Measurement of the nonlinear refractive index of air and other gases at 248 nm

Femtosecond filamentation in transparent media

“…Air (Shimoji et al, 1989) ( Talebpour et al, 1999b) ( Galkin and Tatevian, 1997) N 2 (Ripoche et al, 1997) O 2 ) ) (Mizrahi and Shelton, 1985) (Shaw et al, 1993) Noble gases (Shelton, 1990) ( Perry et al, 1988) ( Dalgarno and Kingston, 1966) (Nurhuda et al, 2002c(Nurhuda et al, , b, 2004 (Li et al, 1999) although high order dispersive terms are less easy to implement in the latter method. The numerical schemes may then even be easily modified so as to introduce mappings between the physical space and the computational space, which transform a regular computational grid into a nonuniform grid in the physical domain.…”

Sensitivity of propagation and energy deposition in femtosecond filamentation to the nonlinear refractive index

“…As an example, extracted 2 n values for the major constituents of air, N 2 and O 2 , show a range of variation exceeding ~100%. Some of this variation can be attributed to nonlinear 3D propagation effects [8,11], unintentional two-beam coupling in degenerate pump-probe experiments owing to the presence of laser-induced Kerr, plasma, and rotational gratings [10,11,13,14], and the laser pulsewidth dependence of the nonlinear response, which had not been directly resolved [8,[10][11][12].…”

“…Experiments that use pulses longer than a few hundred femtoseconds [9,12] cannot distinguish the electronic from rotational response, making such results of limited use for understanding the propagation of ultrashort pulses. Even experiments using pulses that are 90-120 fs [8,10,11,18,19] are barely able to distinguish the two.…”

“…Many indirect measurements of the nonlinear response have appeared in the literature, with the aim of extracting coefficients such as n 2 , the nonlinear index of refraction or Kerr coefficient [7]. Such indirect measurements include spectral analysis after nonlinear propagation [8], spatial profile analysis [9], polarization rotation by induced birefringence [10], and spectral shifts of a probe pulse [11,12]. As an example, extracted 2 n values for the major constituents of air, N 2 and O 2 , show a range of variation exceeding ~100%.…”

Analysis of KrF excimer laser beam modification resulting from ablation under closed thick film flowing filtered water

“…Using Snell"s Law, it can be calculated that a ray passing from the medium of air surrounding the micromachining centre, that possesses a refractive index value of 1.0008 for electromagnetic radiation with a wavelength of 248 nm [33], into the ultra violet (UV) grade fused silica, which possessed a measured refractive index of 1.5084 at the same wavelength [34], resulted in the modification to the path vectors of I a and I b . As the light passed through the fused silica window the angle of refraction of I a , θ ra , was 0.3°, and the angle of refraction of I b was 0.06°.…”