Studies of laser-driven strong field processes subjected to a (quasi-)static field have been mainly confined to theory. Here we provide an experimental realization by introducing a bichromatic approach for high harmonic generation (HHG) in a dielectric that combines an intense 70 femtosecond duration mid-infrared driving field with a weak 2 picosecond period terahertz (THz) dressing field. We address the physics underlying the THz field induced static symmetry breaking and its consequences on the efficient production/suppression of even-/odd-order harmonics, and demonstrate the ability to probe the HHG dynamics via the modulation of the harmonic distribution. Moreover, we report a delay-dependent even-order harmonic frequency shift that is proportional to the time derivative of the THz field. This suggests a limitation of the static symmetry breaking interpretation and implies that the resultant attosecond bursts are aperiodic, thus providing a frequency domain probe of attosecond transients while opening opportunities in precise attosecond pulse shaping.
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http://dx.doi.org/10.1038/s41467-023-38187-0 | DOI Listing |
Sci Rep
January 2025
Laser Research Center, Vilnius University, Saulėtekio Avenue 10, LT-10223, Vilnius, Lithuania.
We present a comparative experimental study of supercontinuum generation in undoped scintillator crystals: bismuth germanate (BGO), yttrium orthosilicate (YSO), lutetium oxyorthosilicate (LSO), lutetium yttrium oxyorthosilicate (LYSO) and gadolinium gallium garnet (GGG), pumped by 180 fs fundamental harmonic pulses of an amplified Yb:KGW laser. In addition to these materials, experiments in yttrium aluminium garnet (YAG), potassium gadolinium tungstate (KGW) and lithium tantalate (LT) were performed under identical experimental settings (focusing geometry and sample thickness), which served for straightforward comparison of supercontinuum generation performances. The threshold and optimal (that produces optimized red-shifted spectral extent) pump pulse energies for supercontinuum generation were evaluated from detailed measurements of spectral broadening dynamics.
View Article and Find Full Text PDFInorg Chem
January 2025
School of Physics and Materials Science, Changji University, Changji 831100, People's Republic of China.
Finding novel efficient nonlinear optical materials with large second-order nonlinearity for the UV spectral range remains a formidable challenge, especially for silicate systems. Using a high-temperature solid reaction in a tight vacuum environment, two ultraviolet nonlinear optical materials with a moderate second harmonic generation (SHG) response have been created: PbSiOC and PbCaSiO. The SHG values they computed are roughly 2.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720, United States.
Microadditive manufacturing has revolutionized the production of complex, nano- to microscale components across various fields. This work investigates two-photon (2P) and three-photon (3P) fluorescence imaging, as well as third-harmonic generation (THG) microscopy, to examine periodic microarchitected lattice structures fabricated using multiphoton lithography (MPL). By immersing the structures in refractive index matching fluids, we demonstrate high-fidelity 3D reconstructions of both fluorescent structures using 2P and 3P microscopy as well as low-fluorescence structures using THG microscopy.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Background: The human brain is a complex inter-wired system that emerges spontaneous functional fluctuations. In spite of tremendous success in the experimental neuroscience field, a system-level understanding of how brain anatomy supports various neural activities remains elusive.
Method: Capitalizing on the unprecedented amount of neuroimaging data, we present a physics-informed deep model to uncover the coupling mechanism between brain structure and function through the lens of data geometry that is rooted in the widespread wiring topology of connections between distant brain regions.
Inorg Chem
January 2025
School of Chemistry and Chemical Engineering, Nanchang University, Nanchang 330031, P. R. China.
Organic-inorganic hybrid lead halides have been extensively studied due to their outstanding physical properties and diverse compositional elements. However, environmentally benign tin-based hybrids with remarkable flexibility in bandgap engineering have been less investigated. Herein, we report the successful design and synthesis of three tin-based organic-inorganic hybrid compounds through precise molecular modification: [Me(i-Pr)N][SnBr] (), [MeCHCl(i-Pr)N][SnBr] (), and [MeCHBr(i-Pr-Br)N][SnBr] ().
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