Optical Add/Drop Multiplexer referred to as OADM, is one of the key components of wavelength division multiplexing (WDM) optical networks. Its function is to selectively receive and transmit certain wavelength channels from the transmission optical path without affecting the transmission of other wavelength channels.
OADM equipment is used in both long-haul trunk lines and metropolitan area networks.
In trunk applications, OADM is the preferred device for intermediate nodes with upper and lower traffic.
The main battlefield of OADM applications is the metropolitan area network, which can be flexible in networking, easy to upgrade and scale up. It is an ideal multi-service transmission platform for metropolitan area network applications.
The OADM allows different wavelength signals of different optical networks to be inserted and multiplexed at different locations. Optical cross-connect (OXC) devices allow different networks to be dynamically combined, allocate wavelength resources on-demand, and implement a wider network interconnection. OADM and optical cross-connect (OXC) devices only send information that needs to be downloaded at the node to the processing device (including ATM switches, SDH switches, and IP routers), the information needn`t processed by the node directly pass through the optical channel, thereby greatly improves the efficiency of the node processing information, and the service processing node must deal with all the arriving IP packets.
Optical Code Division Multiple Access (OCDMA) technology is a good all-optical network networking technology, which avoids the “electronic bottleneck” effect of communication equipment and the queuing delay of network protocols, enabling high-speed information transmission and fast-step asynchronous information access.
With all-optical backbone network composed of OCDMA technology, the information can be carried out either in the node or at any place where the fiber line passes, without affecting the normal transmission of other users on the fiber line. It overcomes the limitation that the upper and lower routes of information in the traditional network can only be carried out in the nodes. The optical up and down roads can be performed at any time between two optical cross-connect nodes or optical switching nodes as needed.
Coarse Wavelength Division Multiplexing (CWDM) and Dense Wavelength Division Multiplexing (DWDM)
The two key WDM technologies are coarse wavelength division multiplexing (CWDM), and dense wavelength division multiplexing (DWDM).
CWDM systems typically provide 8 wavelengths, separated by 20nm, from 1470nm to 1610nm. In order to increase the number of wavelengths, one can also use the 1310nm window so the CWDM channels can be increased to 16. The number of channels is fewer than in DWDM but more than in standard WDM.
DWDM packing WDM channels denser than in CWDM system, it can go up to 80 or even 160 channels / wavelengths, with no more than 0.4nm spacing, roughly over the C-band range of wavelengths. It supports much more wavelengths than that of CWDM MUX DEMUX. DWDM’s tighter wavelength spacing fits more channels onto a single fiber, but cost more to implement and operate.
CWDM spectrum supports data transport rates of up to 4.25Gbps while DWDM is utilized more for large capacity data transport needs of up to 100Gbps. By mapping DWDM channels within the CWDM wavelength spectrum, much higher data transport capacity on the same fiber optic cable can be achieved without any need for changing the existing fiber infrastructure between the network sites. By utilizing CWDM and DWDM network systems or the mixture of them, carriers and enterprisers are able to transport service from 2Mbps up to 200Gbps of data.
The features of OADM:
1. Low Insertion Loss
2. High stability and reliability
3. High channel Isolation
The Application of OADM:
3.Fiber Optic Amplifier
4.CATV Fiberoptic System
Case of OADM: wave division equipment data service transmission network solution
In the construction of the metropolitan/local network, an important backbone node is usually selected in the core layer of the network to construct an OADM ring network. As the core network at the highest level, it is a comprehensive optical transmission platform for voice, data and other services, and plays a vital role in the transmission, scheduling and convergence of services.