Terahertz near-field vectorial imaging of subwavelength apertures and aperture arrays

• Published in: Optics express Vol. 17; no. 17; pp. 15072 - 15086
• Main Authors: Knab, J R, Adam, A J L, Nagel, M, Shaner, E, Seo, M A, Kim, D S, Planken, P C M
• Format: Journal Article
• Language: English
• Published: United States 17.08.2009
• Subjects: Computer Simulation; Equipment Design - methods; Materials Testing; Optics and Photonics; Refractometry - instrumentation; Refractometry - methods; Silicon - chemistry; Surface Plasmon Resonance - methods; Terahertz Spectroscopy - methods
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/oe.17.015072

We present measurements of the complete terahertz (THz) electric near-field distribution, E(x), E(y) and E(z), in both the time- and frequency-domains, for subwavelength apertures and subsections of subwavelength aperture arrays. Measuring the individual components of the THz near-field with subwavelength spatial resolution, as they emerge from these structures, illustrates how the field interacts with the apertures. We observe the small but measurable y- and z-components of the electric field for both single apertures and arrays. Resonant contributions, attributed to Bloch modes, are detected and we observe the presence of a longitudinal field component, E(z), within the different array apertures, which can be attributed to a diffractive effect. These measurements illustrate in detail the individual THz field components emerging from subwavelength apertures and provide a direct measure of two important mechanisms that contribute to the net transmission of light through arrays.