Performance Optimization of a Reconfigurable Waveguide Digital Optical Switch on InGaAsP–InP: Design, Material, and Carrier Dynamics

The design and performance of an InGaAsP-InP 1 times 2 reconfigurable waveguide digital optical switch (RW-DOS) actuated by carrier-induced refractive index modulation is described. Using a device model based on the two-dimensional beam propagation method, we present an analysis of the role of material bandgap, carrier lifetime, and waveguide design on the switch performance. The model results are compared with experimental measurements of carrier-induced index change and switching performance for RW-DOS devices and test structures fabricated in InGaAsP alloys with waveguide core compositions of Q = 1.2, Q = 1.3, and Q = 1.4 mum. We discuss compromises between power consumption, switching speed, and propagation loss. The optimized InGaAsP-InP devices exhibited better than 25-dB switching contrast ratio and require less than 20-mA drive current.