Engineered Dual BIC Resonances in Hybrid Metasurfaces for Controlled Photoluminescence Amplification

Abstract: The development of miniaturized light sources with tunable functionality is crucial for advancing integrated photonic devices, enabling applications in quantum computing, communications, and sensing. Achieving tunable light emission after device fabrication remains a significant challenge, particularly when efficient amplification is required. Hybrid metasurfaces, which integrate several nanostructured materials to form optical resonators, have emerged as promising candidates to overcome these limitations by providing a high degree of flexibility in emission control and enhanced amplification. In this work, we demonstrate tunable amplified photoluminescence (PL) in nanocrystalline silicon (nc-Si) quantum dots (QDs) embedded in a hybrid metasurface consisting of amorphous silicon (a-Si) and a low-loss phase change material (PCM) antimony trisulfide (Sb2S3). The nc-Si QDs maintain a high PL efficiency and stability at elevated temperatures, offering reliable and tunable phase transitions in the PCM. The hybrid metasurface supports dual quasi-bound states in the continuum (BICs) to achieve Q-factors up to 225. The dual BIC cavity enables tunable amplified PL by a factor of 15 with a wavelength shift of up to 105 nm via dimensional modulation. Meanwhile, all-optical tunable PL emission across a 24 nm wavelength range has been achieved when PCMs are tuned from the amorphous to crystalline phase. Furthermore, we propose a high Q-factor metalens to focus the tunable amplified PL, extending the diffraction-limited focusing tunability into the near infrared (NIR). This work paves the way for highly efficient quantum light sources using reconfigurable nanophotonic devices in next-generation photonic systems.