Fiber optic networks already enjoy popular support, a synonym for high-speed and effective in the communication system also has the realization of the large-scale deployment and application. To achieve a transparent, high survivability of AON System is the development of broadband communication network. Optical switching technology as an important basis in AON technologies, the development and application of fiber converters largely determines the direction of future fiber optic networks.
Fiber optic network has the advantages of large information capacity and strong anti-interference ability, its superior performance has been confirmed, and gradually take the place of electronic circuit as the main communication network, become an important way of modern communication.
In fiber optic networks systems, only scientific and reasonable communications architecture can express the advantages of optical fiber system, to make up the ideal of high speed, large capacity, high quality fiber optic network, and the original electronic circuit communication in all optical network is a huge obstacle, to get rid of the influence of the electronic circuit is need to improve optical fiber communication system technology. So optical switching technology, is considered to be one of the most important and new generation of broadband technology.
Optical signal multiplexing generally have space division multiplex(SDM) and time division multiplexing(TDM) and wavelength division multiplexing(WDM) three ways, the corresponding also have space division switching, time-division switching, and wavelength division switching to complete three wavelength division multiplexing channel switching.
WDM technology in optical transmission system are widely used in optical WDM system.
Generally in optical WDM system, in the source port and destination end you need to use the same wavelengths of light to transmit signals, without such multiplexing each multiplexing terminal that need to use the extra multiplexing equipment, thus increasing the cost and complexity for the system. So,if in the WDM system, using wavelength division optical switching on intermediate transport nodes, can meet an additional device implements the source end of the WDM system with the purpose, and can save system resources, improve resource utilization.
Technology of All Optical Network switching
The first step to realize all optical network switching, is based on Optical Add Drop
Multiplexer(OADM) and OXC to achieve wavelength switching, and then further to realize optical packet switching.
Wavelength switching was based on the wavelength of the circuit switching, wavelength of the light signal exchange is to provide end-to-end routing and wavelength channel distribution. In wavelength switching, is to use the corresponding network node equipment, namely transplanting multiplexing with light or optical cross-linking.
Working principle of the OADM is in the way of light to separate in the network node and insert the required wavelength channels. Its main components have a multiplexer and demultiplexer, and optical switch and tunable harmonic and etc.
The OADM working principle is similar to Synchronous Digital Hierarchy(SDH), but one is in the time domain, and the other one is in the optical domain.
And Optical Cross Connect’s function is similar to Data Exchange Control(DXC) in the SDH, but is to achieve in the wavelength of the optical network node path cross connections.
Although optical switching to digital transmission rate (generally more than 10 Gb/s) is required to be higher communication occasions are more appropriate, which can achieve lower transmission costs and greater capacity. But when the system asks for the low transmission rate requirements (refer to below 2.5 Gb/s), use old-fashioned photoelectric conversion way may be more appropriate. So in the current practice,we should select the appropriate system according to the application scenario.
With the development of the future communication network technology and all-optical network, optical switching technology will also to be the more innovative and more efficient way to contribute to the communication network of all-opticalization, become the most important part of social development and people’s life.