Loose tube cables house multiple fibers in a PBT or PP tube with gel or water-swellable powder. As the fibers are not fixed to the tube wall, thermal expansion and tensile loads have limited impact on the. Since the development of fiber optic cable in the mid-1970s, there has been a steady stream of innovations in manufacturing, materials, and network systems which have advanced the fiber optic cable design and capabilities of outside plant cable including loose tube, ribbon, and micro loose tube. Since the development of fiber optic cable in the mid-1970s, there has been a steady stream of innovations in manufacturing, materials, and network systems which have advanced the design and capabilities of outside cables including loose tube, ribbon, and micro loose tube cables. The cable that. Simply put, a loose-tube optical cable is structured with multiple loose tubes stranded around a central strength member. Its unique design offers superior protection, allowing it to maintain high performance in harsh environments.