Final Report Summary - TASMANIA (Theoretical study of molecular spin plasmonics for nanoscale communIcations)
The further miniaturization of information processing devices and the emergent Networks-on-Chip, which facilitate the communication of multiple processor cores in a distributed architecture, require high-speed links at the nanoscale. The speed of electronic links is limited by dissipation losses while optical interconnects are limited in size by the wavelength of light. A possible solution is the use of surface plasmon polaritons, which are optically excited electromagnetic waves localized near the surface of a metallic conductor. They are attractive because of the very small length scales over which it is possible to localize the electromagnetic fields; the resulting large field strengths greatly enhance the scope for the manipulation of the excitations. In order however for plasmons to be useful for nano-scale communications we have to find ways of actively controlling their propagation.
A potential route for active control of plasmons is by using a magnetic field. The TASMANIA project aimed to study the nanoscale interaction of surface plasmon polaritons with magnetic materials. We investigated theoretically and numerically the optical properties and propagation of surface plasmons in magnetic waveguides and cavities consisting of a magnetic dielectric between two sheets of non-magnetic metal. At single magnetic interfaces surface plasmon waves propagate non-reciprocally i.e. the forward and backward waves have different speeds and hence different wavelengths at a given frequency. In a symmetric waveguide however we found that they exhibit reciprocal propagation; the non-reciprocity is manifested instead in the field profile having different distributions for the forward and backward propagating waves. The field profiles are also asymmetric i.e. they electric and magnetic fields are different at the top and bottom interfaces. This offers interesting possibilities to control light-matter interactions at the nanoscale with magnetic fields.
We have shown how the electric field asymmetry allows one to control the coupling of emitters inside a cavity and actively to switch it on and off. We have also demonstrated that both the total emission of radiation from the cavity, and the distribution of the far-field radiation, can be strongly modified by tuning the magnetization of the waveguide. These examples point to the possibility of using magnetic control to switch the propagation of fields in more complex photonics structures.
A potential route for active control of plasmons is by using a magnetic field. The TASMANIA project aimed to study the nanoscale interaction of surface plasmon polaritons with magnetic materials. We investigated theoretically and numerically the optical properties and propagation of surface plasmons in magnetic waveguides and cavities consisting of a magnetic dielectric between two sheets of non-magnetic metal. At single magnetic interfaces surface plasmon waves propagate non-reciprocally i.e. the forward and backward waves have different speeds and hence different wavelengths at a given frequency. In a symmetric waveguide however we found that they exhibit reciprocal propagation; the non-reciprocity is manifested instead in the field profile having different distributions for the forward and backward propagating waves. The field profiles are also asymmetric i.e. they electric and magnetic fields are different at the top and bottom interfaces. This offers interesting possibilities to control light-matter interactions at the nanoscale with magnetic fields.
We have shown how the electric field asymmetry allows one to control the coupling of emitters inside a cavity and actively to switch it on and off. We have also demonstrated that both the total emission of radiation from the cavity, and the distribution of the far-field radiation, can be strongly modified by tuning the magnetization of the waveguide. These examples point to the possibility of using magnetic control to switch the propagation of fields in more complex photonics structures.