Skip to content

What is DWDM and why should you care?


What is DWDM and why should you care?

technology connectivity graphic

Imagine a couple of small trucks moving along a country road in opposite directions, carrying goods between factories and consumers. As the population grows and demand increases, the trucks grow in number and in diversity of goods and traffic increases. At some point, city planners must start adding lanes until eventually the small country road has become a large multi-lane highway with 18-wheelers moving huge volumes of different types of merchandise every day.

A similar rapid expansion in ‘cargo’ has happened in telecommunications. The telecommunications industry and particularly service providers have faced a dramatic and very rapid increase in the volume and type of data their systems must handle. Networks originally built to transmit soundwaves as electrical signals from one phone to another are now faced with managing data and video in real-time from many devices. Since the introduction of the Internet and creation of the Worldwide Web in the 80s and early 90s, within approximately 30 short years, 5G wireless technology is now rolling out and rapidly moving toward the IoT through which virtually all devices can theoretically be interconnected.

Fibre optics and optical communications in general have had significant impact on the telecommunications industry and will continue to do so, with light as a carrier enabling much higher data transmission rates over greater distances and with lower losses compared to electrical signals. To encode data into light to transmit it and decode it back into electrical signals upon receipt, optical communications rely on optical transceivers.

Dense Wavelength Division Multiplexing (DWDM) is transceiver technology developed around 20 years ago that has made optical telecommunications even better. It dramatically increases bandwidth (essentially the amount of data that can be transmitted) over existing fibre networks. Simply put, data from various signals are separated and encoded on different wavelengths and put together (multiplexed) in a single optical fibre. At the receiving end, the wavelengths are separated out again and reconverted into the original digital signals. In other words, DWDM allows different data streams to be sent simultaneously over a single optical fibre without requiring new cables to be laid. It is ‘dense’ reflecting the large number of signals that can be packed in a single fibre. Furthermore, because DWDM connections can be amplified, they can transmit data across very long distances.

The tremendous expansion in data volume afforded with DWDM can be seen in comparison with other optical methods. A standard transceiver, often called a grey transceiver, is a single-channel device – each fibre has a single laser source. You can transmit 10 Gbps with grey optics. Coarse Wavelength Division Multiplexing (CWDM) has multiple channels, although far fewer than possible with DWDM. For example, with a 4-channel CWDM you can transmit 40 Gbps. DWDM can accommodate up to 100 channels. At that capacity, you can transmit 1 Tbps or one trillion bps – 100 times more data than grey optics and 25 times more than CWDM.

While the volume of data transmitted with DWDM is impressive, demand will continue to grow as we move toward IoT and 5G. Adding additional optical transceivers with different wavelengths to a fixed-wavelength DWDM system can significantly increase cost. Tunable DWDM transceivers allow you to control the wavelength (colour) that the laser channel emits adding flexibility and reducing cost. Few companies supply the technology. EFFECT Photonics is among them, with its tunable and cost-effective DWDM technologies that will act as enablers of 5G and IoT, bringing the future to you today.