Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films

We experimentally verify a new class of coherent absorbers based on guided-mode resonance effects in periodic thin films. We design a silicon-based resonant absorber that is fabricated and tested near the 1300-nm wavelength. Implementing phase control, the device can, in principle, be switched between full absorption and full scattering. The first experimental prototype presented herein shows ~78% absorption in the in-phase state. Nearly total scattering is realized in the out-of-phase state. The experimental results agree reasonably well with theory.