Open AccessFrequency dependence of nonlinear absorption in fused silica measured with picosecond pulses at various focal lengths
Author(s) -
Florian Senn,
R.L. Holtz,
Sonja-Michaela Groß-Barsnick,
Uwe Reisgen
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.027628
Subject(s) - optics , materials science , focal length , picosecond , filamentation , absorption (acoustics) , laser , dielectric , saturation (graph theory) , two photon absorption , optoelectronics , physics , lens (geology) , mathematics , combinatorics
Nonlinear absorption is the key process to generate laser-induced in-volume modifications in transparent dielectrics such as waveguides or three-dimensional data matrix codes. We present a comprehensive parameter study about nonlinear absorption in fused silica using a picosecond laser at various focal lengths. Beginning at a focal length of 100 mm, we measure a strong frequency dependence of the saturation absorption. Reducing the focal length results in a decrease of the saturation absorption. After passing a threshold focal length, the saturation absorption increases drastically and the frequency dependence starts to decrease. At the final focal length of 6 mm we measure almost no frequency dependence. In order to explain our measurements, we used the theory of optical breakdown and filamentation. Nonlinear absorption measurement can become a promising tool for better process control during the generation of in-volume modifications in transparent dielectrics.