Self-referenced refractive index sensor based on hybrid mode resonances in 2D metal-dielectric grating

Abstract

In this paper, we propose a refractive index sensor with self-reference performance based on a two-dimensional grating structure, mainly consisting of periodic arrays of triple layer dielectric nanodisks and a continuous substrate separated by a thin gold film. Three reflection dips are observed and manipulated to realize self-reference and high sensing performance due to the excitation of magnetic dipole mode resonance, substrate mode resonance and metal layer assisted guide mode resonance. These hybrid modes have been explained by the distributions of the electric and magnetic fields in the nanostructure. A detailed analysis of the influences of material thickness on the optical properties of the proposed refractive index sensor is also investigated. Moreover, the proposed refractive index sensor demonstrates a high sensing performance, an important application for future biomedical applications, with a bulk refractive index sensitivity of 672 nm RIU −1 (RIU: refractive index unit) and figure of merit of 1050 RIU −1 . Importantly, the function of self-reference is realized simultaneously. Finally, it also shows excellent sensing performance, with the maximum value exceeding 168 000 by measuring the light intensity change in the reflected light at a certain wavelength. This makes it much more suitable for applications in the field of portable detection.

Polarization‐independent dual narrow‐band perfect metamaterial absorber for optical communication

“…To more clearly understand this physical phenomenon, displacement current density distributions were also described in Figure 4 by black arrows. The distribution of the electric field and the magnetic field is characterized by the magnetic dipole resonance 40,41 . Figure 4A explains that the displacement current forms a closed loop from the silicon nano‐disk to the interface between the dielectric layer and the gold layer, and the magnetic field is mainly localized in the center of the Si disk and the dielectric layer.…”

“…The distribution of the electric field and the magnetic field is characterized by the magnetic dipole resonance. 40,41 Figure 4A explains that the displacement current forms a closed loop from the silicon nano-disk to the interface between the dielectric layer and the gold layer, and the magnetic field is mainly localized in the center of the Si disk and the dielectric layer. The magnetic dipole as described above can couple the incident waves into surface plasmon-polaritons (shown in Figure 4B) when the resonance conditions are met, resulting in an absorption peak at a resonance wavelength of 1550 nm.…”

A Self-Referenced Refractive Index Sensor Based on Gold Nanoislands

“…Independently of the principle (SPP or LSP) on which a plasmonic RI sensor is based, external factors, such as vibrations and intensity fluctuations, may affect the sensing accuracy. To mitigate this issue, a variety of self-referenced RI plasmonic sensors have been proposed [ 31 , 32 , 33 , 34 , 35 , 36 ]. These are mostly based on the generation of independent multiple resonances with different sensitivities to the refractive index of the surrounding medium.…”

“…In intensity interrogation schemes, self-referencing is typically achieved by obtaining the quotient between the intensities of two resonances, both equally affected by light intensity fluctuations. Reported self-referenced plasmonic RI sensors include prism-based configurations [ 31 , 32 ] and grating-based structures [ 33 , 34 , 35 , 36 ]; however, to our knowledge, no self-referenced RI sensors based on metal nanoislands have been reported so far.…”

Dual‐channel glucose concentration sensor based on coupled cross‐stacked gratings

“…10 However, the two channels were overlapping partly, which made bad effect on distinguishing the two channels, decreasing the sensing performance. In 2019, a self-referenced RI sensor based on two-dimensional metaldielectric grating showed that the sensitivity of the first and third channel reached to 672 and 445 nm/RIU, which were about 15 and 10 times than that of the second channel, 11 respectively. Nevertheless, such a structure brought difficulty for the detection due to the fact that the reflectivity of the second channel is no more than 50%.…”