Fiber access refers to the complete optical fiber as a transmission medium between the central office and the users. Fiber access can be divided into active and passive optical access. Main fiber optic network is lightwave transmission technology. Development of optical transmission multiplexing quite rapidly, most have been in practical use. Reuse most used are time-division multiplexing (TDM), wavelength division multiplexing (WDM), frequency division multiplexing (FDM), code division multiplexing (CDM) and the like. According to the degree of fiber deep users can be divided into FTTC, FTTZ, FTTO, FTTB, FTTH, etc. Unlike wired telecommunications optical fiber communication, which is the use of metal media transmission signal, optical fiber communication is the use of transparent optical transmission waves. While light and electricity are electromagnetic waves, but the frequency range vary greatly. Usually the highest frequency communication cables from about 9 to 24 megahertz (10^6 Hz), while the operating frequency of the optical fiber at 10^14 ~ 10^15Hz between.