THE DESIGN OF QUANTUM-CONFINED STARK-EFFECT MODULATORS FOR INTEGRATION WITH 1.55 MU-M LASERS

Various factors affecting the design of an optical modulator based on the quantum-confined Stark effect and suitable for integration with a 1.55 mum InGaAs(P) laser are considered. Multiple quantum well (MQW) s tructures comprising various combinations of InP, InGaAs, InGaAsP and InGaAlAs materials are considered both theoretically and experimentall y. Calculations of Stark shifts and overlap integrals, as functions of applied electric field, are used to assess the potential for modulato r performance. A quaternary/quaternary system is shown to give the bes t performance at the wavelength of interest and this has been demonstr ated using MOVPE-grown structures. The calculations of Stark shifts an d wavefunction localization have also been employed to assess the opti mum layer thicknesses in the MQW and are compared with photocurrent da ta.