Room-temperature-grown tungsten oxide hybridized dipole cavities to realize thermally tunable terahertz surface plasmons

Arun Jana, Atul C. Khot, Shreeya Rane, Vaishnavi Sajeev, Tukaram D. Dongale, Tae Geun Kim, Dibakar Roy Chowdhury

Research output: Contribution to journalArticlepeer-review

Abstract

Recent developments in the field of terahertz (THz) subwavelength structures have inspired novel discoveries and innovations involving the use of multidimensional materials in fields such as spectroscopy, photonics, biomedical imaging, nonlinearity, and communication technology. In this context, metal oxide materials with adaptable electronic and optical properties have emerged as promising candidates to realize dynamically reconfigurable THz subwavelength devices. Therefore, we experimentally demonstrated temperature-tunable surface plasmon resonances (SPRs) in an array of tungsten oxide (WO3) hybridized subwavelength cavities. By using THz time-domain spectroscopy, we examined the thermally tunable dielectric properties of a WO3 thin film over a temperature range of 25 °C–110 °C. On the basis of the tunable optoelectronic properties of WO3, we implement a THz subwavelength dipole cavity that can exhibit a temperature-dependent dynamic modification in SPR characteristics. Such tunability could be used to fabricate novel active SPR-based plasmonic devices like temperature sensors, spatial modulators, filters, and integrated THz optoelectronic elements.

Original languageEnglish
Article number114274
JournalOptical Materials
Volume143
DOIs
Publication statusPublished - 2023 Sept

Bibliographical note

Funding Information:
In addition to the SPR frequency tuning, the amplitude of the resonance increases as the temperature increases, as shown in Fig. 4(g). The modulations in the amplitude of the SPR spectra are ascribed to temperature-dependent variations in the permittivity of the WO3 film. As observed in Fig. 2(e) and (f), with increasing temperature, both the real and imaginary parts of the permittivity increase with the enhancement of the loss tangent of the WO3 film. To further investigate the temperature-tunable behavior, finite-element-method-based numerical simulations were conducted. The experimentally determined frequency-dependent permittivity spectra obtained earlier were used in WO3 thin-film hybridized hole array simulations. Fig. 4(g) shows that the numerical simulation results for various temperatures align with the experimentally recorded transmission amplitude modulations, thus providing additional support for the thermally tunable properties of the SPR phenomena in these hybridized surfaces. Furthermore, we computed the modulation depth (MD) of the resonances as a function of temperature defined as MD = |(TP - TD)/TP|, where TP and TD are the transmission amplitudes at f1 and f2 respectively as shown in Fig. 4(h). The obtained MD values are illustrated in Fig. 4(h), where the MD of the device is enhanced to ∼43% at 110 °C. Here, MD serves as a figure of merit demonstrating the switching behavior of the dipole cavities. Therefore, this study shows the potential of the temperature-dependent switching behavior in subwavelength dipole cavity arrays hybridized with a WO3 thin film grown under RT conditions.DRC acknowledges partial support from the SERB project no. CRG/2019/001656. The authors are thankful for the National Research Foundation of Korea (NRF) grant funded by the Korean government (grant no. 2016R1A3B 1908249).

Publisher Copyright:
© 2023 Elsevier B.V.

Keywords

  • Surface plasmon resonance (SPR)
  • Temperature tunability
  • Terahertz (THz)
  • Tungsten dioxide (WO)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Spectroscopy
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Electrical and Electronic Engineering

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