Modeling aspects for high precision absorption measurements

authored by: Walter DIckmann, Johannes DIckmann, Florian F. Bruns, Stefanie Kroker
Abstract: Collinear photothermal deflection spectroscopy (PDS) is a widely used method for the spatially resolved determination of the optical attenuation coefficient. In this work we rigorously model the signal contributions in PDS on semiconductors below the band gap energy. The dependencies of the PDS signal on selected experimental parameters (pump beam intensity, crossing angle, chopper frequency and distance from the pump beam focus) are computed and compared with previous calculation results that are based on simplified assumptions. We find that for high pump beam intensities and sample materials with high two photon absorption coefficients beside the mirage effect nonlinear absorption mechanisms have a strong impact on the signal. Furthermore, we show that angular deflection effects can significantly enhance the PDS signal. For example, the conical refractive index field due to the pump beam divergence leads to an angular deflection at readout points outside the pump beam focus. Considering these additional signal contributions is crucial to determine proper absorption properties.
External Organisation(s): Technische Universität Braunschweig
National Metrology Institute of Germany (PTB)
Type: Conference contribution
Publication date: 21.06.2019
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Computer Science Applications, Applied Mathematics, Electrical and Electronic Engineering
Electronic version(s): https://doi.org/10.1117/12.2525690 (Access: Closed)

BibTeX

@inproceedings{ec40d5a55234400ea890871a7186ff05,
title = "Modeling aspects for high precision absorption measurements",
abstract = "Collinear photothermal deflection spectroscopy (PDS) is a widely used method for the spatially resolved determination of the optical attenuation coefficient. In this work we rigorously model the signal contributions in PDS on semiconductors below the band gap energy. The dependencies of the PDS signal on selected experimental parameters (pump beam intensity, crossing angle, chopper frequency and distance from the pump beam focus) are computed and compared with previous calculation results that are based on simplified assumptions. We find that for high pump beam intensities and sample materials with high two photon absorption coefficients beside the mirage effect nonlinear absorption mechanisms have a strong impact on the signal. Furthermore, we show that angular deflection effects can significantly enhance the PDS signal. For example, the conical refractive index field due to the pump beam divergence leads to an angular deflection at readout points outside the pump beam focus. Considering these additional signal contributions is crucial to determine proper absorption properties.",
keywords = "Absorption, Angular effects, Mirage effect, Photothermal deflection spectroscopy, Pump probe, Ray tracing, Signal modeling, Two-photon absorption",
author = "Walter DIckmann and Johannes DIckmann and Bruns, {Florian F.} and Stefanie Kroker",
note = "Funding Information: W.D. gratefully acknowledges support by the Braunschweig International Graduate School of Metrology B-IGSM and the DFG research training group GrK1952/1 {"}Metrology for Complex Nanosystems{"}. F.F.B. acknowledges support by the cluster of Excellence {"}QuantumFrontiers{"} ExC 2123.; Modeling Aspects in Optical Metrology VII 2019 ; Conference date: 24-06-2019 Through 26-06-2019",
year = "2019",
month = jun,
day = "21",
doi = "10.1117/12.2525690",
language = "English",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
publisher = "SPIE",
editor = "Bernd Bodermann and Karsten Frenner",
booktitle = "Modeling Aspects in Optical Metrology VII",
address = "United States",
}