Advantages and Technologies of All Optical Network

In the existing communication networks based on optical multiplexing, the completion of optical/electrical/optical conversion of each node in the network is still exchanged at the speed of electrical signals processing information. In order to meet the requirements of high speed and large capacity, the electronic components have some disadvantages such as bandwidth limitation, clock offset, serious crosstalk and high power consumption, which brought forth "electronic bottleneck" in communication network. In order to solve this problem, the concept of all-optical network (AON) was put forward. With its good transparency, wavelength routing characteristics, compatibility and scalability, all-optical network has become the first choice of the next generation of high-speed broadband networks.

What is All Optical Network

The all-optical network refers to the whole process of data transmission and exchange from the source node to the end user node are all conducted in the optical domain, that is, end-to-end complete optical path, without the intervention of electrical signals. `

Advantages of All Optical Network

The all-optical communication network based on WDM can enable the communication network to have stronger manageability, flexibility and transparency.  It has the following advantages over the previous communication network and the current optical communication system. 

1. It reduces the use of electronic devices. The flow of optical signal in all-optical network no longer meets the obstacle of photoelectric conversion, which overcomes the difficulty of improving the signal rate of electronic devices on the way, saves a large number of electronic devices, and greatly improves the transmission rate.  

2. It supports multiple protocols. All optical network adopts wavelength division multiplexing technology and selects routing by wavelength, which can provide services of multiple protocols conveniently.

3. It provides high networking flexibility. The all-optical network is very flexible, and a certain wavelength can be extracted or added at any nod

4. It is of high reliability. There is no transformation and storage along the way, and many optical devices in the all-optical network are passive, so it is highly reliable.

Key Technologies in All Optical Network

1. Optical Switching Technology

Optical switching technology can be divided into optical path switching technology and packet switching technology. Optical path switching can be divided into three types, namely, space division (SD), time division (TD) and wave division/frequency division (WD/FD) optical switching, and the combination of these switching forms. In optical packet switching, asynchronous transmission mode is a widely studied mode in recent years.

2. Optical Cross Connection Technology

OXC is a device used in fiber optic network nodes. By cross-connecting optical signals, OXC can flexibly and effectively manage fiber optic transmission networks. It is an important means to achieve reliable network protection/recovery and automatic wiring and monitoring. OXC is mainly composed of optical cross connection matrix, input interface, output interface, management control unit and other modules. To improve OXC reliability, each module has active and standby redundancy structures, and OXC automatically performs active/standby switchover.

3. Optical Add and Drop Multiplexing Technology

In the field of WDM optical networks, more attention is being focused on optical add and drop multiplexers. These devices have the functions of traditional SDH add-and-drop multiplexers (SDHADM) in the time domain in the optical wavelength domain. OADM, in particular, can split a channel from a WDM beam (split function) and generally new information into the optical carrier at the same wavelength ( function). For OADM, there must be a high degree of isolation between the sub-outlet and the insertion port, as well as between the input port and the output port, to minimize the same wavelength interference effect, otherwise the transmission performance will be seriously affected.

4. Fiber Amplifier Technology

Optical amplifier is one of the core technologies for building all-optical communication networks, and also the key element of dense wavelength Division multiplexing (DWDM) systems. The traditional basis of DWDM systems is erbium-doped fiber amplifier (EDFA). The optical fiber has a wide and low loss bandwidth in the 1550 nm window, which can accommodate the optical signals of DWDM to be transmitted on one optical fiber at the same time. After the appearance of EDFA, it quickly replaced the electrical signal regeneration amplifier and greatly simplified the whole optical transmission network.