Hybrid Nanodisk Film for Ultra-Narrowband Filtering, Near-Perfect Absorption and Wide Range Sensing.

Wenli Cui,Jean-Francois Masson,Huixuan Gao,Shuwen Chu,Wei Peng,Xiaolin Luo,Li Yu

doi:10.3390/nano9030334

Abstract

The miniaturization and integration of photonic devices are new requirements in the novel optics field due to the development of photonic information technology. In this paper, we report that a multifunctional layered structure of Au, SiO2 and hexagonal nanodisk film is advantageous for ultra-narrowband filtering, near-perfect absorption and sensing in a wide refractive index (RI) region. This hexagonal nanostructure presented two remarkable polarization independent plasmon resonances with near-zero reflectivity and near-perfect absorptivity under normal incidence in the visible and near-infrared spectral ranges. The narrowest full width at half maximum (FWHM) of these resonances was predicted to be excellent at 5 nm. More notably, the double plasmon resonances showed extremely obvious differences in RI responses. For the first plasmon resonance, an evident linear redshift was observed in a wide RI range from 1.00 to 1.40, and a high RI sensitivity of 600 nm/RIU was obtained compared to other plasmonic nanostructures, such as square and honeycomb-like nanostructures. For the second plasmon resonance with excellent FWHM at 946 nm, its wavelength position almost remained unmovable in the case of changing RI surrounding nanodisks in the same regime. Most unusually, its resonant wavelength was insensitive to nearly all structural parameters except the structural period. The underlying physical mechanism was analyzed in detail for double plasmon resonances. This work was significant in developing high-performance integrated optical devices for filtering, absorbing and biomedical sensing.

Highlights

Surface plasmon polaritons (SPPs) are electromagnetic waves propagating at a metal dielectric interface [1], for which resonance arises in a metallic sub-wavelength structure due to localized SPPs or propagative SPPs
We systematically investigated the use of a layered structure of Au, SiO2 and hexagonal array of Au nanodisks, which can perform well in refractive index (RI) sensing, ultra-narrowband filtering and near-perfect absorption simultaneously, compared to other nanostructures such as square and honeycomb-like nanostructures
We revealed that the first plasmon resonance was associated with a metal–solution interface and was very sensitive to RI, while the second sharp plasmon resonance was mainly associated with propagative surface plasmons (PSPs) of the inner Au film and an optical magnetic resonance of the dielectric interlayer, insensitive to RI

Summary

Introduction

Surface plasmon polaritons (SPPs) are electromagnetic waves propagating at a metal dielectric interface [1], for which resonance arises in a metallic sub-wavelength structure due to localized SPPs or propagative SPPs. Nanodisks are simple to fabricate with a series of photolithography and colloidal lithography techniques [12] They have been shown to possess excellent optical properties for sensing [13], filtering [14], and near-perfect absorption [15]. We systematically investigated the use of a layered structure of Au, SiO2 and hexagonal array of Au nanodisks, which can perform well in refractive index (RI) sensing, ultra-narrowband filtering and near-perfect absorption simultaneously, compared to other nanostructures such as square and honeycomb-like nanostructures. The tuning of the structure parameters on the reflection spectra for dual plasmon resonances was subsequently investigated This nanostructure can integrate a wide variety of functions into a single device, and can be applied in the development of double-channel narrowband filtering, plasmonic narrow spectral absorbers, chemical sensing and biomedical diagnostics

Structure and Characterization

Conclusion

Conclusions