Optimised Spintronic Emitters of Terahertz Radiation for Time-Domain Spectroscopy

Journal article

AbstractSpintronic metal thin films excited by femtosecond laser pulses have recently emerged as excellent broadband sources of terahertz (THz) radiation. Unfortunately, these emitters transmit a significant proportion of the incident excitation laser, which causes two issues: first, the transmitted light can interfere with measurements and so must be attenuated; second, the transmitted light is effectively wasted as it does not drive further THz generation. Here, we address both issues with the inclusion of a high-reflectivity (HR) coating made from alternating layers of SiO2 and Ta2O5. Emitters with the HR coating transmit less than 0.1% of the incident excitation pulse. Additionally, we find that the HR coating increases the peak THz signal by roughly 35%, whereas alternative attenuating elements, such as cellulose nitrate films, reduce the THz signal. To further improve the emission, we study the inclusion of an anti-reflective coating to the HR-coated emitters and find the peak THz signal is enhanced by a further 4%.

Authors: Wagner, FM; Melnikas, S; Cramer, J; Damry, DA; Xia, CQ

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer
• Journal: Journal of Infrared, Millimeter and Terahertz Waves
• Volume: 44
• Issue: 1-2
• Pages: 52-65
• Publication date: 2023-01-24
• DOI: 10.1007/s10762-022-00897-9
• EISSN: 1866-6906
• ISSN: 1866-6892
• Language: English
• Keywords: Femtosecond; Optoelectronics; Radiation; SIGNAL (programming language); Physics; Nanotechnology; Terahertz radiation; Optics; Coating; Materials science; Laser