Generation of ultrashort mid-infrared pulses by use of optical parametric chirped pulse parametric amplification

by Dr Skirmantas Ališauskas (Institute of Photonics, TU Wien, Gusshausstrasse 27/387, Vienna, Austria)

Monday 5 Sept 2016, 14:00 → 15:00 Europe/Berlin

DESY Hamburg

High peak power mid-infrared laser sources are of particular interest because of their role in high harmonic generation, filamentation, and unusual regimes for nonlinear optical phenomena. These applications require as short pulses as possible, preferably sub-two cycle duration due to the ability to expose target to a peak field without causing excessive ionization by the preceding cycles of the pulse. The extension of the OPA output into the mid-infrared range above 3 μm at multi-mJ pulse energy levels and few-cycle pulse width faces principal challenges such as the low Quantum conversion efficiency of the near-infrared pump pulse energy into the mid-infrared idler wave; the lack of efficient transparent nonlinear crystals capable of supporting a few-cycle pulse bandwidth; the difficulties with the generation of mid-infrared seed light, etc. The current challenge is to obtain few-cycle pulses in the 3–4 m range with the energy of several mJ. The target mid-infrared pulse energy level is backed by theoretical predictions and extrapolated experimental data for shorter-wavelengths driver pulses and is required for achieving a phasematched HHG regime. Phase matching ensures a high keV photon flux despite the unfavorable HHG wavelength scaling at the atomic dipole level [1].Parametric source based on KTA crystal have been successfully used for the generation of multimJ pulses in the 3-4 μm range [2], however, the duration is typically limited to sub-100 fs duration due to phase matching bandwidth limitations. This limitation gave rise a demand of number of various external pulse compression techniques based on nonlinear-optical spectral broadening and either subsequent dispersion compensation after the nonlinear interaction or concurrent dispersion compensation in the nonlinear medium itself [3]. References [1] T. Popmintchev et al., “Bright Coherent Ultrahigh Harmonics in the KeV X-ray Regime from Mid-Infrared Femtosecond Lasers”, Science 336, 1287 (2012). [2] G. Andriukaitis et al., “90 GW peak power few-cycle mid-infrared pulses from an optical parametric amplifier”, Opt. Lett. 36 2755 (2011). [3] V. Shumakova et al., “Multi-millijoule few-cycle mid-infrared pulses through nonlinear selfcompression in bulk”, accepted to Nat. Comm. (2016)