In cooperation with the Iranian Nuclear Society

Document Type : Research Paper

Authors

1 دکتر

2 photonic resrearch group

3 faculty/photonics & quantum research school

4 faculty

Abstract

To achieve white light source supercontinuum generation by amplified Ti:sapphire femtosecond laser filamentation in deionized water is experimentally investigated. During the propagation of femtosecond pulses in deionized water the self-focusing phenomenon leads to filamentation and supercontinuum generation. The effect of changing the distance of the focal point from the cell and the effect of the incident femtosecond laser pulse energy variation on the supercontinuum spectra have been studied. At powers close to the critical power, rings, and cone emission form a significant part of the continuum. At very high laser powers, the central white light part covers the entire output signal. A supercontinuum emission with 600 nm width was generated by a 1.19 mJ laser pulse energy. The spectrum broadening due to the Kerr self-focusing and plasma defocusing for 37 femtosecond laser pulses with average power in the range of 420 to 3800 times critical power has been investigated. By increasing the input pulse energy up to 460 µJ which its average power is 2900 times critical power, the width of the spectrum increased asymmetrically, and the blue edge of the spectrum shifted to 400 nm. With a further increase in energy, due to the intensity clamping, no more shift was observed.

Keywords