Strong light-matter coupling in SiGe quantum wells embedded in terahertz patch antenna cavities

We aim at the demonstration of the strong-coupling limit of radiation-matter interaction in terahertz cavities containing SiGe heterostructures that realize parabolic quantum wells. We show by FTIR spectroscopy that SiGe parabolic quantum wells display high-quality intersubband transition lineshapes at 2.7 THz. We have fabricated terahertz cavity arrays with a plasmonic heavily-doped Ge ground plane and we have measured patch antenna resonances in the 3 to 5 THz range.