Hybrid Metasurfaces Enabling Focused Tunable Amplified Photoluminescence Through Dual Bound States in the Continuum

Miniaturized, tunable light sources are essential for integrated photonic devices in quantum computing, communications, and sensing. However, achieving tunable emission post-fabrication remains challenging, especially for efficient amplification. Hybrid metasurfaces that combine multiple nanostructured materials offer a promising solution, enabling enhanced control and amplification of light emission. Here, tunable amplified photoluminescence (PL) is demonstrated in nanocrystalline silicon (nc-Si) quantum dots (QDs) embedded in a hybrid metasurface of amorphous silicon (a-Si) and antimony trisulfide (Sb2S3), a low-loss phase change material (PCM). The nc-Si QDs exhibit stable, efficient PL at high temperatures, while the PCM enables tunable phase transitions. The metasurface supports dual quasi-bound states in the continuum (BICs), achieving Q-factors up to 225 and amplifying PL by a factor of 15 with a wavelength shift of 105 nm via dimensional modulation. Additionally, all-optical PL tunability across a 24 nm range is attained through PCM phase modulation. Furthermore, a high Q-factor metalens is proposed to focus the tunable amplified PL, extending the focused PL tunability into the near-infrared (NIR). This work advances reconfigurable nanophotonic devices for efficient quantum light sources in photonic systems.