Topologically enabled ultrahigh-Q guided resonances robust to out-of-plane scattering

Area of Science:

• Photonics
• Condensed Matter Physics
• Optical Engineering

Background:

• Optical resonators are crucial for science and technology due to their light-confining abilities.
• Fabrication imperfections in optical resonators lead to out-of-plane scattering losses, limiting performance.
• Topological properties offer a new avenue for controlling light and mitigating losses.

Purpose of the Study:

• To theoretically propose and experimentally demonstrate a new class of guided resonances in photonic crystal slabs.
• To suppress out-of-plane scattering losses using the topological nature of these resonances.
• To enhance the quality factors (Q) of optical resonators for improved device performance.

Main Methods:

• Theoretical proposal of guided resonances arising from the merging of bound states in the continuum.
• Experimental demonstration in photonic crystal slabs.
• Characterization of resonance properties and quality factors in the telecommunication regime.

Main Results:

• Demonstrated suppression of out-of-plane scattering losses through topological effects.
• Achieved quality factors as high as 4.9 × 10^5 in the telecommunication regime.
• Observed a 12-fold enhancement in quality factors compared to standard designs, with robust performance across samples.

Conclusions:

• Topological guided resonances offer a robust method to significantly enhance optical resonator quality factors.
• This approach effectively mitigates scattering losses caused by fabrication imperfections.
• The findings pave the way for advancements in topological photonics and improved optoelectronic devices in photonic integrated circuits.