Active quasi-BIC optical vortex generators for ultrafast switching

Abstract The Pancharatnam–Berry phase induced by the winding topology of polarization around a vortex singularity at bound states in continuum (BIC) provides unique approach to optical (OV) generation. BIC-based OV generators have potential outperform their counterparts that rely on spatial variations terms design feasibility, fabrication complexity, and robustness. However, given fact this class originates from topological property photonic bands, responses are generally fixed cannot be dynamically altered, which limits applications systems. Here, we numerically demonstrate silicon crystal slab can used realize optically switchable generation simultaneously exploiting momentum space conjunction with silicon’s nonlinear dynamics. Picosecond switching beams near-infrared wavelengths observed. demonstrated nontrivial nature active significantly expand application BIC toward ultrafast beam generation, high-capacity communication, mode-division multiplexing.