Improved power and far-field pattern of surface-emitting quantum cascade lasers with strain compensation to operate at 4.3 μm

• Published in: Japanese Journal of Applied Physics 2022-05, Vol.61 (5), p.52001
• Main 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
• Format: Article
• Language: English
• Subjects: Circular cylinders; Crystal lattices; Crystal structure; Eigenvectors; far-field pattern; Multi Quantum Wells; Perturbation methods; photonic crystal; Photonic crystals; Quadrupoles; quantum cascade laser; Quantum cascade lasers; surface emission; Symmetry
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/ac5dbb

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 B 2 -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.