30GHz Ge electro-absorption modulator integrated with 3μm silicon-on-insulator waveguide

We demonstrate a compact waveguide-based high-speed Ge electro-absorption (EA) modulator integrated with a single mode 3 mu m silicon-on-isolator (SOI) waveguide. The Ge EA modulator is based on a horizontally-oriented p-i-n structure butt-coupled with a deep-etched silicon waveguide, which transitions adiabatically to a shallow-etched single mode large core SOI waveguide. The demonstrated device has a compact active region of 1.0 x 45 mu m(2), a total insertion loss of 2.5-5dB and an extinction ratio of 4-7.5dB over a wavelength range of 1610-1640nm with. -4V (pp) bias. The estimated Delta alpha/alpha value is in the range of 2-3.3. The 3dB bandwidth measurements show that the device is capable of operating at more than 30GHz. Clear eye-diagram openings at 12.5Gbps demonstrates large signal modulation at high transmission rate. (C) 2011 Optical Society of America