PHOTON SCIENCE

Description

Ultrafast optical laser pulses play a crucial role in many fields: they allow for precise measurements at nanometer length and femto- to attosecond time scales, they provide highest optical peak powers to study fundamental processes at high field strengths and are essential for many industrial applications such as semiconductor manufacturing and healthcare. Traditionally, ultrashort laser pulses with durations reaching from a few 10s of femtoseconds down into the few optical cycle regime have been produced using Tittanium-doped sapphire laser technology. While supporting broad gain bandwidth and thus ultrashort pulse durations, these lasers are limited in repetition rate, providing not more than a few Watts of average power. The growing demand for high-average power ultrashort pulse laser technology, however, has been a driver for the development of alternative ultrashort pulse laser platforms.

We address this demand combing high-average power Ytterbium-based lasers with multi-pass cell (MPC) post-compression. Multi-pass cells represent a new tool for nonlinear optics with quasi-waveguiding properties hybridizing free-space and guided-wave nonlinear optics. They are typically composed of two concave mirrors reflecting a laser beam multiple times back and forth while passing a nonlinear medium used for spectral broadening. The suitable choice of system size, mirror properties and nonlinear medium thereby enables the very efficient post-compression of pico- or femtosecond laser pulses within pulse energies ranging from a few microjoule up to multi-100 millijoules. In addition, very large compression factors can be reached, enabling post-compression of picosecond pulses generated from an ytterbium laser by a factor exceeding 100, as recently demonstrated by us.