Ultra-large index of refraction via quantum interference

Zhiping Wang, Benli Yu, Shenglai Zhen +1 more

R.-H. Rinkleff, L. Spani Molella, A. Rocco +2 more

It is well known that quantum coherence and interference are important mechanisms in tailoring optical properties of atoms and molecules. Examples are the enhancement of the index of refraction, large optical Kerr nonlinearities, and the cancellation of absorption. Nonlinear media provide a variety of new applications, such as ultra-slowing of light propagation, superluminal light propagation, ultra-sensitive magnetometer or high-finesse broadband optical cavities.

Alexandre G. M. Schmidt, Matheus E. Pereira

Dmitri E. Nikonov, Marlan O. Scully

A diagrammatic representation of the steady-state solution for the density matrix of a multilevel atom under the action of coherent classical fields is presented. It provides an intuitive interpretation of the terms corresponding to quantum interference and dynamical Stark splitting in the equations describing the effects of atomic coherence, such as lasing without inversion, electromagnetically induced transparency and ultra-large index of refraction.

Robert A. McCutcheon, Susanne F. Yelin

Rakesh Dhama, Ali Panahpour, Tuomas Pihlava +2 more

In quantum optical Enhancement of Index of Refraction (EIR), coherence and quantum interference render the atomic systems to exhibit orders of magnitude higher susceptibilities with vanishing or even negative absorption at their resonances. Here we show the plasmonic analogue of the quantum optical EIR effect in an optical system and further implement this in a linear all-optical switching mechanism. We realize plasmon-induced EIR using a particular plasmonic metasurface consisting of a square array of L-shaped meta-molecules. In contrast to the conventional methods, this approach provides a scheme to modulate the amplitude of incident signals by coherent control of absorption without implementing gain materials or nonlinear processes. Therefore, light is controlled by applying ultra-low intensity at the extreme levels of spatiotemporal localization. In the pursuit of potential applications of linear all-optical switching devices, this scheme may introduce an effective tool for improving the modulation strength of optical modulators and switches through the amplification of input signals at ultra-low power.