||D. Weaire, B. S. Wherrett, D. A. B. Miller
and S. D. Smith, "Effect of Low-Power Nonlinear Refraction on Laser Beam Propagation
in InSb," Optics Lett. 4, 331-333 (1979).
By use of an expansion in
Gaussian functions we solve the problem of the propagation of a laser beam that has been
passed through a thin slab of nonlinearly refracting material. We compare the theoretical
results for beam profile with experimental measurements for the semiconductor InSb and
confirm that self-defocussing has been observed by D. A. B. Miller, M. H. Mozolowski, A.
Miller, and S. D. Smith [Opt. Commun. 27, 133 (1978)]. The deduced value
for the nonlinear refractive index at ~5 K is -6 x 10-5cm2/W at 1886
cm-1. This implies a third-order optical nonlinearity chi(3) ~ 10-2
esu, much larger than any previously reported for a solid.
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