Terahertz epsilon-near-zero graded-index lens

Area of Science:

• Electromagnetics
• Metamaterials
• Optics

Background:

• Epsilon-near-zero (ENZ) materials offer unique electromagnetic properties.
• Graded-index lenses are crucial for controlling wave propagation.
• Minimizing reflection losses is essential for efficient optical devices.

Purpose of the Study:

• To propose and analyze a novel epsilon-near-zero (ENZ) graded-index converging lens with planar faces.
• To demonstrate control over phase front and minimize Fresnel reflection losses.
• To validate the design through theoretical analysis and numerical simulations.

Main Methods:

• Theoretical analysis using waveguide theory and Fermat's principle.
• Design of a lens composed of perfectly-electric conducting (PEC) waveguides with varying cross-sections.
• Numerical simulations of 2D and 3D lenses in the terahertz regime.

Main Results:

• Individual control of propagation constant and normalized characteristic impedance for each waveguide.
• Achieved desired phase front at the lens output with minimized Fresnel reflection losses.
• Good agreement between theoretical predictions and numerical simulation results.

Conclusions:

• The proposed ENZ graded-index converging lens offers an effective method for terahertz wave manipulation.
• The design enables precise control over wave propagation and reduces energy loss.
• This work provides a foundation for developing advanced terahertz optical components.