Wavelength Division Multiplexing (WDM) is widely used to transmit large amounts of data. This technology enables data streams to be sent over a single optical fiber network and, therefore, maximize the utilization of fiber and the optimization of the network.
WDM networking is used to send data types over fiber networks in the form of light. Different light channels with varying wavelengths are sent simultaneously over a fiber network. This enables the sharing of a single fiber for several services.
A few advantages of wavelength division multiplexing are:
- Improved bandwidth
- Efficient use of fiber
- Cost efficiency
- Substantial savings
1.Types of Wavelength Division Multiplexing
WDM is of two types:
1.Coarse WDM (CWDM)
- They can be divided into a low channel band (1271 nm to 1451 nm) and a high channel band (1471 nm to 1611 nm).
- Wavelength grid is at 20 nm separation as defined in the ITU-T standard G.694.2.
- They are carried on single-mode fibers.
2.Dense WDM (DWDM)
- It can be divided into several bands. The most widely used is the C-band (1530 nm – 1565 nm) with the lowest fiber attenuation and standard optical EDFA amplifiers are used to extend the transmission distance.
- Different channel grids are defined by ITU-T standard G.692.1
2.Understanding Passive Multiplexers
Passive multiplexers include unpowered and pure optical equipment. In this unpowered solution, the transceiver is present directly in the data switch. The output from the transceiver is connected to the unpowered multiplexer that further combines and redistributes the signal.
Passive multiplexers do not have active components, i.e. they do not have optical signal amplifiers and dispersion compensation modules. The DWDM passive link is determined by the optical budget of transceivers used. These passive multiplexers have a high channel capacity and the ability to expand. The transmission distance is limited to the optical transceivers incorporated.
3.Uses of Passive Multiplexers
The major areas where passive multiplexers are used are:
- High-capability metro network.
- High-speed communication lines with high channel capacity.
- Areas that demand improved connectivity.
- Areas that need distributed security.
4.Features of Passive Multiplexers
A few features of passive multiplexers include:
- They provide virtually unlimited bandwidth.
- They support both digital and analog optical signals.
- They offer improved reliability due to the absence of power supply.
- They provide a convenient and compact 1U package.
- They contain multiplexer (MUX) and demultiplexer (De-MUX) as a single package.
5.Benefits and Disadvantages of Using Passive Multiplexers
Advantages of passive multiplexers include:
- Cost-Effectiveness
They need fewer components and minimal engineering, making them cost-effective.
- Minimal Initial Set-Up
They are based on colored optics and hence, do not need to tune wavelengths for all the connections. The colored optics can be simply matched and plugged in.
Passive multiplexers also come with a few disadvantages, which are as follows:
- Reduced Scalability
Passive multiplexers are limited to colored optics that result in lesser wavelengths on the transport fiber. This will include many passive devices in case the system grows, and it may become difficult to manage multiple devices. Furthermore, these devices may include the same wavelength on multiple passive devices, serving different purposes depending on the setup.
- Lesser Control
If there is a need to change the wavelength or connection, the complete connection will need to be disconnected as the wavelength is dependent on the nature of the optic involved.
Wrapping Up
It is important to understand the needs and features of the network before choosing the best-suited multiplexer. This post will allow you to understand the uses and significance of passive multiplexers for better performance of fiber networks at lower costs.
Image Credit – Wikimedia
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