dc.contributor.authorLiang, Guozhen
dc.contributor.authorLiang, Houkun
dc.contributor.authorZhang, Ying
dc.contributor.authorLi, Lianhe
dc.contributor.authorDavies, A. Giles
dc.contributor.authorLinfield, Edmund
dc.contributor.authorYu, Siu Fung
dc.contributor.authorLiu, Hui Chun
dc.contributor.authorWang, Qi Jie
dc.identifier.citationLiang, G., Liang, H., Zhang, Y., Li, L., Davies, A. G., Linfield, E., et al. (2013). Low divergence single-mode surface-emitting concentric-circular-grating terahertz quantum cascade lasers. Optics express, 21(26), 31872-31882.en_US
dc.description.abstractWe report the design, fabrication and experimental characterization of surface-emitting terahertz (THz) frequency quantum cascade lasers (QCLs) with distributed feedback concentric-circular-gratings. Single-mode operation is achieved at 3.73 THz with a side-mode suppression ratio as high as ~30 dB. The device emits ~5 times the power of a ridge laser of similar dimensions, with little degradation in the maximum operation temperature. Two lobes are observed in the far-field emission pattern, each of which has a divergence angle as narrow as ~13.5° × 7°. We demonstrate that deformation of the device boundary, caused by anisotropic wet chemical etching is the cause of this double-lobed profile, rather than the expected ring-shaped pattern.en_US
dc.description.sponsorshipASTAR (Agency for Sci., Tech. and Research, S’pore)en_US
dc.description.sponsorshipMOE (Min. of Education, S’pore)en_US
dc.relation.ispartofseriesOptics expressen_US
dc.rights© 2013 Optical Society of America. This paper was published in Optics Express and is made available as an electronic reprint (preprint) with permission of Optical Society of America. The paper can be found at the following official DOI: [http://dx.doi.org/10.1364/OE.21.031872]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.en_US
dc.subjectDRNTU::Science::Physics::Optics and light
dc.titleLow divergence single-mode surface-emitting concentric-circular-grating terahertz quantum cascade lasersen_US
dc.typeJournal Article
dc.contributor.schoolSchool of Electrical and Electronic Engineeringen_US
dc.contributor.schoolSchool of Physical and Mathematical Sciencesen_US
dc.description.versionPublished versionen_US

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