Optical absorption induced by UV laser radiation in Ge-doped amorphous silica probed by in situ spectroscopy

TL;DR

This study investigates how UV laser radiation induces optical absorption in Ge-doped amorphous silica, revealing the formation of specific absorption peaks and paramagnetic centers through in situ spectroscopy and ESR measurements.

Contribution

It provides new insights into the dynamics of laser-induced absorption and defect formation in Ge-doped silica using combined in situ optical and ESR techniques.

Findings

Identification of two main absorption peaks at 4.5 eV and 5.7 eV

Detection of paramagnetic Ge(1) and Ge-E' centers post-irradiation

Time-dependent evolution of absorption profile

Abstract

We studied the optical absorption induced by 4.7eV pulsed laser radiation on Ge-doped a-SiO2 synthesized by a sol-gel technique. The absorption spectra in the ultraviolet spectral range were measured during and after the end of irradiation with an in situ technique, evidencing the growth of an absorption signal whose profile is characterized by two main peaks near 4.5eV and 5.7eV and whose shape depends on time. Electron spin resonance measurements performed ex situ a few hours after the end of exposure permit to complete the information acquired by optical absorption by detection of the paramagnetic Ge(1) and Ge-E' centers laser-induced in the samples.