Rotating spintronic terahertz emitter optimized for microjoule pump-pulse energies and megahertz repetition rates

Abstract

Spintronic terahertz emitters (STEs) are powerful sources of ultra-broadband single-cycle terahertz (THz) field transients. They work with any pump wavelength, and their polarity and polarization direction are easily adjustable. However, at high pump powers and high repetition rates, STE operation is hampered by a significant increase in the local temperature. Here, we resolve this issue by rotating the STE at a few 100 Hz, thereby distributing the absorbed pump power over a larger area. Our approach permits stable STE operation at a fluence of ~1 mJ/cm${}^2$ with up to 18 W pump power at megahertz repetition rates, corresponding to pump-pulse energies of a few 10 $\mu$J and a power density far above the melting threshold of metallic films. The rotating STE is of interest for all ultra-broadband high-power THz applications requiring high repetition rates. As an example, we show that THz pulses with peak fields of 10 kV/cm can be coupled to a THz-lightwave-driven scanning tunneling microscope at 1 MHz repetition rate, demonstrating that the rotating STE can compete with standard THz sources such as LiNbO${}_3$.

15 pages, 4 figures, supplementary material included

References in corpus (8)

• Spintronic Sources of Ultrashort Terahertz Electromagnetic Pulses
• Enabling high repetition rate nonlinear THz science with a kilowatt-class sub-100 fs laser source
• Single-cycle, MHz-repetition rate THz source with 66 mW of average power
• Phase-resolved Detection of Ultrabroadband THz Pulses inside a Scanning Tunneling Microscope Junction
• Average power scaling of THz spintronic emitters in reflection geometry
• 1-MHz operation of 1.7-cycle multiple plate compression at 35-W average output power
• Spintronic emitters for super-resolution in THz-spectral imaging
• Femtosecond Thermal and Nonthermal Hot Electron Tunneling inside a Photoexcited Tunnel Junction

Cited by in corpus (4)

• A 2D van der Waals Material for Terahertz Emission with Giant Optical Rectification
• Ultrafast Electron Temperature Dynamics in Spintronic Terahertz Emitters Studied by Optical-Pump Terahertz-Probe Spectroscopy
• Laser-driven few-cycle Terahertz sources with high average power
• High-efficiency Pt${}_{75}$Au${}_{25}$-based spintronic terahertz emitters