Because of its small inter mode dispersion,single-mode fiber can support longer transmission distance than multimode fiber.In 100Mbps Ethernet and 1g gigabit network,single-mode fiber can support transmission distance of more than 5km.At present,single-mode fiber is still the mainstream application of optical fiber transmission.
Single mode fiber(SMF)refers to an optical fiber that can only transmit one mode in the working wavelength.Since the core of the optical fiber is very thin(about 10μm),and the refractive index presents a step like distribution.When the normalized frequency V parameter is less than 2.4,theoretically,only single-mode transmission can be formed.In addition,SMF has no multi-mode dispersion,and the transmission bandwidth is wider than that of multi-mode fiber.In addition,the material dispersion and structural dispersion of SMF are added to offset each other,and its composite characteristics just form the characteristics of zero dispersion,which widens the transmission band.It is suitable for long-distance and large capacity optical fiber communication systems,optical fiber local area networks and various optical fiber sensors.
Multi mode fiber(MMF)refers to an optical fiber that can propagate multiple modes in the working wavelength.The core diameter is 50μm.Since there are hundreds of transmission modes,compared with SMF,the transmission bandwidth is mainly dominated by mode dispersion,resulting in time delay and optical pulse broadening after long-distance transmission.It is only applicable to optical fiber communication with small capacity.
In addition to the differences in transmission modes,single-mode fiber and multi-mode fiber have differences in fiber diameter,color of protective cover,transmission light source,transmission distance,bandwidth,price and application scenarios.These differences also determine that single-mode fiber is the mainstream application of fiber transmission,because it conforms to the development of laser technology and people’s demand for long-distance and large information communication.
But will single-mode fiber remain the mainstream?The answer is not necessarily.According to the latest market news,with the vigorous development of communication business,the global network traffic has increased sharply,and the development of ordinary single-core single-mode fiber transmission is limited.In the next few years,the contradiction between the weak growth of optical network and the high bandwidth demand of the market will become increasingly acute,and it has become an important problem to be solved urgently in the optical communication industry.In order to solve the problem of optical communication capacity expansion in the future,the industry recognized technical solution to improve the capacity of single fiber is to use space division multiplexing technology.Multi core fiber,multi-mode fiber or multi-core multi-mode fiber are the inevitable development trend of optical communication transmission.