Those that belong to optical wavelength division multiplexing WDM include

Wavelength Division Multiplexing (WDM) is a fiber-optic technology that combines multiple data signals onto a single optical fiber by assigning each signal a distinct wavelength, significantly increasing the fiber's transmission capacity.OverviewWDM is a method used in fiber-optic communications to transmit multiple optical signals simultaneously over a single fiber by using different wavelengths (colors) of laser light . Each wavelength acts as an independent channel, allowing multiple data streams to travel in parallel without interference, similar to lanes on a multi-lane highway . This approach maximizes the use of existing fiber infrastructure, reducing the need for additional fibers and lowering deployment costs .How WDM WorksAt the transmitting end, a multiplexer (MUX) combines several optical signals, each at a unique wavelength, into a single fiber . At the receiving end, a demultiplexer (DEMUX) separates the combined signals back into individual wavelengths for processing . Some devices, called optical add-drop multiplexers (OADMs), can add or remove specific wavelengths along the fiber without affecting other channels .Types of WDMCoarse Wavelength Division Multiplexing (CWDM): Uses fewer channels with wider spacing (typically 20 nm apart) and is suitable for shorter distances and cost-sensitive applications .Dense Wavelength Division Multiplexing (DWDM): Uses tightly spaced channels (e.g., 0.8 nm or 100 GHz apart) to support high-capacity, long-distance transmission, often in core networks . DWDM can support dozens of channels, each carrying data rates up to 400 Gbps, with aggregate capacities reaching terabits per second .Applications and BenefitsCapacity scaling: WDM allows existing fiber to carry multiple high-speed data streams, delaying or eliminating the need for new fiber deployment .Cost efficiency: Reduces infrastructure and leasing costs by transmitting multiple services over a single fiber .Flexibility: Supports metro networks, data centers, and long-haul telecommunications, enabling upgrades without disrupting existing services .Bidirectional communication: WDM can also enable wavelength-division duplexing, allowing two-way communication over a single fiber . In summary, WDM is a critical technology for modern optical networks, enabling high-capacity, cost-effective, and scalable data transmission by leveraging multiple wavelengths on a single fiber.