Theoretical Study of Transmission Characteristics of Sub-Wavelength Nano-Structured Metallic Grating

Xie

et al. 2014

SPIE Proceedings

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Interactions between different resonance modes in optoelectronic structures may introduce coupled modes that can be utilized to explore special optical functions that cannot be realized by conventional methods. A novel dual band filter based on sub-wavelength metal grating with groove caved in and waveguide layer below is proposed in this paper. The metal grating is caved with a groove in the middle of every metal trip, and a waveguide layer with higher refractive index is placed between the metal grating and glass substrate. Using the finite-difference time-domain (FDTD) method, we research the implied physical mechanism by investigating the transmission spectrum with the changing of the structural parameters and the electromagnetic field distributions at some specific wavelengths, such as peaks and valleys in the transmittance. In our simulation, we chose Ag as the grating material and Drude-Lorentz model is employ to describe the dielectric constant. It is found that the two resonance bands are determined by different structural parameters, which due to different mechanism, FP resonance and waveguide resonance, and we also take the groove cavity mode into account when the standing wave oscillates in the groove and result in the dips between two peaks. Besides, the most notable of these features is that the increase of the grating height doesn't shift these two resonance wavelength at all, and groove parameters only move the first peak wavelength regularly, which could be an excellent candidate for dual band filter in the telecom wavelengths. Our proposed structure with subwavelength may provide potential applications in optoelectronic devices.

Section: Results and Discussmentioning

confidence: 93%

Dual band filter based on subwavelength metal grating with groove caved in and waveguide layer below

Xie

et al. 2014

SPIE Proceedings

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“…1(a) except for a different incidence angle of 46.2 . These parameters are satisfied with surface plasmon excitation condition of the MG [11], [21] 2 n sl sin 1 À m 2 where m ¼ 1 is the diffraction order; n sl ¼ 1:42 is RI of dielectric layer; P ¼ 320 nm is metallic grating period; n sub ¼ 1:46 is RI of substrate; and " m is permittivity of metal silver [18]. At above resonance condition, the energy carried by the incident wave can be transferred to the SPPs, which propagates along the grating/dielectric interface.…”

Section: Resultsmentioning

confidence: 93%

Generation of Multiple Plasmon Resonances in a Nanochannel

Peng

et al. 2013

IEEE Photonics J.

In this paper, we investigate the coupling of surface plasmon based on Kretschmann configuration (KC) to localized and delocalized surface plasmon modes supported by metallic nanowire grating (MG) at the oblique incidence. The designed structure consists of MG deposited on a substrate positioned upside down above a conventional KC at a certain distance. Mode coupling and resonant interactions between KC and MG create two new hybrid plasmon modes with narrow bandwidths and unique spectra features, resulting in two obvious dips in the reflection spectrum. Although both dips respond nonlinearly to the refractive index (RI) of the dielectric layer, surprisingly, the sum of two resonance wavelengths has a good linear approximation in a wider RI range. The simultaneous measurement of two resonance dips makes it more attractive as a surface plasmon resonance analysis technology, which is valuable for high-sensitivity optical sensors.

“…In addition, this mode in the air slit can be considered as a Fabry-Perot cavity that possesses two mirrors of finite reflection at the end of the slit. Due to the symmetry structure with respect to a vertical mirror, the cavity mode bisects the middle section of slit 32–35 . The formation of cavity mode in the air slit leads to high transmission.…”

Section: Resultsmentioning

confidence: 99%

Free-standing plasmonic metal-dielectric-metal bandpass filter with high transmission efficiency

Zhang

Cao

et al. 2017

Sci Rep

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Plasmonic spectrum filtering devices based on metallic nanostructures have attracted wide attention due to their good reliability, ease of fabrication, and wideband tunability. However, the presence of thick substrate significantly limits the structure’s longitudinal size for further optoelectronic integration and reduces the devices’ performance. Here we propose and demonstrate an ultra-thin plasmonic bandpass filter based on free-standing periodic metal-dielectric-metal stack geometry working in the near-infrared wavelength range. The coupling between free-space electromagnetic waves and spatially confined plasmonic modes in the designed structure is systematically investigated. As demonstrated in the calculation and experiment, the free-standing plasmonic filters have more than 90% transmission efficiency and superior angular tolerance. The experimental results are in good agreement with the theoretical calculations. These artificial nanostructured filtering devices may find potential applications in the extremely compact device architectures.