A grating coupler having first and second ends for coupling a light beam to a waveguide of a chip includes a substrate configured to receive the light beam from the first end and transmit the light beam through the second end, the substrate having a first refractive index n1, a grating structure having curved grating lines arranged on the substrate, the grating structure having a second refractive index n1, wherein the curved grating lines have line width w and height d and are arranged by a pitch Λ, wherein the second refractive index n2 is less than first refractive index n1, and a cladding layer configured to cover the grating structure, wherein the cladding layer has a third refractive index n3. The curves of the grating lines are constructed such that the emitting beam is shaped for efficient coupling to another optical component. The curves can also be tilted to reduce coupling back into the waveguide.