High-efficiency radiation beyond the critical angle via phase-gradient antireflection metasurfaces

Area of Science:

• Optics and Photonics
• Metamaterials Science

Background:

• Total internal reflection (TIR) typically confines electromagnetic waves at incident angles exceeding the critical angle in higher refractive index dielectrics.
• Conventional TIR limits efficient wave transmission between media with significant refractive index differences.

Purpose of the Study:

• To overcome the limitations of total internal reflection and achieve high-efficiency transmission.
• To demonstrate a metasurface-based solution for controlling electromagnetic wave propagation beyond the critical angle.

Main Methods:

• Design of a phase-gradient antireflection metasurface on a dielectric surface.
• Application of the reciprocity principle to circumvent traditional TIR limitations.
• Verification through electromagnetic simulations and microwave experiments.

Main Results:

• Achieved high-efficiency transmission beyond the critical angle.
• Demonstrated compensation for transverse wave vectors and impedance mismatch.
• Showcased flexibly-controlled wavefronts for transmitted waves.

Conclusions:

• The developed metasurface effectively transforms total internal reflection into high-efficiency transmission.
• This technology opens new avenues for high-efficiency radiation manipulation.
• Potential applications include waveguide-to-free-space couplers, quantum dots, and light-emitting diodes.