The present disclosure is directed to systems and methods for omniresonant broadband coherent perfect absorption of incoherent light over large bandwidths. The apparatus and methods that enable 100% effective optical absorption in a structure, irrespective of the material from which it is constructed, over a large, continuous bandwidth (omniresonance) in ultrathin devices. Specifically, we demonstrate achromatic optical absorption (omniresonance) in a planar Fabry-Pérot micro-cavity via angularly multiplexed phase-matching. By assigning each wavelength to an appropriate angle of incidence, the micro-cavity is rendered absorbing with continuous spectral range. For example, the linewidth of a single-order 0.7 nm wide resonance is de-slanted in spectral-angular space to become a 70 nm wide achromatic resonance spanning multiple cavity free spectral ranges. The embodied invention can have important applications in, e.g., harvesting solar energy, white-light micro-lasers, and other broadband resonantly enhanced optical effects.