Dynamics of tunable infrared femtosecond pulses

Nearly transform-limited femtosecond pulses, which are tunable in near- and md-infrared regions, have a variety of applications in time-resolved spectroscopy, optical communications, remote sensing, medicine and biology. A number of crystalline lasers (e. g. Cr:LiSAF, Cr:LiSGaF, Cr4+ : YAG and Cr2+ : ZnSe) provide extremely broad fluorescence band while allowing continuous-wave diode-pumped operation. This project intends to advance the femtosecond laser technology as a result of development of high-efficiency oscillators with controlled spectral and energetic characteristics by means of analytical analysis and numerical modelling. Following topics have to be considered: femtosecond operation of solid-state lasers in the presence of Raman self-scattering, cascaded second- order nonlinearity, and other nonlinear effects in the active medium; Kerr-lens mode locking technique in combination with ultrashort pulse modulation due to the dispersive dielectric mirrors and loss saturation in quantum-dot semiconductor saturable absorbers possessing two-photon absorption and optical Stark shift of excitonic resonance; complex nonlinear behaviour of the semiconductor saturable absorber structures such as PbS- and PbSe-microcrystals dispersed in glass matrixes. The theoretical work is supposed to be performed in close interaction with laser experiments in the host institute