A lighting system has one or more light guides capable of guiding light, each comprising a core and two optically smooth faces. A cavity adjacent to two of the optically smooth faces has an opening and a reflective-transmissive surface opposite the opening. A cover having a light source is proximate to and occludes the opening. A major portion of any light emitted from the light source is reflected by the reflective-transmissive surface of the cavity and is injected into the light guides, and a minor portion of any light emitted by the light source is transmitted through the reflective-transmissive surfaces of the cavity and emitted from the lighting system. A light injection coupler is also disclosed that has an optically transmissive housing and suitable for use to couple ends of at least one light guide thereby making a lighting system.