Bound states in the continuum in waveguide arrays within a symmetry classification scheme

Area of Science:

• Photonics
• Waveguide Optics
• Theoretical Physics

Background:

• The Fano-Anderson model describes resonant phenomena in quantum systems.
• Waveguide arrays are crucial for integrated photonic devices.
• Bound states in the continuum (BIC) are exotic states with potential applications.

Purpose of the Study:

• To investigate a modified Fano-Anderson model in a photonic waveguide array.
• To explore the spectral and scattering properties of this system.
• To establish conditions for the existence of bound states in the continuum (BIC).

Main Methods:

• Coupled mode theory was used to analyze spectral and scattering properties.
• Eigenmodes were classified based on structural symmetry.
• Full-wave simulations verified theoretical predictions.
• Weierstrass factorization theorem was applied to interpret scattering spectra.

Main Results:

• Conditions for bound states in the continuum (BIC) were established.
• Eigenmodes were classified by vertical symmetry.
• Fano resonance was explained by the interference of quasi-BIC and leaky modes.
• Theoretical predictions were validated by rigorous simulations.

Conclusions:

• The study provides a theoretical framework for understanding BICs and Fano resonances in waveguide arrays.
• The findings contribute to the design of novel photonic devices.
• The interplay between symmetry, eigenmodes, and resonance phenomena is highlighted.