We describe the first reported direct determination of the 10-µm nonlinear susceptibility in intrinsic Ge through time-resolved ellipse rotation. We found that χ31111 = 2.5 × 10-11 esu and χ31221 = 1.3 × 10-11 esu, significantly below previous estimates.
© 1980 Optical Society of America
D. E. Watkins, C. R. Phipps, Jr., and S. J. Thomas, "Determination of the third-order nonlinear optical coefficients of germanium through ellipse rotation," Opt. Lett. 5, 248-249 (1980)