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-Mechanically tunable terahertz metamaterials

Jining Li^1,2, Charan M. Shah³, Withawat Withayachumnankul¹, Benjamin S.-Y. Ung¹, Arnan Mitchell³, Sharath Sriram³, Madhu Bhaskaran³, Shengjiang Chang², and Derek Abbott¹

¹School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA 5005, Australia
²Institute of Modern Optics, Nankai University, Tianjin 300071, China
³Functional Materials and Microsystems Research Group, RMIT University, Melbourne, VIC 3001, Australia                        

http://apl.aip.org/resource/1/applab/v102/i12/p121101_s1?isAuthorized=no

Electromagnetic device design and flexible electronics fabrication are combined to demonstrate mechanically tunable metamaterials operating at terahertz frequencies. Each metamaterial comprises a planar array of resonators on a highly elastic polydimethylsiloxane substrate. The resonance of the metamaterials is controllable through substrate deformation. Applying a stretching force to the substrate changes the inter-cell capacitance and hence the resonance frequency of the resonators. In the experiment, greater than 8% of the tuning range is achieved with good repeatability over several stretching-relaxing cycles. This study promises applications in remote strain sensing and other controllable metamaterial-based devices.

© 2013 American Institute of Physics