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

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 μm. 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) eigen state 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.

Continuous wave room temperature operation of the GaSb-based photonic crystal surface emitting diode lasers

“…Monolithic epitaxially regrown PCSEL based on nitride, arsenide, and phosphide diode laser technologies operating in visible and near infrared telecom region of spectrum have been demonstrated [1,2,3]. The extension of the PCSEL technology to longer wavelength range above 4 µm was accomplished using quantum cascade laser design [4]. Our research group works on development of the III-V-Sb-based epitaxially regrown diode and cascade diode PCSEL technology targeting continuous wave (CW) room temperature (RT) operation in spectral range from 2 to 4 µm.…”