Simultaneous measurement of pure-optical and thermo-optical nonlinearities induced by high-repetition-rate, femtosecond laser pulses: application to CS 2

Self-organization of spatial solitons

“…While values for n 2 are in general in good agreement, a value of β = 5x10 -11 cm/W (with some dependence on the light intensity) has been reported [39], which is two orders of magnitude higher than the value in ref. [38]. Our calculations show that for such a high coefficient for two-photon absorption the filaments would decay very rapidly within a few hundred micrometers of propagation, which clearly contradicts the experimental results; therefore the lower value was used in the simulation.…”

“…In many cases the formation of plasma in the material creates a negative index change which stabilizes the propagation; however, in our case the intensity of the filaments is well below the threshold for plasma generation [33]. A negative fifth-order nonlinearity was included in the model to account for the stability of the filaments -13 cm/W [38]. The first term on the right hand side accounts for diffraction, the second is Kerr self focusing (third order nonlinearity), the third term accounts for the fifth order nonlinearity and the last term accounts for two-photon absorption.…”

Near-infrared Kerr nonlinearity of Pb(PO3)2–WO3 glasses

“…For the Kerr shutter measurements carbon disulfide ͑CS 2 ͒ was used as the reference material considering n 2 = 3.1ϫ 10 −19 m 2 / W as it was measured in the femtosecond regime by various authors. [19][20][21][22] Figure 2͑a͒ shows the Kerr signal corresponding to sample D for different pump and probe beams intensities while Fig. 2͑b͒ shows the data obtained for CS 2 and samples B and C. The signals have different amplitudes but they were normalized to be shown in the same figure.…”

Near-infrared third-order nonlinearity of PbO–GeO2 films containing Cu and Cu2O nanoparticles

“…The values obtained for n 2 were ͑6.3Ϯ 0.7͒ ϫ 10 −12 cm 2 / W ͑LGF-7͒ and ͑7.0Ϯ 0.7͒ ϫ 10 −12 cm 2 / W ͑LGF-17͒. The experimental setup was calibrated by using liquid CS 2 with n 2 = 2.3 ϫ 10 −15 cm 2 / W. 19 The value of ␣ 2 is determined by measuring ⌬T pv for the detector with open aperture. However, in the present experiment, the samples' NL absorption was smaller than the minimum value that our setup allows to measure, i.e., 660 cm/ GW, because of the small samples' thickness.…”