Ultrahigh FOM and multiple Fano resonances in MIM waveguide systems with half-ring and rectangular cavities

In this study, a metal-insulator-metal (MIM) waveguide with two silver baffles was coupled with a half-ring cavity. Eight Fano resonances were formed. Subsequently, three rectangular cavities were introduced into the initial structure, and 10 Fano resonances were formed. A U-shaped cavity was added to the structure, and 12 Fano resonances were formed. In addition, a wavelength range with a good Fano line shape was selected, and the generation mechanism of Fano resonance within this wavelength range was studied. Furthermore, the effects of different structural parameters on the Fano resonance curve as well as the sensitivity and figure of merit (FOM) of the structure were analyzed. The maximum sensitivity was 2200 nm/RIU, and the maximum FOM value was 7.7 x 10(5). By adding ethanol to the structure, the structure could be used as a temperature sensor with a sensitivity of 0.9 nm/degrees C. Owing to these excellent properties, this structure has potential applications in optical switching, filters, and sensors.

Automated summary

In this study, a metal-insulator-metal (MIM) waveguide with two silver baffles was used to create a series of Fano resonances. Additional rectangular and U-shaped cavities were introduced to create more resonances. The generation mechanism, effects of structural parameters, and potential applications in optical devices were studied. The structure showed high sensitivity and figure of merit (FOM) values, making it suitable for optical switching, filters, and sensors.