A waveguide body comprised of a length from a first end to a second end, and further comprising: a central section extending along the entire length of the waveguide body and comprising a first thickness; a first and a second separate and opposed side sections (20, 22), each of said side sections extending away from the central section along first and second directions and along the length of the waveguide body and comprising second and third thicknesses, respectively; and a coupling portion located in the central section, wherein the coupling portion comprises: a concave first surface, the concave first surface including first portions (102a, 108a) and second portions (102b, 108b), with first and second portions being opposite to each other and defining an elongate coupling cavity extending along the length of the waveguide body; and a curved V-shaped second surface comprising surfaces (46a, 46b) opposite the concave first surface, wherein the surfaces (46a, 46b) redirect light into the first and second side sections (20, 22), respectively, characterized in that the coupling portion further comprises lower surfaces that extend directly from the coupling cavity and are curved in a manner that cause light passing through the lower surfaces to be redirected into the first and second side sections (20, 22), respectively, and in that the side sections further comprise light extraction features to extract light out of opposing surfaces (30, 32) of the side sections as the light propagates through the side sections. a central section extending along the entire length of the waveguide body and comprising a first thickness; a first and a second separate and opposed side sections (20, 22), each of said side sections extending away from the central section along first and second directions and along the length of the waveguide body and comprising second and third thicknesses, respectively; and a coupling portion located in the central section, wherein the coupling portion comprises: a concave first surface, the concave first surface including first portions (102a, 108a) and second portions (102b, 108b), with first and second portions being opposite to each other and defining an elongate coupling cavity extending along the length of the waveguide body; and a curved V-shaped second surface comprising surfaces (46a, 46b) opposite the concave first surface, wherein the surfaces (46a, 46b) redirect light into the first and second side sections (20, 22), respectively, a concave first surface, the concave first surface including first portions (102a, 108a) and second portions (102b, 108b), with first and second portions being opposite to each other and defining an elongate coupling cavity extending along the length of the waveguide body; and a curved V-shaped second surface comprising surfaces (46a, 46b) opposite the concave first surface, wherein the surfaces (46a, 46b) redirect light into the first and second side sections (20, 22), respectively, characterized in that the coupling portion further comprises lower surfaces that extend directly from the coupling cavity and are curved in a manner that cause light passing through the lower surfaces to be redirected into the first and second side sections (20, 22), respectively, and in that the side sections further comprise light extraction features to extract light out of opposing surfaces (30, 32) of the side sections as the light propagates through the side sections.