Quadruple Fano resonances in MIM waveguide structure with ring cavities for multisolution concentration sensing

Area of Science:

• Plasmonics
• Nanophotonics
• Optical Sensing

Background:

• Metal-insulator-metal (MIM) waveguides are crucial for developing advanced optical devices.
• Fano resonances offer sharp spectral features desirable for sensing applications.
• Achieving multiple, independently tunable Fano resonances is a key challenge in integrated optics.

Purpose of the Study:

• To propose and investigate a novel MIM waveguide structure for quadruple Fano resonances.
• To demonstrate the independent tunability of Fano resonance wavelengths.
• To explore the application of this structure for refractive index and multi-solution concentration sensing.

Main Methods:

• Numerical simulations of a proposed MIM waveguide structure.
• Design incorporating a side-coupled elliptical cavity, two half-ring cavities, and a bus waveguide with a circular barrier.
• Analysis of Fano resonance characteristics and sensing performance.

Main Results:

• Successfully generated quadruple Fano resonances in the MIM waveguide structure.
• Demonstrated near-independent tuning of resonant wavelengths by adjusting cavity parameters.
• Achieved a maximum refractive index sensitivity of 1048.6 nm/RIU.
• Showcased simultaneous sensing of plasma, glucose, and NH4Cl concentrations with distinct sensitivities.

Conclusions:

• The proposed MIM waveguide structure effectively produces quadruple Fano resonances with tunable properties.
• The structure exhibits high sensitivity and linearity for refractive index sensing.
• The demonstrated multi-solution concentration sensing capability highlights its potential for complex analytical tasks.
• This work contributes to the advancement of integrated optical sensing technologies using MIM waveguides.