Tunable cavity-enhanced terahertz frequency-domain optical Hall effect
Knight, Sean LU ; Schöche, Stefan ; Kühne, Philipp ; Hofmann, Tino ; Darakchieva, Vanya LU and Schubert, Mathias LU
(2020)
In Review of Scientific Instruments
91(8).
- Abstract
Presented here is the development and demonstration of a tunable cavity-enhanced terahertz (THz) frequency-domain optical Hall effect (OHE) technique. The cavity consists of at least one fixed and one tunable Fabry-Pérot resonator. The approach is suitable for the enhancement of the optical signatures produced by the OHE in semi-transparent conductive layer structures with plane parallel interfaces. Tuning one of the cavity parameters, such as the external cavity thickness, permits shifting of the frequencies of the constructive interference and provides substantial enhancement of the optical signatures produced by the OHE. A cavity-tuning optical stage and gas flow cell are used as examples of instruments that exploit tuning an... (More)
Presented here is the development and demonstration of a tunable cavity-enhanced terahertz (THz) frequency-domain optical Hall effect (OHE) technique. The cavity consists of at least one fixed and one tunable Fabry-Pérot resonator. The approach is suitable for the enhancement of the optical signatures produced by the OHE in semi-transparent conductive layer structures with plane parallel interfaces. Tuning one of the cavity parameters, such as the external cavity thickness, permits shifting of the frequencies of the constructive interference and provides substantial enhancement of the optical signatures produced by the OHE. A cavity-tuning optical stage and gas flow cell are used as examples of instruments that exploit tuning an external cavity to enhance polarization changes in a reflected THz beam. Permanent magnets are used to provide the necessary external magnetic field. Conveniently, the highly reflective surface of a permanent magnet can be used to create the tunable external cavity. The signal enhancement allows the extraction of the free charge carrier properties of thin films and can eliminate the need for expensive superconducting magnets. Furthermore, the thickness of the external cavity establishes an additional independent measurement condition, similar to, for example, the magnetic field strength, THz frequency, and angle of incidence. A high electron mobility transistor (HEMT) structure and epitaxial graphene are studied as examples. The tunable cavity-enhancement effect provides a maximum increase of more than one order of magnitude in the change of certain polarization components for both the HEMT structure and epitaxial graphene at particular frequencies and external cavity sizes.
(Less)
- author
- Knight, Sean
LU
; Schöche, Stefan
; Kühne, Philipp
; Hofmann, Tino
; Darakchieva, Vanya
LU
and Schubert, Mathias
LU
- publishing date
- 2020-08-01
- type
- Contribution to journal
- publication status
- published
- in
- Review of Scientific Instruments
- volume
- 91
- issue
- 8
- article number
- 083903
- publisher
- American Institute of Physics (AIP)
- external identifiers
-
- scopus:85090109497
- pmid:32872950
- ISSN
- 0034-6748
- DOI
- 10.1063/5.0010267
- language
- English
- LU publication?
- no
- additional info
- Publisher Copyright: © 2020 Author(s).
- id
- ffd3c006-edb2-4188-9241-ec9be1c06939
- date added to LUP
- 2025-11-06 16:38:17
- date last changed
- 2025-11-11 15:03:51
@article{ffd3c006-edb2-4188-9241-ec9be1c06939,
abstract = {{<p>Presented here is the development and demonstration of a tunable cavity-enhanced terahertz (THz) frequency-domain optical Hall effect (OHE) technique. The cavity consists of at least one fixed and one tunable Fabry-Pérot resonator. The approach is suitable for the enhancement of the optical signatures produced by the OHE in semi-transparent conductive layer structures with plane parallel interfaces. Tuning one of the cavity parameters, such as the external cavity thickness, permits shifting of the frequencies of the constructive interference and provides substantial enhancement of the optical signatures produced by the OHE. A cavity-tuning optical stage and gas flow cell are used as examples of instruments that exploit tuning an external cavity to enhance polarization changes in a reflected THz beam. Permanent magnets are used to provide the necessary external magnetic field. Conveniently, the highly reflective surface of a permanent magnet can be used to create the tunable external cavity. The signal enhancement allows the extraction of the free charge carrier properties of thin films and can eliminate the need for expensive superconducting magnets. Furthermore, the thickness of the external cavity establishes an additional independent measurement condition, similar to, for example, the magnetic field strength, THz frequency, and angle of incidence. A high electron mobility transistor (HEMT) structure and epitaxial graphene are studied as examples. The tunable cavity-enhancement effect provides a maximum increase of more than one order of magnitude in the change of certain polarization components for both the HEMT structure and epitaxial graphene at particular frequencies and external cavity sizes.</p>}},
author = {{Knight, Sean and Schöche, Stefan and Kühne, Philipp and Hofmann, Tino and Darakchieva, Vanya and Schubert, Mathias}},
issn = {{0034-6748}},
language = {{eng}},
month = {{08}},
number = {{8}},
publisher = {{American Institute of Physics (AIP)}},
series = {{Review of Scientific Instruments}},
title = {{Tunable cavity-enhanced terahertz frequency-domain optical Hall effect}},
url = {{http://dx.doi.org/10.1063/5.0010267}},
doi = {{10.1063/5.0010267}},
volume = {{91}},
year = {{2020}},
}