Increasing terahertz spintronic emission with planar antennas

Spintronic THz emitters, consisting of Ta/Co/Pt trilayers patterned into lateral-sized rectangles in the 10 μm range, have been integrated in planar electromagnetic antennas of various types (dipole, bow-tie, and spiral). The antenna dimensions and shapes have been optimized with the help of electromagnetic simulations so as to maximize antenna efficiency in both narrow-band and broadband geometries at/around 1 THz. The THz emission has been studied using a pump–probe free space electro-optic sampling setup, both for single-emitter geometry and for arrays of emitters. The results show an increase in the detected THz signal for all antenna geometries, with enhancement ratios in the range of three to fifteen, depending on the antenna type and frequency range, together with changes in the emission bandwidth consistent with simulated characteristics.