As the quick development of telecommunications, people’s requirements for bandwidth continue growing. Optical network operators have to face great challenges to meet the demand. In this case, OADM appears. How much do you know about OADM? This article will introduce it for you.
OADM, or optical add-drop multiplexer, is a passive optical device used in WDM technology. Its main function is to selectively separate or add optical signals or multiplex wavelength from one stream of light on a single fiber while other uncorrelated signals will not be affected. According to the wavelength, OADM has passive and active modes. In passive OADM, the add and drop wavelengths are fixed in advance, and it uses thin-film interference filters, fiber gratings, and planar waveguides in networks with WDM systems. Different from passive OADM, active OADM can be set to any wavelength after installation. And it is also more flexible and cheaper than passive OADM.
A traditional OADM consists of three stages: an optical demultiplexer, an optical multiplexer, and between them a method of re-configuring the paths between the demultiplexer, the multiplexer and a set of ports for adding and dropping signals. The demultiplexer separates wavelengths in an input fiber onto ports. The reconfiguration can be achieved by a fiber patch panel or by optical switches which direct the wavelengths to the multiplexer or to drop ports. The multiplexer multiplexes the wavelength channels that are to continue on from demultiplexer ports with those from the add ports, onto a single output fiber.
Fixed optical add drop multiplexer (FOADM) and re-configurable optical add drop multiplexer (ROADM) are the two common types of OADM.
FOADM, sometimes also called configurable optical add drop multiplexers, can add or drop a fixed type or multiple fixed wavelength. In fixed-wavelength OADM, the wavelength has been selected and remains the same until human intervention changes it. FOADMs allow the manufacturers to customize the number of channels, filter specifications, and power equalization but require excessive transporters at each node. Although fixed optical add drop multiplexers lack of flexibility, they have more reliable performance and small delay.
ROADM is a device that can add, block, pass or redirect modulated infrared (IR) and visible light beams of various wavelengths in a fiber optic network. A laser tuned to a particular wavelength can electronically change the selected channel routing through the optical network. Hence, the ROADM provides flexibility for rerouting optical streams, and at the same time it can bypass wrong connections and allow minimal service disruptions.
Before ROADMs appear, signal routing in fiber optic networks was realized by converting the IR or visible beams to electrical signals and routing those signals using conventional electronic switches. The rerouted electrical signals were then converted back into IR or visible beams. Now with the application of ROADM, singles can be easily handled. Therefore, ROADM is widely used in systems that employ wavelength division multiplexing.
As people’s requirements for bandwidth grow rapidly, network mangers not only need to satisfy this demand, but also face the challenge to keep track of all the wavelengths, monitor their correct operation and deploy new wavelengths easily without increasing the operation cost. However, the optical add-drop multiplexers which can couple two or more wavelengths into the same fiber add the required flexibility, and make it easy to add wavelengths or change the wavelength destination providing more convenient over the entire high capacity infrastructure. Therefore, optical add-drop multiplexer is widely used in long-haul optical communication system and metropolitan area network (MAN).
Besides, optical add-drop multiplexers play an important role in WDM networks. The typical applications are CWDM OADM and DWDM OADM. CWDM OADM is applied to optically add/drop one or multiple CWDM channels into one or two fibers. There are various CWDM OADM modules in our website such as 1CH CWDM OADM, 2CH CWDM OADM, 4CH CWDM OADM, 8CH CWDM OADM, 16CH CWDM OADM, etc. When numerous channels can be transmitted through a single fiber network, only selected channels of information are required at a particular place. At this moment, DWDM OADM can add or remove additional wavelengths in the network and make sure the signals spread correctly. There are 100 GHz and 200GHz DWDM OADM modules available for you.
In today’s world of intensive communication needs and requirements, OADM is a vital component in data networks. It plays a key role in improving the network performance and reliability. Now OADM is still progressing. Its great development prospect cannot be ignored.
Originally published at http://www.cwdm-dwdm-oadm.com/blog/a/76/Things-You-Need-to-Know-About-OADM
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