Authors:	Vogel, Tim Omar, Alan Mansourzadeh, Samira Wulf, Frank Martín Sabanés, Natalia Müller, Melanie Seifert, Tom S. Weigel, Alexander Jakob, Gerhard Kläui, Mathias Pupeza, Ioachim Kampfrath, Tobias Saraceno, Clara J.
Title:	Average power scaling of THz spintronic emitters efficiently cooled in reflection geometry
Online publication date:	17-Oct-2022
Year of first publication:	2022
Language:	english
Abstract:	Metallic spintronic terahertz (THz) emitters have become well-established for offering ultra-broadband, gapless THz emission in a variety of excitation regimes, in combination with reliable fabrication and excellent scalability. However, so far, their potential for high-average-power excitation to reach strong THz fields at high repetition rates has not been thoroughly investigated. In this article, we explore the power scaling behavior of tri-layer spintronic emitters using an Yb-fiber excitation source, delivering an average power of 18.5 W (7 W incident on the emitter after chopping) at 4(X) kHz repetition rate, temporally compressed to a pulse duration of 27 fs. We confirm that a reflection geometry with back-side cooling is ideally suited for these emitters in the high-average-power excitation regime. In order to understand limiting mechanisms, we disentangle the effects on THz power generation by average power and pulse energy by varying the repetition rate of the laser. Our results show that the conversion efficiency is predominantly determined by the incident fluence in this high-average-power, high-repetition-rate excitation regime if the emitters are efficiently cooled. Using these findings, we optimize the conversion efficiency and reach highest excitation powers in the back-cooled reflection geometry. Our findings provide guidelines for scaling the power of THz radiation emitted by spintronic emitters to the milliwatt-level by using state-of-the-art femtosecond sources with multi-hundred-Watt average power to reach ultra-broadband, strong-field THz sources with high repetition rate.
DDC:	530 Physik 530 Physics
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 08 Physik, Mathematik u. Informatik
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-7932
Version:	Published version
Publication type:	Zeitschriftenaufsatz
Document type specification:	Scientific article
License:	CC BY
Information on rights of use:	https://creativecommons.org/licenses/by/4.0/
Journal:	Optic express 30 12
Pages or article number:	20451 20468
Publisher:	Optica
Publisher place:	Washington, DC
Issue date:	2022
ISSN:	1094-4087
Publisher DOI:	10.1364/OE.453539
Appears in collections:	JGU-Publikationen