Plasmonic Sensors Based on Funneling Light Through Nanophotonic Structures

Abstract

We present a refractometric sensor realized as a stack of metallic gratings with subwavelength features and embedded within a low-index dielectric medium. Light is strongly confined through funneling mechanisms and excites resonances that sense the analyte medium. Two terminations of the structure are compared. One of them has a dielectric medium in contact with the analyte and exploits the selective spectral transmission of the structure. The other design has a metallic continuous layer that generates surface plasmon resonances at the metal/analyte interface. Both designs respond with narrow spectral features that are sensible to the change in the refractive index of the analyte and can be used for sensing biomedical samples.

Enabling selective absorption in perovskite solar cells for refractometric sensing of gases

“…Even more, in the design # III at λ =783 III nm, the spectral shift, λ Δ , is negligible and precludes its operation using spectral interrogation methods. This fact is in agreement with the physical interpretation of this peak as a selective transmitance through the slits 62 . The FOM results summarized in Table 2 are moderate compared with previously reported figures [1][2][3][4][6][7][8][9] .…”

“…The peak at λ III corresponds to the strongest field distribution at the active layer. However, as we will see when analyzing its behavior with respect to the index of refraction of the analyte, this peak does not shift significantly in wavelength when changing the index of refraction, and should not be caused by a plasmonic resonance but by selective transmission through the apertures 62 .…”

“…2c). The radiation at λ II funnels through the gap until reaching the active layer 62 . The peak at λ III corresponds to the strongest field distribution at the active layer.…”

Infrared plasmonic refractive index sensor utilizing 2D grating of nano-bowtie particles for both gas and liquid

“…In such a process, the wider interaction range between SPs and analytes means higher RI sensing sensitivity, and the narrower full width at half maximum (FWHM) of the resonance peak characterized by spectrum means higher detection accuracy. Tremendous works have been devoted to designing the plasmonic structures which can excite strong resonance intensity (high signal contrast) and narrow FWHM [17,[19][20][21][22][23][24][25][26][27][28][29][30][31]. Zhang et al proposed a LSP sensor with gold nanograting on the top of planar metallic film.…”

Funneling of Oblique Incident Light through Subwavelength Metallic Slits

“…As a near-surface effect, light funneling is the main mechanism [ 4 , 5 , 6 , 10 , 11 , 12 ] for the extraordinary optical transmission phenomenon, in addition to surface plasmonics [ 2 , 3 , 4 , 5 , 10 , 11 ], and Fabry–Pérot resonance [ 4 , 5 , 6 , 10 , 11 , 12 ]. The charges accumulate at an interrupted surface [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ] as illuminated by the incident light and draw the wave energy into its vicinity due to diffraction effects. The interaction between the incident fields and the radiation fields generated by the accumulated charge causes the incident energy to flow into the enhanced opening.…”