Terahertz room-temperature integrated parametric source (TREASURE)
The European Commission supports a research project focused on the development of an electrically driven terahertz source, operating at room temperature. This pan-european project involves partners from University Paris Diderot, Wurzburg University, Commissariat à l’Energie Atomique (CEA), Technical University of Denmark and Alpes Lasers. The project is known as TREASURE – Terahertz room-temperature integrated parametric source.
Our role in the TREASUE project is the investigation of mechanisms for efficient coupling of THz radiation from the source, a wavelength-sized microring resonator, to a collimated free-space beam with well-controlled polarization.
The TREASURE device itself is a microring laser based on stimulated emission from semiconductor quantum dots operating in the near-IR. The optical modes in this cavity are whispering gallery modes. Two modes within the gain bandwidth of the quantum dot active medium are selected, and nonlinear interaction between the two modes in the microring laser leads to generation of radiation at the difference frequency, which falls in the THz frequency range.
In the figure below you see the calculated modal pattern of the m = 4 THz mode of the device, oscillating at 5.18 THz. One of the challenges of the project is to design a geometry which allows efficient coupling of this highly symmetric mode into a forward-propagating plane wave with good beam profile and directivity.
The project TREASURE acknowledges the financial support of the Future and Emerging Technologies (FET) programme within the 7th Framework Programme for Research of the European Commission, under FET-Open grant number: 250056.