Otimização estrutural de sensores ópticos baseados em moléculas fotônicas: mitigação da dependência térmica para aplicações de alta precisão

Abstract

Optical sensors based on resonant microcavities have gained prominence by combining high sensitivity with strong potential for integration on silicon photonic platforms. However, temperature variations can induce spectral shifts of the resonances, introducing uncertainties that degrade the repeatability and accuracy of refractive-index measurements. In this context, this dissertation investigates a passive approach to mitigate thermal dependence through structural optimization of a photonic-molecule-based sensor, with emphasis on the trade-off between sensitivity and thermal stability. The adopted methodology combines modeling and computational simulations to systematically assess how geometric modifications influence the device spectral response under controlled temperature variation and under different external-medium conditions. Resonances are identified across the spectrum, and thermal drift is quantified, enabling comparison of trends among configurations and the definition of consistent metrics for stability and detection performance. Beyond the physical analysis, practical aspects related to implementation feasibility and typical fabrication constraints in integrated photonics foundries are discussed, bringing the study closer to realistic deployment scenarios. The results show that structural modifications can reduce the thermal sensitivity without compromising refractive-index sensitivity, indicating that the thermal response is predominantly governed by the device geometry and the modal field distribution. It is also observed that specific geometric choices lead to distinct trade-off behaviors between stability and sensitivity, allowing the identification of configurations that perform better under each criterion and highlighting a potentially more balanced configuration.