Origin of the anisotropic Beer-Lambert law from dichroism and birefringence in β-Ga2O3
Adnan, Md Mohsinur Rahman ; Schubert, Mathias LU
and Myers, Roberto C.
(2024)
In Applied Physics Letters
125(8).
- Abstract
The anisotropic optical absorption edge of β-Ga2O3 follows a modified Beer-Lambert law having two effective absorption coefficients. The absorption coefficient of linearly polarized light reduces to the least absorbing direction beyond a critical penetration depth, which itself depends on polarization and wavelength. To understand this behavior, a Stokes vector analysis is performed to track the polarization state as a function of depth. The weakening of the absorption coefficient is associated with a gradual shift of linear polarization to the least absorbing crystallographic direction in the plane, which is along the a-exciton within the (010) plane or along the b-exciton in the (001) plane. We show that strong... (More)
The anisotropic optical absorption edge of β-Ga2O3 follows a modified Beer-Lambert law having two effective absorption coefficients. The absorption coefficient of linearly polarized light reduces to the least absorbing direction beyond a critical penetration depth, which itself depends on polarization and wavelength. To understand this behavior, a Stokes vector analysis is performed to track the polarization state as a function of depth. The weakening of the absorption coefficient is associated with a gradual shift of linear polarization to the least absorbing crystallographic direction in the plane, which is along the a-exciton within the (010) plane or along the b-exciton in the (001) plane. We show that strong linear dichroism near the optical absorption edge causes this shift in β-Ga2O3, which arises from the anisotropy and spectral splitting of the physical absorbers, i.e., excitons. The linear polarization shift is accompanied by a variation in the ellipticity due to the birefringence of β-Ga2O3. Analysis of the phase relationship between the incoming electric field to that at a certain depth reveals the phase speed as an effective refractive index, which varies along different crystallographic directions. The critical penetration depth is shown to be correlated with the depth at which the ellipticity is maximal.
(Less)
- author
- Adnan, Md Mohsinur Rahman
; Schubert, Mathias
LU
and Myers, Roberto C.
- organization
- publishing date
- 2024-08
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Applied Physics Letters
- volume
- 125
- issue
- 8
- article number
- 081103
- publisher
- American Institute of Physics (AIP)
- external identifiers
-
- scopus:85201874394
- ISSN
- 0003-6951
- DOI
- 10.1063/5.0226902
- language
- English
- LU publication?
- yes
- id
- a8af6236-acf4-4820-91c5-20b907f94683
- date added to LUP
- 2024-10-28 12:46:21
- date last changed
- 2025-04-04 14:52:39
@article{a8af6236-acf4-4820-91c5-20b907f94683,
abstract = {{<p>The anisotropic optical absorption edge of β-Ga<sub>2</sub>O<sub>3</sub> follows a modified Beer-Lambert law having two effective absorption coefficients. The absorption coefficient of linearly polarized light reduces to the least absorbing direction beyond a critical penetration depth, which itself depends on polarization and wavelength. To understand this behavior, a Stokes vector analysis is performed to track the polarization state as a function of depth. The weakening of the absorption coefficient is associated with a gradual shift of linear polarization to the least absorbing crystallographic direction in the plane, which is along the a-exciton within the (010) plane or along the b-exciton in the (001) plane. We show that strong linear dichroism near the optical absorption edge causes this shift in β-Ga<sub>2</sub>O<sub>3</sub>, which arises from the anisotropy and spectral splitting of the physical absorbers, i.e., excitons. The linear polarization shift is accompanied by a variation in the ellipticity due to the birefringence of β-Ga<sub>2</sub>O<sub>3</sub>. Analysis of the phase relationship between the incoming electric field to that at a certain depth reveals the phase speed as an effective refractive index, which varies along different crystallographic directions. The critical penetration depth is shown to be correlated with the depth at which the ellipticity is maximal.</p>}},
author = {{Adnan, Md Mohsinur Rahman and Schubert, Mathias and Myers, Roberto C.}},
issn = {{0003-6951}},
language = {{eng}},
number = {{8}},
publisher = {{American Institute of Physics (AIP)}},
series = {{Applied Physics Letters}},
title = {{Origin of the anisotropic Beer-Lambert law from dichroism and birefringence in β-Ga<sub>2</sub>O<sub>3</sub>}},
url = {{http://dx.doi.org/10.1063/5.0226902}},
doi = {{10.1063/5.0226902}},
volume = {{125}},
year = {{2024}},
}