Qiu, Y, Meng, K, Wang, W et al. (5 more authors) (2023) Efficient free-space to on-chip coupling of THz-bandwidth pulses for biomolecule fingerprint sensing. Optics Express, 31 (2). pp. 2373-2385. ISSN 1094-4087
Abstract
Wide bandwidth THz pulses can be used to record the distinctive spectral fingerprints related to the vibrational or rotational modes of polycrystalline biomolecules, and can be used to resolve the time-dependent dynamics of such systems. Waveguides, owing to their tight spatial confinement of the electromagnetic fields and the longer interaction distance, are promising platforms with which to study small volumes of such systems. The efficient input of sub-ps THz pulses into waveguides is challenging owing to the wide bandwidth of the THz signal. Here, we propose a sensing chip comprised of a pair of back-to-back Vivaldi antennas feeding into, and out from, a 90° bent slotline waveguide to overcome this problem. The effective operating bandwidth of the sensing chip ranges from 0.2 to 1.15 THz, and the free-space to on-chip coupling efficiency is as high as 51% at 0.44 THz. Over the entire band, the THz signal is ∼42 dB above the noise level at room temperature, with a peak of ∼73 dB above the noise. In order to demonstrate the use of the chip, we have measured the characteristic fingerprint of α-lactose monohydrate, and its sharp absorption peak at ∼0.53 THz was successfully observed, demonstrating the promise of our technique. The chip has the merits of efficient in-plane coupling, ultra-wide bandwidth, ease-of-integration, and simple fabrication. It has the potential for large-scale manufacture, and can be a strong candidate for integration into other THz light-matter interaction platforms.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title,journal citation, and DOI. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Electronic & Electrical Engineering (Leeds) > Pollard Institute (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 12 Jan 2023 17:42 |
Last Modified: | 25 Jun 2023 23:13 |
Published Version: | http://dx.doi.org/10.1364/oe.477664 |
Status: | Published |
Publisher: | Optica |
Identification Number: | 10.1364/oe.477664 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:195149 |