Thin film sensing in a planar terahertz meta-waveguide

Abstract

In this paper, we explore sensing characteristics of a terahertz meta-waveguide consisting of a one-dimensional array of periodically arranged subwavelength scale split-ring resonators (SRRs). The substrate of the meta-waveguide structure has two layers. The lower one is made of metal, whereas the upper layer is made of a dielectric. On the top of it, metallic SRRs are placed. The meta-waveguide is capable of guiding the fundamental as well as higher-order terahertz modes along the designed structures. We analyze the sensing capability of the meta-waveguide by covering it with the thin film analyte. The waveguide transmission properties are observed for varying refractive index of the analyte. Different sensing parameters such as frequency shift, sensitivity, figure of merit (FoM) of resonance modes supported by the meta-waveguide have been studied. The obtained values of sensitivity and FoM indicates better sensing capability of the meta-waveguide rather than meta-designs in the transmission approach. We also employ coupled harmonic oscillator model in order to interpret and validate the numerical observations. The meta-waveguide designs can open alternate avenues for sensing thin film analytes with greater sensitivity.

Enhancement of wide-band trace terahertz absorption spectroscopy based on microstructures: a review

“…Additionally, electromagnetic wave propagation within waveguides offers a better signal-to-noise ratio. Over the past few years, sensing platforms have used several kinds of metal and dielectric waveguides such as single wire waveguide, 28 microstrip line, 29 coplanar waveguide, 30,31 Goubau line waveguide, 32 photonic Bragg waveguide, 33 photonic crystal, 34 PMMA grating waveguide tube, 35 and so on. The boosting of wide-band terahertz absorption spectroscopy of trace-amount analytes is based on the local effects of the metal and dielectric waveguides on electromagnetic fields.…”

Resonant excitation of terahertz surface magnetoplasmons by optical rectification over a rippled surface of n-type indium antimonide

“…Electromagnetic radiation with a frequency ranging from 0.3 to 10 × 10 12 Hz refers to terahertz (THz) gap (Shumyatsky & Alfano 2011). Recently, THz has attracted a lot of interest because its frequency application can be used in spectroscopy (Afsah-Hejri et al 2019;Spies et al 2020), communication (Yang et al 2020;Ghazialsharif et al 2023;Katyba et al 2023), imaging in medical diagnostics (Peng et al 2020;Zhang et al 2020;Wang 2021), sensing (Islam et al 2022;Lai et al 2023;Tan et al 2023), detection (Lewis 2019), etc. Terahertz radiation can be generated by a variety of techniques and processes, such as laser-plasma interaction Manendra et al 2020), electron beam-plasma interaction (Yang et al 2022;Gupta, Gurjar & Jain 2023), photoconductivity antenna (Isgandarov et al 2021;Lu et al 2022;Sandeep & Malik 2023), electron beam or laser interaction with a semiconductor or metal (Liu et al 2007;Davidson et al 2020;Dong et al 2021), nonlinear mixing of lasers (Kumar, Rajouria & KK 2013;Kumar et al 2017Kumar et al , 2023Srivastav & Panwar 2022), optical rectification (Lee et al 2000;Yeh et al 2007;Aoki, Savolainen & Havenith 2017) and second and third harmonic generation Gour et al 2022) etc.…”

Principles of Measuring Thickness and Refractive Index of Thin Dielectric Film by Using Multiresonance Archimedean Spiral Metasurfaces with C Resonator in the Terahertz Frequency Range

“…However, since the wavelength in the THz range can be as big as several hundreds or thousands of micrometers, it is almost impossible to measure very thin films with conventional methods, such as conventional THz time domain spectroscopy [8,9]. Scientists have proposed different solutions to this problem, including waveguides [10][11][12], photonic crystals [13], as well as plasmonic structures [14] and metasurfaces [15]. Due to the variety of principles, functions, and requirements of thin-film sensing approaches, it is difficult to compare the performance of these techniques.…”