Fano resonances of coupled magnetic-dipole modes in a dielectric triplet for precise discrimination of deep-subwavelength microspheres

Mie resonances in dielectric particles play a crucial role in light-matter interaction, characterized by strong multipolar optical responses and low dissipative losses. This study presents an innovative methodology for precise discrimination of the size and quantity of deep-subwavelength microspheres by leveraging Fano resonances in coupled magnetic-dipole (MD) modes of a CaTiO₃-ceramic-particle triplet. The multifaceted characteristics of coupled MD resonances exhibit high sensitivity and specificity in detecting minute changes in the ambient environment. The alignment of theoretical and experimental results demonstrates the reliability and accuracy of our approach, highlighting its versatility and adaptability. This principle of deep-subwavelength measurement can also be appreciated at the nanoscale, indicating great potential for its applications in biological detection, chemical sensing, and environmental monitoring. The multifaceted Fano resonances of coupled Mie dipole modes establish a robust framework for future research in real-time monitoring and precision detection.