High-transmission linear-to-circular polarization converter based on a polymer relief grating structure

Area of Science:

• Optics and Photonics
• Electromagnetism
• Materials Science

Background:

• Polarization manipulation of sub-terahertz (sub-THz) waves is crucial for advanced communication and sensing technologies.
• Existing polarization converters often face limitations in cost, performance, or bandwidth.

Purpose of the Study:

• To develop a simple, cost-effective, and high-performance transmissive polarization converter for sub-THz waves.
• To demonstrate its functionality as a quarter-wave plate and explore its potential for other polarization manipulations.

Main Methods:

• Design and fabrication of a transmissive-type polarization converter using a polymer relief grating.
• Development of a new synthetic criterion and formulae for polarization converter design.
• Utilized modified polarimetry measurements with terahertz time-domain spectroscopy (THz-TDS).

Main Results:

• Achieved high transmittance (>96.99%) and polarization conversion ratio (>97.29%) at 140 GHz (D-band).
• Demonstrated high ellipticity (0.97 ± 0.03) over a wide bandwidth (28.57%).
• Validated converter's ability to function as an attenuator or half-wave plate when cascaded.

Conclusions:

• The polymer relief grating offers a promising, high-performance solution for sub-THz wave polarization control.
• The developed converter is versatile and can be extended to other frequency regimes.
• The proposed design and measurement methods provide valuable tools for sub-THz optics.