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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

We introduce a novel technique to mitigate the adverse effects of atmospheric turbulence on astronomical imaging. Utilizing a video-to-image neural network trained on simulated data, our method processes a sliding sequence of short-exposure…

Instrumentation and Methods for Astrophysics · Physics 2024-05-09 Spencer Bialek , Emmanuel Bertin , Sébastien Fabbro , Hervé Bouy , Jean-Pierre Rivet , Olivier Lai , Jean-Charles Cuillandre

Diffusion models are typically trained using pointwise reconstruction objectives that are agnostic to the spectral and multi-scale structure of natural signals. We propose a loss-level spectral regularization framework that augments…

Machine Learning · Computer Science 2026-03-04 Satish Chandran , Nicolas Roque dos Santos , Yunshu Wu , Greg Ver Steeg , Evangelos Papalexakis

A thermal atomic ensemble-based laser source with superior frequency stability is proposed that relies on the accumulated contributions from an abundance of nonzero-transverse-velocity atomic ensembles. Compared with the traditional case in…

Atomic Physics · Physics 2020-12-08 Haosen Shang , Duo Pan , Xiaogang Zhang , Xiaobo Xue , Tiantian Shi , Jingbiao Chen

We present a novel and simple method of stabilizing the laser phase and frequency by polarization spectroscopy of an atomic vapor. In analogy to the Pound-Drever-Hall method, which uses a cavity as a memory of the laser phase, this method…

Atomic Physics · Physics 2012-09-05 Yoshio Torii , Hideyasu Tashiro , Nozomi Ohtsubo , Takatoshi Aoki

We show experimentally that the terahertz (THz) emission of a plasma, generated in air by a two-color laser pulse (containing a near IR frequency and its second harmonic), can be enhanced by the addition of an 800-nm pulse. We observed…

Terahertz (THz) technologies, generally defined as operating in the 0.1-10THz range, bridge the gap between electronic and photonic devices. Because THz radiation passes readily through materials such as plastics, paper and cloth it can be…

Using a 3D fully-vectorial nonlinear time-domain analysis we numerically investigate the generation of terahertz radiation by pumping a photonic crystal microcavity out of resonance. High quality factors and a quadratic susceptibility lead…

Optics · Physics 2009-11-11 Andrea Di Falco , Claudio Conti , Gaetano Assanto

Low fluence illumination sources can facilitate clinical transition of photoacoustic imaging because they are rugged, portable, affordable, and safe. However, these sources also decrease image quality due to their low fluence. Here, we…

Image and Video Processing · Electrical Eng. & Systems 2020-04-21 Ali Hariri , Kamran Alipour , Yash Mantri , Jurgen P. Schulze , Jesse V. Jokerst

We construct a terahertz time-domain spectrometer (THz-TDS) system based on photoconductive antenna (PCA). A 800 nm Ti sapphire femtosecond laser with 80 MHz repetition rate provides the pump and probe laser pulse, which has a 45 fs pulse…

Optics · Physics 2014-08-11 Jitao Zhang , Wei-Ren Ng , Mingguang Tuo , Min Liang , M. E. Gehm , Hao Xin

Optically induced ultrafast switching of single photons is demonstrated by rotating the photon polarization via the Kerr effect in a commercially available single mode fiber. A switching efficiency of 97\% is achieved with a $\sim1.7$\,ps…

Quantum Physics · Physics 2019-03-27 Connor Kupchak , Jennifer Erskine , Duncan G. England , Benjamin J. Sussman

The mechanism of the terahertz (THz) wave generation (TWG) in dual-color fields is elucidated within the theoretical framework of single-atom based strong field approximation (SFA). Evaluating the transition dipole moment, the…

Quantum Physics · Physics 2019-04-30 Kaixuan Zhang , Yizhu Zhang , Shuai Li , Xincheng Wang , Tian-Min Yan , Y. H. Jiang

In this paper possibilities of a stabilization of large amplitude fluctuations in an intracavity-doubled solid-state laser are studied. The modification of the cross-saturation coefficient by the effect of spatial hole-burning is taken into…

Chaotic Dynamics · Physics 2015-06-26 Monika E. Pietrzyk , Miltcho B. Danailov

Interference of light fields plays an important role in various high-precision measurement schemes. It has been shown that super resolving phase measurements beyond the standard coherent state limit can be obtained either by using maximally…

Quantum Physics · Physics 2013-10-08 Emanuele Distante , Miroslav Jezek , Ulrik L. Andersen

It is shown, that diffusion of saturated gain (e.g. diffusion of population inversion in lasers) causes, and/or enhances a modulational instability of generated light field. In case of a subcritical system (e.g. a laser with saturable…

Pattern Formation and Solitons · Physics 2009-10-31 Kestutis Staliunas

The terahertz (THz) frequency range, bridging the gap between microwave and infrared frequencies, presents unparalleled opportunities for advanced imaging, sensing, communications, and spectroscopy applications. Terahertz photonics, in…

A stable reference light source based on an LED (Light Emission Diode) is presented for stabilizing the conversion gain of the opto-electronic system of a gamma- and fast-neutron radiographic and tomographic imaging device. A constant…

Instrumentation and Detectors · Physics 2010-02-09 M. Weierganz , D. Bar , B. Bromberger , V. Dangendorf , G. Feldman , M. B. Goldberg , M. Lindemann , I. Mor , K. Tittelmeier , D. Vartsky

High-power, continuously tunable narrowband terahertz (THz) sources are essential for advancing nonlinear optics, THz-driven material dynamics, and ultrafast spectroscopy. Conventional techniques typically impose a trade-off between pulse…

Achieving control over light-matter interaction in custom-tailored nanostructures is at the core of modern quantum electrodynamics [1-15]. In ultrastrongly coupled systems [5-15], excitation is repeatedly exchanged between a resonator and…

Mesoscale and Nanoscale Physics · Physics 2018-07-03 Andreas Bayer , Marcel Pozimski , Simon Schambeck , Dieter Schuh , Rupert Huber , Dominique Bougeard , Christoph Lange

Active control of optical nonlinearity is essential for advancing next-generation electronics and photonics, including high-speed wireless communications, optical information processing, and nonlinear signal manipulation. However, achieving…