Improved power and far-field pattern of surface-emitting quantum cascade lasers with strain compensation to operate at 4.3 μm. (1st May 2022)

• Record Type: Journal Article
• Authors: Yao, Yuanzhao; Ikeda, Naoki; Chalimah, Siti; Kuroda, Takashi; Sugimoto, Yoshimasa; Mano, Takaaki; Koyama, Hiromi; Hashimoto, Rei; Kaneko, Kei; Kakuno, Tsutomu; Ookuma, Shinji; Togawa, Ryuichi; Ohno, Hiroshi; Saito, Shinji; Takahashi, Naoki; Tanimura, Hirotaka; Takagi, Shigeyuki; Sakoda, Kazuaki
• Is Part Of: Japanese journal of applied physics. Volume 61:Number 5(2022)
• Publication Date: 2022-05-01
• Subjects: quantum cascade laser -- photonic crystal -- surface emission -- far-field pattern; Physics -- Periodicals; 621.05
• DOI: 10.35848/1347-4065/ac5dbb
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: We fabricated surface-emitting quantum cascade lasers with photonic crystal resonators whose active layers were strain-compensated InGaAs/AlInAs multiple quantum wells to operate at 4.3 μ m. We tested two kinds of square-lattice photonic crystals consisting of circular and pentagonal InGaAs cylinders as a unit structure. We examined their output power and far-field pattern to find that both of them were improved by lowering the photonic-crystal symmetry to achieve a high extraction efficiency. The maximum output power was 50 mW at 77 K and the far-field pattern was a single peak with a divergence angle smaller than 1° for the pentagonal cylinder structure. In addition, we attributed the lasing mode to a B2 -symmetric (quadrupole) eigenstate on the Γ point for the circular cylinder structure by observing the polarization dependence of the far-field pattern and comparing it with calculations by the k · p perturbation method.