“…Two-dimensional PCs are of great interest in research as they possess ultra-high light confinement compared with 1D PCs and are easier to fabricate and have a simpler design than 3D PC structures. Two-dimensional PC-based optical devices, such as optical sensors [12][13][14], strain sensors [15], filters [16,17], switches [18,19], demultiplexers [20,21], power splitters [22] and optical directional couplers [23], have been reported previously.…”