Optical system for coupling light into a waveguide

An optical system for coupling light into a waveguide, comprising:

• a waveguide having a portion for guiding light along a first direction,
• a coupler arranged at said portion of the waveguide, wherein the coupler has a surface with a grating structure formed therein for directing light into the waveguide, the surface having a normal which is orthogonal to the first direction, and
• a cladding layer embedding the coupler, the cladding layer having an optical path changing structure formed therein, the optical path changing structure having a refractive surface and a reflective surface, each forming an acute angle with respect to the surface of the coupler,
• wherein, for light which enters the optical path changing structure through the refractive surface along a second direction which is orthogonal to said normal, the refractive surface is arranged to refract the light such that it is directed towards the reflective surface along a third direction which is different from the second direction, and
• wherein the reflective surface is arranged to reflect the light of the third direction such that it is directed towards the grating structure of the coupler along a fourth direction.