Unlocking complex optical vortices with flat optics

Area of Science:

• * Photonics and Optics
• * Metamaterials and Nanophotonics

Background:

• * Optical vortices (OVs) with orbital angular momentum (OAM) are crucial for high-dimensional information encoding.
• * Traditional OV generation methods suffer from bulky setups, high costs, and limited control.
• * Optical metasurfaces present a compact, cost-effective, and controllable alternative.

Purpose of the Study:

• * To review advanced metasurface platforms for manipulating optical vortices.
• * To discuss emerging complex OV types and nonlinear metasurface techniques.
• * To highlight progress and challenges in OAM detection and high-capacity systems.

Main Methods:

• * Review of optical metasurface designs for OV generation and manipulation.
• * Discussion of various complex OV structures (composite, grafted, comblike, multispectral, arbitrary shapes).
• * Analysis of nonlinear metasurface approaches for OV generation.

Main Results:

• * Metasurfaces enable compact and versatile generation of diverse optical vortices.
• * Progress in OAM detection and mode discrimination is reviewed, identifying challenges for high-capacity systems.
• * Key applications include OAM-based holography, super-resolution microscopy, structured-light trapping, and quantum state engineering.

Conclusions:

• * Metasurfaces are a transformative technology for advanced optical vortex manipulation.
• * Significant challenges remain in high-capacity OAM systems and nonlinear metasurface applications.
• * Future prospects involve further development of metasurface-enabled OV technologies for diverse applications.