Broadband THz absorption spectrometer based on excitonic nonlinear optical effects

Majeed, A., Ivanov, P., Stevens, B., Clarke, E., Butler, I., Childs, D., Kojima, O. and Hogg, R. (2019) Broadband THz absorption spectrometer based on excitonic nonlinear optical effects. Light: Science and Applications, 8, 29. (doi:10.1038/s41377-019-0137-y) (PMID:30886706) (PMCID:PMC6414654)

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Abstract

A broadly tunable THz source is realized via difference frequency generation, in which an enhancement to χ(3) that is obtained via resonant excitation of III–V semiconductor quantum well excitons is utilized. The symmetry of the quantum wells (QWs) is broken by utilizing the built-in electric-field across a p–i–n junction to produce effective χ(2) processes, which are derived from the high χ(3). This χ(2) media exhibits an onset of nonlinear processes at ~4 W cm−2, thereby enabling area (and, hence, power) scaling of the THz emitter. Phase matching is realized laterally through normal incidence excitation. Using two collimated 130 mW continuous wave (CW) semiconductor lasers with ~1-mm beam diameters, we realize monochromatic THz emission that is tunable from 0.75 to 3 THz and demonstrate the possibility that this may span 0.2–6 THz with linewidths of ~20 GHz and efficiencies of ~1 × 10–5, thereby realizing ~800 nW of THz power. Then, transmission spectroscopy of atmospheric features is demonstrated, thereby opening the way for compact, low-cost, swept-wavelength THz spectroscopy.

Item Type:Articles (Letter)
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ivanov, Dr Pavlo and Kojima, Professor Osamu and Hogg, Professor Richard and Butler, Iain and Childs, Dr David
Authors: Majeed, A., Ivanov, P., Stevens, B., Clarke, E., Butler, I., Childs, D., Kojima, O., and Hogg, R.
College/School:College of Science and Engineering
College of Science and Engineering > School of Engineering
College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Light: Science and Applications
Publisher:Nature Publishing Group
ISSN:2095-5545
ISSN (Online):2047-7538
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Light: Science and Applications 8:29
Publisher Policy:Reproduced under a Creative Commons License

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