Impact of deformation potential scattering on free-carrier induced optical nonlinearities: An experimental study in GaAs
Kotov, V Stiens, J Shkerdin, G Ranson, W De Tandt, C Borghs, Gustaaf Vounckx, R #
Amer inst physics
Journal of Applied Physics vol:91 issue:7 pages:3992-3999
We present results of the experimental determination of the optical nonlinearities induced by heating free electrons distributed in the multivalley conduction band of highly doped n-GaAs. We propose a very sensitive multilayer leaky waveguide structure for transverse magnetic polarized waves in order to drastically reduce the required optical intensities. We explain in depth the dependence of the optical nonlinearity on doping concentration and deformation potentials. For a doping concentration n(o) of 7.6x10(18) cm(-3), we found a nonlinear refractive index value n(2)approximate to(1-/+0.2)x10(-6) cm(2)/W at lambda=10.6 mum, by fitting nonlinear reflection measurements with an equivalent intervalley deformation potential value Lambda(LL)=(1.0+/-0.30)x10(9) eV/cm. (C) 2002 American Institute of Physics.