Abstract
Ultrashort pulse lasers have significant implications across a wide range of applications from metrology, material science to secondary radiation sources or particle acceleration. Strong-field physics relies heavily on these pulses with a duration of only a few optical cycles. Since most of frequently used lasers have a narrow gain bandwidth due to the energy levels of the amplifying medium, it is hard to generate amplified laser pulses directly from the oscillator. Therefore, a post-compression technique is preferred, where the pulses are spectral broadened first and then compressed. High-harmonic generation (HHG) is an extreme nonlinear optical process in which new electromagnetic radiation from the ultraviolet region till the soft-X-ray region are generated from the interaction of strong field laser pulses with matter. HHG provides a versatile tool to study various electronic properties and dynamics pictures of atoms, molecules, and solids. Extending the high-harmonic cutoff frequency in gases has been shown to be beneficial when the driving laser wavelength is increased, or a few-cycle pulse is utilized.
We perform pulse post-compression with filamentation broadening technique for multi-cycle laser pulses at different wavelengths in the near-infrared region. For continuous tuning of the chirp, the compression stage will employ a set of chirped mirrors as well as an additional glass wedge pair. The target is to get few-cycle laser pulses with high efficiency and good spatial beam profile. The intense, few-cycle light pulses at different center wavelengths will be used in the next step to advance the cutoff frequency in high-harmonic signals in various materials toward the water-window region. Furthermore, strong field-solid interaction also be studied with high-harmonic spectroscopy toward low temperatures.
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