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


Michael Lobet, Iñigo Liberal, Erik N. Knall, M. Zahirul Alam, Orad Reshef, Robert W. Boyd, Nader Engheta, and Eric Mazur. 2020. “Fundamental Radiative Processes in Near-Zero-Index Media of Various Dimensionalities.” ACS Photonics, 7, Pp. 1965-1970. Publisher's Version


ABSTRACT: Spontaneous emission, stimulated emission and absorption are the three fundamental radiative processes describing light−matter interactions. Here, we theoretically study the behavior of these fundamental processes inside an unbounded medium exhibiting a vanishingly small refractive index, i.e., a near-zero-index (NZI) host medium. We present a generalized framework to study these processes and find that the spatial dimension of the NZI medium has profound effects on the nature of the fundamental radiative processes. Our formalism highlights the role of the number of available optical modes as well as the ability of an emitter to couple to these modes as a function of the dimension and the class of NZI media. We demonstrate that the fundamental radiative processes are inhibited in 3D homogeneous lossless zero-index materials but may be strongly enhanced in a zero-index medium of reduced dimensionality. Our findings have implications in thermal, nonlinear, and quantum optics as well as in designing quantum metamaterials at optical or microwave frequencies.

KEYWORDS: near-zero index materials, spontaneous emission, stimulated emission, absorption, fundamental radiative processes

Last updated on 02/01/2021