CROW-based Fano structures for all optical switching devices

Area of Science:

• Photonics and Optical Engineering
• Nanophotonics
• Waveguide Devices

Background:

• Fano resonances (FRs) are crucial for optical switching applications.
• Coupled resonator optical waveguides (CROWs) offer a platform for manipulating light.
• Existing Fano switch designs may lack steepness and asymmetry.

Purpose of the Study:

• To present an improved optical Fano switch design utilizing CROWs.
• To achieve steeper and highly asymmetric Fano resonances.
• To demonstrate an ultra-compact device application based on the proposed Fano structure.

Main Methods:

• A novel topological design for CROW-based structures.
• Utilizing the variational theorem to explain the origin of FRs.
• Numerical finite difference time domain (FDTD) simulations.
• Comparison with theoretical coupled mode theory (CMT).

Main Results:

• The proposed CROW-based design achieves steeper and highly asymmetric Fano resonances.
• Tuning the number of nanocavities in CROWs improves the Fano spectrum.
• An improvement of 55.25% in the slope ratio to linewidth was observed from single to CROW5.
• Successful demonstration of an ultra-compact device utilizing the CROW-based Fano structure.

Conclusions:

• The improved CROW-based optical Fano switch design enhances Fano resonance characteristics.
• The number of nanocavities is a critical parameter for optimizing Fano spectrum performance.
• The proposed structure shows significant potential for ultra-compact photonic device applications.