A brief analysis of next generation optical networking development "trends" (1)

1. the development of China's fiber network

At the end of 1979 's optical communication system in Beijing, Shanghai, Wuhan and other places successively trial, after 20 years of rapid development, China has formed cable lengths in excess of 100 000 km, and optical communication of high-tech research areas also made great progress.

At that time our trial system incorporates 850nm wavelength multimode fiber, its transfer rates low and performance is not perfect. Into the 1980s China adopt 1300nm (later renamed 1310nm) wavelength of single-mode optical fiber communication system window. In the late 1980s, China optical communication technology into development for fiber, digital communication technology-based communication system, into the 1990s, China's optical network technology to be rapidly. Advanced SDH system new technology in China optical network building played a major role in our country in the world to adopt new technology SDH system, the earliest and most of the country of the optical fiber communication systems reach the world advanced level of optical fiber communication technology.

Our country has been built across the South and the East, through the "eight transverse longitudinal eight" fibre backbone communication networks, the route to our broadband communication network for further development has laid a solid foundation.

Advanced 1550nm doped fiber amplifier (EDFA) and dense wavelength division multiplexing (DWDM) and other high-tech has been applied to the core network in China. Our fiber optic network and related technology has entered the ranks of world advanced level, entered the 21st century development of optical fiber network is to enable our SONET frame further reasonable improvement is the development of new optical fiber network. The 21st century the world will enter the information and knowledge economy, our fiber optic communications network development facing the opportunities and challenges, convinced that the country has been built on the basis of fiber-optic network, our fiber optic network construction will toward smart, rich broadband development, China's fiber networks for China's economic construction play a major role.

2. the main technology of optical fiber network

2.1 fibre optic technology

Fibre production technology have now been fundamental mature, is now available for mass production, today's commonly used is zero dispersion wavelength λ 0 = 1.3 μm SM Fiber, and zero dispersion wavelength λ 0 = 1.55 μm SM Fiber has successfully developed, and has entered the practical stage, it is 1.55 μ m wavelength attenuation is small, about 0.22dB/km, therefore more suitable for long-distance bulk transfer, the optimization of the long distance the backbone transmission medium.

While people on long wave fiber, its transmission distance in theory can reach thousands of kilometers, can achieve repeaterless transmission distance, but it is still a theory of phase.

2.2 fibre optic amplifier

1550nm (Er) doped fiber amplifier (EDFA), doped fiber amplifier for digital, analog and coherent optical communication relays, you can transfer different bit rates, and can simultaneously transmit certain wavelengths of light signal.

In the fiber-optic network upgrade, analogue signals into digital signals, from low bit rate to high bit rate, the system uses the optical multiplexing technology expansion, having to change the doped amplifier circuits and devices. Doped amplifiers can be used as optical receiver preamplifier optical transmitter rear amplifier and light device compensation amplifiers.

2.3. broadband access

In view of the different circumstances of commercial and residential users have a variety of broadband access solutions.

Access system mainly completed three major features: high speed transmission, reuse/routing, network extension. At present, the access system of mainstream technology are:

ADSL technology in twisted-pair copper wire to transmit on economic per second a few megabits of information, it shall support the traditional voice service, and support for data-oriented ADSL Internet access, Central Office Access multiplex equipment will reuse the data flow, the routing to a packet network, voice traffic to the PSTN, ISDN or other packet network.

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