WDM

WDM is an acronym that can refer to several distinct concepts across technology and organizations. Two widely used meanings are Wavelength Division Multiplexing in fiber-optic communications and the Windows Driver Model for Windows operating systems. In historical contexts, WDM has also referred to the World Development Movement, a UK-based advocacy group now known as Global Justice Now.

Wavelength Division Multiplexing (WDM) increases fiber capacity by carrying multiple light wavelengths on one fiber. Each wavelength carries a separate data stream. CWDM and DWDM differ in channel spacing and channel count. Typical ITU-like bands use wavelengths around 1260–1625 nm; essential components include multiplexers/demultiplexers, optical add/drop multiplexers, and optical amplifiers. WDM enables high-capacity long-haul and metro networks and data-center interconnections but requires precise wavelength control, dispersion management, and higher equipment costs.

The Windows Driver Model is a kernel-level driver framework introduced by Microsoft to unify driver development across Windows. It replaced older architectures such as VxD and supports plug-and-play, power management, and a common IRP-based interface with the kernel. Later, Windows Driver Frameworks (KMDF and UMDF) built on WDM by providing higher-level abstractions. WDM remains foundational for many existing drivers, though newer frameworks are preferred for new development.

World Development Movement was a United Kingdom–based advocacy organization formed in the 1970s that focused on global justice and development issues. The group used the acronym WDM and later rebranded as Global Justice Now.