Latest Issue
2024 Year 4 Volume 1 Issue
- Abstract：As a driving source for many nonlinear vortex phenomena, such as the generation of isolated attosecond optical vortices, terahertz vortices, etc., terawatt-class few-cycle short-wave infrared vortex lasers are now attracting widespread attention. However, because the vortex characteristics of optical vortices are difficult to maintain in the amplification and compression stages, the generation of high-intensity few-cycle vortex lasers is still in the exploratory stage. In this article, we report 20-Hz, 18.6-mJ, 60-fs, and 1.45-μm infrared vortex lasers with 1, 2, and 3 topological charges successfully generated in an optical parametric chirped pulse amplification system. A clean intensity node at the beam center is observed and highly stable propagation in free space is demonstrated. Moreover, this high-energy vortex pulse is spectrally broadened in multiple thin plates and temporally compressed to 10.59 fs (2.2 optical cycles) with chirped mirrors, corresponding to a peak power of 1.08 TW, while highly preserving the vortex information. We believe that the generated high-energy few-cycle vortex laser has important applications from vortex optics to strong-field physics.12|1|0Updated：2024-10-22
- Abstract：Photoelectron spectroscopy in intense laser fields has proven to be a powerful tool for providing detailed insights into molecular structure. The ionizing molecular orbital, however, has not been reconstructed from the photoelectron spectra, because its phase information is difficult to access. Here, we propose a method to retrieve the phase information of the ionizing molecular orbital. By analyzing the interference pattern in the photoelectron spectrum, the weighted coefficients and the relative phases of the constituent atomic orbitals for a molecular orbital can be extracted. With this information, we reconstruct the highest occupied molecular orbital of N2. Our work provides a reliable and straightforward approach for reconstructing molecular orbitals with the photoelectron spectroscopy.11|0|0Updated：2024-10-22
- Abstract：We investigate the spatial characteristics of high-order harmonic radiation generated in argon and observe cross-like patterns in the far field. An analytical model describing harmonics from an astigmatic driving beam reveals that these patterns result from the order and generation position-dependent divergence of harmonics. Even small amounts of driving field astigmatism may result in cross-like patterns, coming from the superposition of individual harmonics with spatial profiles elongated in different directions. By correcting the aberrations using a deformable mirror, we show that fine-tuning the driving wavefront is essential for optimal spatial quality of the harmonics.8|0|0Updated：2024-10-22
- Abstract：Single-shot 2-dimensional optical imaging of transient phenomena is indispensable for numerous areas of study. Among existing techniques, compressed ultrafast photography (CUP) using a chirped ultrashort pulse as active illumination can acquire nonrepetitive time-evolving events at hundreds of trillions of frames per second. However, the bulky size and conventional configurations limit its reliability and application scopes. Superdispersive metalenses offer a promising solution for an ultracompact design with a stable performance by integrating the functions of a focusing lens and dispersive optical components into a single device. Nevertheless, existing metalens designs, typically optimized for the full visible spectrum with a relatively low spectral resolution, cannot be readily applied to active-illumination CUP. To address these limitations, here, we propose single-shot compressed ultracompact femtophotography (CUF) that synergically combines the fields of nanophotonics, optical imaging, compressed sensing, and deep learning. We develop the theory of CUF’s data acquisition composed of temporal–spectral mapping, spatial encoding, temporal shearing, and spatiotemporal integration. We also develop CUF’s image reconstruction via deep learning. Moreover, we design and evaluate CUF’s crucial components—a static binary transmissive mask, a superdispersive metalens, and a 2-dimensional sensor. Finally, using numerical simulations, CUF’s feasibility is verified using 2 synthetic scenes: an ultrafast beam sweeping across a surface and the propagation of a terahertz Cherenkov wave.5|0|0Updated：2024-10-22
Research
- Abstract：Particle acceleration driven by intense lasers has long been a frontier of research in the field of laser engineering physics due to its extremely high acceleration gradient. Recently, dielectric laser accelerators (DLAs) have become a new research hotspot due to their ability to achieve gigavolt-per-meter acceleration gradients on compact chip-level all-optical structures. In comparison to the currently widely used solid-state laser with a 1-μm wavelength, long-wave infrared (LWIR) lasers with a length of about 10 μm offer several unique advantages, including the ability to obtain a large electric charge of particle beams and lower energy divergence. These advantages have been validated in plasma-based laser accelerators as well as DLAs. Although the system is still in its early stages of development, the use of LWIR lasers for driving DLAs has special significance, including but not limited to easier processing of optical chips and larger acceleration channels. This review will provide a detailed introduction to this field from 2 aspects: DLAs and ultrashort and ultraintense LWIR lasers based on CO2 laser amplifiers.6|0|0Updated：2024-10-22
Review
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