Design of a broadband Ge_1-xSi_x electro-absorption modulator based on the Franz-Keldysh effect with thermal tuning

We present the design of an adiabatic taper coupled Ge_1-xSi_x electro-absorption modulator, which is based on Franz-Keldysh effect. The device has an active region of 0.8×50 µm², an extinction ratio of more than 6 dB and an insertion loss less than 3 dB at the wavelength of 1550 nm. The operating bandwidth can be broadened to more than 90 nm by an AlN block assisted heater with only 6.2 mW energy consumption. Moreover, the operating wavelength shift caused by material composition deviation can be compensated to the expected wavelength by thermal tuning. This design may play an important role in next-generation, high-density optical integrations for datacom and high-performance computing.