High speed carrier-depletion modulators with 1.4V-cm VπL integrated on 0.25μm silicon-on-insulator waveguides

We demonstrate a very efficient high speed silicon modulator with an ultralow pi-phase-shift voltage-length product V pi L = 1.4V-cm. The device is based on a Mach-Zehnder interferometer (MZI) fabricated using 0.25 mu m thick silicon-on-insulator (SOI) waveguide with offset lateral PN junctions. Optimal carrier-depletion induced index change has been achieved through the optimization of the overlap region of carriers and photons. The 3dB bandwidth of a typical 1mm long device was measured to be more than 12GHz. An eye-diagram taken at a transmission rate of 12.5Gb/s confirms the high speed capability of the device. (C) 2010 Optical Society of America