An Ultrashort Pulsed Light Source in the VUV - Tunable in the Vicinity of 133 nm

Abstract

Powerful ultrashort laser pulses in the vacuum ultraviolet (VUV) spectral range are of great interest for investigating ultrafast dynamics in atomic and molecular systems, such as in pump-probe studies of photoionization and photodissociation. To freely select arbitrary electronic transitions, achieving wavelength tunability is highly desirable but challenging to attain.

In this thesis, an ultrashort pulsed light source with a central wavelength of 133 nm is realized, employing a step-wise manipulation scheme of ultrashort laser pulses generated by a Ti:Sa laser system. The second harmonic, centered around 400 nm, serves as the fundamental for third-harmonic generation (THG) in a pulsed gas cell. By utilizing xenon as the nonlinear medium, VUV pulse energies of up to 1.5 microjoule are achieved, with a THG conversion efficiency of 0.0017.

A significant advancement toward a wavelength-tunable source is attained through a proof of concept for tunability in the VUV range. The technique is based on the variation of the fundamental wavelength in the Fourier plane of a 4f geometry, which is also used for pulse compression. By shifting the wavelength of the UV radiation over a range of 10 nm, a wavelength shift of 2.8 nm is observed in the resulting VUV light.