Tailoring light and heavy holes of GaAsP-AlGaAs quantum wells by using interdiffusion for polarization-independent amplifier applications

A theoretical study of the polarization-independent (PI) optical gain using group III and group V interdiffusion for under- and over-strained GaAsP-AlGaAs quantum wells (QW´s), respectively, is presented here. The group III interdiffusion generates a large enough Al concentration into the well of the under-strained QW for providing PI optical gain while this can be achieved in the over-strained QW through the reduction of the P concentration in the well by group V interdiffusion. When the well width increases, the required extent of interdiffusion to obtain PI optical gain increases for the case of group V diffused QW´s, but, for the case of group III diffused QW´s, the required extent of interdiffusion is not sensitive to the well width. In addition, the introduction of Al in the well layer of QW´s can shorten and lengthen the group III and group V interdiffusion, respectively, for providing the PI optical gain. Similar results can also be obtained by increasing the P concentration in the well layer. Consequently, group III and group V interdiffusion can be used to achieve PI optical gain in the under- and over-strained QW´s, respectively, for use in PI optical amplifiers. A range of the extent of interdiffusion can be used to obtain the PI gain although the value of the PI gain may reduce. Besides, the operating wavelength can be blue-shifted in group III interdiffusion and red-shifted in group V interdiffusion. Moreover, TE and TM optical gain peaks can be adjusted using interdiffusion for laser applications.