Abstract. This paper introduces a proposal for a linearly width graded photonic crystal featuring a central defect layer specifically designed for sensing applications. The design entails incorporating alternating layers of a dielectric material onto a glass substrate. Introducing intentional porosity within each layer facilitates analyte infiltration and enhances sensitivity. Comprehensive analysis is conducted to optimize the number of the dielectric layers, their width, and the porosity percentage. A multilayer structure is constructed using porous silicon material. The porosity level and structural parameters are fine-tuned to achieve the highest attainable sensitivity. Influence of the type and width of the defect layer and the number of dielectric layers, along with the incidence angle, on sensor sensitivity, quality factor and detection limit are analyzed using the transfer matrix method. The sensitivities of the graded and non-graded structures are compared. The linearly graded geometry provides an average sensitivity of 786 nm/RIU with the average detection limit of 7.21×10^-3. Furthermore, the paper assesses different sensing parameters such as sensor resolution, detection limit, and signal-to-noise ratio, making the studied structure advantageous for sensor application.

Keywords: linear width grading, photonic crystal, sensors, sensitivity.

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