An optical system (100, 200, 300, 400) for coupling light into a waveguide, comprising: a waveguide (102, 202, 302, 402) having a portion for guiding light along a first direction (106, 206, 306), a coupler (108, 208, 308, 408) arranged at said portion of the waveguide (102, 202, 302, 402), wherein the coupler (108, 208, 308, 408) has a surface with a grating structure (111, 211, 311) formed therein for directing light into the waveguide (102, 202, 302, 402), the surface having a normal (112, 212, 312) which is orthogonal to the first direction (106, 206, 306), and a cladding layer (140, 240, 340, 440) embedding the coupler (108, 208, 308, 408) and surrounding the waveguide (102, 202, 302, 402), the cladding layer (140, 240, 340, 440) having an optical path changing structure (120, 220, 320, 420) formed therein, the optical path changing structure (120, 220, 320, 420) having a refractive surface (122, 222, 322, 422) and a reflective surface (124, 224, 324, 424), each forming an acute angle (α,β) with respect to the surface of the coupler (108, 208, 308, 408), wherein, for light which enters the optical path changing structure (120,220,320,420) through the refractive surface (122, 222, 322, 422) along a second direction which is orthogonal to said normal, the refractive surface (122, 222, 322, 422) is arranged to refract the light such that it is directed towards the reflective surface (124, 224, 324, 424) along a third direction which is different from the second direction, and wherein the reflective surface (124, 224, 324, 424) is arranged to reflect the light of the third direction such that it is directed towards the grating structure (111, 211, 311) of the coupler (108, 208, 308, 408) along a fourth direction. a waveguide (102, 202, 302, 402) having a portion for guiding light along a first direction (106, 206, 306), a coupler (108, 208, 308, 408) arranged at said portion of the waveguide (102, 202, 302, 402), wherein the coupler (108, 208, 308, 408) has a surface with a grating structure (111, 211, 311) formed therein for directing light into the waveguide (102, 202, 302, 402), the surface having a normal (112, 212, 312) which is orthogonal to the first direction (106, 206, 306), and a cladding layer (140, 240, 340, 440) embedding the coupler (108, 208, 308, 408) and surrounding the waveguide (102, 202, 302, 402), the cladding layer (140, 240, 340, 440) having an optical path changing structure (120, 220, 320, 420) formed therein, the optical path changing structure (120, 220, 320, 420) having a refractive surface (122, 222, 322, 422) and a reflective surface (124, 224, 324, 424), each forming an acute angle (α,β) with respect to the surface of the coupler (108, 208, 308, 408), wherein, for light which enters the optical path changing structure (120,220,320,420) through the refractive surface (122, 222, 322, 422) along a second direction which is orthogonal to said normal, the refractive surface (122, 222, 322, 422) is arranged to refract the light such that it is directed towards the reflective surface (124, 224, 324, 424) along a third direction which is different from the second direction, and wherein the reflective surface (124, 224, 324, 424) is arranged to reflect the light of the third direction such that it is directed towards the grating structure (111, 211, 311) of the coupler (108, 208, 308, 408) along a fourth direction.