Formation of plasma channels in distilled water by femtosecond laser pulses in the mid-infrared range

Experimental studies of the parameters of plasma channels formed in distilled water under the action of high power laser pulses with wavelengths of 1050, 1105, 1200, 1300, 1500, 1700 nm with durations of 130, 310, 100, 150, 110 and 80 fs, respectively, were carried out. As a result, the nonlinear refractive index of water was experimentally determined and the quadratic dependence of the critical self-focusing power on the pump wavelength was confirmed. The values of the critical self-focusing power for the wavelengths considered in this work are in the range of 3.8–17.8 MW.