Terahertz frequency-wavelet domain deconvolution for stratigraphic and subsurface investigation of art painting

Junliang Dong ; J. Bianca Jackson ; Marcello Melis ; David Giovanacci ; Gillian C. Walker ; Alexandre Locquet ; John W. Bowen, and D. S. Citrin

Abstract:

Terahertz frequency-wavelet deconvolution is utilized specifically for the stratigraphic and subsurface investigation of art paintings with terahertz reflective imaging. In order to resolve the optically thin paint layers, a deconvolution technique is enhanced by the combination of frequency-domain filtering and stationary wavelet shrinkage, and applied to investigate a mid-20th century Italian oil painting on paperboard, After Fishing, by Ausonio Tanda. Based on the deconvolved terahertz data, the stratigraphy of the painting including the paint layers is reconstructed and subsurface features are clearly revealed, demonstrating that terahertz frequency-wavelet deconvolution can be an effective tool to characterize stratified systems with optically thin layers.

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Double Fano resonance with externally driven subradiant mode

Y.U. Lee ; J.W. Wu

Abstract:

In this study, we observe that a dark mode is not necessarily prerequisite for an asymmetric Fano resonance to take place in plasmonic structures. The characteristic asymmetry feature of Fano resonance is retained in a plasmonic structure when both superradiant and subradiant oscillators are externally driven. Double Fano resonances are experimentally and theoretically observed where a common subradiant driven oscillator is coupled with two superradiant oscillators. As a classical analogue of a four-level tripod atomic system, the extinction spectrum of the composite metamaterial exhibits a coherent effect based on double Fano resonances. Transfer of the absorbed power between two orthogonal superradiant oscillators is shown to be mediated by the common subradiant oscillator.

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Identification of traditional Chinese medicines by using terahertz time-domain spectroscopy

Jun Zhou

Abstract:

Terahertz time-domain spectroscopy (THz-TDS) has been applied to the identification of traditional Chinese medicines. It was found that THz-TDS combined with chemometrics can be used to identify traditional Chinese medicines very well.

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THz spatial filter integrating bimaterial switching for sensors

Varittha Sanphuang ;  Niru K. Nahar ;  John L. Volakis

Abstract:

We propose a THz spatial filter using frequency selective surfaces (FSS) integrated with bimaterial actuator for switching. The actuator consists of two materials that have different thermal expansion rates and can be designed based on temperature tuning. The goal for this design is to develop high performance reconfigurable filters operating in the THz band. The filter was fabricated using gold as filter pattern on silicon substrate. SiO2 and Al were used as bimaterial actuators. Simulations show excellent transmittance (>80%). Allowing different gap of the actuator (up and down), the peak frequency can vary from 0.35 to 0.37 THz.

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