Light emitting device and panel

A back-light source comprises a plurality of light-emitting devices, each light-emitting device having a light-emitting package and a lens surface. In at least some of the light emitting devices, the radius of curvature in one direction of the lens surface is different from the radius of curvature in another direction such that one of the radii of curvature of the lens is greater than the other radius of curvature. In particular, one radius of curvature is equal to or smaller than half the length of the device. The other radius of curvature is equal to or greater than half the length of the device. As such, the lens has different focal lengths in different directions. The light-emitting package can have a plurality of light-emitting sources of a single color or of different colors.