The study of second harmonic generation of the femtosecond laser pulses with a 950 nm central wavelength

摘要

The paper presents the results of theoretical and experimental studies of the second harmonic generation process in the Ti:sapphire femtosecond complex, which includes a generator of the femtosecond pulse, stretcher, regenerative amplifier, two multi-pass amplifiers, compressor and second-harmonic generator. This complex provides the 50-fs pulses with energy of 20 mJ and it is used as a master oscillator in THL-100 hybrid laser system, which operates in the visible region at a wavelength of 475 nm. Experiments and calculations for various beam parameters of the fundamental harmonic, such as radiation intensity, spatial profile of the beam and the level of the noise component were performed. It is theoretically shown that in the absence of the noise component in the beam of the fundamental wave a good uniformity of the second harmonic should be observed. When making the amplitude heterogeneities in the first harmonic even greater heterogeneities in the second harmonic are appeared. It is experimentally shown that with increasing of energy beam the inhomogeneity of the second harmonic beam increases.