We investigate the characteristics of multi-mode resonances in T-shape air slots at terahertz frequencies. Our results show that the multimode resonance is caused by the structural complexity of the T-shape air slot resonators. Each resonance mode corresponds to a distribution of electric charges determined by the structural dimensions. Understanding the characteristics of multimode resonance may be useful for achieving versatile and custom-designed optical devices and realizing a wide variety of platforms with a high sensitivity for sensing biological materials.
