Two-photon absorption and Kerr coefficients of silicon for 850-2200 nm

The degenerate two-photon absorption coefficient beta and Kerr nonlinearity n(2) are measured for bulk Si at 300 K using 200 fs pulses with carrier wavelength of 850 <lambda < 2200 nm for which indirect gap transitions occur. With a broad peak near the indirect gap and maximum value of 2 +/- 0.5 cm/GW, the dispersion of beta compares favorably with theoretical calculations of Garcia and Kalyanaraman [J. Phys. B 39, 2737 (2006)]. Within our wavelength range, n(2) varies by a factor of 4 with a peak value of 1.2x10(-13) cm(2)/W at lambda=1800 nm. (C) 2007 American Institute of Physics.