Infrared optical absorption in imperfect parabolic quantum wells

The effects of possible imperfections on the infrared optical absorption and on the charge-density profile of wide parabolic quantum wells (WPQW’s) are studied. We consider effects that can arise from the finite width of WPQW’s, from the existence of a quartic component in the confining potential, and from the existence of a region of flat potential in the center of the well. Within the local-density approximation, we confirm that a perfect WPQW absorbs light only at the bare harmonic-oscillator frequency, and show that the effects of small imperfections of the types considered on the absorption spectrum are twofold: a shift in the location of the main peak and the appearance of new peaks nearby.