Abstract

There has been considerable interest in the development of second-order optical nonlinearities in an integrated format in semiconductors for second harmonic generation, optical parametric amplification and oscillation and all-optical switching by the cascade process.^1,2 Non-zero second-order nonlinear optical coefficients d₁₅, d₃₁ and d₃₃ can be obtained by growing asymmetric heterostructures. These have the potential to be phase-matched either by domain reversal during growth for vertical emission, or by quantum well disordering for the large conversion efficiencies potentially available with a co-propagating geometry. Earlier estimates of second-order nonlinear optical coefficients made several simplifying assumptions: (1) only the most resonant terms are retained so results are strictly only valid for near resonant (and potentially lossy) cases. (2) bands were treated in either parabolic approximation or mixing restricted to just heavy and light-holes. (3) as a consequence inter-sub-band matrix elements were based on a E · r interaction in contrast to the more rigorous A · p interaction normally employed for semiconductors. This can lead to a considerable underestimation of nonlinear optical coefficients.

© 1996 IEEE