Integrated devices based on spin-orbit photonics.
In recent years several breakthrough have been achieved in wavefront shaping owing to the technological advances in metasurface fabrication. This has led to the whole new field of planar optics wherein the phase and polarization of the beam can be modified due to the Geometric Phase associated with the inhomogeneous distribution of the individual nanostructures. Several novel devices have been proposed, but all these devices work mainly in the plane-wave approximation, i.e., propagation length is much shorter than the Rayleigh length. However many of the integrated photonic devices, including the fundamental component, a waveguide works at lengths much larger than the Rayleigh length. This Project aims to study novel integrated photonic devices based on spin-orbit interactions in anisotropic materials with an inhomogeneous distribution of optic axis resulting in Pancharatnam-Berry Phase (PBP). Tailoring the PBP it is possible to guide light in the absence of any gradient in refractive index, the latter conventionally employed in standard photonic waveguides. In this Project novel integrated photonic components and devices with new functionalities based on PBP will be developed, e.g, directional couplers, polarization-dependent routers, PBP based resonators, fully exploiting the vectorial nature of light by coupling its spin and angular momenta. The Project will mainly focus on liquid crystals where the optic axis can be easily tailored to obtain the desired transverse patterns. However, other materials like structured photopolymer, structured vertical cavity surface emitting laser will also be considered. In the nonlinear regime light itself writes an inhomogeneous distribution of the optic axis resulting in dynamic integrated devices which will be then polymerized to freeze them permanently. Summarizing, the Project will disclose new scenarios for linear and nonlinear integrated optics and enable light guiding and signal routing in structured anisotropic media.