Characterization of plasmas driven by laser wavelengths in the 1.064-10.6 $\mu$m range as future extreme ultraviolet light sources

TL;DR

This study investigates how laser wavelength influences the properties and efficiency of plasmas used as EUV light sources, revealing a wavelength-dependent absorption and a peak conversion efficiency near 4 μm.

Contribution

It provides detailed numerical simulations showing the dependence of EUV plasma characteristics on laser wavelength and identifies the optimal wavelength for maximum conversion efficiency.

Findings

Maximum conversion efficiency occurs near 4 μm wavelength.

Radiative losses dominate the power balance across all wavelengths.

A shift from kinetic to radiative losses with increasing wavelength.

Abstract

We characterize the properties of extreme ultraviolet (EUV) light source plasmas driven by laser wavelengths in the $\lambda_{\mathrm{laser}} = 1.064 - 10.6 $ $\mu$m range. Detailed numerical simulations of laser-irradiated spherical tin microdroplet targets reveal a strong laser-wavelength dependence on laser light absorptivity and the conversion efficiency of generating EUV radiation. Radiative losses are found to dominate the power balance for all laser wavelengths, and a clear shift from kinetic to in-band radiative losses with increasing laser wavelength is identified. We find that the existence of maximum conversion efficiency, near $ \lambda_{\mathrm{laser}} = 4 $ $\mu$m, originates from the interplay between the optical depths of the laser light and the in-band EUV photons for this specific target geometry.