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Optical networking covers a broad range of technologies and solutions with the capabilities to allow enormous amounts of data to traverse a single network link. Optical networking is a very effective method for establishing a scalable, high-capacity network while unlocking a floodgate of capacity available in a dark fiber pair. 

With the use of wavelength division multiplexing (WDM) technologies such as coarse wavelength division multiplexing (CWDM) or dense wavelength division multiplexing (DWDM), data signals from different sources can be combined, or multiplexed, so they can share a single dark pair while maintaining complete separation of the individual data streams.

Below is an example of a solution without WDM, where multiple dedicated fibers pairs are used for each separate service. Without WDM, multiple services and data rates cannot share the same fiber pair. For this type of solution, the cost of turning up additional services requires utilizing an extra available fiber pair, or possibly having to lease an additional pair each time another service is needed.

dedicated fiber pair diagram
Dedicated fiber pair

This next example illustrates multiple data signals flowing across a WDM equipped optical network, using separate individual wavelengths to transmit multiple services over a single fiber pair. The wavelengths are sent to a passive optical device called a multiplexer, which combines them, allowing to transmit the multiple services over a single fiber pair simultaneously. All the wavelengths travel down the common fiber pair and are separated at the far end of the fiber link using a passive optical splitter called a demultiplexer.

WDM diagram
WDM diagram
Light beam
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Because data signals are carried on distinct isolated wavelengths, the streams — also called channels — remain separated and do not interfere with each other. This is a very effective solution for overcoming potential fiber exhaust as it allows for scalable method to significantly increase network bandwidth without having to spend capital on new fiber construction projects or the need to purchase leased lines from a service provider, which often have high re-occurring costs for bandwidths rates of 10Gb and greater. 

Because of their ability to handle so much data and capabilities to transport across long links between geographically dispersed sites, optical networks are utilized by organizations spanning many industries using DWDM technology as an integral part of their long-haul, core and metropolitan area networks.   

Seven key advantages of WDM and optical networking

1. Large capacity

The potential transmission bandwidth of ordinary optical fiber used for data communications is vast, but its utilization rate is often very low. 

Optical transport networks using WDM technology provide the capabilities to increase the transmission capacity and make full use of the enormous bandwidth potential of optical fiber. For example, today's DWDM networks commonly use up to 96 (and theoretically more) separate wavelengths or channels of data that can be multiplexed into a composite optical signal transmitted on a single optical fiber pair. 

In effect, one fiber pair is transformed into multiple virtual fibers. So, if you were to multiplex 96 100Gbps circuits onto one fiber, you would increase the carrying capacity of that fiber from 100Gbps to 9.6Tbps of capacity.

This approach optimizes the utilization of metro, regional and long-haul fiber assets, which in the long run translates into the ability to deliver higher capacity at a lower cost. 

2. Transparent transmission of data

Because optical transport systems are a physical layer, or Layer-1 platform, they perform multiplexing and demultiplexing functions according to the wavelengths of light. This means they are "transparent" to the transmission of data regardless of the signal's rate and electrical modulation mode. 

WDM technology used in both CWDM and DWDM platforms puts data from different sources together on an optical fiber with each signal carried at the same time on its own separate light wavelength. Because the channels are physically distinct and don't interfere with each other thanks to the properties of light, each of the channels can use different data formats and each can be transmitted at different data rates, allowing channels to carry varying services such as Gigabit Ethernet, FC-SAN, Video, SONET and TDM over a single fiber pair.

3. Maximize network investments and dark fiber utilization

From both technical and economic perspectives, potentially unlimited transmission capacity is one of the primary advantages of WDM optical transport technology. Not only can the current investment in fiber plant be preserved, but it can also be optimized by a factor of 96 or more in today's common DWDM systems. 

4. Scalability

CWDM and especially DWDM systems are easily expanded as a single fiber can be divided into many channels. 

As demands change, more capacity can be added, either by simple equipment upgrades or by increasing the number of wavelengths used on the fiber, without expensive upgrades. 

In the expansion and development of the optical transport network, additional services can be turned up on available wavelengths. Active line card modules can be replaced with units that support either higher bandwidth service rates or leverage the capabilities of muxponders to carry multiple data streams over a single wavelength. Capacity can be obtained for the cost of the equipment, and the existing fiber plant investment is retained.

5. Overcome distance limitations

Optical transport systems are capable of transmitting large loads of capacity over long distances with DWDM systems capable of supporting links beyond 120km and up to thousands of kilometers with the capabilities of optical amplifiers and signal regeneration.

6. Flexibility and resiliency

Optical transport systems can be deployed in multiple topology schemes (P2P, Linear Chain, Ring). 

Today's DWDM ROADM platforms are also capable of being deployed in resilient mesh topologies and can be implemented with various protection mechanisms and schemes to ensure reliability.

7. Simplified operations

Today's WDM networks can also offer simple to use, integrated management solutions that significantly improve operational efficiency. DWDM networks combined with ROADM technology provide fast, simple, and dynamic provisioning of network connections giving organizations the ability to provide high-bandwidth services in days rather than months, and their staff are also able to remotely identify and resolve issues in a much more time-effective manner.


With the rise in bandwidth needs driven by 4K/8K streaming video, 5G mobile networks, cloud computing, data backup and replication and latency-sensitive applications, the need for a high-capacity Layer-1 optical transport network to support future bandwidth growth is critical.

Bandwidth-intensive workloads and latency-sensitive applications such as cloud computing, storage replication, data backup and migration, content distribution and disaster recovery solutions are increasing demand for organizations to deploy high-capacity connections between office sites, data center facilities and disaster recovery locations

Organizations are increasingly deploying their own optical networking solutions, leveraging DWDM platforms for transporting multiple 10G and 100G services in order to keep up with the constant demand for capacity driven by bandwidth-hungry applications.  

Instead of bonding together multiple 1Gbps or 10Gbps leased line circuits to accommodate escalating traffic growth, these organizations can increase network efficiency while decreasing reoccurring monthly OPEX costs by using higher capacity 100Gbps wavelength connections.

Today, the advent of optical networks platforms utilizing 100G technology coupled with coherent optics means that organizations can more easily upgrade their backbone, core and edge networks with the right amount of bandwidth for their applications to ensure that their users have a consistent experience, and their network is not constrained by capacity limitations. 

Utilizing high-capacity optical transport solutions, provides organizations with the scalability, operational efficiency, and performance needed to ensure their customers and end-users have reliable, high bandwidth, low latency connectivity needed for real-time access and mission-critical applications.  

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