Polarisation insensitive multifunctional metasurfaces based on all-dielectric nanowaveguides

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metasurfaces, or 2D metamaterials, offer precise control over electromagnetic wave properties like amplitude, phase, and polarization.
• Current research seeks cost-effective, efficient, low-loss, and polarization-insensitive metasurface applications.
• Hydrogenated amorphous silicon (a-Si:H) presents a promising dielectric material with low visible light absorption for on-chip photonic devices.

Purpose of the Study:

• To design and demonstrate an ultra-thin, cost-effective, and polarization-insensitive metasurface for simultaneous phase control.
• To utilize hydrogenated amorphous silicon (a-Si:H) for enhanced performance in the visible spectrum.
• To integrate lens and helical beam phase profiles for generating optical vortices with orbital angular momentum.

Main Methods:

• Fabrication of an ultra-thin transmissive metasurface using hydrogenated amorphous silicon (a-Si:H).
• Utilizing the principle of index waveguiding to achieve precise phase manipulation.
• Designing the metasurface to incorporate dual phase profiles (lens and helical beam).

Main Results:

• Demonstration of an ultra-thin metasurface capable of simultaneous phase control.
• Achieved polarization-insensitivity, enhancing versatility for various applications.
• Generation of highly concentrated optical vortices in the visible domain with focused, ring-shaped profiles carrying orbital angular momentum.

Conclusions:

• Hydrogenated amorphous silicon (a-Si:H) is a viable, cost-effective material for advanced metasurface applications.
• The proposed metasurface design enables miniaturized on-chip generation of optical vortices.
• This work advances the development of polarization-insensitive, multifunctional photonic devices.