Four Basic Elements in a WDM System

by http://www.fiber-mart.com

We know that fiber can carry more data over long distances than any other physical medium. That makes fiber a very precious material. And how to make the most use of your fiber plant becomes a question. So there comes Wavelength Division Multiplexing (WDM).
Why Should We Deploy WDM ?
WDM can multiply your fiber capacity by creating virtual fibers. The foundation of WDM lies in the ability to send different data types over fiber networks in the form of light. By allowing different light channels, each with a unique wavelength, to be sent simultaneously over an optical fiber network, a single virtual fiber network is created. Instead of using multiple fibers for each and every service, a single fiber can be shared for several services. In this way WDM increases the bandwidth and maximizes the usefulness of fiber. Since fiber rental or purchase accounts for a large share of networking costs, substantial costs can be saved through the application of WDM. Next I will introduce to you the basic four elements in the form of a WDM system.
The Core Technology of WDM System
Generally speaking, a WDM system consists of four elements, that are transceiver, multiplexer, patch cord and dark fiber. The following text will explain them to you respectively.
Fiber Optic Transceivers. Optical transceivers are wavelength-specific lasers that convert data signals from SAN or WAN to optical signals that can be transmitted into the fiber. Each data stream is converted into a signal with a light wavelength that is an unique color. Due to the physical properties of light, channels cannot interfere with each other. Therefore, all WDM wavelengths are independent. Creating virtual fiber channels in this way can reduce the number of fibers required. It also allows new channels to be connected as needed, without disrupting the existing traffic services.
Optical Multiplexers. The WDM multiplexer, sometimes referred to as the Mux, is the key to optimizing, or maximizing, the use of the fiber. The multiplexer is at the heart of the operation, gathering all the data streams together to be transported simultaneously over a single fiber. At the other end of the fiber the streams are demultiplexed and separated into different channels again.
Patch cord. The transceiver transmits the high-speed data protocols on narrow band wavelengths while the multiplexer is at the heart of the operation. The patch cable is the glue that joins these two key elements together. LC fiber patch cables are popular, which connect the output of the transceiver to the input on the multiplexer.
Dark fiber. A requisite for any WDM solution is access to a dark fiber network. The most common way of transporting optical traffic over an architecture is by using a fiber pair. One of the fibers is used for transmitting the data and the other is used for receiving the data. This allows the maximum amount of traffic to be transported. At times only a single fiber is available. Because different light colors travel on different wavelengths, a WDM system can be built regardless. One wavelength is used to send data and a second one to receive it.

Four Basic Elements in a WDM System

by http://www.fiber-mart.com

We know that fiber can carry more data over long distances than any other physical medium. That makes fiber a very precious material. And how to make the most use of your fiber plant becomes a question. So there comes Wavelength Division Multiplexing (WDM).
Why Should We Deploy WDM ?
WDM can multiply your fiber capacity by creating virtual fibers. The foundation of WDM lies in the ability to send different data types over fiber networks in the form of light. By allowing different light channels, each with a unique wavelength, to be sent simultaneously over an optical fiber network, a single virtual fiber network is created. Instead of using multiple fibers for each and every service, a single fiber can be shared for several services. In this way WDM increases the bandwidth and maximizes the usefulness of fiber. Since fiber rental or purchase accounts for a large share of networking costs, substantial costs can be saved through the application of WDM. Next I will introduce to you the basic four elements in the form of a WDM system.
The Core Technology of WDM System
Generally speaking, a WDM system consists of four elements, that are transceiver, multiplexer, patch cord and dark fiber. The following text will explain them to you respectively.
Fiber Optic Transceivers. Optical transceivers are wavelength-specific lasers that convert data signals from SAN or WAN to optical signals that can be transmitted into the fiber. Each data stream is converted into a signal with a light wavelength that is an unique color. Due to the physical properties of light, channels cannot interfere with each other. Therefore, all WDM wavelengths are independent. Creating virtual fiber channels in this way can reduce the number of fibers required. It also allows new channels to be connected as needed, without disrupting the existing traffic services.
Optical Multiplexers. The WDM multiplexer, sometimes referred to as the Mux, is the key to optimizing, or maximizing, the use of the fiber. The multiplexer is at the heart of the operation, gathering all the data streams together to be transported simultaneously over a single fiber. At the other end of the fiber the streams are demultiplexed and separated into different channels again.
Patch cord. The transceiver transmits the high-speed data protocols on narrow band wavelengths while the multiplexer is at the heart of the operation. The patch cable is the glue that joins these two key elements together. LC fiber patch cables are popular, which connect the output of the transceiver to the input on the multiplexer.
Dark fiber. A requisite for any WDM solution is access to a dark fiber network. The most common way of transporting optical traffic over an architecture is by using a fiber pair. One of the fibers is used for transmitting the data and the other is used for receiving the data. This allows the maximum amount of traffic to be transported. At times only a single fiber is available. Because different light colors travel on different wavelengths, a WDM system can be built regardless. One wavelength is used to send data and a second one to receive it.
Conclusion
WDM has revolutionized the cost of network transport. Thanks to WDM, fiber networks can carry multiple Terabits of data per second over thousands of kilometers with a low cost that is unimaginable less than a decade ago. At FS, we offer a comprehensive portfolio of WDM transmission modules to support the network applications of enterprise and service provider customers.

The Application of Optical Passive Components in WDM System

by http://www.fiber-mart.com

Based on the DWDM technology, the all-optical network make full use of fiber optic cables which have huge transmission capacity, it must be the next-generation high reliability, fast speed information network technology. Fiber optic attenuators are widely and important optical passive components, especially in the all-optical network.
Optical attenuator is applied into WDM system upstream and downstream node channel, power balance, EDFA gain flatness, optical communication lines, system evaluation, research and adjustments, correction and so on. It is in accordance with customers’ requirements by absorbing or reflecting off part of the optical power and then reduce the signal power as expectation. It’s position in the optical fiber network just shown in the figure.
In the WDM system, EDFA is a necessary component, it is quite important for achieving all-optical network communication. However, because of the limitation of gaining window ports for EDFA, it makes different wavelengths have different gain multiplier, it leaded to energy imbalance between the channels of a WDM sytstem. Then it will result in following three problems:
Received Energy imbalance will beyond the allowed dynamic range finally.
Accumulation of SNR imbalance can cause gain of a certain wavelength of BER, it may lower than the required BER (bit error rate).
Because of the shortage of the gain, the minimum signal power of the channel may be lower than the sensitivity of the receiver.
In the DWDM optical network which has multiple contact node, such as MAN, the transmission distances and the volume of the business between the different channels are different, each channel’s transmission must be balanced, including power, BER, signal to noise ratio and so on. The application of variable fibre optic attenuator is the first solution in the system.
Moreover, optical attenuators are also important for optical telecommunication link and the test for the system. Fiber optic cable link and the system need to be examined before laying them, then it can insure some performance parameters of the system or link road, so that it is easy to do some optimization test. So we need to simulate the actual situation, mainly the proper attenuation for the signal, then we will find out the actual situation after the long distance transmission.
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