An analysis of the performance of Franz-Keldysh electroabsorption waveguide modulators

We present an analysis of the performance limits of the Franz-Keldysh effect (FKE) waveguide modulators, based on the optimization of the material figures of merit related to device performance. This leads to a unique design approach in which the detuning energy and the thickness of the active material determine the required drive voltage and the available bandwidth. A large-core waveguide is used to minimize insertion loss. The overall performance is compared with a similar waveguide modulator based on the quantum confined Stark effect (QCSE). The conclusion is that, because of the relatively small /spl Delta//spl alpha/ available from Franz-Keldysh effect, the power-bandwidth ratio of the optimized FKE modulator is about an order of magnitude poorer than the optimized QCSE modulator.<
>