Design of a novel periodic asymmetric intra-step-barrier coupled double strained quantum well electroabsorption modulator at 1.55 μm

A novel structure for electroabsorption modulator at 1.55 μm with In(1−x−y)Ga(x)Al(y)As periodic asymmetric intra-step-barrier coupled double strained quantum well (AICD-SQW) is proposed. The intra-step-barrier in the structure provides a high optical saturation power due to delayed red shift. The asymmetric strained well layers reduce the oscillator strength at zero field, and as a result a lower insertion loss is obtained. This is due to the deep separation of electron and heavy hole wave functions. This structure shows that electroabsorption modulator (EAM) properties such as large change in absorption, high extinction ratio, large Stark shift, very low insertion loss, zero chirp, and higher figures of merit are possible to be achieved simultaneously as compared with intra-step quantum well (IQW). In numerical analysis, the exciton equation in momentum space is solved numerically, using Gaussian quadrature method (GQM), to obtain the exciton binding energy and oscillator strength. The asymmetric quantum well structure Hamiltonian is numerically solved by transfer matrix method (TMM), to obtain the electron and hole subband energy levels, taking the strain into account. The electroabsorption coefficient is calculated for different applied electric field for TE input light polarization. The EAM parameters such as extinction ratio, insertion loss, chirp and the figures of merit are calculated and the performances of AICD-SQW are compared with IQW.