In this blog, ETU-LINK will take you through what SWDM short wavelength division multiplexing is. As super data center traffic continues to grow exponentially year after year, the bandwidth requirements of data centers are getting higher and higher, and the construction of next-generation data centers requires lower cost and wider bandwidth transmission media. The cost advantage of vertical cavity surface emitting laser (VCSEL) light source makes multimode fiber still the preferred cost-effective cabling solution for data centers.

However, most of the 40G and 100G multimode optical modules use 4-way parallel transmission, so the use of these parallel optical modules will multiply the number of data center cabling and make maintenance more difficult. To solve this problem, SWDM short-wave wavelength division multiplexing (WDM) technology has emerged, which draws on the wavelength division multiplexing (WDM) technology of single-mode fiber and extends the wavelength range used for transmission from 850nm to 850nm-950nm, using a cost-effective short-wave vertical cavity surface emitting laser (VCSEL) light source and optimized broadband OM5 multimode fiber. It supports four wavelengths on a single multimode fiber, reducing the number of fiber cores required to 1/4 of the original number, while increasing the effective mode bandwidth and extending the transmission distance of the fiber.

When the wavelength is greater than 850nm, the dispersion bandwidth of the multimode fiber increases and the transmission distance increases.The operating wavelength used in SWDM technology starts from 850nm and increases every 30nm, i.e., 880nm, 910nm and 940nm, thus the operating wavelength of the broadband multimode fiber is in the range of 850 nm-950nm. In the shortwave WDM module, four different wavelengths are multiplexed onto a single multimode fiber. At the receiving end of the module, the signals are demultiplexed and converted into parallel electrical signals.

Optical modules using SWDM technology are 40G QSFP+ SWDM4 and 100G QSFP28 SWDM4, which have a dual-fiber LC interface and operate in the wavelength range of 850nm-950nm. Using SWDM4 multimode optical modules can save 75% of fiber usage compared to parallel SR4 optical modules, which is very effective for cost saving and cabling simplification.

SWDM modules create greater value for data center customers by leveraging the capabilities of existing 10G fiber infrastructure, helping customers save on capital expenditures while operationally reducing the need to deploy new fiber and enabling equipment upgrades.