Phase behavior near total absorption by a metallic grating.

Area of Science:

• Physics
• Optics
• Electromagnetism

Background:

• Metallic gratings exhibit complete absorption of specific diffracted orders when illuminated by S-polarized electromagnetic waves.
• This phenomenon is associated with two distinct experimental behaviors near resonant anomalies.

Purpose of the Study:

• To investigate the phase behavior of cycloidal metallic gratings with varying groove-depth-to-period ratios.
• To explain the experimentally observed behaviors near resonant anomalies using electromagnetic theory.
• To provide additional insights into the zeros of the scattering matrix in the complex plane.

Main Methods:

• Utilizing an exact differential method for precise calculations.
• Analyzing phase versus angle-of-incidence curves.
• Employing an algorithm based on the electromagnetic theory of gratings.

Main Results:

• Calculated phase versus angle-of-incidence curves for cycloidal metallic gratings.
• Demonstrated that the grating theory algorithm accurately models experimentally observed resonant anomaly behaviors.
• Identified the significance of scattering matrix zeros in the complex plane.

Conclusions:

• The electromagnetic theory of gratings effectively explains resonant anomalies in metallic gratings.
• The study provides a theoretical framework for understanding complete absorption phenomena.
• Analysis of scattering matrix zeros offers deeper insights into grating electromagnetics.