Patch antenna microcavity terahertz sources with enhanced emission

• Published in: Applied physics letters Vol. 109; no. 14
• Main Authors: Madéo, J., Todorov, Y., Gilman, A., Frucci, G., Li, L. H., Davies, A. G., Linfield, E. H., Sirtori, C., Dani, K. M.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 03-10-2016
• Subjects: Antenna arrays; Applied physics; Electroluminescence; Emission analysis; Microcavities; Patch antennas; Periodic variations; Q factors; Terahertz frequencies
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4963891

We study the emission properties of an electroluminescent THz frequency quantum cascade structure embedded in an array of patch antenna double-metal microcavities. We show that high photon extraction efficiencies can be obtained by adjusting the active region thickness and array periodicity as well as high Purcell factors (up to 65), leading to an enhanced overall emitted power. Up to a 44-fold increase in power is experimentally observed in comparison with a reference device processed in conventional mesa geometry. Estimation of the Purcell factors using electromagnetic simulations and the theoretical extraction efficiency are in agreement with the observed power enhancement and show that, in these microcavities, the overall enhancement solely depends on the square of the total quality factor.