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Title: Single-mode narrow beam divergence surface-emitting concentric-circular-grating terahertz quantum cascade lasers
Authors: Khanna, Suraj P.
Liang, Guozhen
Liang, Houkun
Zhang, Ying
Li, Lianhe
Davies, A. Giles
Linfield, Edmund
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.
DOI: 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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