  Plasmonic color filters employing a single optically-thick nanostructured
metal layer have recently generated considerable interest as an alternative to
colorant-based color filtering technologies, due to their reliability, ease of
fabrication, high color tunability. However, their relatively low transmission
efficiency (~30%) is an important challenge that needs to be addressed. The
present work reports, for the first time, a novel plasmonic subtractive color
filtering scheme that exploits the counter-intuitive phenomenon of
extraordinary low transmission (ELT) through an ultrathin nanostructured metal
film. This approach relies on a fundamentally different color filtering
mechanism than that of exsiting plasmonic additive color filters, and achieves
unusually high transmission efficiencies of 60~70% for simple architectures.
Furthermore, owing to short-range interactions of surface plasmon polaritons at
ELT resonances, our design offers high spatial resolution color filtering with
compact pixel size close to the optical diffraction limit (~{\lambda}/2),
creating solid applications ranging from imaging sensors to color displays.
