This document may differ from the final, published version of the research and has been made available online in accordance with publisher policies. To read and/or cite from the published version of the research, please visit the publisher's website (a subscription may be required.) 1  Abstract: A plasmonic Mach-Zehnder interferometer (MZI) for temperature sensing is reported in the terahertz (THz) regime. The MZI is formed by embedding a semiconductor (SC) layer into a silicon membrane, where

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... the SC layer supports two independent propagating surface plasmon polariton (SPP) waves on both surfaces. The temperature-sensitive phase difference between these two SPP waves gives rise to the modulation of the transmitted intensity. The results show that the MZI sensor possesses a sensitivity and a Figure of Merit (FoM) as high as 8.9 × 10 -3 THz/K and 117, respectively. Theoretical calculations indicate that the further improvement in sensing performance is still possible through optimization of the structure. Moreover, an investigation of structural perturbations indicates that the MZI has a good tolerance to the fabrication errors. The compact MZI-based waveguide structure may find important applications in areas of sensing and integrated THz circuits.