Giant second-order optical nonlinearities in anharmonic-oscillator potential wells: Perturbation theory calculations

The second-order nonlinear optical effects in anharmonic-oscillator potential wells due to resonant intersubband transitions are studied in detail, and their origins are clarified further. The calculated results show the second-order nonlinear effects root in an anharmonic oscillation of electrons deviating asymmetrically from an ideal harmonic oscillation, and the more the deviation degree and the asymmetry of systems, the larger the second-order nonlinearities. The most important point is very giant optical rectification (OR) and second-harmonic generation (SHG) susceptibilities may be obtained over 10-410-4 and 10-5m/V, respectively, which are over six orders of magnitude greater than those in bulk GaAs, by optimizing the structure parameters. The giant optical nonlinearities may have profound consequences as regards improvements of optical devices and more extensive application in the field of optoelectronics.