Parametrically Resonant Surface Plasmon Polaritons

The surface electromagnetic waves that propagate along a metal-dielectric or a metal-air interface are called surface plasmon polaritons (SPPs). However, as the tangential wavevector component is larger than what is permitted for the homogenous plane wave in the dielectric medium this poses a phase-matching issue. In other words, the available spatial vector in the dielectric at a given frequency is smaller than what is required by SPP to be excited. The most commonly known technique to bypass this problem is by using the Otto and Kretschmann configurations. A glass prism is used to increase the available spatial vector in dielectric/air. Other methods are evanescent field directional coupling and optical grating. Even with all these methods, it is still challenging to couple the SPPs having a large propagation constant.  

A novel way to efficiently inject the power into SPPs is via temporal modulation of the dielectric adhered to the metal. The dielectric constant is modulated in time using an incident pump field. As a result of the induced changes in the dielectric constant, spatial vector shortage is eliminated. In other words, there is enough spatial vector in the dielectric to excite SPPs. As SPPs applicability is widely studied in numerous applications, this method gives a new way of evoking SPPs. Hence, this technique opens new possibilities in the surface plasmon polariton study. One of the applications that we discuss in details is the optical limiting.