Broadband circularly polarizing dichroism with high efficient plasmonic helical surface

Area of Science:

• Plasmonics and Nanophotonics
• Optical Metamaterials
• Mid-Infrared Optics

Background:

• Circular polarization dichroism (CPD) is crucial for various optical applications.
• Existing broadband circular polarizers often face challenges in efficiency and fabrication complexity.
• Plasmonic nanostructures offer tunable optical properties for polarization control.

Purpose of the Study:

• To propose and demonstrate a novel, simple, and efficient broadband circular polarizer.
• To investigate the performance of single-cycle, single-helical plasmonic surfaces for CPD.
• To explore the impact of gold film coverage on CPD characteristics.

Main Methods:

• Fabrication of single-cycle, single-helical plasmonic surface arrays using 3D laser writing.
• Deposition of gold films (partial and complete coverage) onto helical structures.
• Experimental characterization of circular polarization dichroism in the mid-infrared range (3-5 µm).
• Comparison of experimental results with electromagnetic simulations.

Main Results:

• Achieved high circular polarization dichroism up to 80% with partially gold-covered helical surfaces.
• Demonstrated significant CPD of 65% with completely gold-covered helical surfaces.
• Experimental CPD values showed excellent agreement with simulation predictions.
• The proposed structure exhibits broadband operation in the mid-IR spectrum.

Conclusions:

• The single-cycle, single-helical plasmonic surface is a highly efficient broadband circular polarizer.
• The design offers advantages in ease of fabrication and scalability to other frequencies.
• This plasmonic structure represents a promising platform for advanced polarization optics.