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|Title:||Single-mode narrow beam divergence surface-emitting concentric-circular-grating terahertz quantum cascade lasers||Authors:||Khanna, Suraj P.
Davies, A. Giles
Lim, Dau Fatt
Tan, Chuan Seng
Yu, Siu Fung
Liu, Hui Chun
Wang, Qi Jie
|Issue Date:||2012||Source:||Liang, G., Liang, H., Zhang, Y., Khanna, S. P., Li, L., Davies, A. G., et al. (2012). Single-mode narrow beam divergence surface-emitting concentric-circular-grating terahertz quantum cascade lasers. 2012 Photonics Global Conference (PGC).||Abstract:||Single-mode surface-emitting terahertz quantum cascade lasers with second-order concentric-circular-gratings are firstly demonstrated. The gratings are designed for single-mode operation and surface emission for efficient and directional optical power out-coupling. The first structure exhibits single-mode operation over the entire dynamic range with a side-mode-suppression-ratio of around 30 dB, and a six-fold rotationally symmetric far-field pattern, while a modified structure demonstrates single-mode operation with an improved beam divergence, whose far-field patteren consists of two lobes, each of which has a beam divergence within 13.5°×7° (full-width at half-maximum, FWHM). In addition, the devices show a peak output power approximately three times higher than in conventional ridge-waveguide lasers of similar size, whilst maintaining similar threshold current densities and maximum operating temperatures.||URI:||https://hdl.handle.net/10356/97872
|DOI:||http://dx.doi.org/10.1109/PGC.2012.6458023||Rights:||© 2012 IEEE.||Fulltext Permission:||none||Fulltext Availability:||No Fulltext|
|Appears in Collections:||EEE Conference Papers|
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