We present a single-layer color router for solid-state image sensors with 0.5 μm size pixels, which is currently the state of the art in sub-micrometer pixels. Unlike other single-layer approaches, a single-layer color router separates colors directly at its output without the need for additional external propagation. Despite being a significant simplification of an ideal color router, a color router made of a single layer achieves very high optical efficiency (0.7–0.8) for the red, green, and blue color channels while simultaneously featuring low crosstalk. These results also improve on the predicted performance of single-layer approaches that rely on an additional external propagation distance to separate colors, typically for pixels that are larger than the 0.5 μm shown here. To gain further insight, we show the importance of the non-propagating, near-field contributions for creating highly efficient color separation devices.
Catrysse et al. (Mon,) studied this question.