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Visible light communication (VLC) has the potential to supplement the growing demand for wireless connectivity. In order to realise the full potential of VLC, channel models are required Discrete channel models based on semi-hidden Markov…

Signal Processing · Electrical Eng. & Systems 2019-02-20 Daniel G. Holmes , Ling Cheng , Mulundumina Shimaponda-Nawa , Ayokunle D. Familua , Adnan M. Abu-Mahfouz

We describe a new method to produce intensity stable, highly coherent, narrow-band x-ray pulses in self-seeded free electron (FEL) lasers. The approach uses an ultra-short electron beam to generate a single spike FEL pulse with a wide…

Accelerator Physics · Physics 2020-07-29 Erik Hemsing , Aliaksei Halavanau , Zhen Zhang

FLASH is the first free electron laser user facility operating in the vacuum ultraviolet and soft x-ray wavelength range. Many user experiments require knowledge of the spatial and temporal coherence properties of the radiation. In this…

Accelerator Physics · Physics 2016-04-20 E. A. Schneidmiller , M. V. Yurkov

Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process. In this work, we investigate this multiplexing via computation of the…

Atomic Physics · Physics 2016-05-30 Paul Hockett , Matthias Wollenhaupt , Thomas Baumert

The generation of optical pulses at ultra low bias level, thus low energy cost, is explored in a commercial microcavity semiconductor laser in view of testing the principle of energy efficient information encoding in potential integrated…

Optics · Physics 2019-03-27 Tao Wang , Gaofeng Wang , Gian Piero Puccioni , Gian Luca Lippi

We present a new scheme for establishing longitudinal coherence in the output of X-ray FELs. It uses a sequence of undulators and delay chicanes and the careful tailoring of the initial e-beam with time dependent focusing. Simulation of a…

Accelerator Physics · Physics 2020-10-07 Paul J. Channell

The use of a non-one-dimensional distributed feedback, arising through Bragg diffraction in spatially periodic systems (natural and artificial (electromagnetic, photonic) crystals), forms the foundation for the development of volume free…

Optics · Physics 2012-11-21 Vladimir Baryshevsky

An analytical expression for the self coherence function of a microcavity and partially coherent source is derived from first principles in terms of the component self coherence functions. Excellent agreement between the model and…

Optics · Physics 2009-11-10 R. F. Oulton , P. N. Stavrinou , G. Parry

We theoretically propose a multidimensional high-harmonic echo spectroscopy technique which utilizes strong optical fields to resolve coherent electron dynamics spanning an energy range of multiple electron Volts. Using our recently…

This work focuses on the incoherent and coherent combination of pulsed laser beams, building on previous research [1] that addressed the combination of continuous-wave laser beams. For the pulsed combination, we have focused on the temporal…

Optics · Physics 2024-12-05 Hocine Djellout

The limits of applicability of the Lang-Kobayashi (LK) model for a semiconductor laser with optical feedback are analyzed. The model equations, equipped with realistic values of the parameters, are investigated below solitary laser…

Ultrafast lasers have become one of the most powerful tools in coherent nonlinear optical spectroscopy. Short pulses enable direct observation of fast molecular dynamics, whereas broad spectral bandwidth offers ways of controlling nonlinear…

Chemical Physics · Physics 2015-05-13 X. G. Xu , S. O. Konorov , J. W. Hepburn , V. Milner

We present a 1.75-GHz self-referenceable frequency comb from a vertical external-cavity surface-emitting laser (VECSEL) passively modelocked with a semiconductor saturable absorber mirror (SESAM). The VECSEL delivers 231-fs pulses with an…

The density matrix in the Lindblad form is used to describe the behavior of the Free-Electron Laser (FEL) operating in a quantum regime. The detrimental effects of the spontaneous emission on coherent FEL operation are taken into account.…

Accelerator Physics · Physics 2018-12-26 H. Fares , G. R. M. Robb , N. Piovella

Due to their sub picosecond temporal resolution, coherent Raman spectroscopies have been proposed as a viable extension of Spontaneous Raman (SR) thermometry, to determine dynamics of mode specific vibrational energy content during out of…

In order to meet requirements of the synchrotron radiation users, a fully coherent VUV free electron laser (FEL) has been preliminarily designed. One important goal of this design is that the radiation wavelength can be easily tuned in a…

Accelerator Physics · Physics 2013-06-24 Li He-Ting , Jia Qi-Ka

High-brightness femtosecond-to-attosecond pulses are indispensable for probing electron dynamics on their fundamental temporal scales. X-ray free-electron lasers (XFELs) at high repetition rates will facilitate high-statistics measurements…

Accelerator Physics · Physics 2026-05-01 Junhao Liu , Zhen Wang , Lanpeng Ni , Yujie Lu , Chao Feng , Zhentang Zhao

Volume Free Electron Laser (VFEL) was proposed in [1-4]. It can operate in the wide spectral range from microwaves to X-rays. To simulate the processes which take place in VFEL the superradiance from a short electron pulse moving in a…

Optics · Physics 2016-09-08 Vladimir G. Baryshevsky , Konstantin G. Batrakov

We study the perspectives of measuring the phenomenon of vacuum birefringence predicted by quantum electrodynamics using an x-ray free-electron laser (XFEL) alone. We devise an experimental scheme allowing the XFEL beam to collide with…

High Energy Physics - Phenomenology · Physics 2021-09-02 Felix Karbstein , Chantal Sundqvist , Kai S. Schulze , Ingo Uschmann , Holger Gies , Gerhard G. Paulus

Aims. The simulation of three-wave interaction based plasma emission, thought to be the underlying mechanism for Type III solar radio bursts, is a challenging task requiring fully-kinetic, multi-dimensional models. This paper aims to…

Solar and Stellar Astrophysics · Physics 2015-12-02 J. O. Thurgood , D. Tsiklauri