Concentric microcavities for cylindrical vector beam lasers

Cylindrical vector (CV) beams with polarization singularities have attracted intense research interest because of their important applications in optical trapping and manipulation, imaging, and high-speed optical communication. In this Letter, we propose a high-speed integrated device designed to emit fundamental CV beams, including both radially and azimuthally polarized beams. The device is composed of two grating-assisted concentric microcavities based on an InP platform. The microcavity with only a second-order grating shallowly etched on the top is optimized and used for improved azimuthally polarized CV beam emission. Another microcavity with both a triangular-shaped side grating and a rectangular-shaped top grating is employed for radially polarized CV beam lasing. The proposed devices can be further developed to be compatible with wavelength-division multiplexing and mode-division multiplexing techniques. They hold great potential in CV beam-based classical and quantum communication systems.