Optical second-harmonic generation from unbiased single Ga/sub 1-x/Al/sub x/As quantum wells with symmetric structures

The nonlinear optical susceptibilities of various quantum-well Ga/sub 1-x/Al/sub x/As compounds grown by molecular beam epitaxy were measured by pumping with a Q-switched and mode-locked Nd:YAG laser. The contribution of second-harmonic waves from the bulk nonlinear susceptibility and the electrical dipole sheet in the quantum well was calculated separately. The measured second-harmonic reflectivity decreases as the silicon doping concentration increases and its angular variation follows the Bloembergen and Pershan theory. Both the experimental and theoretical results indicate that the electron gas and dipole sheet in the unbiased single quantum wells have a negligible effect on the second-order nonlinear generation.<
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