Imaging of modes in a silicon nitride optical waveguide by photoelectron microscopy

Modes in a tapered rectangular silicon nitride optical waveguide on silicon were viewed using high-magnification photoelectron microscopy. A thin cesium antimonide photocathode film was deposited on the guide, with laser illumination introduced through an optical fiber attached to the substrate edge. Although elaborate preparation of the sample and chamber for ultrahigh-vacuum is not necessary, high-resolution images were obtained; hence, this method is suitable for practical application.<>