8 th International conference on Research in Engineering, Science and Technology Paris, France November2-4, 2018 166 Design of photonic crystal microcavity side- coupler to a waveguide based pressure sensor Chayma Mosbah 1 , Ahlem Benmerkhi 1 , Mohamed Bouchemat 1 , and Touraya Bouchemat 1 1 Frères Mentouri Constantine1 University, Department of electronics, Laboratory L.M.I Constantine, Algeria Abstract A novel design of two-dimensional photonic crystal pressure sensor based on microcavity coupled to waveguide is proposed. This sensor consists of photonic crystal microcavity side-coupler to a waveguide. The complex of microcavity and waveguide are formed by removing one hole, and eliminating the central row of holes, respectively. The radius of the holes localized in next alternating holes along the waveguide is changed, in order to enhance the quality factor and sensitivity. Then we applied the different pressures from 1 to 6 GPa by 1 GPa increment at each step. By using finite difference time domain method method, the simulation results demonstrate that when the pressure change the resonant wavelength shifts, the transmission efficiency is varied and quality factor increase. Keywords: Photonic crystal, microcavity, waveguide, pressure sensor, sensitivity Introduction Photonic crystals (PhCs) have very important properties for realization of future and active optical devices [1], such as: optical filters [2], optical switches [3], multiplexers [4], demultiplexers [5] sensors [6] and fibers [7]. Photonic crystal (PhC) is a periodically arranged dielectric material. The periodic variation of the refractive index gives rise to a unique band structure, and may have a Photonic Band Gap (PBG) [1,8]. PBG have properties to control and guide the electromagnetic wave at the scale of optical wavelength [9]. Among the optical devices, PhC based sensors are more attractive in research and scientific community due to their ultra-compact size, high sensitivity [10]. Sensor devices is employed for several sensing application such as: refractive index [11], temperature