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Views: 699 Author: Addams Publish Time: 2026-06-10 Origin: Site
In 2026, big data has permeated our lives. We watch high-definition videos online, use AI to help us work and live, store data in the cloud, and use intelligent driving functions in vehicles. Behind each of these applications, massive amounts of data are rapidly traversing between nodes in data centers, metropolitan area networks, and backbone networks. The data connections between these nodes rely on optical modules. Optical modules perform photoelectric conversion, transforming electrical signals into optical signals suitable for long-distance transmission, enabling long-distance, low-latency data transmission. Under the pressure of high bandwidth demands in existing networks, transmission speeds are gradually increasing each year. However, with the continuous increase in speed, the transmission performance of a single channel is approaching its physical limits. Every increase in speed brings a multiplied increase in cost and power consumption. In this predicament, wavelength division multiplexing (WDM) technology has emerged as another way to break the deadlock: since a single channel has reached its limit, multiple channels are combined for transmission. If quality is insufficient, quantity compensates, doubling the transmission bandwidth. This is the fundamental solution for high bandwidth and long-distance transmission in current networks.
If we consider optical fiber as a wide highway, and optical signals as trucks carrying data, then the data transported by a single truck per unit time is limited. To increase the transmission bandwidth per unit time, the simplest method is to use multiple trucks transporting data simultaneously. Wavelength division multiplexing (WDM) technology works in this way, modulating the signal with light of different wavelengths. Each wavelength is a channel, and simultaneous transmission through different channels increases the transmission bandwidth. Of course, in practical applications, WDM technology is quite complex. Because optical wavelength resources are limited, different channel spacings are used to better utilize these resources. The industry mainly classifies these standard channel spacings into two categories:
CWDM (Coarse Wavelength Division Multiplexing): The optical wavelength covers the range of 1270~1610nm, with a wavelength spacing of approximately 20nm. Optical signals in this range have relatively high attenuation, low dispersion, and lower cost, making them suitable for medium-to-short distance scenarios of 10~40km.
DWDM (Dense Wavelength Division Multiplexing): This technology covers the entire C-band (approximately 1530 nm - 1565 nm) and L-band (approximately 1570 nm - 1610 nm) with wavelength spacing as small as 0.8 nm or even 0.4 nm (100 GHz/50 GHz). Optical signals in this range exhibit relatively low attenuation but high dispersion, requiring the use of optical amplifiers. It enables ultra-long-distance transmission. With increasing bandwidth demands, in addition to the traditional C-band and L-band, DWDM is now expanding into the O-band (1260 nm - 1360 nm) to meet the transmission requirements of different scenarios.
In the early stages of optical module development, engineers primarily focused on increasing the speed of a single channel, relying on more advanced electrical chips and lasers, such as from 10G to 25G, and then to 50G PAM4. However, increasing the speed inevitably leads to higher signal noise, i.e., bit errors. With each increase in speed, the design complexity and power consumption of the optical module increase exponentially to eliminate the newly added bit errors. This approach has reached its limit. The introduction of wavelength division multiplexing (WDM) technology allows multiple signals to be transmitted over a single optical fiber. This enables optical modules to "assemble" multiple low-speed signals into a single high-speed signal, effectively doubling the transmission bandwidth. For example, 100G CWDM4 multiplexes four 25G optical signals into a single 100G optical signal, which is then demultiplexed at the receiving end to reconstruct the four 25G optical signals. Furthermore, by increasing the rate of a single channel, this method can be used to achieve even higher rates, significantly reducing the reliance on single-channel rate limits and easily doubling the overall module speed. This, in turn, greatly reduces the design complexity and power consumption of optical modules.
In metropolitan area networks (MANs), transmission distances are long and the services required are complex. Fiber optic resources are extremely limited, making it impractical to lay dedicated fiber optic cables for individual services. In such cases, wavelength division multiplexing (WDM) technology becomes the inevitable choice. Through WDM, multiple services can be transmitted within a single fiber. Using EDFA and DCM, the transmission distance can exceed the module's nominal value, achieving stable transmission over ultra-long distances. This expands the application range of optical modules and promotes the development of DCO coherent optical technology, making long-distance metropolitan area transmission possible.
With the continuous development of AI and breakthroughs in optical module technology, WDM technology allows optical modules to maintain small size, low power consumption, and hot-swappability while continuously pushing the bandwidth limits, bringing faster and more stable network connections. This continuously drives network progress and development, bringing more possibilities to our networks. Let us look forward to the near future. YXFiber, a professional one-stop solution provider.
