title: Observation of an exceptional point in a chaotic optical microcavity.
abstract: We present spectroscopic observation of an exceptional point or the transition point between mode crossing and avoided mode crossing of neighboring quasieigenmodes in a chaotic optical microcavity of a large size parameter. The transition to the avoided mode crossing was impeded until the degree of deformation exceeded a threshold deformation owing to the system's openness also enhanced by the shape deformation. As a result, a singular topology was observed around the exceptional point on the eigenfrequency surfaces, resulting in fundamental inconsistency in mode labeling.
authors.affiliation: School of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
authors.forename: Sang-Bum
authors.initials: SB
authors.lastname: Lee
authors.forename: Juhee
authors.initials: J
authors.lastname: Yang
authors.forename: Songky
authors.initials: S
authors.lastname: Moon
authors.forename: Soo-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Jeong-Bo
authors.initials: JB
authors.lastname: Shim
authors.forename: Sang Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Jai-Hyung
authors.initials: JH
authors.lastname: Lee
authors.forename: Kyungwon
authors.initials: K
authors.lastname: An