Design and Computational Study of a Two Dimensional Photonic Crystal Based Ethanol Sensor

This research article provides a computational study of light interaction with two dimensional photonic crystal (PhC) structure. This PhC structure is used to measure ethanol percentage in liquid water by identifying and computing mid gap wavelength shift. Analysis of the Maxwell's equations that govern the photon behaviour in the periodic structure is discussed in detail for PhC structures. The photonic band gap (PBG) which prohibits the photon momentum in certain directions in the crystal is computed using plane wave expansion (PWE) method by deriving solutions to the eigenvalue equation. A two dimensional (2D) PhC structure is designed by taking 18 × 17 number of holes on a dielectric slab. This holes on the dielectric configuration is used to sense the ethanol level in liquid water. The PBG width for the design in transverse electric mode is [ωa/2πc] ranging from 0.3841 to 0.4428. The band gap size Δλ 480 nm and mid gap wavelength λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf>= 2391.2 nm is achieved from the structure. The sensor achieves a sensitivity of 10645.24 nm/RIU and a transmission ratio more than 94%. This structure is a suitable candidate for ethanol sensing applications as it offers a wide bandgap for light propagation.