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High resolution field measurement of coherent THz waves in sub-wavelength structures

English title High resolution field measurement of coherent THz waves in sub-wavelength structures
Applicant Feurer Thomas
Number 119934
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Microelectronics. Optoelectronics
Start/End 01.04.2008 - 31.03.2010
Approved amount 248'368.00
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Keywords (7)

Ultrafast Optics; Terahertz Spectroscopy; Sub-Wavelength Structures; Metamaterials; Photonic Crystals; single-cycle THz; plasmonics

Lay Summary (English)

Lead
Lay summary
With the advent of the field of plasmonics the need to measure and simulate field propagation in and through materials supporting surface plasmon polaritons became extremely important. Plasmonics is, loosely speaking, concerned with sub-diffraction optics and sub-wavelength device structures where the underlying processes are surface plasmon assisted. Measuring electromagnetic fields coupled to surface plasmons, however, requires techniques which have a spatial resolution much smaller than the wavelength of the electromagnetic field itself. In the optical regime only near-field techniques are available, yet, near field scanning methods are difficult to perform, are only able to measure the field in close proximity to the tip, and may influence and, thus, disturb the original field distribution quite substantially. Moreover, true field measurements require either interferometric or heterodyne method to assess the coherent properties of the field.

Here, we propose to measure surface plasmon assisted near-field effects in the THz regime and to use our recently established fully coherent field measurement technique to measure the THz electromagnetic field distribution. The method exhibits adequate spatial and temporal resolution. The key is, to use visible femtosecond pulses to generate and to detect the THz fields within a suitable crystal platform. The metallic structures required can easily be incorporated within the crystalline platform and are also relatively easy to fabricate because the THz fields have center wavelengths of several hundreds of microns. With this technique we should be able to measure the electromagnetic field interacting with the surface plasmons and also enhanced coupling mediated through surface corrugation or arrays of micro-structures, such as holes et cetera. From those spatially resolved field measurements we expect to shed some more light onto the detailed mechanisms responsible for effects like enhance transmission through arrays of holes. As long as we remain in the linear regime the results may just be scaled to the visible regime.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
130391 THz near-field imaging of meta-materials and related structures 01.04.2010 Project funding (Div. I-III)
111693 High resolution field measurement of coherently shaped terahertz waves in sub-wavelength structures and metamaterials 01.04.2006 Project funding (Div. I-III)

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