High-Q resonance in GeSn-based bound states in the continuum microcavity

In recent years, the investigations of lasers based on group IV material have been limited by the low quality (Q) factor of the resonant modes. With the improvement of the optical bound states in the continuum (BICs) in various dielectric systems, we propose a novel design that takes advantages of both the direct bandgap dielectric material GeSn and the BIC phenomenon. In addition to the demonstration of the unprecedented high-Q factors (i.e., ∼10¹⁰) that improve the emission process, the vertical symmetry broken structure can emit light at the wavelength of 1870 nm with higher luminous intensity (i.e., ∼24). The modulation effect of the material and geometric parameters on the Q value and the luminous intensity of the structure are also demonstrated. Our investigations provide useful guidelines for potential applications such as on-chip light sources in group IV photonics and optical communications.