Fig. 6: Extracting ϵ(ω) of α-MoO₃ along the y-direction.

a FTIR-measured reflectance spectra for polarizer angles ψ = 90° (y-axis, red curve) and ψ = 45° with respect to the x-axis (blue curve), for the flake shown in Fig. 5a. b,c Extracted real and imaginary parts of the refractive index, n_y(ω) and k_y(ω) respectively as a function of frequency. The data points corresponding to the flake shown in Fig. 5a are marked as red and blue circles whereas the black data points correspond to flakes of other thicknesses. The error bars in panels (b) and (c) indicate the estimation error on n_y(ω_d) and k_y(ω_d,RB) respectively.