On-chip generation of adjustable cylindrical vector beams

Cylindrical vector (CV) beams have sparked considerable interest due to their extraordinary vectorial properties, desirable for applications ranging from microscopy to high energy physics. Increasing demand for cost-effective, small-footprint photonics has fueled the development of photonic integrated circuits (PICs) capable of generating structured light beams in recent years. This technology however suffers from low reconfigurability, limiting the variety of CV beams that can be generated from these devices. In this article, we propose a novel design to overcome this limitation, which exploits the polarization-dependent response of annular gratings embedded into a microring resonator to generate re-configurable CV beams. We demonstrate the viability of the device in a proof-of-principle experiment including spatially resolved Stokes measurements.