title: What is and what is not electromagnetically induced transparency in whispering-gallery microcavities.
abstract: There has been an increasing interest in all-optical analogues of electromagnetically induced transparency and Autler-Townes splitting. Despite the differences in their underlying physics, both electromagnetically induced transparency and Autler-Townes splitting are quantified by a transparency window in the absorption or transmission spectrum, which often leads to a confusion about its origin. While the transparency window in electromagnetically induced transparency is a result of Fano interference among different transition pathways, in Autler-Townes splitting it is the result of strong field-driven interactions leading to the splitting of energy levels. Being able to tell objectively whether an observed transparency window is because of electromagnetically induced transparency or Autler-Townes splitting is crucial for applications and for clarifying the physics involved. Here we demonstrate the pathways leading to electromagnetically induced transparency, Fano resonances and Autler-Townes splitting in coupled whispering-gallery-mode resonators. Moreover, we report the application of the Akaike Information Criterion discerning between all-optical analogues of electromagnetically induced transparency and Autler-Townes splitting and clarifying the transition between them.
authors.affiliation: Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Peng
authors.affiliation: Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Sahin Kaya
authors.initials: SK
authors.lastname: Özdemir
authors.affiliation: Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Weijian
authors.initials: W
authors.lastname: Chen
authors.affiliation: 1] Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama 351-0198, Japan [2] Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA.
authors.forename: Franco
authors.initials: F
authors.lastname: Nori
authors.affiliation: Department of Electrical and Systems Engineering, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Lan
authors.initials: L
authors.lastname: Yang