Metamaterial for enhanced light-matter coupling

Patch-antenna metamaterial has already proven to be a successful way to improve the performances of quantum detectors up to room temperature and to simplify the light-matter coupling geometry required to satisfy the constraints imposed by inter-sub-band selection rules. However, this structure can be further optimised in order to maximise the absorption of the incoming light and minimise the losses of photons. The optimization strategy presented in this work focuses on the study of the empty cavities, that is the double metal resonators without active region enclosed inside. It aims to determine the optimal geometrical parameters to reach the critical coupling regime, investigating how the array periodicity and the cavity thickness affect the response of the system to the external radiation. The experimental characterization of the reflectivity of these structures has been complemented with Finite Element Method (FEM) simulations, which have proven to be a valuable tool to evaluate the response of a certain configuration as long as non-idealities of the real system are properly included in the simulated model. Thus, the response of an array of patch antennas filled with GaInAs/AlInAs heterostructure has been simulated as preliminary step before the fabrication of the actual device. The combination of the performances enhancement obtained with the patch-antenna metamaterial and an adequate design of the active region can lead to the implementation of integrated photonics, where a single device can have multiple functions.