We analyze the characteristics of plasmonics-based enhancement of a wire-grid polarizer (WGP) by rigorous coupledwave analysis (RCWA). We consider blazed WGP (bWGP) for improvement of polarimetric performance based on plasmonic momentum-matching in the metal/dielectric interface. The analysis used a model of triangular wire-grids approximated with five graded layers of identical thickness. We have compared the performance to that of a conventional WGP (cWGP) with a corresponding lamellar grating shape profile. As a performance measure, we calculated transmittance (TR) and extinction ratio (ER). It was found that TR in both cases tends to decrease monotonically with a longer period (Λ). The maximum TR of bWGPs is lower than cWGPs. On the other hand, maximum ER of bWGPs is much higher than that of cWGPs, particularly at a longer period, with an extinction peak peaked at Λ = 800 nm. For cWGPs, an extinction peak is observed at Λ = 200 nm with comparable enhancement (~42 dB). We have also computed relative TR (RTR) and relative ER (RER) for assessment of performance relative to cWGP. RTR decreases slowly in a manner similar to TR, however, RER increases exponentially with a longer wire-grid period. The results suggest that strong localization of near-fields observed with bWGPs can be used to improve polarimetric performance of a WGP.
In this report, we describe improvement of image resolution in surface plasmon resonance microscopy (SPRM) which suffers from poor quality due to severe surface plasmon (SP) propagation. Our approach takes two-channel momentum sampling by switched light incidence followed by minimum filtering to implement spatially switched SPRM (ssSPRM). The performance evaluated with periodic wires in comparison with conventional SPRM and bright-field microscopy shows that the effect of SP propagation can be circumvented and the effective decay length of SPRM is calculated to increase by only 7% compared to that of bright-field images.
Plasmonic optical trapping allows trapping and manipulation of micro- and even nanometer-sized particles using localized and enhanced electric fields by plasmon resonance in metallic nanostructure. We consider an optical conveyor belt consisting of an array of nanodisks acting as optical tweezers with different sizes to implement a system to trap and manipulate particles through a laser-induced gradient force. An electric field induced and localized at each optical resonator is sensitive to the wavelength and polarization. The maximum electric field is enhanced at resonant wavelength depending on the shape and size of the plasmonic nanostructure used for light localization. By changing the light wavelength and polarization, the position of localized light induced in the disk can be determined and nanoparticles can be moved to a desired location through the variation of resonance conditions without any mechanical forces.