What's Single Mode Optical Fiber ?

This is to point to in the working wavelength, optical fiber can transmit a propagation mode, usually referred to as single-mode fiber (SMF: Single ModeFiber). 
At present, in the cable and optical communication, is the most widely used fiber.
Because, the core of the fiber is very thin (about 10 PM) and refractive index is step shape distribution, angelica sinensis, a frequency V parameters < 2.4, in theory, can only form a single-mode transmission. In addition, the SMF multi-mode dispersion, not only transmission band optical fiber is more wide, more plus the SMF material dispersion and the addition of a dispersion offset structure, the synthetic characteristic form zero dispersion characteristics, to broaden the transmission band.
SMF, on the basis of different dopant and there are many types of the way of manufacturing. Depressed tubulovillous adenoma cladding Fiber (DePr - essed Clad Fiber), the cladding forming dual structure, adjacent Fiber core cladding, the land layer outside the refractive index is lower. In addition, there is a match type of cladding fiber, the cladding refractive index distribution is uniform.