Nonlinear intersubband transitions in different shaped quantum wells under intense laser field

• The absorption coefficients and the refractive index changes depend on both ILF parameter and QW shape.
• ILF leads to major modifications in the shape of the confining potential of QWs.
• For SQW the intersubband absorption spectrum shows blue or red shift by increasing ILF.
• For PQW, GQW and VQW the absorption spectrum shows always red shift by increasing ILF.

In this study, the intersubband optical absorption coefficients and the refractive index changes are calculated in a square quantum well (SQW), a parabolic quantum well (PQW), a graded quantum well (GQW) and a V-shaped quantum well (VQW), without and with the intense laser field (ILF). Our results show that the position and the magnitude of the linear, nonlinear and total absorption coefficients and refractive index changes depend on ILF parameter and the quantum well (QW) shape. While for SQW the intersubband absorption spectrum shows blue shift up to the critical ILF value, this spectrum shows red shift for greater ILF values than this certain value. Whereas, for PQW, GQW and VQW the absorption spectrum shows always red shift by increasing ILF. Thus, the intersubband absorption coefficients and the refractive index changes which can be suitable for great performance optical modulators and multiple infrared optical device applications can be easily obtained by tuning ILF value and QW shape.