When: Tuesday, November 19, 2024, 11:00 AM - 12:00 PMWhere: Scape Canalside TR1 , Mile End
Speaker: Dr Alexander Valavanis
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The terahertz band of the electromagnetic spectrum contains spectral signatures of numerous important atmospheric gas-phase species (e.g., O, OH within the mesosphere–lower thermosphere), which cannot readily be observed remotely in other spectral bands.
However, Earth observation at THz frequencies faces significant challenges, both in terms of a lack of instrumentation (e.g., sources, detectors, and optics), and experimental design (e.g., strong atmospheric attenuation, and a relatively limited catalogue of spectroscopic data). We will discuss recent progress in THz instrumentation for gas spectroscopy applications, based on quantum-cascade laser (QCL) sources. These compact semiconductor devices provide powerful, narrowband THz emission, and can be tailored to emit anywhere in the ~2–5THz band. We will discuss state-of-the art laser performance, and a range of techniques being developed to integrate QCLs and bespoke THz optical components within satellitecompatible receiver systems. Laboratory-based gas-phase analysis methods will also be discussed, including “detector-free” self-mixing interferometry (SMI) and Fourier-Transform interferometry (FTIR)schemes, and real-time sensing using antenna-coupled field-effect transistor detectors.
About the Speaker:
Dr Alexander Valavanis is an associate professor within the School of Electronic and Electrical Engineering at the University of Leeds. His research focuses on terahertz-frequency instrumentation for atmospheric and space research, with particular interest in the design and applications of quantumcascade laser systems. He holds a UKRI Future Leaders Fellowship and has led several UK Space Agencycontracts to develop THz satellite instrumentation. He works extensively with industrial and academic partners, including RAL Space, TK Instruments, Goethe University Frankfurt, the University of Cambridge, and University College London. He is currently a co-investigator in the EPSRC "TeraCom" programme grant to develop ultra-wideband wireless communications systems in the THz frequency band.