title: Thresholdless crescent waves in an elliptical ring.
abstract: By introducing symmetry-breaking in geometry, we reveal the existence of thresholdless crescent waves, i.e., nonlinear diffractionless modes pinged to the boundary of a curvature, in an elliptical ring. An effective nonlinear Schrödinger equation along the azimuthal direction is derived by taking the transformation in the curvilinear coordinate of elliptical symmetry, which illustrates the formation of trapping potentials (barriers) along the semi-major (minor) axis. Our results demonstrate an alternative but efficient approach to access optical modes with a variety of inhomogeneous potentials.
authors.affiliation: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Kuan-Hsien
authors.initials: KH
authors.lastname: Kuo
authors.forename: YuanYao
authors.initials: Y
authors.lastname: Lin
authors.forename: Ray-Kuang
authors.initials: RK
authors.lastname: Lee