment-insensitive and damage-resistant alternative to solid pinholes.

Findings

Effective cleaning of 266 nm laser beam profile with 76% energy transmission.

89% of side lobe energy absorbed by ozone, improving beam quality.

Process adaptable to other gases and laser wavelengths.

Abstract

This letter presents a spatial filter based on saturated absorption in gas as a replacement for the solid pinhole in a lens-pinhole-lens filtering system. We show that an ultraviolet laser pulse focused through ozone will have its spatial profile cleaned if its peak fluence rises above the ozone saturation fluence. Specifically, we demonstrate that a 5 ns 266 nm beam with 4.2 mJ of initial energy can be effectively cleaned by focusing through a 1.4% ozone-oxygen mixture, with about 76% of the main beam energy transmitted and 89% of the side lobe energy absorbed. This process can be adapted to other gases and laser wavelengths, providing alignment-insensitive and damage-resistant pinholes for high-repetition-rate high-energy lasers.