Broadband all-dielectric meta-devices for visible perfect vortex beams generation

Conventional optical elements are typically designed for a specific wavelength and have limited functionality, hindering their practical applications and integration with on-chip devices. Recently developed artificially engineered structures overcome this constraint but at the cost of added design complexity. Here, we present broadband single-layered metadevices capable of integrating multiple functionalities that generate nondiffracting perfect vortex beams for visible wavelengths (475 to 650 nm). To realize highly efficient all-dielectric meta-devices, zinc sulfide material is exploited due to its large transparent window with a sufficiently high refractive index in the visible regime. The nondiffracting response provides a significantly long propagation distance without abrupt divergence. Moreover, shorter optical wavelengths provide more data bandwidth when mixed with a high topological charge (n = 8) of the perfect vortex beam, which paved the path towards the realization of numerous applications such as optical tweezing, quantum information processing, and optical communication.