Photonic‐Defect Cavities as Next‐Generation Room‐Temperature Microlasers: A Comparative Study with Micropillars

Abstract Room‐temperature operable microlasers are essential for advancing quantum photonics and integrated photonic circuits, enabling a wide range of practical applications. In this study, the lasing performance of two types of optically pumped InGaAs quantum dot microcavities – namely, micropillar and photonic‐defect cavities — is systematically compared at elevated temperatures. A comprehensive analysis of device designs through simulations, followed by the fabrication and experimental studies of both structures, allows for a direct performance evaluation. Excitation‐power‐dependent input/output measurements confirm lasing up to 200 K in the micropillar case, where the performance is constrained by sidewall losses, pump power absorption, and inefficient heat dissipation. In contrast, the photonic‐defect cavity demonstrates stable continuous‐wave lasing even at room‐temperature (300 K), attributed mainly to superior thermal management in the quasi‐planar cavity design. Additionally, in the photonic‐defect cavity with low‐absorbing upper mirror, Raman spectroscopy verifies efficient optical pumping, while second‐order autocorrelation measurements provide unambiguous proof of lasing at 300 K. Overall, the quasi‐planar geometry of the photonic‐defect cavity shows high temperature stability and supports flexible fabrication, establishing it as a promising concept for practical microlaser applications.