The role of permanent dipoles on the intensity-dependent nonlinear optical properties in asymmetric coupled quantum wells under a static electric field

• Our results reveal that in contrast to previous studies in which the effects of the permanent dipole moments were ignored they can play an important role in the nonlinear optical response.
• Our results show that the effects of the permanent dipoles on the corresponding optical processes depend crucially on the direction and strength of the static electric field, especially for large optical intensities.
• in contrast to previous studies, our results do not show the misleading effects of bleaching, negative absorption or positive dispersion near or at resonance.

We study theoretically the intensity-dependent nonlinear optical properties of an asymmetric coupled quantum well under a static electric field. Effects such as nonlinear absorption, optical rectification and refractive index are investigated theoretically by using the density matrix equations including the permanent dipole terms. Our results show that the effects of the permanent dipoles on the corresponding optical processes depend crucially on the direction and strength of the static electric field, especially for large optical intensities. Another interesting result of this work is that the nonlinear optical spectra studied here saturate with an increasing optical intensity and specifically the optical spectra in the case that the permanent dipoles are considered reach saturation for lower intensities than when the permanent dipoles are not considered.

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