A plastic-molded single-mode 50%-fiber connector with a 2-D fiber arrangement which provides demountable and interchangeable connections for single-mode fiber ribbons is described. A plastic molded plug contains five layers of single-mode ten-fiber ribbons. The plugs are aligned accurately by two guide pins and are held stable by a rectangular guide sleeve and a clamp spring. The connector has a cross-sectional area of 4 × 6 mm2 and a fiber density per unit area of 2.08 fibers/mm2. Measurements of fiber positions in the molded plug, using a computer-assisted measuring microscope, are reported. Connection losses for fabricated single-mode fiber connectors at a wavelength of 1.3 μm with an index-matching material are also shown. The connectors exhibit an average connecting loss of 1.2 dB for the single-mode fibers.