Frustrated Total Internal Reflection: Resonant and Negative Goos-H\"anchen Shifts in Microwave Regime

TL;DR

This paper investigates resonant and negative Goos-H"anchen shifts in microwave frustrated total internal reflection systems, revealing frequency-dependent resonances and negative shifts linked to specific material and structural configurations.

Contribution

It introduces new observations of resonant and negative GHSs in microwave FTIR setups, expanding understanding of wave behavior at interfaces in this regime.

Findings

GHSs show periodic resonances with frequency and air layer thickness.

Negative GHSs observed with TE polarization in FSS-based FTIR system.

Resonant GHSs are not directly correlated with reflected energy variations.

Abstract

It is well-known that the variations of Goos-H\"anchen shifts (GHSs) are closely associated with the enengy-flux provided by evanescent states in the case of total internal reflection. However, when the frustrated internal total reflection (FTIR) is realized with a Polymethyl Methacrylate (PMMA) double-prism system operated in the microwave frequency range of 8.2 GHz to 12.4 GHz, we observe that the GH shifts for the reflected beam show periodic resonances with varying the operation frequency or the air layer thickness, which is different from the variation of the corresponding reflected energy. Moreover, in another FTIR based system introduced by a composite absorptive material slab with a two-dimensional top layer of frequency selective surface (FSS), the GHSs for reflected beam are discovered as not only resonant but also negative with the incidence of transverse electric that is TE polarized.