  We theoretically study the effect of Dzyaloshinskii-Moriya interaction (DMI)
on the focusing of a spin-wave lens that is constructed by a circular interface
between two magnetic films. We analytically derive the generalized Snell's law
in the curved geometry and the position of the focal point which exhibits a
peculiar off-axial focusing behavior. We uncover a strong dependence of the
focal point on both the material parameters and the frequency of incident spin
waves. Full micromagnetic simulations compare well with theoretical
predictions. Our findings would be helpful to manipulate spin waves in chiral
magnets and to design functional magnonic devices.
