Saturday, January 27, 2018

Abstract-Terahertz master-oscillator power-amplifier quantum cascade laser with a grating coupler of extremely low reflectivity




Huan Zhu, Haiqing Zhu, Fangfang Wang, Gaolei Chang, Chenren Yu, Quan Yan, Jianxin Chen, Lianhe Li, A. Giles Davies, Edmund H. Linfield, Zhou Tang, Pingping Chen, Wei Lu, Gangyi Xu, and Li He

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-2-1942

A terahertz master-oscillation power-amplifier quantum cascade laser (THz-MOPA-QCL) is demonstrated where a grating coupler is employed to efficiently extract the THz radiation. By maximizing the group velocity and eliminating the scattering of THz wave in the grating coupler, the residue reflectivity is reduced down to the order of 10−3. A buried DFB grating and a tapered preamplifier are proposed to improve the seed power and to reduce the gain saturation, respectively. The THz-MOPA-QCL exhibits single-mode emission, a single-lobed beam with a narrow divergence angle of 18° × 16°, and a pulsed output power of 136 mW at 20 K, which is 36 times that of a second-order DFB laser from the same material.
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.

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