Refractive index sensing with optical bound states in the continuum.

Area of Science:

• Photonics and optical sensing
• Dielectric metamaterials
• Bound states in the continuum (BICs)

Background:

• Refractive index sensing is crucial for various applications, including chemical detection and disease diagnostics.
• Optical bound states in the continuum (BICs) offer unique properties for enhancing light-matter interactions.
• Dielectric gratings provide a versatile platform for manipulating light and creating BICs.

Purpose of the Study:

• To investigate the potential of optical BICs in dielectric gratings for high-sensitivity refractive index sensing.
• To derive analytical expressions for the sensitivity and figure of merit of BIC-based sensors.
• To propose an optimization design approach for engineering effective refractive index sensors.

Main Methods:

• Perturbative approach to analyze the spectral vicinity of BICs.
• Derivation of differential sensitivity and figure of merit.
• Numerical simulations to validate analytical results.
• Development of an optimization design strategy.

Main Results:

• An analytical formula for maximal sensitivity using optical BICs was derived.
• The differential sensitivity and figure of merit were calculated for BIC-based sensors.
• Numerical simulations confirmed the theoretical predictions.
• An optimization design approach was proposed.

Conclusions:

• Optical BICs in dielectric gratings are highly effective for refractive index sensing.
• The derived analytical formulas provide a basis for sensor design and optimization.
• The proposed optimization strategy enables the engineering of high-performance BIC-based sensors.