Ultra High Speed: optical switching/Optical routing creates all Optical Networks

Original Author: Li Guangcheng, vice president of beacon Communication Technology Co., Ltd.

With the advancement of society, the social needs of emerging data services such as broadband video, multimedia services, real-time and quasi-real-time IP-based services that can greatly enrich and improve the communication performance and quality of people are growing. As emerging businesses consume a large amount of bandwidth resources, high-speed broadband integrated service networks have become the development trend of communication networks in this century. Optical fiber has a huge bandwidth. The transmission loss is low in the range of 1.55 nm near the wavelength of μm. The formula f = c/λ indicates the frequency, λ indicates the wavelength, and c = 3x108 m/s indicates the speed of light, we can know that the corresponding bandwidth of 1012 nm is about 25THz1THz = Hz ). In the vicinity of the wavelength of 1.3 μm, there is also a bandwidth of about 25 THz available. In this way, the theoretical transmission bandwidth provided by an optical fiber is about 50THz. However, the current maximum transmission rate of the serial electrical signal is 40 Gbps, that is, the rate is used for transmission over the optical fiber, and only 1‰ of the optical fiber capacity is used. Among the numerous Network Technology Implementation Solutions, the electronic technology-based network solution is difficult to complete the transmission and exchange of high-speed broadband integrated services because it is limited by the device's maximum working rate of 40 Gb, there will also be a bandwidth bottleneck in the network ". Only the optical fiber-based all-optical network solution can provide high-speed and large-capacity transmission and processing capabilities, break the "bottleneck" of information transmission, and can adapt to the bandwidth needs of high-speed broadband services for a long time. All-optical network (all-optical communication network) means that the optical information flow always exists in the form of light during transmission and switching, without the need for optical/electrical, electrical/optical conversion. That is to say, the transmission of information from the source node to the target node is always in the optical domain, and the wavelength becomes the most basic building block unit of the all-optical network. Because all signal transmission in all optical networks is carried out in all optical networks, all optical networks have signal transparency. It implements route selection through wavelength selection devices. With its excellent transparency, wavelength routing characteristics, compatibility, and scalability, all optical networks have become the first choice for next-generation high-speed and ultra-high-speed broadband networks.

All optical networks have the following advantages: 1) providing huge bandwidth. 2) compared with wireless or copper wires, the processing speed is high and the error rate is low. 3) All Optical Networks that adopt optical path switching have protocol transparency, that is, there is no limit on the signal form. Different rates and protocols are allowed to facilitate the flexibility of network applications. 4) Multiple passive optical devices are used in the all-optical network, eliminating the need for huge optical/electrical/optical conversion workloads and equipment, improving the overall network switching speed, reducing costs and improving reliability.

In an ideal all-optical network, all functions such as signal switching, routing, transmission, and recovery are carried out in the form of light. Currently, all-optical networks are not all optical networks, but optical information flows exist in the form of light in the transmission and switching process, and are controlled using circuit methods. From the current situation and development trend of optoelectronic components, it is unrealistic and unnecessary to achieve all-optical network. The all-optical network consists of three layers: core network, metro network, and access network. The basic structure is similar to that of the three layers: DWDM System, optical amplifier, OADM (optical plug-in Multiplexing), and OXC (optical cross-connection device) and other devices. All Optical Networks have three basic types: Star Network, total network, and tree network. Technologies related to all-optical networks include optical switching/Optical routing all-optical switching, optical cross-connection, all-optical relay, and optical plug-in multiplexing.

Optical switching/Optical routing is a key Optical Node technology in all-optical networks. It mainly completes optical signal switching and routing between any optical fiber ports at optical nodes. The most important task it completes is wavelength conversion. Because it is essentially processing the wavelength of light, it is more accurate to say that optical switching/Optical routing should be called wavelength switching/wavelength routing. The advantages of all-optical networks, such as bandwidth advantages, transparent transmission, and interface cost reduction, are embodied through this technology. In terms of functions, optical switching/Optical routing, OXC, and OADM are sequential and inclusive. That is, OADM is a special case of OXC, while OXC is a special case of optical switching/Optical routing. As OXC and optical switching/Optical routing are still developing, the naming of optical switching/Optical routing is currently chaotic. Some companies call existing OADM and OXC Optical Switching series Optical Switching), and some others call it Optical Router ). Therefore, most of the current optical switching/Optical routing uses OXC or even OADM for the time being.