Asymmetric two-step GaAlAs quantum well for cascaded second-order processes

An asymmetric two-step GaAlAs quantum-well suitable for applications that employ the cascading second-order nonlinear effect is proposed. The existence of a large /spl chi//sub zzz//sup (2)/ (d/sub 33/) second-order susceptibility tensor based on transitions between the light hole and the conduction band at a wavelength of 1.55 /spl mu/m is demonstrated. The expression for /spl chi//sub zzz//sup (2)/ is obtained using the density matrix formalism and the envelope function approximation including the valence band-mixing model. The magnitude of the /spl chi//sub zzz//sup (2)/ is estimated to be of the same order as that of the bulk GaAs material and /spl chi//sub xzx//sup (2)/.<
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