Figure 4
From: Fabry-Perot cavity resonance enabling highly polarization-sensitive double-layer gold grating
(a) Colormap of the round-trip propagation phase, γ, as a function of wavelength, λ, and BCB thickness, tBCB, for TM-polarized incident light. The white dash-dot lines indicate where the FP cavity resonance condition of \(\gamma =-\,2\pi ,\,-\,4\pi ,\,-\,6\pi \) is satisfied. Colormaps of (b) TM transmission (red dash line represents the first-order SPP resonance at the interface of the lower Au grating/Si) and (c) extinction ratio obtained by CST-simulation of the entire double-layer Au grating structure (blue regions of A1, A2, A3 have low extinction ratio due to the transmission peaks for TE-polarized light). The black-horizontal lines in (a–c) denote the double-layer Au grating with tBCB = 0.25 μm.
