femtosecond regime
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2022 ◽  
Author(s):  
Ren Bo ◽  
Shi Kai-Zhong ◽  
Shou-Feng Shen ◽  
Wang Guo-Fang ◽  
Peng Jun-Da ◽  
...  

Abstract In this paper, we investigate the third-order nonlinear Schr\"{o}dinger equation which is used to describe the propagation of ultrashort pulses in the subpicosecond or femtosecond regime. Based on the independent transformation, the bilinear form of the third-order NLSE is constructed. The multiple soliton solutions are constructed by solving the bilinear form. The multi-order rogue waves and interaction between one-soliton and first-order rogue wave are obtained by the long wave limit in multi-solitons. The dynamics of the first-order rogue wave, second-order rogue wave and interaction between one-soliton and first-order rogue wave are presented by selecting the appropriate parameters. In particular parameters, the positions and the maximum of amplitude of rogue wave can be confirmed by the detail calculations.PACS numbers: 02.30.Ik, 05.45.Yv.


Author(s):  
Shuo Zhou ◽  
Jun-Fei Zhao ◽  
Lei Wang

Abstract We investigate the nonautonomous molecule waves of the inhomogeneous Hirota equation describing the propagation of femtosecond pulses in inhomogeneous fibers. By employing the characteristic line analysis, the breather molecules of the inhomogeneous Hirota equation under different cases of dispersion and nonlinear modulation are obtained. We find that the inhomogeneous coefficients d2(z) and d3(z) have influences on the distance between atoms. In addition, we introduce the state transitions to the nonautonomous breather molecules and reveal that there is no full-transition mode for the inhomogeneous Hirota equation.


Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Di Lin ◽  
Yutong Feng ◽  
Zhengqi Ren ◽  
David J. Richardson

Abstract Numerous approaches have been developed to generate optical vortex beams carrying orbital angular momentum (OAM) over the past decades, but the direct intracavity generation of such beams with practical output powers in the femtosecond regime still remains a challenge. Here we propose and experimentally demonstrate the efficient generation of high-peak-power femtosecond optical vortex pulses from a Mamyshev oscillator (MO) based on few-mode polarization-maintaining (PM) ytterbium-doped fibers (YDFs). By employing an appropriate intracavity transverse spatial mode selection technique, ultrafast pulses carrying OAM with selectable topological charge of l = ±1 are successfully generated with an average output power of ∼5.72 W at ∼24.35 MHz repetition rate, corresponding to a single pulse energy of ∼235 nJ. The chirped pulses can be compressed to ∼76 fs outside the cavity, leading to a pulse peak power of ∼2.2 MW. To the best of our knowledge, this is by far the highest pulse energy and peak power for optical vortex pulses ever generated directly from a fiber oscillator. This unprecedented level of performance should be of great interest for a variety of applications including materials processing and imaging.


2021 ◽  
Vol 8 ◽  
Author(s):  
Zhengguo Xiao ◽  
Yu Fang ◽  
Yinglin Song ◽  
Yanchao She ◽  
Changhai Tian ◽  
...  

A nitrogen-doped diamond crystal with (111) orientation was synthesized with an NaN3 additive in the FeNi-C system at a pressure of 6.5 GPa and a temperature of 1,310°C, using the temperature gradient growth (TGG) method. Spectroscopic properties such as the absorption spectrum and the Raman spectrum as well as the Fourier transform infrared (FTIR) spectrum were studied. FTIR spectroscopy of the C-N vibrational modes at 1,344 and 1,130 cm−1 suggested a nitrogen content of 310 ppm. Its nonlinear optical (NLO) response was investigated using the Z-scan technique under the femtosecond regime. Due to the presence of nitrogen defects, the synthesized crystal performed large nonlinear absorption under both 800- and 532-nm wavelength excitations. However, intrinsic diamond only experiences nonlinear refraction under these two wavelength excitations. Its broadband NLO properties indicated that nitrogen-doped diamond crystals were suitable for the application of ultrafast optical devices.


2021 ◽  
Vol 19 (8) ◽  
pp. 081403
Author(s):  
Bin Ma ◽  
Jiaqi Han ◽  
Jing Li ◽  
Ke Wang ◽  
Shuang Guan ◽  
...  

2020 ◽  
Vol 7 (4) ◽  
pp. 478-495
Author(s):  
Daniel Metzner ◽  
Markus Olbrich ◽  
Peter Lickschat ◽  
Alexander Horn ◽  
Steffen Weißmantel

AbstractThis study intends to present a simple two-temperature model (TTM) for the fast calculation of the ablation depth as well as the corresponding effective penetration depth for stainless steel by considering temperature-dependent material parameters. The model is validated by a comparison of the calculated to the experimentally determined ablation depth and the corresponding effective penetration depth in dependence on the pulse duration (200 fs up to 10 ps) and the fluence. The TTM enables to consider the interaction of pulsed laser radiation with the electron system and the subsequent interaction of the electrons with the phonon system. The theoretical results fit very well to the experimental results and enable the understanding of the dependence of the ablation depth and of the effective penetration depth on the pulse duration. Laser radiation with a pulse duration in the femtosecond regime results in larger ablation depths compared to longer-pulsed laser radiation in the picosecond regime. Analogously to the ablation depth, larger effective penetration depths are observed due to considerably higher electron temperatures for laser radiation with pulse durations in the femtosecond regime.


2020 ◽  
Vol 37 (10) ◽  
pp. 2822
Author(s):  
Maciej Kowalczyk ◽  
Xuzhao Zhang ◽  
Valentin Petrov ◽  
Pavel Loiko ◽  
Xavier Mateos ◽  
...  

2020 ◽  
Vol 126 (6) ◽  
Author(s):  
E. Terasawa ◽  
T. Shibuya ◽  
D. Satoh ◽  
Y. Moriai ◽  
H. Ogawa ◽  
...  

Author(s):  
Robert Schoenlein ◽  
Thomas Elsaesser ◽  
Karsten Holldack ◽  
Zhirong Huang ◽  
Henry Kapteyn ◽  
...  

Over more than a century, X-rays have transformed our understanding of the fundamental structure of matter and have been an indispensable tool for chemistry, physics, biology, materials science and related fields. Recent advances in ultrafast X-ray sources operating in the femtosecond to attosecond regimes have opened an important new frontier in X-ray science. These advances now enable: (i) sensitive probing of structural dynamics in matter on the fundamental timescales of atomic motion, (ii) element-specific probing of electronic structure and charge dynamics on fundamental timescales of electronic motion, and (iii) powerful new approaches for unravelling the coupling between electronic and atomic structural dynamics that underpin the properties and function of matter. Most notable is the recent realization of X-ray free-electron lasers (XFELs) with numerous new XFEL facilities in operation or under development worldwide. Advances in XFELs are complemented by advances in synchrotron-based and table-top laser-plasma X-ray sources now operating in the femtosecond regime, and laser-based high-order harmonic XUV sources operating in the attosecond regime. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.


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