Optical modulator using a serpentine dielectric layer between silicon layers

Apparatus comprising:

• a first silicon layer, the first silicon layer having a plurality of trenches formed therein, wherein the first silicon layer is n-doped;
• a dielectric layer lining the first silicon layer, wherein a cross section of the dielectric layer relative to a direction of propagation of light through the apparatus comprises a substantially serpentine shape;
• a second silicon layer disposed on the dielectric layer and filling the one or more trenches, wherein the second silicon layer is undoped;
• and
• a layer of p-doped silicon disposed between the dielectric layer and the second silicon layer, the layer of p-doped silicon lining the dielectric layer, wherein the layer of p-doped silicon is thinner than the second silicon layer.