A highly sensitive optofluidic-gas sensor using two dimensional photonic crystals

Photonic crystals (PCs) are optical structures based on periodic arrays of dielectric materials. These structures enable the manipulation of photons as semiconductors do for electrons. Many optical devices with miniature sizes have been designed based on novel properties of PCs. In this paper, we proposed a new refractive index sensor with high sensitivity and high quality factor, which is implemented in a two dimensional PC with a hexagonal lattice structure. The proposed sensor has been constructed using a PC waveguide surrounded by two rows of ring-shaped holes. The emersion of Fabry-Perot interference pattern within the transmission band and its role in the determination of the features of the proposed refractive index sensor has been investigated. The finite-difference time-domain simulation results indicate that in the case of filling the holes of central waveguide and its surrounding ring-shaped holes by different materials with refractive indices from n = 1 to n = 1.5, a high sensitivity of 575 nm/RIU and a high quality factor of 7070 is achieved, which makes the proposed design applicable for liquid and also gas sensing.