“…Photonic crystals (PhCs) [5,6] are formed by periodically arranging different materials at the scale of wavelength, which can prohibit the propagation of light beam within a certain frequency scope and it is known as photonic bandgap (PBG). The PhC defects (formed by changing the shape, size and position of the scattereres at certain region) can localize photons and form the localized modes at the particular frequencies within PBG, and it is extensively applied in various optical devices, such as waveguides [7,8], splitters [9][10][11], filters [12,13], sensors [14][15][16][17]. In recent years, the biosensors based on PhC defects have attracted much attention due to their advantages of high sensitivity, fast response, no label, no pollution, high selectivity, high safety and so on [18,19].…”