# Transformation Optics for Plasmonics: from Metasurfaces to Excitonic Strong Coupling

## TL;DR

This paper reviews how Transformation Optics can be used to analyze and design plasmonic metasurfaces and nanocavities, highlighting advances in broadband absorption and strong coupling at the single emitter level.

## Contribution

It provides a comprehensive overview of the application of Transformation Optics to plasmonics, including design strategies for metasurfaces and analytical treatment of strong coupling phenomena.

## Key findings

- Design of broadband absorbing plasmonic metasurfaces
- Quasi-analytical description of plasmon-exciton strong coupling
- Framework for analytical modeling of sub-wavelength phenomena

## Abstract

We review the latest theoretical advances in the application of the framework of Transformation Optics for the analytical description of deeply sub-wavelength electromagnetic phenomena. First, we present a general description of the technique, together with its usual exploitation for metamaterial conception and optimization in different areas of wave physics. Next, we discuss in detail the design of plasmonic metasurfaces, including the description of singular geometries which allow for broadband absorption in ultrathin platforms. Finally, we discuss the quasi-analytical treatment of plasmon-exciton strong coupling in nanocavities at the single emitter level.