We report on the generation of high energy femtosecond pulses at 1 MHz repetition rate from a fiber laser pumped optical parametric amplifier (OPA). Nonlinear bandwidth enhancement in fibers provides the intrinsically synchronized signal for the parametric amplifier. We demonstrate large tunability extending from 700 nm to 1500 nm of femtosecond pulses with pulse energies as high as 1.2 muJ when the OPA is seeded by a supercontinuum generated in a photonic crystal fiber. Broadband amplification over more than 85 nm is achieved at a fixed wavelength. Subsequent compression in a prism sequence resulted in 46 fs pulses. With an average power of 0.5 W these pulses have a peak-power above 10 MW. In particular, the average power and pulse energy scalability of both involved concepts, the fiber laser and the parametric amplifier, will enable easy up-scaling to higher powers.
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http://dx.doi.org/10.1364/oe.14.004765 | DOI Listing |
Comput Methods Biomech Biomed Engin
January 2025
Department of Clinical Surgery, Cty Clin Emergency Hosp, Sibiu, Romania.
This study examines heat transfer and nanofluid-enhanced blood flow behaviour in stenotic arteries under inflammatory conditions, addressing critical challenges in cardiovascular health. The blood, treated as a Newtonian fluid, is augmented with gold nanoparticles to improve thermal conductivity and support drug delivery applications. A hybrid methodology combining finite element method (FEM) for numerical modelling and artificial neural networks (ANN) for stability prediction provides a robust analytical framework.
View Article and Find Full Text PDFAtoms in Rydberg states are an important building block for emerging quantum technologies. While excitation to Rydberg orbitals is typically achieved in more than tens of nanoseconds, the physical limit is in fact much faster, at the ten picoseconds level. Here, we tackle such ultrafast Rydberg excitation of a rubidium atom by designing a dedicated pulsed laser system generating 480 nm pulses of 10 ps duration.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
We present velocity-map imaging (VMI) of photoelectrons detached from anions using an optical parametric amplifier operating at a repetition rate as high as 100 kHz. The light source generates femtosecond (fs) laser pulses tunable from near-infrared to ultraviolet (310-2600 nm), which interact synchronously with mass-selected anion bunches. We demonstrate this technique by measuring two-dimensional projections of photoelectrons ejected from silver trimer anions, Ag3-, across a photon energy range from 2.
View Article and Find Full Text PDFJ Chem Phys
December 2024
Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
Generating wavelength-tunable picosecond laser pulses from an ultrafast laser source is essential for femtosecond stimulated Raman scattering (FSRS) measurements. Etalon filters produce narrowband (picosecond) pulses with an asymmetric temporal profile that is ideal for stimulated resonance Raman excitation. However, direct spectral filtering of femtosecond laser pulses is typically limited to the laser's fundamental and harmonic frequencies due to very low transmission of broad bandwidth pulses through an etalon.
View Article and Find Full Text PDFCureus
October 2024
Internal Medicine Department, Shalamar Hospital, Lahore, PAK.
Introduction: Rheumatic heart disease (RHD) results from chronic inflammation and fibrosis of heart valves following untreated rheumatic fever, yet its immunopathology, particularly involving T helper 17 (Th17) cells and their cytokines, is not fully understood. Th17 cells are prominent drivers of inflammation and have been linked to various autoimmune diseases, suggesting their potential role in RHD-related valve damage. This study examines Th17-associated cytokines-interleukin (IL)-17, IL-6, IL-23, and IL-21-in RHD.
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