Freeman, JR orcid.org/0000-0002-5493-6352, Ponnampalam, L, Shams, H et al. (7 more authors) (2017) Injection locking of a terahertz quantum cascade laser to a telecommunications wavelength frequency comb. Optica, 4 (9). pp. 1059-1064.
Abstract
High resolution spectroscopy can not only identify atoms and molecules, but can also provide detailed information on their chemical and physical environment, and relative motion. In the terahertz frequency region of the electromagnetic spectrum, where many molecules have fundamental vibrational modes, there is a lack of powerful sources with narrow linewidths that can be used for absorption measurements or as local oscillators in heterodyne detectors. The most promising solid-state source is the THz frequency quantum cascade laser (QCL), however, the linewidth of this compact semiconductor laser is typically too broad for many applications and its frequency is not directly referenced to primary frequency standards. In this work we injection lock a QCL operating at 2 THz to a compact fibre-based telecommunications wavelength frequency comb, where the comb line spacing is referenced to a microwave frequency reference. This results in the QCL frequency locking to an integer harmonic of the microwave reference, and the QCL linewidth reducing to the multiplied linewidth of the microwave reference, < 100 Hz. Furthermore, we perform phase-resolved detection of the locked QCL and measure the phase noise of the locked system to be –75 dBc/Hz at 10 kHz offset from 2 THz carrier.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. |
Keywords: | Lasers, injection-locked; Semiconductor lasers, quantum cascade; Far infrared or terahertz; Phase measurement |
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 EPSRC EP/J017671/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 14 Aug 2017 11:25 |
Last Modified: | 16 Oct 2017 14:22 |
Status: | Published |
Publisher: | Optical Society of America |
Identification Number: | 10.1364/OPTICA.4.001059 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:120094 |