High-Temperature Stability of 8.8 μm Quantum Cascade Lasers with a Compositionally Modulated Hollow Active-Region Design

초록

Quantum cascade lasers (QCLs) operating in the mid infrared (Mid-IR) spectral range are indispensable for high sensitivity sensing and spectroscopy; however, their continuous wave performance is often hindered by significant thermal accumulation and thermally activated carrier leakage. In this work, we demonstrate a high-performance InGaAs/InAlAs QCL emitting at 8.8 μm that incorporates an innovative hollow active region design realized through local compositional modulation. The proposed structure utilizes a simplified active-region scheme with only two alloy compositions, facilitating precise growth control via metal-organic chemical vapor deposition (MOCVD) while maintaining high structural integrity, as confirmed by high resolution X-ray diffraction and transmission electron microscopy. By increasing the energy separation between the upper lasing level and higher-lying leakage states to more than 60 meV, the fabricated devices exhibited exceptional thermal stability. Experimental results show a threshold current density of 2.66 kA/cm2 at 293 K and a peak optical output power of approximately 1.5 W. Notably, the device exhibited characteristic temperatures of T0 = 222 K and T1 = 200 K, which are among the higher values reported for MOCVD-grown QCLs operating in this wavelength range. These findings suggest that the compositionally modulated hollow structure provides a practical and effective pathway for developing thermally robust, high-power Mid-IR QCLs suitable for advanced industrial and medical applications. © 2009-2012 IEEE.

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