Building on WDM, Dense Wavelength Division Multiplexing (DWDM) technology emerged in the early 1990s. This article explores the origin, development, and key technological breakthroughs of DWDM. Wavelength division multiplexers are fundamental to the functioning and performance of integrated photonic circuits, with applications ranging from optical interconnects to sensing and quantum technologies. 28 Tbps data rates transmission under various weather conditions" Journal of Optical Communications, vol. The optical link between the terminals requires a data rate in the terabyte range which is typically realized by transmitting multiple wavelengths though one common channel.