Exploiting effective media to make meniscus lenses for surface plasmon polariton focusing

Here, we present the exploitation of classical optics techniques to design plasmonic meniscus lenses for focusing surface plasmon polaritons. To accomplish this, we adapted the lens maker equation to incorporate the effective refractive index of surface plasmon polaritons traveling in dielectric-dielectric-metal and dielectric-metal configurations. The device discussed here is designed using a silicon nitride meniscus-shaped block positioned on a semi-infinite gold slab with an operational wavelength of
$\boldsymbol{\lambda}_{\mathbf{0}}=\mathbf{633}\mathbf{nm}$
. The performance of the lens is then evaluated in terms of power enhancement, focal position, and transverse spatial resolution.