DESIGN OF INGAAS-INALAS MULTIPLE-QUANTUM-WELL (MQW) OPTICAL MODULATORS

Design of InGaAs-InAlAs multiple-quantum-well (MQW) optical modulators is described by employing the step segment method (SSM); the three-dimensional beam propagation method (3-D BPM), and the lumped element circuit model. Optical waveguides are treated as materials with complex refractive index. Field distributions, power confinement factors (GAMMA-factors), propagation losses, etc. are calculated. It is found that the overlap integral is needed to calculate accurately coupling losses between the optical waveguides and single-mode fibers in place of the simple Gaussian beam-coupling formula and that quasi-single-mode propagation can be obtained even for thick core structures. Design procedures for the driving voltage and frequency characteristics are also discussed.