An ultrasensitive angular interrogation metasurface sensor based on the TE mode surface lattice resonance.

Area of Science:

• Nanophotonics and Plasmonics
• Optical Sensing Technologies
• Metasurface Engineering

Background:

• Localized surface plasmon resonance (LSPR) metasurfaces enhance nanoscale light-matter interactions but lack the sensitivity of prism-coupled surface plasmon polaritons (SPPs).
• Existing angular sensing methods often suffer from sensitivity loss at larger angles.

Purpose of the Study:

• To propose and demonstrate an ultrasensitive angular interrogation sensor.
• To leverage the transverse electric mode surface lattice resonance (SLR) mechanism in all-metal metasurfaces for enhanced sensing.
• To investigate the influence of the air-solution interface refraction on SLR position and sensitivity.

Main Methods:

• Theoretical derivation of the sensitivity function, emphasizing the refraction effect at the air-solution interface.
• Experimental implementation using an all-metal metasurface and the SLR mechanism.
• Utilizing a broadband light source for angular sensing and defining the measured SLR wavelength at normal incidence.

Main Results:

• The proposed SLR sensor demonstrates significantly improved sensitivity performance over a wide angle.
• The experimental sensitivity achieved is 4304.35°/RIU, an order of magnitude higher than SPP sensors.
• The use of broadband illumination and normal incidence measurement avoids sensitivity loss associated with large angles.

Conclusions:

• The study presents a novel theory and a practical approach for achieving ultrasensitive angular sensing.
• The all-metal metasurface based on SLR offers a promising platform for high-performance refractive index sensing.
• This work advances the field of nanoscale optical sensing with enhanced sensitivity and practical measurement strategies.