We present a simple yet highly sensitive single-beam experimental technique for the determination of both the sign and magnitude of n2. The sample is moved along the z direction of a focused Gaussian beam while the repetitively pulsed laser energy is held fixed. The resultant plot of transmittance through an aperture in the far field yields a dispersion-shaped curve from which n2 is easily calculated. A transmittance change of 1% corresponds to a phase distortion of ≃ λ/250. We demonstrate this method on several materials using both CO2 and Nd:YAG laser pulses.
© 1989 Optical Society of America
Original Manuscript: February 24, 1989
Manuscript Accepted: June 11, 1989
Published: September 1, 1989
M. Sheik-bahae, A. A. Said, and E. W. Van Stryland, "High-sensitivity, single-beam n2 measurements," Opt. Lett. 14, 955-957 (1989)