Study on the Effect of Substitutional Doping of Ce Atomic on the Damage Properties of Fused Silica

TL;DR

This study explores how adding cerium atoms to fused silica affects its laser damage resistance and optical properties.

Contribution

The paper reveals how cerium doping introduces defect states that alter fused silica's electronic and optical behavior.

Findings

Cerium doping creates deep-level defect states that narrow the band gap and redshift the absorption edge.

Ce-4f orbitals dominate the defect states, with neighboring atoms influencing their depth and distribution.

Ce contamination reduces laser damage resistance at 355 nm, confirmed by LIDT tests and spectral analysis.

Abstract

In high-power laser systems, extrinsic impurities—particularly Ce introduced during conventional ring polishing—have been identified as critical contributors to the degradation of laser-induced damage resistance in fused silica optical components. This study systematically investigates the effects of cerium substitutional doping on the electronic structure and optical properties of fused silica, integrating first-principles density functional theory calculations with experimental characterizations. The results demonstrate that substitutional incorporation of cerium atoms into the fused silica framework introduces deep-level defect states within the band gap, resulting in band gap narrowing and absorption edge redshift of the material. The energy position of the defect states depends on the Ce doping configuration. Among them, the Ce-4f orbital constitutes the dominant component of the defect state’s electronic structure, while the neighboring atomic orbitals such as O-2p and Si-3s/3p participate in bonding through hybridization, thereby determining the depth and distribution characteristics of the defect levels. The optical absorption edge of cerium-doped fused silica undergoes a significant redshift from the intrinsic value of 222 nm to 468 nm in the dual-Ce adjacent-site doping configuration, thereby endowing the material with substantial optical absorption capability at a wavelength of 355 nm. μ-UVPL spectroscopy combined with μ-XRD and other characterization analyses confirmed that the characteristic emission peak at 450 nm on the surface region of fused silica originated from Ce-related defect centers; this spectral feature was consistent with the defect state electronic structure predicted by the diatomic nearest-neighbor doping model. LIDT tests further indicated that the Ce-contaminated area significantly weakened the material’s laser damage resistance under 355 nm laser irradiation. This study further explained the mechanism by which traditional polishing-induced Ce element doping causes the low laser damage threshold of fused silica optical components, providing a theoretical basis for improving their performance.

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