Abstract
The miniaturization and integration of photonic devices are new requirements in the fast-growing optics field. In this paper, we focus on a feature-rich sub-wavelength nanograting-coated single-layer metal film. The numerical results show that the reflection behaviors of this proposed structure can realize bidirectional dual-channel ultra-narrowband polarized filtering and bidirectional wavelength-modulated sensing in a wide refractive index (RI) range from 1.0 to 1.4 for incident angle of 10° with transverse-magnetic (TM) polarized illumination at wavelengths between 550 nm to 1500 nm. Moreover, the bidirectional properties of filtering and sensing are not obviously decreased when increasing incident angle from 10° to 30°, and decreasing incident angle from 10° to 0°. The calculated RI sensitivity can be up to 592 nm/RIU with a high figure of merit (FOM) of 179.4 RIU−1. More to the point, this nanograting has a simple structure and is less sensitive to the height and shape of grating ridge, which provides great convenience for the fabrication of devices. The other thing that is going on is that this structure can also realize synchronously tunable color filtering, including green to red, with high color purity in the visible band by choosing the period. The underlying physical mechanism is analyzed in detail, and is primarily attributed to surface plasmon polariton (SPP) resonance and dipole resonance at double plasmon resonance wavelengths. This work has tremendous potential in developing multipurpose and high-performance integrated optical devices such as spectral filters, colored displays and plasmon biomedical sensors.
Highlights
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.license.In recent years, the various plasmonic nanostructures have drawn great attention in applications such as thermal emitters [1], color filters [2,3,4], solar cells [5,6], chemical and biological sensors [7,8,9], imaging devices [10,11,12], etc
The underlying physical mechanism is analyzed in detail, and is primarily attributed to surface plasmon polariton (SPP) resonance and dipole resonance at double plasmon resonance wavelengths
It can perform well in bidirectional ultra-narrowband polarized filtering, wide-range refractive index (RI) sensing for wavelength modulation with TM polarized illumination at incident angle of 10◦
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The various plasmonic nanostructures have drawn great attention in applications such as thermal emitters [1], color filters [2,3,4], solar cells [5,6], chemical and biological sensors [7,8,9], imaging devices [10,11,12], etc Among these nanostructures, periodic nanogratings are playing a crucial role in this rapidly growing plasmonics research field [13,14,15]. We present a feature-rich sub-wavelength nanograting-coated singlelayer metal film It can perform well in bidirectional ultra-narrowband polarized filtering, wide-range RI sensing for wavelength modulation with TM polarized illumination at incident angle of 10◦. To trace its physical origin, SPP resonance and dipole resonance play key roles This structure is promising for multifunctional integrated applications in multispectral filtering, colored displays and plasmon biomedical sensing
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