Experiments and numerical simulation were performed for verification of the role of femtosecond pulse chirp for supercontinuum generation in photonic crystal fiber. We demonstrate that injection of high power negatively chirped pulses near zero dispersion point brings an advantage over positively chirped pulses resulting in additional collision between solitons and in development of a significantly broader spectrum. Coupling between Raman induced solitons and dispersive waves generated by higher order dispersion was proven to be the key mechanism behind the results.
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http://dx.doi.org/10.1364/OE.18.016733 | DOI Listing |
In this paper, we demonstrate a high-contrast front-end laser system based on Yb: YAG solid-state laser for Ti: sapphire terminal amplification. An ultrafast Yb: YAG solid-state laser is used to generate a broad-spectrum seed through white light generation (WLG), and then the signal light near 1600 nm is amplified by three-level colinear optical parametric chirped pulse amplification (OPCPA). Finally, a fs second harmonic generation (SHG) is used to obtain a laser output with a central wavelength of 795 nm, a pulse width of 40.
View Article and Find Full Text PDFWe demonstrate a dual-crystal Yb:YAG bulk regenerative amplifier that delivers a hundred-watt average power and millijoule-class pulse energy. The repetition rate of the presented laser is tunable from 50 kHz to 300 kHz, with the highest pulse energy and laser power of 1.9 mJ and 108.
View Article and Find Full Text PDFHigh-order solitons exhibit fascinating dynamics during their propagation in anomalous dispersion media. High-order soliton dynamics have been intensively exploited for extreme pulse compression and coherent ultra-broadband spectrum generation. Despite recent advances, most previous studies have been restricted to soliton propagation external to a laser cavity, leaving the intracavity generation and evolution of high-order solitons less explored.
View Article and Find Full Text PDFUltrasonics
January 2025
Medical Ultrasound Department for the Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, Jiangsu 215163, China. Electronic address:
Shear Wave Elastography (SWE) is an imaging technique that detects shear waves generated by tissue excited by Acoustic Radiation Force (ARF), and characterizes the mechanical properties of soft tissue by analyzing the propagation velocity of shear wave. ARF induces a change in energy density through the nonlinear propagation of ultrasound waves, which drives the tissue to generate shear waves. However, the amplitude of shear waves generated by ARF is weak, and the shear waves are strongly attenuated in vivo.
View Article and Find Full Text PDFNat Methods
January 2025
Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA.
Super-resolution imaging of cell metabolism is hindered by the incompatibility of small metabolites with fluorescent dyes and the limited resolution of imaging mass spectrometry. We present ultrasensitive reweighted visible stimulated Raman scattering (URV-SRS), a label-free vibrational imaging technique for multiplexed nanoscopy of intracellular metabolites. We developed a visible SRS microscope with extensive pulse chirping to improve the detection limit to ~4,000 molecules and introduced a self-supervised multi-agent denoiser to suppress non-independent noise in SRS by over 7.
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