Engineering the Losses and Beam Divergence in Arrays of Patch Antenna Microcavities for Terahertz Sources

Abstract

We perform a comprehensive study on the emission from finite arrays of patch antenna microcavities designed for the terahertz range by using a finite element method. The emission properties including quality factors, far-field pattern and photon extraction efficiency are investigated for etched and non-etched structures as a function of the number of resonators, the dielectric layer thickness and period of the array. In addition, the simulations are achieved for lossy and perfect metals and dielectric layers, allowing to extract the radiative and nonradiative contributions to the total quality factors of the arrays. Our study show that this structure can be optimized to obtain low beam divergence (FWHM <10°) and photon extraction efficiencies >50% while keeping a strongly localized mode. These results show that the use of these microcavities would lead to efficient terahertz emitters with a low divergence vertical emission and engineered losses.

Monolithic Patch-Antenna THz Lasers with Extremely Low Beam Divergence and Polarization Control

“…Details about the fabrication process are presented in Methods. As shown in our previous numerical work, 21 periodic arrays formed by a large number of patch resonators provide enhanced quality factors compared to the low-Q single resonator allowing self-lasing from the patch. The square microresonators are connected along one direction by subwavelength wires of length d and width of 2 μm.…”

Patch Antenna Microcavities THz Quantum Cascade Lasers

“…However, the use of DM microcavities for emitters has been challenging due to the low photon out-coupling efficiency and extreme divergence of the far-field radiation inherent to the strong confinement in the DM microcavity. Recently we have studied numerically the possibility to use arrays of patch antenna microcavities (PAMs) to overcome those limitations [6]. Here we present a study on the emission properties of arrays of PAMs based on quantum cascade (QC) active regions.…”