Abstract-Terahertz Localized Surface Plasmon Resonances in Coaxial Microcavities

http://onlinelibrary.wiley.com/doi/10.1002/adom.201300021/abstract

1. Withawat Withayachumnankul^1,2,*, 
2. Charan Manish Shah², 
3. Christophe Fumeaux¹,
4. Korbinian Kaltenecker^3,4, 
5. Markus Walther³, 
6. Bernd M. Fischer^1,4, 
7. Derek Abbott¹,
8. Madhu Bhaskaran², 
9. Sharath Sriram^2,*

Coaxial microcavities etched into the surface of a doped silicon substrate are shown to support localized surface plasmon resonances at terahertz frequencies. The underlying mechanism involves coupling freely propagating terahertz waves with surface plasmon polaritons (SPPs), which propagate in a coaxial mode along the cavity walls in the axial direction. A Fabry–Pérot resonance is built up when the SPP wavenumber appropriately relates to the cavity depth. Owing to the Ohmic loss of the silicon at terahertz frequencies, the energy of the resonating SPPs is largely dissipated, leading to a modified reflection spectrum. Strong field enhancement is observed inside the cavities at resonance. The theoretical analysis is supported by numerical and experimental results. This study is a promising pathway for development of terahertz devices with applications in the areas of photonic integrated circuits, molecular sensing, and subwavelength imaging.

Abstract-Terahertz scattering by dense media

Mayank Kaushik¹, Brian W.-H. Ng¹, Bernd M. Fischer^1,2, and Derek Abbott¹

¹Centre for Biomedical Engineering (CBME) and School of Electrical and Electronic Engineering, The University of Adelaide, SA 5005, Australia
²Institut Franco-Allemand de Recherches de Saint Louis, 68301 Saint Louis Cedex, France 

http://apl.aip.org/resource/1/applab/v100/i24/p241110_s1?isAuthorized=no

Frequency dependent absorption of a given material at distinct frequencies in the terahertz (THz) range is commonly used as a spectral fingerprint for material identification and classification. However, in the presence of strong scattering, these features can often become distorted or altered. Thus, there is an important need to understand how scattering from a sample alters the THz signal. In this letter, we propose an iterative algorithm that builds on the effective field theory proposed by P. C. Waterman and R. Truell [J. Math. Phys. 2, 512–537 (1961)] and offers a rather simple and computationally efficient method for accurately explaining the multiple scattering response of a medium.

© 2012 American Institute of Physics