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Coherent diffractive imaging is a technique that recovers the sample image by numerically inverting its diffraction pattern. We propose a generalization of this method for the inversion of multi-wavelength data. Using this approach, we show…

Optics · Physics 2020-05-08 Erik Malm , Edwin Fohtung , Anders Mikkelsen

Polarization is one of the basic properties of electromagnetic waves conveying valuable information in signal transmission and sensitive measurements. Conventional methods for advanced polarization control impose demanding requirements on…

Creating materials with time-variant properties is critical for breaking reciprocity that imposes fundamental limitations to wave propagation. However, it is challenging to realize efficient and ultrafast temporal modulation in a photonic…

Optics · Physics 2022-11-11 Xuexue Guo , Yimin Ding , Yao Duan , Xingjie Ni

Kramers-Kronig (KK) analysis has been widely used to extract the optical conductivity spectrum from a broad range of reflectance spectrum obtained from far-infrared to ultraviolet frequency ranges. In this study, we present how measurement…

Optics · Physics 2024-09-11 Jeong Woo Han

Removing distortions in coherent anti-Stokes Raman scattering (CARS) spectra due to interference with the nonresonant background (NRB) is vital for quantitative analysis. Popular computational approaches, the Kramers-Kronig relation and the…

Signal Processing · Electrical Eng. & Systems 2022-07-08 Charles H. Camp

Due to high dynamic range and ease of use, continuous wave terahertz spectroscopy is an increasingly popular method for optical characterization of components used in cosmic microwave background (CMB) experiments. In this work, we describe…

Instrumentation and Methods for Astrophysics · Physics 2024-07-09 Gaganpreet Singh , Rustam Balafendiev , Zeshen Bao , Thomas J. L. J. Gascard , Jon E. Gudmundsson , Gagandeep Kaur , Vid Primožič

Complex field imaging, which captures both the amplitude and phase information of input optical fields or objects, can offer rich structural insights into samples, such as their absorption and refractive index distributions. However,…

Optics · Physics 2024-05-30 Jingxi Li , Yuhang Li , Tianyi Gan , Che-Yung Shen , Mona Jarrahi , Aydogan Ozcan

We present an experimental and computational study of the nonlinear optical response of conduction electrons to intense terahertz (THz) electric field. Our observations (saturable absorption and an amplitude-dependent group refractive…

Mesoscale and Nanoscale Physics · Physics 2017-03-14 Shukai Yu , Kate H. Heffernan , Diyar Talbayev

Implicit representations like Neural Radiance Fields (NeRF) showed impressive results for photorealistic rendering of complex scenes with fine details. However, ideal or near-perfectly specular reflecting objects such as mirrors, which are…

Computer Vision and Pattern Recognition · Computer Science 2023-10-17 Leif Van Holland , Ruben Bliersbach , Jan U. Müller , Patrick Stotko , Reinhard Klein

With the growing demand for efficient power electronics, SiC-based devices are progressively becoming more relevant. In contrast to established methods such as the mercury capacitance-voltage technique, terahertz spectroscopy promises a…

Electronic wave functions of planar molecules can be reconstructed via inverse Fourier transform of angle-resolved photoelectron spectroscopy (ARPES) data, provided the phase of the electron wave in the detector plane is known. Since the…

Other Condensed Matter · Physics 2016-09-23 Pavel Kliuiev , Tatiana Latychevskaia , Juerg Osterwalder , Matthias Hengsberger , Luca Castiglioni

Optical phase-spaces represent fields of any spatial coherence, and are typically measured through phase-retrieval methods involving a computational inversion, interference, or a resolution-limiting lenslet array. Recently, a weak-values…

Optics · Physics 2018-09-12 Samuel H. Knarr , Daniel J. Lum , James Schneeloch , John C. Howell

We analyzed the behavior of the complex Fourier spectrum of the angle-resolved light scattering pattern (LSP) of a sphere in the framework of the Wentzel-Kramers-Brillouin (WKB) approximation. Specifically, we showed that the phase value at…

Optics · Physics 2023-01-26 Andrey V. Romanov , Valeri P. Maltsev , Maxim A. Yurkin

We have developed a detector which records the full polarisation state of a terahertz (THz) pulse propagating in free space. The three-electrode photoconductive receiver simultaneously records the electric field of an electromagnetic pulse…

Other Condensed Matter · Physics 2009-09-29 E. Castro-Camus , J. Lloyd-Hughes , M. D. Fraser , H. H. Tan , C. Jagadish , M. B. Johnston

Coherent diffractive imaging is unique as the only route for achieving diffraction-limited spatial resolution in the extreme ultraviolet and X-ray regions, limited only by the wavelength of the light. Recently, advances in coherent short…

Based on the classical Lorentz model of the index of refraction, a new method is presented for the extraction of the complex index of refraction from the extinction efficiency of homogeneous and layered dielectric spheres that…

Optics · Physics 2022-06-28 Kalpa de Silva , Proity Akbar , Reinhold Blümel

Accurately measuring the geometry and spatially-varying reflectance of real-world objects is a complex task due to their intricate shapes formed by concave features, hollow engravings and diverse surfaces, resulting in inter-reflection and…

Computer Vision and Pattern Recognition · Computer Science 2024-12-16 Jing Yang , Pratusha Bhuvana Prasad , Qing Zhang , Yajie Zhao

For a number of optical applications, it is advantageous to precisely tune the refractive index of a liquid. Here, we harness a well-established concept in optics for this purpose. The Kramers-Kronig relation provides physical connection…

Fourier transform-based methods enable accurate, dispersion-free simulations of time-domain scattering problems by evaluating solutions to the Helmholtz equation at a discrete set of frequencies sufficient to approximate the inverse Fourier…

Numerical Analysis · Mathematics 2025-10-29 Oscar P. Bruno , Manuel A. Santana

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