Coupled GaAs/AlGaAs quantum-well electroabsorption modulators for low-electric-field optical modulation

Abstract

Experimental and theoretical studies are presented for exciton transitions in p-i-n GaAs/AlGaAs multiple coupled-quantum-well structures where each quantum well consists of two identical wells with a thin barrier. Electroabsorption and photocurrent studies are carried out to identify how the excitonic peaks respond to transverse electric fields. With a careful choice of the dimensions of the coupled quantum well, it is seen that the lowest heavy-hole exciton peak moves at a rate ∼2.5 faster than in a square well. Thus strong modulation is obtained at much lower electric fields. The nature of the higher-energy transitions is also studied.