Broadband Spintronic Terahertz Source with Peak Electric Fields Exceeding 1.5 MV/cm

Spintronic terahertz emitters (STEs) are desirable broadband terahertz sources, but their limited signal strength has hindered practical application. By optimizing the photonic and thermal environment, the authors present an STE that could overcome this obstacle. Benchmarking against the state-of-the-art terahertz emitters based on optical rectification, this STE delivers strong terahertz pulses with comparable peak electric field and fluence, and offers additional features such as broadband radiation, easy alignment, and rotation of the terahertz polarization plane without power loss. This work will open up a promising pathway to nonlinear terahertz spectroscopy with spintronic sources.