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Laser-plasma accelerators (LPAs), producing high-quality electron beams, provide an opportunity to reduce the size of free-electron lasers (FELs) to only a few meters. A complete system is proposed here, which is based on FEL technology and consists of an LPA, two undulators, and other magnetic devices. The system is capable to generate carrier-envelope phase stable attosecond pulses with engineered waveform. Pulses with up to~60~nJ energy and 90 to~400~attosecond duration in the 30 to 120~nm wavelength range are predicted by numerical simulation. These pulses can be used to investigate ultrafast field-driven electron dynamics in matter., Comment: 6 pages, 4 figures

We develop a method for mapping the anharmonic lattice potential using the time-dependent electric field of the transmitted pulse through thin sample supported by a substrate of non-negligible thickness. Assuming linear propagation in the substrate we fully take into account internal reflection in it while the sample can show arbitrary nonlinear response. We examine the effect of frequency averaging appropriate for broad-band pulse and compare the results taking into account the full frequency dependence. We illustrate the procedure applying it to a model based on recently observed ferroelectric soft-mode nonlinearity in SrTiO$_3$., Comment: 15 pages, 10 figures

Practical aspects of the robust method we recently proposed for producing few-cycle attosecond pulses with arbitrary waveform in the extreme ultraviolet spectral range are studied numerically. It is based on the undulator radiation of relativistic ultrathin electron layers produced by inverse free-electron laser process. Optimal conditions for nanobunching are given; attosecond pulse energy and waveform, and their stability are studied. For K=0.8 undulator parameter, carrier-envelope-phase stable pulses with >45 nJ energy and 80 as duration at 20 nm, and >250 nJ energy and 240 as duration at 60 nm are predicted with 31 mrad and 13 mrad phase stability, respectively.

We investigate the interplay of diffraction and nonlinear effects during propagation of very short light pulses. Adapting the factorization approach to the problem at hand by keeping the transverse-derivative terms apart from the residual nonlinear contributions we derive an unidirectional propagation equation valid for weak dispersion and reducing to the slowly-evolving-wave-approximation for the case of paraxial rays. Comparison of numerical simulation results for the two equations shows pronounced differences when self-focusing plays important role. We devote special attention to modelling propagation of ultrashort terahertz pulses taking into account diffraction as well as Kerr type and second order nonlinearities. Comparing measured and simulated wave forms we deduce the value of the nonlinear refractive index of lithium niobate in the terahertz region to be three orders of magnitude larger than in the visible., Comment: 14 pages, 7 figures

A robust method for producing half-cycle - few-cycle pulses in mid-infrared to extreme ultraviolet spectral ranges is proposed. It is based on coherent undulator radiation of relativistic ultrathin electron layers, which are produced by microbunching of ultrashort electron bunches by a TW power laser in a modulator undulator. According to our numerical calculations it is possible to generate as short as 10 nm long electron layers in a single-period modulator undulator having an undulator parameter of only K=0.25 and which is significantly shorter than the resonant period length. By using these electron layers the production of carrier-envelope-phase stable pulses with up to a few nJ energy and down to 30 nm wavelength and 70 as duration is predicted., Comment: 5 pages, 4 figures

There are implementations and proposals for using microwave or optical radiation for electron acceleration, undulation, deflection, and spatial as well as temporal focusing. Using terahertz (THz) radiation in such applications can be superior to microwave or optical radiation since THz pulses can be generated with significantly smaller temporal jitter to the electron bunch to be manipulated as compared to microwave pulses, and contrary to the optical pulses, the much larger wavelength of THz pulses compares well with typical sizes of electron bunches. Recently generation of ultrashort THz pulses with 1 MV/cm focused electric field was demonstrated, and it is predicted that THz pulses with even 100 MV/cm focused field will be possible. According to the first results of our analytical and numerical studies this field strength is high enough for manipulation of relativistic electron beams by polarised THz pulses in various geometries. It is possible, e.g., to construct a 30 cm long THz undulator for saturated FEL working at 9.6 nm wavelength using electron bunches with 100 MeV energy and 0.42 nC charge., Comment: 4 pages, 4 figures