Polarization-controlled confined Tamm plasmon lasers

The polarization of light represents the orientation of the vibration of the light wave. It is a property which is intrinsic to the transverse nature of electromagnetic waves, and, as such, it carries information. Polarized coherent light sources, as lasers for example, are always needed in different domains of photonics, such as spectroscopy and optical communications. In this context, the authors have realized a new hybrid metal/semiconductor micro-laser emitting linearly polarized coherent light. This has been made possible thanks to the exploitation of the confinement of Tamm plasmon modes by means of an anisotropic geometry of rectangular shape. Tamm plasmons are surface optical modes existing at the interface between a metallic film and a multilayer dielectric stack, namely, a distributed Bragg reflector. They feature optical properties in between cavity modes and surface plasmon modes, and they have the great advantage of being very easily laterally confined just by acting on the metallic part of the structure. In this work, the authors have demonstrated that an anisotropic confinement of Tamm plasmon modes allows for the existence of energy-split polarized modes, which lead to a single mode laser emission with a degree of linear polarization in excess of 90%, given that a good tuning between the Tamm mode and the gain medium is achieved.