Semnan University Press Journal of Modeling in Engineering 2008-4854 23 83 2025 12 22 Investigating the Effects of Increasing the Optical Path Length on the Optical Response of a Whispering Gallery Mode-Based Micro-Disk Resonator by Using Curved Waveguides Investigating the Effects of Increasing the Optical Path Length on the Optical Response of a Whispering Gallery Mode-Based Micro-Disk Resonator by Using Curved Waveguides 157 165 9716 10.22075/jme.2025.35597.2744 FA Fatemeh Aghaei Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran Saeed Golmohammadi Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran Hamid Bahador Department of Electrical and Computer Engineering, University of Mohaghegh Ardabili, Ardabil, Iran Hadi Soofi Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran Journal Article 2024 10 13 Nowadays, biosensors based on whispering gallery mode play a special role in optical sensors due to their simple theory and suitable optical response for single-molecule and single-virus detection. In the meantime, micro-disk resonators have received attention because of their low fabrication cost, high selectivity, and accuracy. In this work, we study the effects of the waveguide's shape and curvature on the micro-disk sensor's optical response based on whispering waves. The distance between waveguide and resonator effects on the sensor parameters has been investigated. Finally, the most suitable distance has been selected for the sensor's optimal performance. By improving the structure, the sensitivity for the first and second modes with a 180° curve to 50 nm/RIU and 52 nm/RIU and a 90° curve to 47nm/RIU and 48nm/RIU, respectively. The simulation results show that the greater the curvature of the waveguide, the longer the optical path length. Also, the sensor's performance is improved. This sensor can be used to detect single molecular particles in the medical and environmental fields. Nowadays, biosensors based on whispering gallery mode play a special role in optical sensors due to their simple theory and suitable optical response for single-molecule and single-virus detection. In the meantime, micro-disk resonators have received attention because of their low fabrication cost, high selectivity, and accuracy. In this work, we study the effects of the waveguide's shape and curvature on the micro-disk sensor's optical response based on whispering waves. The distance between waveguide and resonator effects on the sensor parameters has been investigated. Finally, the most suitable distance has been selected for the sensor's optimal performance. By improving the structure, the sensitivity for the first and second modes with a 180° curve to 50 nm/RIU and 52 nm/RIU and a 90° curve to 47nm/RIU and 48nm/RIU, respectively. The simulation results show that the greater the curvature of the waveguide, the longer the optical path length. Also, the sensor's performance is improved. This sensor can be used to detect single molecular particles in the medical and environmental fields. https://modelling.semnan.ac.ir/article_9716_d809468746c0e53ad04a47a16cc2b72b.pdf