About the Cover: Electromagnetic field profiles in ridged silicon and slotted silicon waveguides with nanometer scale gaps. The cover depicts SEM images of a normal ridged waveguide, as well as a slotted waveguide, fabricated using the silicon layer of a standard silicon-on-insulator substrate. The calculated intensity of the electromagnetic field is shown in the colored images. These can be calibrated with the color bar on the left, which ranges from zero (deepest blue at bottom) to 1 x 10⁸ V/cm (deepest orange at top), assuming 1 W of propagating power. The three images at the bottom represent slot widths of 200, 100, and 50 nm. The faint background image shows a micrograph of a portion of a slotted waveguide coupler. The distance between the ring resonator and the straight waveguide is roughly 200 nm. Acknowledgements: This image is courtesy of Michael Hochberg, Tom Baehr-Jones, and Suzanne Hunter.