A high-frequency GaAs optical guided-wave electrooptic interferometric modulator

The characteristics and frequency response of a GaAs monolithic guided-wave interferometric modulator operating at 1.3 μm are presented. The interfetometer consists of three-guide coupler input and output sections and single-mode p+-n--n+ slab-coupled rib-waveguide active arms. The measured electrical bandwidth of an interferometer with 2 mm long active arms was 2.2 GHz and limited by parasitics. This corresponds to a small signal optical bandwidth of ≈ 3.0 GHz when the interferometer is biased in a linear portion of the optical output versus voltage characteristics. Reduction of parasitics should result in a substantial increase in the bandwidth of these devices.