Abstract: A 3D printing system includes a 3D printer configured to receive as input a coated or un-coated optical fiber, to coat the optical fiber in the case of an input un-coated optical fiber, to treat an outer coating of the coated optical fiber, and to precisely output the coated optical fiber onto a specific location on a substrate such that the coated optical fiber is securely attached to the substrate via the treated outer coating. The 3D printer has a nozzle head that includes treating element for treating, such as heating or curing, the outer coating of the coated optical fiber. The 3D printer also includes a movement mechanism, such as an XYZ gantry, coupled to the nozzle head such that the nozzle head can be precisely moved relative to the substrate for well controlled placement of the treated coated optical fiber on the substrate.