EXPERIMENTAL-STUDY OF THE SUPERCONTINUUM SPECTRAL WIDTH EVOLUTION IN CO2 GAS

Experimental results on the evolution, as a function of pressure, of t he supercontinuum spectrum generated in CO2 gas (1-40 atm) by weakly f ocussed 1 ps pulses at 593 nm are described. They are adequately fitte d by a self-phase modulation model including the effect of self-steepe ning of the pulse. Above a given pressure optical breakdown appears in the gas. Optical breakdown during supercontinuum generation affects d ifferently the behaviour of the red and blue side broadenings since th e blue side stops broadening after a certain pressure while the red si de keeps increasing.