Keeley, J orcid.org/0000-0001-5251-6648, Freeman, J orcid.org/0000-0002-5493-6352, Valavanis, A orcid.org/0000-0001-5565-0463 et al. (10 more authors) (2016) Spectral Characterisation of a Terahertz QCL through Self-Mixing. In: IQCLSW 2016, 04-09 Sep 2016, Cambridge, UK.
Abstract
The use of a single terahertz (THz) quantum cascade laser (QCL) device as both emitter and detector in a self-mixing (SM) scheme allows for the development of fast, sensitive and compact coherent systems for imaging and interferometry [1]. In this scheme, radiation re-injected to the laser cavity interferes (‘mixes’) with the intra-cavity electric field, causing small variations in the fundamental laser parameters, as described in the seminal paper by Lang and Kobashi (L–K) [2]. In particular, the voltage perturbation induced by optical feedback is described by a sinusoidal variation dependent on both the external cavity length LExt and the emission frequency under feedback ν, and is given byΔVsm ∝ cos(2 v/c). As such, interferometric fringes can be acquired in a SM system by simply changing the external cavity length and concurrently monitoring the terminal voltage of the device. In this work we demonstrate the use of SM interferometry for performing spectral characterisation of a multi-mode THz QCL in a scheme that offers much reduced experimental complexity when compared with typical Fourier Transform infrared spectroscopy (FTIR) systems. In addition, we report the first direct measurements of the perturbation of the lasing frequency under feedback, and compare the results with predictions from the L–K model.
Metadata
Item Type: | Conference or Workshop Item |
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Authors/Creators: |
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Keywords: | self-mixing; terahertz; quantum cascade laser; characterisation |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Electronic & Electrical Engineering (Leeds) > Pollard Institute (Leeds) |
Funding Information: | Funder Grant number EPSRC EP/J002356/1 Royal Society WM110032 EPSRC EP/J017671/1 Royal Society WM150029 |
Depositing User: | Symplectic Publications |
Date Deposited: | 15 Sep 2016 13:31 |
Last Modified: | 03 Feb 2018 08:11 |
Status: | Published |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:104669 |