Fig. 2: Photonic band gaps in Yukawa-potential amorphous structures.

a Scanning electron micrograph (SEM) of an amorphous nanostructure with T^* = 0.2, r = 110 nm, and h = 220 nm, fabricated onto a silicon-on-insulator (SOI) wafer. Scale bar: 1 μm. Insets show zoom-in SEMs of two structures with r = 110 nm (top left) and r = 120 nm (bottom right). Scale bars: 250 nm. b Comparison of transmission spectra of the PhC and amorphous structure with the same thickness and hole radius and with T^* = 0.4. The latter are calculated for propagation along the x- and y-axes. The right y-axis indicates the transmission in arbitrary units for the PhC band gap (green) scaled to show the match between amorphous and PhC band gaps. The cyan shade is a marker for the band gap region of the reference photonic crystal. c Measured transmission spectra corresponding to YPAS with T^* = 0.2 and hole radius of top: 110 nm and middle: 120 nm, and with T^* = 0.4 and bottom: 120 nm respectively. The blue and black lines are the experimentally measured spectra in x- and y- directions and smoothed via Savitsky-Golay filtering; the red line is the numerically computed spectra by importing the actual fabricated structure in the software. The cyan shade is a marker for the band gap region. d Computed band gap dependence on T^*, where the line bars indicate the region of suppressed transmission according to 10-dB fall-off from the dielectric and air band lev- els, while the circle pointer shows the minimum transmission point. The dotted line is a guide to the eye. In the inset, the transmission spectra determined for different values of T^* are shown by stacking each line, whose y-axis values correspond to transmission in arbitrary values, with the same scale for each line. The PhC slab corresponds to T^* = 0 and for comparison purposes, the spectrum in this case and in b is determined by averaging the PhC spectra over the propagation directions.