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Spintronic terahertz emitters with integrated metallic terahertz cavities

Authors :
Mičica Martin
Wright Adrien
Koleják Pierre
Lezier Geoffrey
Postava Kamil
Hawecker Jacques
De Vetter Anna
Tignon Jerome
Mangeney Juliette
Jaffres Henri
Lebrun Romain
Tiercelin Nicolas
Vanwolleghem Mathias
Dhillon Sukhdeep
Source :
Nanophotonics, Vol 13, Iss 10, Pp 1899-1907 (2024)
Publication Year :
2024
Publisher :
De Gruyter, 2024.

Abstract

Spintronic terahertz emitters (STEs), based on optical excitation of nanometer thick ferromagnetic/heavy metal (FM/HM) heterojunctions, have become important sources for the generation of terahertz (THz) pulses. However, the efficiency of the optical-to-THz conversion remains limited. Although optical techniques have been developed to enhance the optical absorption, no investigations have studied the application of THz cavities. Here, to enhance the THz efficiency of STEs in a selected THz spectral range, FM/HM structures are realized on ultra-thin sapphire layers with metallic mirrors to create λ/4 THz resonant cavities. THz emission time domain spectroscopy of these STE/sapphire/mirror heterostructures, with sapphire thicknesses ranging from 110 µm to 25 µm, shows enhancement of the emitted THz field that fits the λ/4 cavity resonance with up to a doubling of the field in the spectrum, and in agreement with temporal simulations of the emitted THz pulse. By taking advantage of birefringent materials, we further show the potential of control of the polarization state of the emitted THz pulse. This work shows the potential of enhancing and engineering THz emission from STEs using THz cavities that can be controlled over a broad spectral range, which can be easily combined with optical cavities.

Details

Language :
English
ISSN :
21928614
Volume :
13
Issue :
10
Database :
Directory of Open Access Journals
Journal :
Nanophotonics
Publication Type :
Academic Journal
Accession number :
edsdoj.1ff053090225486a8fab675b5be64492
Document Type :
article
Full Text :
https://doi.org/10.1515/nanoph-2023-0807