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Terahertz (THz) wave manipulation based on laser filaments-plasma channels formed by femtosecond laser-induced air ionization-has emerged as a promising platform for free-space THz applications. However, in-situ characterization of the…

Terahertz (THz) waves are electromagnetic waves in the 0.1 to 10 THz frequency range, and THz imaging is utilized in a range of applications, including security inspections, biomedical fields, and the non-destructive examination of…

Image and Video Processing · Electrical Eng. & Systems 2023-12-05 Woon-Ha Yeo , Seung-Hwan Jung , Seung Jae Oh , Inhee Maeng , Eui Su Lee , Han-Cheol Ryu

This work presents a fast direct solver strategy allowing full-wave modeling and dosimetry at terahertz (THz) frequencies. The novel scheme leverages a preconditioned combined field integral equation together with a regularizer for its…

Numerical Analysis · Mathematics 2023-10-25 Viviana Giunzioni , Giuseppe Ciacco , Clément Henry , Adrien Merlini , Francesco P. Andriulli

English: This paper concerns the image reconstruction from a few projections in Computed Tomography (CT). The main objective of this paper is to show that the problem is so ill posed that no classical method, such as analytical methods…

Data Analysis, Statistics and Probability · Physics 2007-05-23 Ali Mohammad-Djafari

An approach to diffraction tomography is investigated for two-dimensional image reconstruction of objects surrounded by an arbitrarily-shaped curve of sources and receivers. Based on the integral theorem of Helmholtz and Kirchhoff, the…

Mathematical Physics · Physics 2014-11-20 G. T. Clement

We propose an all-optical Knife Edge characterization technique and we demonstrate its working principle by characterizing the sub-{\lambda} features of a spatially modulated Terahertz source directly on the nonlinear crystal employed for…

In this work, we present a novel approach to photothermal super resolution based thermographic resolution of internal defects using two-dimensional pixel pattern-based active photothermal laser heating in conjunction with subsequent…

Image and Video Processing · Electrical Eng. & Systems 2023-03-01 Julien Lecompagnon , Philipp Daniel Hirsch , Christian Rupprecht , Mathias Ziegler

Terahertz (THz) generation by optical rectification in LiNbO$_3$ (LN) is a widely used technique for generating intense THz radiation. The spatiotemporal characterization of THz pulses from these sources is currently limited to far-field…

The nonlinear optical response of materials under high-intensity electromagnetic fields is key to advancing THz optical technologies. This study introduces a theoretical approach to estimate the nonlinear refractive index coefficient n2 of…

Providing continuous bandwidth over several tens of GHz, the Terahertz (THz) band (0.1-10 THz) supports space-air-ground integrated network (SAGIN) in 6G and beyond wireless networks. However, it is still mystery how THz waves interact with…

Systems and Control · Electrical Eng. & Systems 2023-08-03 Zhirong Yang , Weijun Gao , Chong Han

A non-iterative method of reconstruction is proposed from data of MRI system and of a harmonic electro-magnetic field at Larmor frequency. The method is based on the exact analytic formula for the contrast source function. A geometric…

Numerical Analysis · Mathematics 2019-05-13 Victor Palamodov

Following recent advances in terahertz (THz) technology, there is a consensus on the crucial role of THz communications in the next generation of wireless systems. Aiming at catalyzing THz communications research, we propose TeraMIMO, an…

Thermoelectric measurement of the dimensionless zT parameter requires multiple physical quantities to be measured, therefore there is great interest to find an experimental setup capable of measuring all these properties at once. Previous…

We propose a stable and fast reconstruction technique for parallel-beam (PB) tomographic X-ray imaging, relying on the discrete pseudo-polar (PP) Radon transform. Our main contribution is a resampling method, based on modern sampling…

Numerical Analysis · Computer Science 2018-03-29 Shahar Tsiper , Yonina C. Eldar

We report on terahertz (THz) radiation under electrical pumping from a degenerate semiconductor possessing an electron accumulation layer. In InN, the random grating formed by topographical defects provides high-efficiency coupling of…

Materials Science · Physics 2015-05-19 T. V. Shubina , N. A. Gippius , V. A. Shalygin , A. V. Andrianov , S. V. Ivanov

The Diffuse Optical Tomography (DOT) has received considerable attention in the recent years in the field of biomedical imaging and disease detection. However, imaging through highly diffusive medium is a challenge and stability is always…

Image and Video Processing · Electrical Eng. & Systems 2020-03-31 Tapan Das , P. K. Dutta

We present a temporally-multiplexed dual-colour terahertz (THz) imaging technique using THz-to-optical conversion in atomic vapour. By rapidly alternating the pump laser frequency, we sequentially excite two atomic states, each absorbing a…

Atomic Physics · Physics 2025-07-16 Lucy A. Downes , C. Stuart Adams , Kevin J. Weatherill

The emission properties of terahertz(THz) photoconductive antenna (PCA) have been numerically studied by three-dimensional finite-difference-time-domain method based on the full-wave model. The dependence of the THz radiation on various…

Optics · Physics 2014-07-11 Jitao Zhang

We study iterative signal reconstruction in computed tomography (CT), wherein measurements are produced by a linear transformation of the unknown signal followed by an exponential nonlinear map. Approaches based on pre-processing the data…

Optimization and Control · Mathematics 2024-07-19 Vasileios Charisopoulos , Rebecca Willett

Topo-Tomography (TT) is a synchrotron-based X-ray diffraction imaging technique used to characterize grain shape and crystal orientation in polycrystalline samples. This work aims to provide a decisive and fundamental understanding of 3D…

Computational Physics · Physics 2025-10-13 Zheheng Liu , Nicola Vigano , Henry Proudhon , Wolfgang Ludwig