Nonlinear optical absorption in an n-InGaAsP/p-InP heterodoping superlattice

Abstract

Absorptive optical nonlinearity in an n-InGaAsP/p-InP heterodoping superlattice grown by vapor phase epitaxy is investigated. Although change in the absorption coefficient per an excited carrier obtained for the doping superlattice is comparable to that of bulk material, larger nonlinear absorption is induced by unit-intensity light illumination. This enhancement is attributable to prolonged carrier recombination lifetime due to the separation of electrons and holes in space. The nonlinear absorption caused by accumulated photocarriers can be explained by the combination of two effects: blocking of direct band-to-band transition in real space (band filling effect), and change in probability of indirect transition in real space (Franz–Keldysh effect) due to a modified internal electric field.