Fig. 3: Transmittance via FTIR micro-spectroscopy.
From: Deeply subwavelength mid-infrared phase retardation with α-MoO3 flakes
a Schematic of the beam path of the FTIR microscope and sample in transmission mode, including sketches of the polarization state of the incoming and outgoing light. b Transmittance spectra of α-MoO3 on a Si substrate. T∥ and T⊥ represent the transmittance with parallel and perpendicular output polarizer, respectively, where both are normalized to the transmittance of the bare silicon substrate. Inset shows the height profile of the flake measured using AFM. c α-MoO3 flake thickness d plotted against maximum conversion wavelength. The data point obtained from the spectrum in Fig. 3b is highlighted with the arrow. The background color map shows TMM calculations of the ER, the solid light blue curve represents linear-to-linear conversion (e = 1), the dashed black contours mark areas where ψ is within ± 5∘ (inner contour line) and ± 10° (outer contour line) from ψ = 90∘, and the green dots are experimental data. d Highest conversion ratio extracted from the same flakes as in c, with thicknesses shown in the upper panel.
