MOSCAP and 3D taper

High speed optical modulators are important for a number of applications served by silicon photonics. Here we present our recent work towards high speed free carrier accumulation based optical modulators where a high speed and efficient operation is achieved. Such silicon optical modulators typically need to be built in sub-micrometre sized waveguides which are challenging to couple light to and from. Also presented are experimental results from a buried 3D-taper that is able to couple efficiently between a waveguide of height ~1.5um and a 220nm high waveguide. Losses below 0.6dB are achieved limited by the loss of the material used.