40 GHz modulation bandwidth of electroabsorption modulator with narrow-mesa ridge waveguide

We have developed the EA modulator with narrow-ridge waveguide to obtain the sufficient extinction ratio with the shorter modulators. Narrowing the waveguide reduces device capacitance from 0.12 pF to 0.08 pF without decrease of the extinction ratio. The modulation bandwidth of 40 GHz at -1 V bias voltage, and the extinction ratio of 15 dB at 0 V to -2.5 V operation voltage are obtained. From the viewpoint of frequency bandwidth and extinction ratio for practical use, it may be concluded that the narrow mesa waveguide structure is suitable for 40 Gb/s optical transmitter devices.