We report high-rate, computer-controlled femtosecond pulse shaping by use of an electro-optical gallium arsenide optical phased-array modulator with 2304 controlled waveguides. It provides fast modulation speed of both spectral phases and amplitudes. Limited by the driving electronics of our current setup, we were able to update a pulse shape in approximately 30 ns. This technique paves the way toward individual shaping of every single pulse of typical femtosecond mode-locked oscillators.
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http://dx.doi.org/10.1364/ol.30.002796 | DOI Listing |
J 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 PDFPhys Rev E
November 2022
Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prospect 53, Moscow 119991, Russia.
The generation of terahertz (THz) radiation under the effect of a femtosecond laser pulse on a transparent semibounded plasma in a constant magnetic field is studied. It is shown how the generation patterns of THz radiation depend on the laser pulse duration and the ratio between the cyclotron and plasma frequencies of electrons. In each of the modes considered, the total energy per unit area, spectral composition, and pulse shape of the generated THz radiation are found.
View Article and Find Full Text PDFBased on the time-independent rate equations and nonlinear Schrödinger equation, we simulate a 200 MHz all-polarization-maintaining (PM) mode-locked Yb-doped fiber laser. The cavity round trip evolution toward stable mode locking is present. Additionally, the gain coefficients along the gain fiber as well as the pulses, chirp, and spectra at different locations in the cavity are examined.
View Article and Find Full Text PDFPhys Rev E
April 2022
Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA.
We demonstrate the sensitivity of the plasma composition in the filament wake channel in a dense gas to the temporal shape of the driving femtosecond laser pulse. During the pulse, the electrons released via strong-field ionization and driven by oscillating laser field are actively engaged in collisional processes with neutral neighbor atoms, including inverse Bremsstrahlung, impact ionization, and collisional excitation. By the end of the pulse, these collisional processes produce considerable numbers of additional free electrons (or ionized atoms) and excited atoms, and these contents of the filament wake channel determine its subsequent evolution dynamics.
View Article and Find Full Text PDFSci Rep
March 2022
Regional Center for Special Optics and Optoelectronic Systems (TOPTEC), Institute of Plasma Physics, Czech Academy of Science V.V.I., Za Slovankou 1782/3, 182 00, Prague 8, Czech Republic.
A targeted shaping of complex femtosecond pulse waveforms and their characterization is essential for many spectroscopic applications. A 4f pulse shaper combined with an advanced pulse characterization technique should, in the idealized case, serve this purpose for an arbitrary pulse shape. This is, however, violated in the real experiment by many imperfections and limitations.
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