Does 4B in fiber optic cable represent single-mode

Single-mode optical fiber

OverviewQuadruply clad fiberHistoryCharacteristicsConnectorsFiber optic switchesExternal links

In fiber optics, a quadruply clad fiber is a single-mode optical fiber that has four claddings. Each cladding has a refractive index lower than that of the core. With respect to one another, their relative refractive indices are, in order of distance from the core: lowest, highest, lower, higher. A quadruply clad fiber has the advantage of very low macrobending losses. It also has two zero-dispersion points, and moderately low dispersion over a wider wavelength range than a singly clad fiber