Adapting terahertz spintronic emitters towards maximum performance

The boom in terahertz technologies of the last few decades is now not limited to the use of electric charge, but also fully exploits spin. Revolutionary spintronic terahertz emitters (STEs) offer versatile usage under a wide range of visible and infrared excitation wavelengths, arbitrary reflection/transmission excitation geometries, and utilization with most femtosecond oscillators and amplifiers. STE emission results in a 30THz-broad and gapless spectrum with easily controllable polarization. However, the optical-to-terahertz conversion efficiency is lower than traditional THz sources. Here, we demonstrate experimentally the enhancement of factor 6 in STEs power, which is the highest improvement nowadays. We integrate STEs with our optimized photonic cavities and provide procedures on how to dramatically increase efficiency.