Vibrational Nonlinear Response of Complex Molecules: Nature and Measurements in the THz Range

Fuente: arXiv
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Main Authors: Nabilkova, Aleksandra, Guselnikov, Mikhail, Ismagilov, Azat, Melnik, Maksim, Kozlov, Sergey, Tcypkin, Anton
Format: Preprint
Published: 2025
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author Nabilkova, Aleksandra
Guselnikov, Mikhail
Ismagilov, Azat
Melnik, Maksim
Kozlov, Sergey
Tcypkin, Anton
author_facet Nabilkova, Aleksandra
Guselnikov, Mikhail
Ismagilov, Azat
Melnik, Maksim
Kozlov, Sergey
Tcypkin, Anton
contents The nonlinear optical response of materials under high-intensity electromagnetic fields is key to advancing THz optical technologies. This study introduces a theoretical approach to estimate the nonlinear refractive index coefficient n2 of complex molecules by summing contributions from individual vibrational bonds, which are extracted from structurally simpler molecules predominantly consist of corresponding type of bond. Using water, alpha-pinene, and CO2 as reference materials, we predict n2 for isopropanol as 4.7*10^(-9) cm^2/W. Z-scan measurements with pulsed THz radiation yield n2 = (2.5+-0.5)*10^(-9) cm^2/W, validating our model. This bond-based decomposition links microscopic bond vibrations and macroscopic nonlinear coefficients, offering a framework for understanding molecular nonlinear optics and guiding the design of THz nonlinear materials.
format Preprint
id arxiv_https___arxiv_org_abs_2504_03383
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Vibrational Nonlinear Response of Complex Molecules: Nature and Measurements in the THz Range
Nabilkova, Aleksandra
Guselnikov, Mikhail
Ismagilov, Azat
Melnik, Maksim
Kozlov, Sergey
Tcypkin, Anton
Optics
The nonlinear optical response of materials under high-intensity electromagnetic fields is key to advancing THz optical technologies. This study introduces a theoretical approach to estimate the nonlinear refractive index coefficient n2 of complex molecules by summing contributions from individual vibrational bonds, which are extracted from structurally simpler molecules predominantly consist of corresponding type of bond. Using water, alpha-pinene, and CO2 as reference materials, we predict n2 for isopropanol as 4.7*10^(-9) cm^2/W. Z-scan measurements with pulsed THz radiation yield n2 = (2.5+-0.5)*10^(-9) cm^2/W, validating our model. This bond-based decomposition links microscopic bond vibrations and macroscopic nonlinear coefficients, offering a framework for understanding molecular nonlinear optics and guiding the design of THz nonlinear materials.
title Vibrational Nonlinear Response of Complex Molecules: Nature and Measurements in the THz Range
topic Optics
url https://arxiv.org/abs/2504.03383