Yue Zhao, Jin-Chuan Zhang, Chuan-Wei Liu, Ning Zhuo, Shen-Qiang Zhai, Li-Jun Wang, Jun-Qi Liu, Shu-Man Liu, Feng-Qi Liu, and Zhan-Guo Wang
http://www.etoponline.org/prj/abstract.cfm?uri=prj-6-8-821
Power scaling in a broad area quantum cascade laser (QCL) tends to deteriorate beam quality with the emission of a multiple-lobe far-field pattern. In this paper, we demonstrate a coupled ridge waveguide QCL array consisting of five elements with chirped geometry. In-phase mode operation is secured by managing supermode loss with properly designed geometries of ridges. A single-lobe lateral far-field with a near diffraction limited beam pattern was obtained in the whole current dynamic range. The devices were fabricated with the wet and dry etching method. The regrowth technique of the InP:Fe insulation layer and InP:Si waveguide layer was employed. Such a structure has the potential to optimize the beam quality of the recently reported high-power broad-area QCL with a reduced cascade number.
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