Generation of coherent XUV radiation at different interaction lengths using the ultrashort laser system

Generation of short wavelengths is obtained using the gas cells having different lengths. A Ti:sapphire laser system at 1kHz or 10Hz repetition rate is used to produce high harmonic generation (HHG). The gas cell producing optimum harmonic spectrum is determined using the 1kHz laser system. The optimum harmonic signal is obtained under the phase-matched condition. The total harmonic yield is increased by adjusting argon gas pressure in the different gas cell lengths (length of the interaction mediums). Harmonics up to the 27th order are obtained. The 1D model is used for the calculation of harmonic yield at different interaction lengths. The high-power laser system at the 10Hz repetition rate is used to generate high-order harmonics. The harmonic orders are extended to the 35th harmonic in argon gas. A harmonic spectrum in H2 gas is generated using different pump laser power. The power dependence of the harmonic signal from H2 gas is obtained. The variation of the harmonic spectrum for the different cell parameters is explained as a constructive or destructive buildup of generated harmonics while they propagate through the gas cell.