title: Formation mechanism of guided resonances and bound states in the continuum in photonic crystal slabs.
abstract: We develop a formalism, based on the mode expansion method, to describe the guided resonances and bound states in the continuum (BICs) in photonic crystal slabs with one-dimensional periodicity. This approach provides analytic insights to the formation mechanisms of these states: the guided resonances arise from the transverse Fabry-Pérot condition, and the divergence of the resonance lifetimes at the BICs is explained by a destructive interference of radiation from different propagating components inside the slab. We show BICs at the center and on the edge of the Brillouin zone protected by symmetry, BICs at generic wave vectors not protected by symmetry, and the annihilation of BICs at low-symmetry wave vectors.
authors.affiliation: The Innovative Institute of Electromagnetic Information and Electronic, Zhejiang University, Hangzhou 310027, China.|The Electromagnetics Academy at Zhejiang University, Zhejiang University, Hangzhou 310027, China.
authors.forename: Xingwei
authors.initials: X
authors.lastname: Gao
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.|Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Chia Wei
authors.initials: CW
authors.lastname: Hsu
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.|Physics Department and Solid State Institute, Technion, Haifa 32000, Israel.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhen
authors.affiliation: The Innovative Institute of Electromagnetic Information and Electronic, Zhejiang University, Hangzhou 310027, China.|The Electromagnetics Academy at Zhejiang University, Zhejiang University, Hangzhou 310027, China.|Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Lin
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Joannopoulos
authors.affiliation: Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Marin
authors.initials: M
authors.lastname: Soljačić
authors.affiliation: The Innovative Institute of Electromagnetic Information and Electronic, Zhejiang University, Hangzhou 310027, China.|The Electromagnetics Academy at Zhejiang University, Zhejiang University, Hangzhou 310027, China.
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Chen