In this paper we present a novel slab lens based on artificial graded index medium. The lens is realized by etching 1-D subwavelength gratings into a high index slab waveguide to achieve the desired effective index distribution. A graded index profile is achieved by gradually modifying the duty cycle of the grating along the horizontal axis, whereas the beam is confined in the vertical direction by the slab waveguide. The proposed device is very attractive for various applications, including mode matching, coupling, guiding, imaging, optical signal processing, while offering the intrinsic advantages of monolithic, on-chip integration. The device is analyzed analytically numerically.