Confining the light wave by using non-Euclidean transformation optics

A new way to understand why some inhomogeneous dielectric medium can be used for confining the light wave has been given by using non-Euclidean transformation optics. We show that special inhomogeneous dielectric medium, which corresponds to a dip in the reference space, can be used for focusing a plane wave. If we set an absorber at the appropriate position of this medium, we can highly confine the light on the subwavelength scale.