Among all the single mode fiber types, G.652 fiber is by far the most widely installed single mode fiber optic cable globally. So this fiber category is also known as the standard SMF. G.652 fiber is designed to have a zero-dispersion wavelength near 1310 nm, therefore it is optimized for operation in the 1310nm band and can also operate at 1550 nm. The first edition of G.652 fiber was standardized in 1984 and now it has four subcategories: G.652.A, G.652.B, G.652.C and G.652.D. All the four variants have the same G.652 core size of 8-10 micrometer. Today’s OS2 fibers are generally G.652.C or G.652.D, and the A and B categories are less used. The table below gives the attenuation, macrobending loss, polarization-mode dispersion (PMD), and mode filed diameter (MFD) of G.652 fiber subcategories.