Simulation for embedded-defects foam terahertz images of active bifocal terahertz imaging system at 0.22 THz based on geometric optics

A single-pixel terahertz imaging system based on compressed sensing

We describe a terahertz imaging system that uses a single pixel detector in combination with a series of random masks to enable high-speed image acquisition. The image formation is based on the theory of compressed sensing, which permits the reconstruction of a N-by-N pixel image using much fewer than N2 measurements. This approach eliminates the need for raster scanning of the object or the te...

An Anti-Reflection Coating for Silicon Optics at Terahertz Frequencies

A method for reducing the reflections from silicon optics at terahertz frequencies has been investigated. In this study, we used thin films of parylene as an anti-reflection (AR) layer for silicon optics and show low-loss behavior well above 1 THz. Transmittance spectra are acquired on double-sided-parylene-coated, high-resistivity, single-crystal silicon etalons between 0.45 THz and 2.8 THz. M...

Non-linear graphene optics for terahertz applications

The linear electrodynamic properties of graphene – the frequency-dependent conductivity, the transmission spectra and collective excitations – are briefly outlined. The non-linear frequency multiplication effects in graphene are studied, taking into account the influence of the self-consistent-field effects and of the magnetic field. The predicted phenomena can be used for creation of new devic...

Multilevel silicon diffractive optics for terahertz waves

A multilevel microfabrication process has been developed to produce silicon Fresnel lenses for terahertz waves. A repeated binary fabrication process was used to create lenses with up to eight levels in complexity and these lenses have been compared to both less complex structures and refractive optic lenses. The microfabrication required deep reactive ion etching and multilevel resist processi...

Characterization of Defects in Fiber Composites Using Terahertz Imaging