Optical fibres are favourable tabletop laboratories to investigate both coherent and incoherent nonlinear waves. In particular, exact solutions of the one-dimensional nonlinear Schrödinger equation such as fundamental solitons or solitons on finite background can be generated by launching periodic, specifically designed coherent waves in optical fibres. It is an open fundamental question to know whether these coherent structures can emerge from the nonlinear propagation of random waves. However the typical sub-picosecond timescale prevented—up to now—time-resolved observations of the awaited dynamics. Here, we report temporal ‘snapshots' of random light using a specially designed ‘time-microscope'. Ultrafast structures having peak powers much larger than the average optical power are generated from the propagation of partially coherent waves in optical fibre and are recorded with 250 femtoseconds resolution. Our experiment demonstrates the central role played by ‘breather-like' structures such as the Peregrine soliton in the emergence of heavy-tailed statistics in integrable turbulence.

Temporal imaging systems are outstanding tools for single-shot observation of optical signals that have irregular and ultrafast dynamics. They allow long time windows to be recorded with femtosecond resolution, and do not rely on complex algorithms. However, simultaneous recording of amplitude and phase remains an open challenge for these systems.Here we present a new heterodyne time-lens arrangement that efficiently records both the amplitude and phase of complex signals, while keeping the performances of classical time-lens systems (∼ 200 fs) and field of view (tens of ps). Phase and time are encoded onto the two spatial dimensions of a camera. We demonstrate direct application of our heterodyne time lens to turbulent-like optical fields and optical rogue waves generated from nonlinear propagation of partially coherent waves inside optical fibres. We also show how this phase-sensitive time-lens system enables digital temporal holography to be performed with even higher temporal resolution (80 fs).Simultaneous measurement of the amplitude and phase of ultrafast complex optical signals is a a key question in modern optics and photonics [1][2][3][4][5][6]. This kind of detection is needed for the characterization of various fundamental phenomena such as e.g. supercontinuum [7,8], optical rogue waves (RWs) [9-11], or soliton dynamics in mode-locked lasers [12,13]. The task remains a particulary challenging open problem when femtosecond resolution and long time windows are simultaneously required. These requirements are found for exemple in the context of nonlinear statistical optics and of the characterization of random light [14] or in the study of spatio-temporal dynamics of lasers [15].In the quest for long-window and ultrafast recording tools, temporal imaging devices, such as time-lenses, are considered as promising candidates. Time-lenses enable femtosecond time evolutions to be manipulated so that they can be magnified in time [16][17][18] or spectrally encoded [10,17,19] with high fidelity. These signals evolution replica can thus be recorded using a simple GHz oscilloscope (for time-magnification systems) or a singleshot optical spectrum analyzer [10]). No special algorithms are necessary for retrieving the ultrafast power evolutions, long windows can be recorded (up to hun-dreds of picoseconds), and the method is suitable for recording continuous-wave (i.e., non-pulsed) complex signals. Recently, temporal imaging systems have thus begun to play a central role in fundamental studies dealing with nonlinear propagation of light in fibers leading for example to the emergence of rogue waves and integrable turbulence [10,11,20], where recording long temporal traces with femtosecond resolution is mandatory. Commercial devices are also available in the market (by Pi-coLuz LLC).However, a range of applications is still hampered by the need to also record the phase evolution of long and complex ultrafast optical signals. Extension of temporal imaging has been performed in this direction, by performing heterodyning ...

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With gigaelectron-volts per centimetre energy gains and femtosecond electron beams, laser wakefield acceleration (LWFA) is a promising candidate for applications, such as ultrafast electron diffraction, multistaged colliders and radiation sources (betatron, compton, undulator, free electron laser). However, for some of these applications, the beam performance, for example, energy spread, divergence and shot-to-shot fluctuations, need a drastic improvement. Here, we show that, using a dedicated transport line, we can mitigate these initial weaknesses. We demonstrate that we can manipulate the beam longitudinal and transverse phase-space of the presently available LWFA beams. Indeed, we separately correct orbit mis-steerings and minimise dispersion thanks to specially designed variable strength quadrupoles, and select the useful energy range passing through a slit in a magnetic chicane. Therefore, this matched electron beam leads to the successful observation of undulator synchrotron radiation after an 8 m transport path. These results pave the way to applications demanding in terms of beam quality.

This report presents the conceptual design of a new European research infrastructure EuPRAXIA. The concept has been established over the last four years in a unique collaboration of 41 laboratories within a Horizon 2020 design study funded by the European Union. EuPRAXIA is the first European project that develops a dedicated particle accelerator research infrastructure based on novel plasma acceleration concepts and laser technology. It focuses on the development of electron accelerators and underlying technologies, their user communities, and the exploitation of existing accelerator infrastructures in Europe. EuPRAXIA has involved, amongst others, the international laser community and industry to build links and bridges with accelerator science — through realising synergies, identifying disruptive ideas, innovating, and fostering knowledge exchange. The Eu-PRAXIA project aims at the construction of an innovative electron accelerator using laser- and electron-beam-driven plasma wakefield acceleration that offers a significant reduction in size and possible savings in cost over current state-of-the-art radiofrequency-based accelerators. The foreseen electron energy range of one to five gigaelectronvolts (GeV) and its performance goals will enable versatile applications in various domains, e.g. as a compact free-electron laser (FEL), compact sources for medical imaging and positron generation, table-top test beams for particle detectors, as well as deeply penetrating X-ray and gamma-ray sources for material testing. EuPRAXIA is designed to be the required stepping stone to possible future plasma-based facilities, such as linear colliders at the high-energy physics (HEP) energy frontier. Consistent with a high-confidence approach, the project includes measures to retire risk by establishing scaled technology demonstrators. This report includes preliminary models for project implementation, cost and schedule that would allow operation of the full Eu-PRAXIA facility within 8—10 years.