Flat Helical Nanosieves

TL;DR

This paper demonstrates a nanosieve-based approach for full manipulation of optical vortices, enabling complex light control in ultrathin devices through geometric phase modulation of spin light, with potential applications in nano-photonics and integrated optics.

Contribution

It introduces a novel nanosieve design that achieves comprehensive optical vortex control, including generation, hybridization, and focusing, using over 121,000 spatially-rotated nano-sieves for geometric phase manipulation.

Findings

Achieved full manipulation of optical vortices using nanosieve-based devices.

Enabled native interference measurement without traditional interferometry.

Bridged singular optics and integrated optics with ultrathin, flexible elements.

Abstract

Compact and miniaturized devices with flexible functionalities are always highly demanded in optical integrated systems. Plasmonic nanosieve has been successfully harnessed as an ultrathin flat platform for complex manipulation of light, including holography, vortex generation and non-linear processes. Compared with most of reported single-functional devices, multi-functional nanosieves might find more complex and novel applications across nano-photonics, optics and nanotechnology. Here, we experimentally demonstrate a promising roadmap for nanosieve-based helical devices, which achieves full manipulations of optical vortices, including its generation, hybridization, spatial multiplexing, focusing and non-diffraction propagation etc., by controlling the geometric phase of spin light via over 121 thousands of spatially-rotated nano-sieves. Thanks to such spin-conversion nanosieve helical elements, it is no longer necessary to employ the conventional two-beam interferometric measurement to characterize optical vortices, while the interference can be realized natively without changing any parts of the current setup. The proposed strategy makes the far-field manipulations of optical orbital angular momentum within an ultrathin interface viable and bridges singular optics and integrated optics. In addition, it enables more unique extensibility and flexibility in versatile optical elements than traditional phase-accumulated helical optical devices.