OPTIMIZATION OF MULTIPLE QUANTUM-WELL STRUCTURES FOR WAVE-GUIDE ELECTROABSORPTION MODULATORS

A systematic approach for optimizing the performance of a multiple quantum well electroabsorption waveguide modulator is presented. The primary criterion of the modulator performance for digital and analog applications is taken to be the change of transmission DELTA-T at a given applied electric field. The design variables used to maximize DELTA-T include the device length (L), as well as the quantum well width and composition which determine the electroabsorption (DELTA-alpha) and the residual absorption (alpha-0) at a given photon wavelength. Within the range of DELTA-T that can satisfy the system requirement, the L is then minimized to maximize the bandwidth. The effect of the guided wave index profile and the electrical properties of the p-i-n structure on the bandwidth and the drive voltage requirement is discussed. Calculated results are presented for AlGaAs-GaAs quantum well modulators based upon published data.