Ultrabroadband single-cycle terahertz pulses with peak fields of 300 kV cm$^{-1}$ from a metallic spintronic emitter

TL;DR

This paper demonstrates a metallic spintronic emitter capable of generating ultrabroadband, single-cycle terahertz pulses with peak fields of 300 kV/cm, covering a spectrum from 1 to 10 THz, enabling advanced nonlinear matter control.

Contribution

It introduces a novel metallic spintronic thin-film stack as a broadband terahertz source with high peak fields and ultrashort pulse duration, expanding the capabilities of terahertz generation.

Findings

Peak terahertz field of 300 kV/cm achieved.

Spectrum extends from 1 to 10 THz without gaps.

Pulse duration of 230 fs demonstrated.

Abstract

To explore the capabilities of metallic spintronic thin-film stacks as a source of intense and broadband terahertz electromagnetic fields, we excite a W/CoFeB/Pt trilayer on a large-area glass substrate (diameter of 7.5 cm) by a femtosecond laser pulse (energy 5.5 mJ, duration 40 fs, wavelength 800 nm). After focusing, the emitted terahertz pulse is measured to have a duration of 230 fs, a peak field of 300 kV cm$^{-1}$ and an energy of 5 nJ. In particular, the waveform exhibits a gapless spectrum extending from 1 to 10 THz at 10% of amplitude maximum, thereby facilitating nonlinear control over matter in this difficult-to-reach frequency range and on the sub-picosecond time scale.