InGaAs/InAlAs quantum-well electroabsorption waveguide modulators with large-core waveguide structure: design and characterization

The design and the systematic characterization of the waveguide and the material properties of a modulator based on InGaAs/InAlAs quantum-well material for 1.5-µm operation are described. Following our previously developed theoretical design algorithm for optimizing the total performance of waveguide electroabsorption modulators [IEEE J. Quantum Electron, 29, 2476 (1993)], we designed an unconventional waveguide structure with a large passive core to yield better coupling efficiency for standard optical fibers and a thin active layer that yields a small optical-confinement factor. To evaluate the performance of this waveguide modulator, experimental methods for measuring the coupling efficiency, the optical-filling factor, and the absorption coefficient of the waveguide modulator and for characterizing the material properties were developed. The limitations of the material and the waveguide design, and the generalization of the limited set of experimental results based on a specific modulator to the design of more-general waveguide modulators are discussed.