Davies, AG

Dean, P

Kundu, I

Li, LH

Linfield, EH

Valavanis, A

White Rose Research Online

This is a repository copy of Electrically-controlled frequency tuning of terahertz quantum cascade lasers over 190 GHz using a coupled cavity with integrated photonic lattice.White Rose Research Online URL for this paper:http://eprints.whiterose.ac.uk/111460/Version: Accepted VersionConference or Workshop Item:Kundu, I orcid.org/0000-0002-3564-1903, Dean, P, Valavanis, A orcid.org/0000-0001-5565-0463 et al. (3 more authors) (Accepted: 2017) Electrically-controlled frequency tuning of terahertz quantum cascade lasers over 190 GHzusing a coupled cavity with integrated photonic lattice. In: Optical Terahertz Science and Technology (OTST 2017), 02-07 Apr 2017, London, UK. (Unpublished) eprints@whiterose.ac.ukhttps://eprints.whiterose.ac.uk/Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Electrically-controlled frequency tuning of terahertz quantum cascade lasers over 190 GHz using a coupled cavity with integrated photonic lattice  Iman Kundu*, Paul Dean, Alexander Valavanis, Lianhe Li, Edmund H. Linfield, and A. Giles Davies  School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, U. K. *I.Kundu@leeds.ac.uk  Terahertz (THz) frequency quantum cascade lasers (QCLs) are compact unipolar semiconductor sources of THz radiation, in which photons are generated through intersubband electron transitions [1]. THz QCLs typically use ridge waveguides, and emit multiple frequencies characteristic of Fabry–Pérot cavities. However, several THz applications, such as trace gas detection, spectroscopy, feedback-interferometry-based imaging, atmospheric observations, and security screening, require a widely frequency tuneable and single-mode THz source. Moreover, the current and tempera ure tuning of THz QCLs are only ~–5 MHz/mA and –34 to –100 MHz/K, respectively [2]. As such, development of an electrically-controlled frequency tuneable THz QCL is still a technological challenge.  We previously demonstrated electrically-controlled discrete, and quasi-continuous Vernier frequency tuning of THz QCLs using an optically coupled cavity (CC) approach, comprising a lasing (active) cavity and a tuning (passive) cavity [3, 4]. We have also demonstrated continuous tuning of a CC mode without any degradation of output power by integrating a finite-defect-site photonic lattice (PL) into the lasing cavity [4]. We recently improved our PL design and have engineered spectral emission, and frequency tuning from such PL-QCLs [5]. Here, we report the progress made towards improving the spectral coverage from our next generation of electrically-controlled frequency tuenable THz CC-PL-QCLs.  Frequency emission in our previous CC-QCLs was controlled only through localised e ectrical Joule heating of the tuning cavity (driven sub-threshold). Here, we have additionally driven our tuning cavity above threshold, and exploited mutual coupling and cavity pulling effects to enhance continuous frequency tuning [6]. Furthermore, we have also integrated a PL into the lasing cavity, allowing discrete tuning of CC modes. Through a combination of the discrete tuning a d cavity pulling effect, in conjunction with thermal effects, we have recorded frequency tuning over 190 GHz (side mode suppression 20–40dB), including a ~100 GHz quasi-continuous tuning from ~3.47–3.57 THz [Fig. 1] from a THz CC PL QCL based on an active region reported in Ref. [7].   Fig. 1. Normalised emission spectra (offset and rearranged) showing tuneable fr quency emission from a THz CC PL QCL over a bandwidth of 190 GHz, for a range of driving currents, and temperatures.  References [1] R. Köhler, et al., Nature 417, 156–159 (2002). [2] M. S. Vitiello and A. Tredicucci, IEEE Trans. Terahertz Sci. Technol. 1, 76–84 (2011). [3] I. Kundu et al., Opt. Express 22, 16595–16605 (2014). [4] I. Kundu et al., “Quasi-continuous frequency tunable terahertz quantum cascade lasers with coupled cavity and integrated photonic lattice,” Opt. Express, accepted (2016). [5] I. Kundu et al., “Frequency tunability and spectral control in terahertz quantum cascade lasers with a phase-adjusted finite-defect-site photonic lattice,” in preparation (2016). [6] D. Turčinková et al., Appl. Phys. Lett. 106, 131107 (2015). [7] M. Wienold et al., Electron. Lett. 45, 1030–1031 (2009). 3.4 3.5 3.6 3.7Frequency (THz)Norm. Inten.

Electrically-controlled frequency tuning of terahertz quantum cascade lasers over 190 GHz using a coupled cavity with integrated photonic lattice

https://eprints.whiterose.ac.uk/111460/1/Abs_OTST2017_IKetal_CC-THz-PL-QCL.pdf

Electrically-controlled frequency tuning of terahertz quantum cascade lasers over 190 GHz using a coupled cavity with integrated photonic lattice

Abstract

Similar works

Full text

Available Versions

White Rose Research Online