Camera-aware color routers optimized for imaging information

Abstract

Nanophotonic color routers are conventionally optimized under a normal plane wave against fixed targets. A camera satisfies neither condition: each sensor position integrates a finite-numerical-aperture cone whose chief ray varies across the field. We show this mismatch changes which design scores best: re-scored under the camera pupil, the highest-scoring plane-wave design is overtaken and the plane-wave ranking no longer holds, so the optimum depends on the source model. We design a single-etch silicon nitride router under this illumination ensemble, scoring it by the imaging information its measurements preserve about the reconstructed image. The router collects 2.8 times the photoelectrons of a color-filter array and is, to our knowledge, the only single-layer color router that surpasses it in image information under low light (below about $14$~dB). We fabricate the router and a plane-wave reference, and the fabricated router's measured routing reproduces this low-light crossover.

35 pages, 19 figures. Includes supplementary material