Patch antenna microcavity arrays for THz sources*

Terahertz radiation has remained underexplored because of a lack of efficient sources and detectors while covering wide-ranging applications for imaging, security or wireless communications. Novel hybrid structures consisting in antenna-coupled microresonators have shown the possibility of confining THz radiation into subwavelength volumes (< 10^-5 λ³), combining enhanced light-matter interaction and antennas to in- or out-couple radiation [1]. We present a study based on finite element simulations of the THz emission from finite arrays of patch-antenna microcavities. Emission properties can be engineered solely with the design parameters of the array. By tuning them, the structure can provide a complete control on the radiative and non-radiative losses of the microresonators, low beam divergence (<FWHM 10°) and high photon extraction efficiencies (> 50%) [2]. We used this design to demonstrate experimentally strong enhancement of spontaneous emission from a quantum cascade active region. Our results pave the way in achieving THz lasers with low divergence, single mode operation and optimized losses. [1] J. Madéo,et.al., Appl.Phys.Lett.109,141103(2016) [2] J. Madéo,et.al J. Infrd Milli Terahz Waves,38:1321-1330(2017)