An illumination device (200-b; 200-c; 200-d) comprising: a light source (210-b; 210-c; 210-d) configured to emit, during operation, light in an emission angular range, wherein a prevalent direction of propagation of the emitted light (106-b; 106-c; 106-d) in the emission angular range is different from a direction of an optical axis (102-c) of the illumination device; and an optical coupler (220-b; 220-c; 220-d) comprising a transparent material, the optical coupler having an input aperture disposed within a first plane, an exit aperture (225-b; 225-c; 225d) disposed within a second plane, the second plane intersecting the first plane at an acute angle, and a first side surface (224-b; 224-c; 224-d) and a second side surface (223-b; 226-c; 226-d) arranged between the input aperture and the exit aperture (225-b; 225-c; 225-d), the second plane being oriented perpendicularly to the optical axis (102-c) of the illumination device, wherein the optical coupler (220-b; 220-c; 220-d) receives, through the input aperture from the light source (210-b; 210-c; 210-d), the light emitted in the emission angular range, wherein the first side surface (224-b; 224-c; 224-d) and the second side surface (223-b; 226-c; 226-d) redirect the received light via total internal reflection to the exit aperture (225-b; 225-c; 225-d), wherein the second side surface (223-b, 226-c; 226-d) comprises a flat portion adjacent to the exit aperture (225-b; 225-c; 225-d) and oriented along the optical axis (102-c) of the illumination device (200-b; 200-c; 200-d) and wherein the first side surface (224-b; 224-c; 224-d) includes a curved portion, and wherein the redirected light is issued through the exit aperture in a redirected angular range, wherein the illumination device further comprises: a light guide (230-b; 230-c; 230-d) comprising a receiving end and an opposing end that are disposed along the optical axis (102-c) of the illumination device (200-b; 200-c; 200-d), wherein the receiving end is arranged to receive the light issued by the optical coupler, (220-b; 220-c; 220-d) wherein the light guide (230-b; 230-c; 230-d) is configured to guide the light received at the receiving end in a forward direction toward the opposing end; and an optical extractor (220-b; 220-c; 220-d) located at the opposing end and configured to output the guided light into an ambient environment as output light. a light source (210-b; 210-c; 210-d) configured to emit, during operation, light in an emission angular range, wherein a prevalent direction of propagation of the emitted light (106-b; 106-c; 106-d) in the emission angular range is different from a direction of an optical axis (102-c) of the illumination device; and an optical coupler (220-b; 220-c; 220-d) comprising a transparent material, the optical coupler having an input aperture disposed within a first plane, an exit aperture (225-b; 225-c; 225d) disposed within a second plane, the second plane intersecting the first plane at an acute angle, and a first side surface (224-b; 224-c; 224-d) and a second side surface (223-b; 226-c; 226-d) arranged between the input aperture and the exit aperture (225-b; 225-c; 225-d), the second plane being oriented perpendicularly to the optical axis (102-c) of the illumination device, wherein the optical coupler (220-b; 220-c; 220-d) receives, through the input aperture from the light source (210-b; 210-c; 210-d), the light emitted in the emission angular range, wherein the first side surface (224-b; 224-c; 224-d) and the second side surface (223-b; 226-c; 226-d) redirect the received light via total internal reflection to the exit aperture (225-b; 225-c; 225-d), wherein the second side surface (223-b, 226-c; 226-d) comprises a flat portion adjacent to the exit aperture (225-b; 225-c; 225-d) and oriented along the optical axis (102-c) of the illumination device (200-b; 200-c; 200-d) and wherein the first side surface (224-b; 224-c; 224-d) includes a curved portion, and wherein the redirected light is issued through the exit aperture in a redirected angular range, wherein the illumination device further comprises: a light guide (230-b; 230-c; 230-d) comprising a receiving end and an opposing end that are disposed along the optical axis (102-c) of the illumination device (200-b; 200-c; 200-d), wherein the receiving end is arranged to receive the light issued by the optical coupler, (220-b; 220-c; 220-d) wherein the light guide (230-b; 230-c; 230-d) is configured to guide the light received at the receiving end in a forward direction toward the opposing end; and an optical extractor (220-b; 220-c; 220-d) located at the opposing end and configured to output the guided light into an ambient environment as output light. a light guide (230-b; 230-c; 230-d) comprising a receiving end and an opposing end that are disposed along the optical axis (102-c) of the illumination device (200-b; 200-c; 200-d), wherein the receiving end is arranged to receive the light issued by the optical coupler, (220-b; 220-c; 220-d) wherein the light guide (230-b; 230-c; 230-d) is configured to guide the light received at the receiving end in a forward direction toward the opposing end; and an optical extractor (220-b; 220-c; 220-d) located at the opposing end and configured to output the guided light into an ambient environment as output light.