Photonic-doped epsilon-near-zero media for coherent perfect absorption

Coherent perfect absorption increases light absorption to 100% via appropriate interference of waves and provides attractive opportunities for flexible control of light absorption. In this work, we demonstrate that the coherent perfect absorption can be realized using photonic doping of epsilon-near-zero media with both lossless and lossy defects. Based on photonic doping theory, the epsilon-near-zero medium with defects can be homogenized as an effective medium. We find that the lossless defects can tune the effective permeability to be zero, and the lossy defects can further tune the effective permeability to be a pure imaginary value to realize the coherent perfect absorption. Moreover, we show that the doping scheme enables many ways to control absorption, such as multiple channels and multiple doping defects, etc. Our work reveals a unique approach for advanced coherent perfect absorption with flexible control functionalities.