1 Current Status of WDM Technology Development
In recent years, data communication has developed rapidly, IP business volume has exploded, and IP TV service is gradually opened to users and accepted by a certain class of people. Its realization must rely on a communication network with a huge transmission capacity. In the past, it was mainly a telephone communication network, and the method used was circuit switching, but at present, this method no longer meets the requirements of development. The multimedia communication of computer operation through packet switching is the main operation mode of today's data communication network. Sufficiently large capacity is the core of the communication network. With the rapid increase of various communication services, capacity expansion is imperative. There are three ways to expand the capacity of optical network transmission: TDM, SDM and WDM. At present, the bottleneck of my country's digital transmission speed is TDM technology, so the communication business of the current society has higher requirements for high-speed, large-capacity digital transmission, so the utilization rate of EDM and TDM will decrease, and
WDM optical transmission network system is constantly increasing. mature and gain better prospects for future development.
2 Communication network realizes the development of optical WDM
For the digital signal carried by TDM technology, one optical fiber can only transmit one optical carrier, and the highest digital transmission rate is only 10Gbit/s, which limits the increase of digital rate to a certain extent. EDFA is an EDFA amplifier introduced every 100Km along the line, which can successfully realize super-capacity and long-distance signal transmission. Due to the use of EDFA amplifiers, the originally immature WDM technology is more perfect. The currently used WDM technology can have n channels of various network units operated by different wavelengths at the same time, which can expand the capacity of the communication network by n times. Through analysis, it can be seen that if more optical channels with different wavelengths are used, the capacity of the communication network will also increase accordingly. The expansion of WDM technology can make good use of multiple channels to expand the capacity of the optical communication network many times. Therefore, the realization of the communication network from the electrical communication network to the optical communication network is an inevitable trend of communication development.
3 Application of WDM Technology in
Optical Transmission System
3.1 Basic principle of WDM technology
The client is connected to the specific wavelength of the end station of the WDM system. When the specific wavelength signal enters the OMU unit, it will be combined with other wavelength optical signals on it. The combined signal is sent to the OBA to increase the power of the service. It is amplified. During this process, the monitoring signal does not participate in the amplification. At the same time, the monitoring signal is added to the line and sent to the line to connect with the optical amplification device of the relay station and monitor the signal up and down. Finally, it is sent to the destination end station and then sent to the OPA to continue. The service signal is developed and the monitoring signal is issued. At this stage, the monitoring signal still does not participate in the amplification. The amplified service signal enters the ODU demultiplexing unit to restore the wavelength and then enters the destination client.
3.2 Application of WDM system in practice
The WDM system uses a large number of passive components in power control. Long-distance digital transmission will cause the power to drop rapidly. Therefore, certain measures must be taken to ensure that the output optical power meets the requirements of line transmission. Reasonable control is related to the overall performance of the WDM line. With the gradual development of
WDM technology, WDM system can effectively reduce the cost of WDM in long-distance transmission due to the use of EDFA multi-wave amplifier. Because WDM technology can transmit several or dozens of different wavelengths in single-mode fiber, this large-capacity long-distance transmission can greatly reflect its superiority and save fiber. Compared with the traditional SDH system, the number of relay devices used is greatly reduced, but the WDM system does not support some important functions such as monitoring of system error performance and determination of connection integrity. The application of WDM system in the long-distance network calculates the cost according to each wavelength. The WDM system in the area network has the scalability of the wavelength, and can quickly provide new services by simply adding wavelengths. At the same time, network switching and recovery can be realized through WDM technology, making the formation of its optical network more economical and flexible.
4 The Development Direction of WDM Technology
Since its birth, WDM technology has been rapidly popularized, applied and developed because of its remarkable advantages and strong vitality. In the future development of WDM technology, there will be optical add-drop multiplexers, optical cross-connect devices, variable wavelength lasers and all-optical regenerators, etc., all of which can solve many of the shortcomings of current WDM technology. more mature and complete.
