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Author: Elsaesser, Thomas × Author: Grafenstein, Lorenz von × Start date: 2010 × WGL Institute: MBI ×

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    Generation of millijoule few-cycle pulses at 5 μm by indirect spectral shaping of the idler in an optical parametric chirped pulse amplifier
    (Washington, DC : Soc., 2018) Bock, Martin; Grafenstein, Lorenz von; Griebner, Uwe; Elsaesser, Thomas
    Spectral pulse shaping in a high-intensity midwave-infrared (MWIR) optical parametric chirped pulse amplifier (OPCPA) operating at 1 kHz repetition rate is reported. We successfully apply a MWIR spatial light modulator (SLM) for the generation of ultrashort idler pulses at 5 μm wavelength. Only bulk optics and active phase control of the 3.5 μm signal pulses via the SLM are employed for generating compressed idler pulses with a duration of 80 fs. The 80-fs pulse duration corresponds to less than five optical cycles at the central wavelength of 5.0 μm. The pulse energy amounts to 1.0 mJ, which translates into a peak power of 10 GW. The generated pulse parameters represent record values for high-intensity MWIR OPCPAs.
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    Few-cycle 65-µJ pulses at 11.4 µm for ultrafast nonlinear longwave-infrared spectroscopy
    (Washington, DC : Optical Society of America, OSA, 2022) Fuertjes, Pia; Bock, Martin; Grafenstein, Lorenz von; Ueberschaer, Dennis; Griebner, Uwe; Elsaesser, Thomas
    Low-energy excitations can provide insight into the basic ultrafast nonequilibrium dynamics of condensed matter. High-energy femtosecond pulses in the long-wavelength infrared are required to induce such processes, and can be generated in an optical parametric chirped pulse amplification (OPCPA) system comprising three GaSe stages. A femtosecond Cr:ZnS laser serves as the front-end, providing the seed for the 2.0-µm pump and the 2.4-µm signal pulses without nonlinear conversion processes. The OPCPA system is pumped at 2.05 µm by a picosecond Ho:YLF regenerative amplifier at a 1-kHz repetition rate. The recompressed idler pulses at 11.4 µm have a duration of 185 fs and an unprecedented energy of 65 µJ, corresponding to a pump-to-idler conversion efficiency of 1.2%. Nonlinear transmission experiments in the range of the L2 infrared band of liquid water demonstrate the potential of the pulses for nonlinear vibrational spectroscopy of liquids and solids.