OICC Press Journal of Theoretical and Applied Physics 2251-7235 20 2 2026 04 30 Ultra-Compact and Highly Sensitive Pressure Sensor Based on a 2D Photonic Crystal Square-Ring Resonator for High-Pressure Range (0 to 10 GPa) 10.57647/jtap.2026.2002.13 EN Elhachemi Kouddad Telecommunication and Digital Signal Processing Laboratory, Department of Telecommunications, Faculty of Electrical Engineering, University Djillali Liabes, Sidi-Bel-Abbes 22000, Algeria; Department of Electrical Engineering, Faculty of Science and Technology. University of Adrar 01000, Algeria https://orcid.org/0000-0001-8983-5634 Hassan Dahbi Department of Electrical Engineering, Faculty of Science and Technology. University of Adrar 01000, Algeria Sououdi Boumediene Chabani Department of Electrical Engineering, Faculty of Science and Technology. University of Adrar 01000, Algeria Islam Hassani Department of Electrical Engineering, Faculty of Science and Technology. University of Adrar 01000, Algeria; Sustainable Development and Informatics Laboratory (LDDI), University of Adrar, Algeria Nourddine Kaddouri Department of Electrical Engineering, Faculty of Science and Technology. University of Adrar 01000, Algeria Journal Article 2026 04 30 This study presents an optical platform for pressure sensing based on a square-ring resonator. Numerical simulations reveal a shift in the resonant frequency towards lower frequencies, concomitantly with a shift in the resonant wavelength towards higher wavelengths, in response to an increase in applied pressure. Two simulation methodologies, the plane wave expansion (PWE) method and the finite-difference time-domain (FDTD) method, were employed to extract the guided mode and analyze the functional characteristics of the proposed sensor under varying pressure constraints. The envisioned structure is distinguished by a high-quality factor, a sensitivity of approximately 4.39 nm/GPa over a dynamic range from 0 to 10 GPa, and an ultra-compact footprint of 274 μm². These properties render this structure particularly suitable for integration into microscale photonic integrated circuits.