Power scalable ultrafast laser systems based on ultra-broadband optical parametric amplification (OPA) at longer (>2 µm) wavelengths are desirable for shorter cut-off wavelengths in high-harmonic generation and for driving hard X-ray plasma sources. They will benefit from operation around degeneracy. For all-solid-state chirped pulse OPA (OPCPA) this requires not only sub-50 fs oscillators as alternatives to Ti:sapphire seed sources but also novel laser systems operating at half the seed wavelength with longer pulse durations from few 100 fs up to few 100 ps or even nanoseconds as pump sources. Picosecond pulses amplified in Yb-based modules will be optimum for pumping OPCPA schemes operating in the few-cycle regime seeded by ultrafast 2-µm lasers while moving to yet longer wavelengths in the mid-IR requires amplified picosecond or nanosecond pulses in the 2-µm spectral range. Depending on the particular wavelengths, extreme OPA bandwidths can be obtained with specially designed pulse shaping schemes and nonlinear crystals also away from degeneracy. A great deal of the activities within this project is devoted to exploring components for such systems which includes characterization and testing of various laser and nonlinear materials in diverse operational regimes. The first complete OPA system for use in other MBI projects, a novel 100-kHz few-cycle OPCPA source, is pumped at ~1 µm and seeded near 1.5 µm, with the option for generation of broadband femtosecond pulses also at ~3 µm. The first two OPA stages of this system were completed in 2015, providing output energies already at the desired level. The work on the second large scale OPCPA system targeting the 5-µm wavelength range in the mid-IR and aiming at sub-100 fs, 1 kHz pulses, has continued in 2015 with the development of the pump channel at ~2 µm with unprecedented output parameters and implementation of the pulse shaping/stretching and synchronization.
- Structural dynamics in molecules using time-resolved holography with photoelectrons → MIR pulses (project 2.3)
- Strong-field ionization and electron charge dynamics in Van-der-Waals molecules → CEP-stable NIR pulses (project 2.2)
- Laser driven ultrafast x-ray source for dynamic structural analysis → high energy MIR pulses (project 3.3)
Optical Parametric Chirped Pulse Amplification (OPCPA) systems