Engineering the absorption spectra of thin film multilayer absorbers for enhanced color purity in cmy color filters

A thin film of dielectric material on metal provides a simple and cost-effective platform for absorbing light of a specific wavelength that can be desirably tuned by tailoring the thin film thickness. This property of controlled absorption can lead to realizing various exciting applications such as absorbers and color filters. The primary concern, however, in using such multilayer configurations for color filtering is color purity, which is generally low as compared to patterned resonant structures that employ costly nanofabrication techniques. We report a practical design technique to achieve filters of cyan, magenta, and yellow (CMY) with enhanced color purity, polarization-insensitive, and angle-insensitive functionalities. The design involves dielectric thin film layer sandwiched between an ultra-thin metal-layer and ground plane. We demonstrate several multilayer material configurations that provide advantages over the current state-of-the-art color filters in terms of color purity. The proposed devices can find applications in high-resolution color printing, digital imaging, holographic displays, and sensing.