Figure - available from: Journal of Physics B Atomic Molecular and Optical Physics
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(a) Schematic diagram of the experimental set-up for the spatio-temporal measurement of the IAP generated in a tow-color driving field. BS, beam splitter; DM, dichroic mirror; DL, delay line; HWP, half-wave plate; WGP, wire grid polarizer. (b) Spatially-resolved harmonic spectrum driven by the 1300 nm fundamental field alone. (c) Same as (b), but for the two-color driving field synthesized by the 1300 nm fundamental and 800 nm assistant laser fields. (d) On-axis harmonic spectra driven by the one-color (red line) and two-color (blue line) laser field, respectively.
Source publication
Characterizing an isolated attosecond pulse (IAP) is essential for its potential applications. A complete characterization of an IAP ultimately requires the determination of its electric field in both time and space domains. However, previous methods, like the widely-used RABBITT and attosecond streaking, only measure the temporal profile of the atto...
Citations
... The HHG process can be well explained by the semiclassical three-step model: electronic ionization, acceleration, and recombination in intense fields [2]. In recent decades, HHG is attracting intense interest worldwide because of its potential applications in the production of a coherent XUV source and attosecond pulses (APs) [3][4][5]. This allows tracing and controlling ultrafast processes in many disciplines with high spatio-temporal resolution [6,7]. ...
The generation of highly elliptically polarized high-order harmonics (EPHHs) is indispensable for investigating chirality-sensitive light-matter interactions. Recently, high-order harmonic generation (HHG) with controllable ellipticity and helicity has attracted considerable attention. In this work, we theoretically demonstrate the possibility of generating broadband EPHHs with the same helicity from mixed gases in orthogonal two-color fields. There is a specific relative phase between the HHG from different gas components of the mixture. In addition, manipulation of the phase difference can be achieved by controlling the alignment angle of the molecule in mixed gases. It enables us to selectively enhance one helicity component of the high-order harmonics in a wide spectral range. This scheme paves a way for possibly generating elliptically polarized attosecond pulses.
... Recently, the all-optical measurement technique was applied to characterize the attosecond pulses generated from relativistic plasma mirrors [24]. And, an all-optical method for the complete spatio-temporal characterization of isolated attosecond pulses has also been demonstrated [25]. ...
... As for the in situ scheme, the all-optical FROG also applies the PCGPA to retrieve the temporal profile of an isolated attosecond pulse from the photon spectrogram. However, previous works only demonstrated the reconstruction of pulses with a duration of several hundred attoseconds [22][23][24][25]. In this work, we investigate whether it is valid to reconstruct isolated attosecond pulses shorter than 100 attoseconds. ...
The characterization of attosecond pulses is crucial for attosecond metrology. In this work, we investigate the isolated attosecond pulse reconstruction with the all-optical method. The results show that this method can characterize isolated attosecond pulses with a duration shorter than 50 attoseconds. Moreover, we develop a deep learning scheme to characterize isolated attosecond pulses. Through supervised learning, the deep neural network learns the mapping from the photon spectrograms to attosecond pulses. It allows complete characterization of the amplitude and phase of isolated attosecond pulses. Compared to the conventional principal component generalized projections algorithm, the reconstruction with our neural network shows superior quality and robustness to noise. Also, the reconstruction computation time is significantly reduced to a few seconds.
... backed with a phosphor screen [53]. The spectrally resolved images are recorded using a charge-coupled device (CCD) camera. ...
High-energy, few-cycle laser pulses are essential for numerous applications in the fields of ultrafast optics and strong-field physics, due to their ultrafast temporal resolution and high peak intensity. In this work, different from the traditional hollow-core fibers and multiple thin solid plates, we represent the first demonstration of the octave-spanning supercontinuum broadening by utilizing multiple ultrathin liquid films (MTLFs) as the nonlinear media. The continuum covers a range from 380 to 1050 nm, corresponding to a Fourier transform limit pulse width of 2.5 fs, when 35 fs Ti:sapphire laser pulse is applied on the MTLFs. The output pulses are compressed to 3.9 fs by employing chirped mirrors. Furthermore, a continuous high-order harmonic spectrum up to the 33rd order is realized by subjecting the compressed laser pulses to interact with Kr gas. The utilization of flowing water films eliminates permanent optical damage and enables wider and stronger spectrum broadening. Therefore, this MTLFs scheme provides new solutions for the generation of highly efficient femtosecond supercontinuum and nonlinear pulse compression, with potential applications in the fields of strong-field physics and attosecond science.
Attosecond streaking provides an extremely high temporal resolution for characterizing light pulses and photoionization processes with attosecond (10−18 s) accuracy, which employs a laser as a streaking field to deflect electrons generated by photoionization. The current attosecond streaking requires a time delay scan between the attosecond pulses and streaking field with attosecond accuracy and a femtosecond range, which is difficult to realize real-time measurement. In this study, we theoretically propose a non-collinear attosecond streaking scheme without the time delay scan, enabling real-time and even the potential to perform single-shot attosecond pulse measurement. In the proposal, time-delay information is projected into longitudinal space, both horizontally and vertically, enabling attosecond pulse characterization with temporal-spatial coupling. From our calculation, down to 70 as pulses with pulse front and wavefront tilt are characterized with high accuracy. Our study not only provides a method toward real-time attosecond pulse measurement, but also an approach for attosecond pump-probe experiments without time delay scan.
