Ge quantum-well waveguide modulator at 1.3μm

We report on the developments of Ge/SiGe quantum well (QW) waveguide modulators operating at 1.3 mu m. First we studied QW structures grown on a 13-mu m SiGe buffer on bulk silicon. Light was directly coupled and propagated in the active region. Using a 3-mu m wide and 50-mu m long modulator, an extinction ratio larger than 4 dB was obtained for a drive voltage lower than 5 V in a 15 nm wavelength range. Then simulations were performed to evaluate the performances of an integrated modulator on silicon on insulator (SOT) platform. An eigenmode expension method was used to model the vertical optical coupling between SOT waveguide and Ge/SiGe devices. It is shown that a reduction of the thickness of the buffer leads to a significant improvement in the performances (extinction ratio, insertion loss) and footprint of the waveguide-integrated devices.