All-optical control of surface plasmons by second-harmonic generation

TL;DR

This paper demonstrates a theoretical method for controlling surface plasmon polaritons using second-harmonic generation, enabling unidirectional plasmon launching and potential applications in nanodevices for information transmission.

Contribution

It introduces a novel all-optical control technique for surface plasmons using nonlinear frequency mixing in a simple slit-based metal film system.

Findings

Unidirectional surface plasmon launching achieved through nonlinear interference.

Efficient generation of second harmonic fields in metal via optical nonlinearities.

Potential for nanodevices to encode digital information in plasmon fields.

Abstract

Light with light control of surface plasmon polaritons is theoretically demonstrated. A barely simple and compact source of these waves consists in a finite number of slits (evenly spaced) perforating a metal film. The system scatters electromagnetic fields in one side of the metal film when it is illuminated from the opposite side by a polarized light source. High intensity light sources moreover efficiently generate light at second harmonic and higher frequencies in the metal led by optical nonlinearities. It is shown how the mixing of fields scattered by the slits from a weak beam at $\lambda$ wavelength, with the second harmonic fields generated by a high intensity $2 \lambda$ beam, creates a destructive interference of surface plasmons in one of the two possible directions of emission from the slits, while these are enhanced along the opposite direction. The unidirectional launching of surface plasmons is due to the different properties of symmetry at $\lambda$ whether they are linearly or nonlinearly generated. It is envisaged a nanodevice which might allow sending digital information codified in the surface plasmon field or be used to build ultra-narrow bandwidth surface plasmon frequency combs.