MEASUREMENT OF LOWEST-ORDER NONLINEAR SUSCEPTIBILITY IN 3-5 SEMICONDUCTORS BY SECOND-HARMONIC GENERATION WITH A CO2 LASER

Both the magnitude and sign of the nonlinear susceptibility d14NL(-2,) describing second-harmonic generation at 10.6 have been measured in wedge-shaped semiconducting samples using a Q-switched CO2 laser. The results are (in units of 10-6 esu): d14=+1.0 for InAs, +0.45 for GaAs, +0.26 for GaP, and +1.5 for GaSb. The limits of error are discussed, and the results are compared with previous experimental data and with several recent theoretical calculations. The effect of uniaxial compression on the coherence length for second-harmonic generation is also measured. © 1969 The American Physical Society.