Your fiber can carry 40 times more data. You probably haven't been told that.

What is this actually about?

A standard optical connection transmits data on a single wavelength of light, meaning one channel and one data stream. WDM (Wavelength Division Multiplexing) changes the math because instead of one channel, you have many, each on a different wavelength of light, all simultaneously within the same physical fiber.

Think of radio stations. Trójka broadcasts on 98.8 MHz, Radio Zet on 97.7 MHz, and RMF on 96.0 MHz. They all broadcast at the same time, through the same air, without interfering with each other. WDM does exactly the same thing with light in an optical fiber. One physical fiber suddenly behaves like eight, sixteen, forty, or more separate cables. Physical infrastructure costs remain the same, while bandwidth increases.

Three types of WDM and which one fits your needs

CWDM is the simplest and most cost-effective variant. Channels are spaced further apart, which allows for the use of simpler components and cheaper modules. It supports up to eighteen channels with a range of up to several dozen kilometers. It is ideal for campus networks, building-to-building connections, and initial metro deployments. It offers a low barrier to entry and quick implementation.

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DWDM packs channels tightly next to each other. Instead of eighteen, it provides forty, eighty, or more channels. It works with optical amplifiers, which opens up the possibility of transmission over hundreds or thousands of kilometers. This is the technology used for telecommunications operator backbones and long-distance data center interconnects.

The O-Band is a relatively new variant that deserves special attention. Salumanus was one of the first companies in the world to introduce complete optical network solutions based on the O-band transmission spectrum. These solutions operate without optical amplifiers because, for G.652 fiber, chromatic dispersion in the O-band is near zero, allowing data to be transmitted up to 30 km without additional equipment. The result is a reduction in network construction costs by approximately 50 percent, with the total cost of ownership over five years being about 80 percent lower.

Why now?

Just a few years ago, deploying WDM systems required large investments and specialized teams. Today, the situation has changed significantly for four reasons at once.

First, modules are much cheaper. The global optical module market is growing at an annual rate of 13.86 percent, and its value is expected to exceed $24 billion by 2029. Greater production scale means lower prices for customers. Second, modules are much easier to use. A few years ago, coherent optical modules were large, power-hungry, and required expensive transponders. Today, a GBC Photonics coherent module slides directly into a router port like a standard transceiver and consumes up to ten times less power than traditional transponder solutions.

Third, standardization. The emergence of 400ZR and OpenZR+ standards has brought interoperability between modules from different manufacturers, so you are no longer tied to a single vendor and their closed ecosystem. Fourth, the IP over DWDM trend is gaining momentum. Operators are increasingly stating that IP over DWDM is genuinely cheaper, allowing for savings on energy consumption and server room space. Salumanus is seeing a growing volume of inquiries and orders in this very area.

Why does it make financial sense?

New fiber in a city costs anywhere from tens to hundreds of thousands of zlotys per kilometer. On top of that, there are months of project planning, permits, and excavation work. Leasing fiber from an operator costs between 80 and 150 zlotys per kilometer annually, and costs grow linearly with every new fiber.

A WDM system on existing fiber costs a fraction of that, and deployment takes days or weeks. You can start small, with just a few channels, and expand the network as needed without replacing cables or interrupting traffic. Companies that have deployed IP over DWDM architectures instead of traditional transponder-based systems report backbone capital expenditure savings of around 65 percent, a reduction in data center floor space usage of up to 80 percent, and power consumption savings ranging from 70 percent at the network edge to 90 percent in the core.

Who is already using it?

Telecommunications operators build backbone networks on DWDM to connect cities and countries. Regional internet providers with their own fiber infrastructure multiply backbone capacity without laying new cables. Data centers connect their locations with terabit-level bandwidth. Small and medium-sized data centers and internet providers currently relying mainly on 10G connections see the O-Band as a viable and economically attractive alternative. There is one common denominator: everyone has fiber and wants more out of it, and WDM is the answer.