Bragg condition for scattering into a guided optical mode

Abstract

We theoretically investigate light scattering from an array of atoms into the guided modes of a waveguide. We observe that the scattering of a plane wave laser field into the waveguide modes is dramatically enhanced for angles that deviate from the geometric Bragg angle. This modified Bragg condition arises from the dispersive interactions between the guided light and the atoms. We analytically identify various parameter regimes in which the scattering rate features a qualitatively different dependence on the atom number, such as linear, quadratic, oscillatory or constant behavior. In combination with rigorous numerical calculations, we demonstrate that these scalings are independent from a possible asymmetry of the atom-light coupling. Finally, we show that our findings are robust against voids in the atomic array, facilitating their experimental observation and potential applications. Our work sheds new light on collective light scattering and the interplay between geometry and interaction effects, with implications reaching beyond the optical domain.

Cooperative states and shift in resonant scattering of an atomic ensemble

“…Thus, it is expected that the ordering-enhanced emission is more significant in atomic arrays. Indeed, it has been reported that the ordered arrays show a clearer doubled-peak profile in emission spectrum [40,41]. Our results explain the origin of the optical response from an intrinsic point of view.…”