Optimization Of Coupling From A Sub-wavelength Metal Nanoaperture To A Gaussian Mode

We model the surface resonance effects in a 1D-array of corrugations on a metal-dielectric film with a sub-wavelength nanoaperture, following the earlier work by Moreno et-al [Moreno:2003]. We are interested in computing the coupling of the highly-directional light field emerging from the metal nanoaperture to the lowest-order Gaussian mode. We follow the approach by Vasilyev [Vasilyev:2005], to compute the coupling to a fundamental Gaussian mode.

We have developed an optimization routine to compute the field emission patterns from a metal nanoaperture, resonant wavelength and transmission coupling to fundamental Gaussian mode for various geometrical parameters of the metal nanoastructure. We optimize for maximum T (power transmittance to the lowest order mode) and T/L (ratio of transmittance to loss to higher order modes) assuming the zero absorption so that all reflected light can be potentially recycled in metal nanocavity.

This optimization work on the geometrical parameters of the cavity can be useful in fabricating a high Q cavity with desired resonant wavelength for the future construction of a high-efficiency single-photon emitter.