Fig. 1: Truncated two-dimensional (2D) photonic crystal (PhC) structure, supporting edge bound state in the continuum (BIC).
From: Observation of edge bound states in the continuum at truncated silicon pillar photonic crystal
a Top and (b) birds-eye-view of scanning electron microscope (SEM) images of Si pillar PhCs and ridge waveguides after the deposition of 7.3 nm thick alumina film. The white dashed box corresponds to the inset of SEM image (black dashed box). Si pillars with 1.5 μm height lie on approximately 0.9 μm SiO2 pillars. c The design of Si pillar PhC system and Si ridge waveguides on silicon on insulator (SOI) wafer (top view). The PhC structures under consideration have a lattice constant (period) of a = 600 nm, diameter Dt = 260 nm for the terminating layer and D = 160 nm for the rest of Si pillars, height H = 1.5 μm. The number of periods along the x- and y-axis is Nx = 33 and Ny = 15, including the terminating layer, giving the Si pillar PhC area of 19.8 × 9.0 μm. d Schematic illustration of the experimental setup for end-fire coupling to measure transmission spectra through 2DPhC (side view). Coupling and out-coupling of light is done by polarization-maintaining (PM) fibers. The width of both Si ridge waveguides is w = 1.0 μm, and their lengths are approximately 4 mm long for both input and out-coupling parts.
