In various embodiments, free-space optical collimator and multi-channel wavelength division multiplexers including free-space optical collimators are provided. In one embodiment, for example, a free-space optical collimator includes a base having a length, a generally flat bottom surface and a top surface. A groove is disposed along the top surface of the base extending through the length of the base. A lens is disposed within the groove of the base and a fiber optic pigtail is disposed generally adjacent to a focal point of the lens. The lens and fiber optic pigtail are aligned within the groove to reduce an off-angle offset of an optical light signal propagating through the free-space optical collimator. In other embodiments, a process of producing a free-space optical collimator is also provided.