Fig. 3: Tuning the HPhPs with periodic tuner patterns of different skew angles.
From: In-plane hyperbolic polariton tuners in terahertz and long-wave infrared regimes
a Schematic showing 1D periodic tuner patterns with a skew angle θ. b Experimental reflectance spectra of 1D periodic tuner patterns with different θ, showing that when θ increases, the resonance in Band 1 clearly blueshifts, whereas a reverse trend appears in Band 2, and a slow variation of the resonance occurs in Band 3. The widths of the ribbons are kept at w = 480 nm. The colored spheres depict the resonance frequencies. c HPhPs resonance frequency, ω0, as a function of θ, showing the consistence between the calculation and experimental results. The false color plot represents the calculated Imrp(θ, ω) of the air/α-MoO3/SiO2/Si multilayered structure. The colored spheres correspond to the experimental resonance peaks extracted from the curves in (b). d−f Polariton isofrequency contours (IFCs) at different frequencies in Band 1 (d), Band 2 (e), and Band 3 (f), respectively, showing clear hyperbola for Band 1 and 2, while an ellipse for Band 3. The false color plots represent the Imrp(ω, qPhPsx, qPhPsy). The colored spheres in the first quadrant represent the experimental resonance peaks at 695.0 ± 0.9, 738.0 ± 0.8, 773.0 ± 0.7, 851.0 ± 0.9, 870.0 ± 0.9, and 895.0 ± 0.9 cm−1. Spheres in other quadrants are duplicated according to the symmetry of the measurement scheme and the α-MoO3 crystal. The wavevectors in (c−f) are normalized by the thickness d of the α-MoO3 flake. Parameters qPhPsx and qPhPsy represent the x and y components of the polariton wavevector, respectively.
