High-Q multimodal guided-surface lattice resonances in index-discontinuous environments

Area of Science:

• Metasurfaces
• Nanophotonics
• Optical Engineering

Background:

• Surface lattice resonances (SLRs) are crucial for subwavelength optical devices.
• Existing high-quality factor (high-Q) SLR methods require homogeneous dielectric environments, limiting their application.
• This limitation hinders the development of advanced optical devices and sensors.

Purpose of the Study:

• To introduce guided-surface lattice resonances (gSLRs) as a novel approach to overcome the environmental limitations of traditional SLRs.
• To demonstrate high-Q multimodal resonances in index-discontinuous environments using gSLRs.
• To explore the application of gSLRs in sensitive biosensing platforms.

Main Methods:

• Integrating nanoparticle arrays within slab waveguides to create gSLRs.
• Analyzing the coupling between scattered light and Bloch modes.
• Modulating resonance properties by adjusting nanoparticle array vertical displacement.
• Investigating gSLRs in metasurfaces with metallic substrates for enhanced sensitivity.
• Developing and validating a mathematical sensing model including biochemical kinetics.

Main Results:

• Achieved high-Q multimodal resonances (Q-factor of 1489) in index-discontinuous environments.
• Demonstrated continuous modulation of coupling strength and resonance intensity.
• Validated gSLRs for biosensing with a limit-of-detection as low as 0.65 pM for Bovine Serum Albumin (BSA).

Conclusions:

• gSLRs offer a robust platform for high-Q optical resonances independent of homogeneous dielectric environments.
• The tunable nature of gSLRs allows for precise control over optical properties.
• gSLRs integrated with metallic substrates show significant promise for highly sensitive biosensing applications.