Coherent Perfect Absorption via Photonic Doping of Zero‐Index Media

Abstract

Coherent perfect absorption, as time‐reversed lasing, is achieved via appropriate interference of waves in absorbers and provides attractive opportunities for flexible control of light scattering and absorption. Here, the authors theoretically and experimentally demonstrate the realization of coherent perfect absorption by using photonic doping of zero‐index media with absorptive defects. Interestingly, the coherent perfect absorption is independent of the size and shape of this “doped” zero‐index medium absorber, as well as the position of the doping defects. This exceptional absorption property can be well explained via the photonic doping theory for zero‐index media. Moreover, the authors demonstrate that the doping scheme also enables novel ways to control absorption, such as multiple channels and multiple doping defects, etc. This work proposes a unique doping approach for advanced coherent perfect absorption with versatile control functionalities.

Fundamental Radiative Processes in Near-Zero-Index Media of Various Dimensionalities

“…Our results are relevant for recent experimental demonstrations of various classes of NZI media. 16,[27][28][29][30] To begin, we consider a two-level system, {|e} , |g}} with transition dipole moment p = p u z embedded in a 3D unbounded lossless homogeneous material with a transition frequency ω. First, we evaluate the influence of a NZI background on spontaneous emission, and then we discuss how these conclusions apply to the absorption and stimulated emission processes.…”

“…This is relevant since some metamaterial implementations of NZI media often exhibit a reduced dimensionality. 16,[26][27][28][29][30] We start by following the quantization procedure proposed by Milonni 35,36 , where the two-level system can be modelled with the following Hamiltonian (See details in SI 33 ):…”

Dirac-like cone-based electromagnetic zero-index metamaterials

“…6: cloaking in waveguide). On the other hand, the waveguide filled with a DCZIM can achieve coherent perfect absorption by doping the DCZIM with absorptive defects 87 .…”

Pulse Reshaping in Double-zero-index Photonic Crystals with Dirac-like-cone Dispersion

“…However, located at BZ boundaries, effective parameter retrieval to PC with Dirac cone is impossible. With the help of the wave tunneling property of DZI materials, cloaking in the waveguide [15][16][17][18][19] , wavefront engineering 20,21 , coherent perfect absorption with configurability 22 and transmissive invisibility cloaking 23 are proposed and demonstrated. As only pure dielectrics with reasonable permittivities are needed, the similar principles have been extended to higher frequencies 24,25 and even acoustic regime 26 .…”