A High-Sensitivity Refractive-Index Sensor Based on Plasmonic Waveguides Asymmetrically Coupled with a Nanodisk Resonator

A high-sensitivity plasmonic refractive-index sensor based on the asymmetrical coupling of two metal-insulator- metal waveguides with a nanodisk resonator is proposed and simulated in the finite-difference time domain. Both analytic and simulated results show that the resonance wavelengths of the sensor have an approximate linear relationship with the refractive index of the materials which are filled into the slit waveguides and the disk- shaped resonator. The working mechanism of this sensor is exactly due to the linear relationship, based on which tile refractive index of the materials unknown can be obtained from the detection of the resonance wavelength. The measurement sensitivity can reach as high as 6.45 × 10-7, which is nearly five times higher than the results reported in the recent literature [Opt. Commun. 300 （2013） 265]. With an optimum design, the sensing value can be further improved, and it can be widely applied into the biological sensing. Tile sensor working for temperature sensing is also analyzed.

Design and applications of lattice plasmon resonances

With their unique optical properties associated with the excitation of surface plasmons, metal nanoparticles （NPs） have been used in optical sensors and devices. The organization of these NPs into arrays can induce coupling effects to engineer new optical responses. In particular, lattice plasmon resonances （LPRs）, which arise from coherent interactions and coupling among NPs in periodic arrays, have shown great promise for realizing narrow linewidths, angle-dependent dispersions, and high wavelength tunability of optical spectra. By engineering the materials, shapes, sizes, and spatial arrangements of NPs within arrays, one can tune the LPR-based spectral responses and electromagnetic field distributions to deliver a multitude of improvements, including a high figure-of-merit, superior light-matter interaction, and multiband operation. In this review, we discuss recent progress in designing and applying new metal nanostructures for LPR-based applications. We conclude this review with our perspective on the future opportunities and challenges of LPR-based devices.

Distributed parametric modeling and simulation of light polarization states using magneto-optical sensing based on the Faraday effect

To solve the problems encountered in practical processes of magneto-optical sensing, the infinitesimal distributed-parameter model and finite-element accumulation of different dielectric properties of micromaterials were used to describe the evolution of light polarization states, instead of the previously commonly used method of lumped-parameter simulation, thus essentially explaining the mechanism of sensing, magneto-optical effects, and related factors, and achieving multiphysics coupling using the COMSOL finite-element analysis method. Considering the cases of the Faraday effect without and with line birefringence, the magneto-optical effect and output characteristics of an infinitesimal magneto-optical sensor were simulated and studied. The results verified the effectiveness of the infinitesimal sensor model. Because the magnetic field, stress, and temperature changes alter the dielectric properties of magneto-optical materials, the finite-element accumulation method lays a good foundation for research on theoretical analysis and performance of magneto-optical sensors affected by factors such as the magnetic field, temperature, and stress.