Tunable ultrabroadband hybrid THz emitter combining a spintronic THz source and a GaSe crystal

TL;DR

This paper presents a hybrid THz emitter combining spintronic sources and GaSe crystals, achieving ultrabroadband, tunable, high-amplitude THz spectra from 1 to 40 THz with ultrashort pulses and controllable phase.

Contribution

It introduces a novel hybrid THz emitter that enables tunable, ultrabroadband THz generation with high spectral amplitude and ultrashort pulse duration, advancing THz spectroscopy capabilities.

Findings

Achieved continuous 1-40 THz spectrum with high amplitude.

Generated ultrashort 32 fs THz pulses.

Demonstrated tunable carrier-envelope phase control.

Abstract

Linear terahertz time-domain spectroscopy (THz-TDS) is a sensitive probe for material characterization including thickness measurements of thin layers. These applications critically rely on a sufficiently large bandwidth, which is not straightforwardly available in typical THz-TDS systems. Here, we introduce a hybrid THz-emitter concept based on a spintronic THz emitter that is deposited onto a thin freestanding GaSe nonlinear crystal. By tuning the parameters of this hybrid emitter, we generate an ultrabroadband spectrum covering the full range from 1 to 40 THz without any gaps at high spectral amplitudes, resulting in ultrashort THz-pulse durations of only 32 fs. Finally, we demonstrate the straightforward tunability of the carrier-envelope phase from unipolar or bipolar THz pulses with ultrashort duration.