Photonic‐defect cavities as next‐generation room‐temperature microlasers: a comparative study with micropillars

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.