Sum frequency generation by intersubband transition in step quantum wells

Using two CO/sub 2/ lasers, sum frequency generation was achieved in step quantum wells via intersubband transition processes. The power from each continuous wave (CW) CO/sub 2/ lasers was kept low such that the total power onto the sample was below 2 W. The observed sum frequency signal obeyed the polarization selection rule predicted by the simple effective mass envelope function model. The experimentally determined and calculated second order susceptibility values are in reasonable agreement.<
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