Initial optical signals propagate downstream through a primary transmitting GRIN lens and a primary receiving GRIN lens that are joined at an optical interface. A secondary transmitting GRIN lens, or another type of optical device, is joined to the primary receiving GRIN lens at the optical interface, and a secondary receiving GRIN lens, or another type of optical device, is joined to the primary transmitting GRIN lens at the optical interface. Extracted optical signals are transmitted from the primary transmitting GRIN lens to the secondary receiving GRIN lens and, inserted optical signals are transmitted from the secondary transmitting GRIN lens into the primary receiving GRIN lens. The secondary GRIN lenses are angularly displaced from one another so that extracted optical signals consist solely of the information of the initial optical signals and an extracted portion of the optical energy of the initial optical signals. A composite optical signal, which propagates downstream through the receiving GRIN lens, includes the information of the initial optical signals, the unextracted portion of the optical energy of the initial optical signals, and all of the inserted optical signals. The secondary GRIN lenses are substantially smaller than the primary GRIN lenses, such that the secondary GRIN lenses have a minimal impact upon the transmission of the initial optical signals from the primary transmitting GRIN lens to the primary receiving GRIN lens.