An illumination system (100; 100'; 200) comprising: a housing (105; 105"; 205) extending along a first direction, and including a dielectric core (102; 502) coated with a layer of material (104; 504) comprising a metal, wherein a portion of the housing is configured as a substrate including traces; a plurality of light-emitting elements (LEEs) secured to the substrate, the light emitting elements being arranged along the first direction; one or more optical couplers extending in a forward direction orthogonal to the first direction, the optical couplers positioned to receive light emitted by the LEEs and configured to collimate the received light, wherein the optical couplers are mechanically connected with the housing, and wherein the LEEs are operatively connected to power via the traces, characterized in that: the illumination system further comprises: a redirecting surface spaced apart from the one or more optical couplers at a first distance along the forward direction, the redirecting surface configured to reflect the collimated light to an ambient environment as output light in a backward angular range; a light guide that includes a receiving end arranged and configured to receive the collimated light from the one or more optical couplers, an output end optically coupled with the redirecting surface, and two opposing side surfaces extending from the receiving end to the output end, the two opposing side surfaces arranged and configured to guide the collimated light from the receiving end in the forward direction toward the output end of the light guide; and an optical extractor that includes the redirecting surface and an output surface with a curved cross-section, the output surface arranged and configured to transmit the output light to the ambient environment in the backward angular range. a housing (105; 105"; 205) extending along a first direction, and including a dielectric core (102; 502) coated with a layer of material (104; 504) comprising a metal, wherein a portion of the housing is configured as a substrate including traces; a plurality of light-emitting elements (LEEs) secured to the substrate, the light emitting elements being arranged along the first direction; one or more optical couplers extending in a forward direction orthogonal to the first direction, the optical couplers positioned to receive light emitted by the LEEs and configured to collimate the received light, wherein the optical couplers are mechanically connected with the housing, and wherein the LEEs are operatively connected to power via the traces, characterized in that: the illumination system further comprises: a redirecting surface spaced apart from the one or more optical couplers at a first distance along the forward direction, the redirecting surface configured to reflect the collimated light to an ambient environment as output light in a backward angular range; a light guide that includes a receiving end arranged and configured to receive the collimated light from the one or more optical couplers, an output end optically coupled with the redirecting surface, and two opposing side surfaces extending from the receiving end to the output end, the two opposing side surfaces arranged and configured to guide the collimated light from the receiving end in the forward direction toward the output end of the light guide; and an optical extractor that includes the redirecting surface and an output surface with a curved cross-section, the output surface arranged and configured to transmit the output light to the ambient environment in the backward angular range. a redirecting surface spaced apart from the one or more optical couplers at a first distance along the forward direction, the redirecting surface configured to reflect the collimated light to an ambient environment as output light in a backward angular range; a light guide that includes a receiving end arranged and configured to receive the collimated light from the one or more optical couplers, an output end optically coupled with the redirecting surface, and two opposing side surfaces extending from the receiving end to the output end, the two opposing side surfaces arranged and configured to guide the collimated light from the receiving end in the forward direction toward the output end of the light guide; and an optical extractor that includes the redirecting surface and an output surface with a curved cross-section, the output surface arranged and configured to transmit the output light to the ambient environment in the backward angular range.