Highly efficient broadband double-sided Fresnel lens for THz range

Area of Science:

• Optics and Photonics
• Terahertz (THz) Technology

Background:

• Modern passive terahertz (THz) systems demand efficient optical components with high numerical aperture.
• Existing optical elements may not meet the combined requirements of performance, cost, and weight for THz applications.

Purpose of the Study:

• To propose and evaluate a new type of optical element for THz applications: a broadband double-sided Fresnel-like lens.
• To optimize the lens thickness for minimal attenuation, low material cost, and reduced weight.
• To achieve achromatic properties within the target THz wavelength range.

Main Methods:

• Design and theoretical optimization of a double-sided Fresnel-like lens structure.
• Material selection and thickness optimization for desired optical and physical properties.
• Experimental validation using time-domain spectroscopy (TDS).

Main Results:

• The proposed diffractive lens demonstrates broadband operation suitable for THz applications.
• Optimized thickness leads to significantly low signal attenuation and reduced physical weight.
• The lens exhibits achromatic characteristics across the specified THz spectrum.
• Experimental results from TDS confirm the theoretical predictions and performance.

Conclusions:

• The developed double-sided Fresnel-like lens is a promising optical element for passive THz setups.
• It effectively addresses the need for high-performance, cost-effective, and lightweight THz optical components.
• The lens's achromatic nature enhances its utility in broadband THz systems.