Wideband coherent perfect absorber based on white-light cavity.

We present a new concept for a broadband coherent perfect absorber (CPA), utilizing the properties of white-light cavities. The designed structure attains coherent absorption over a wide spectrum (40 nm), overcoming the single-frequency limitation of conventional CPAs. A closed form analytic description is presented, supplemented by finite difference time-domain simulations for Si-based devices, demonstrating flat, wide-band power absorption. A new integrated-optics-based pulse absorber/terminator and optical modulator based on these devices are proposed and analyzed.