The term WDM-PON is the acronym for the term Wavelength Division Multiplexing Passive Optical Network, which is a new generation NG-PON2 technology. 

WDM-PON networks initially used 1500 and 1310 nm transmissions for downstream and upstream, respectively. Wavelength division multiplexing is a technology where multiple optical signals are multiplexed into a single fiber. For this, several different wavelengths are used through lasers (colors of light) to transport different signals. WDM systems allow many high-speed TDM (time division multiplexing) channels to be multiplexed onto a single fiber, increasing the transmission capacity of the system.

In WDM-PON technology, each client has a wavelength (colors of light) reserved to communicate with the OLT. One of the channel division methods for users is the use of AWG (Array Waveguide Grating), it works as a passive wavelength router, determining that the input optical signal is routed to a certain output port depending on the length. wavelength, working as follows, the OLT sends all wavelengths with the desired information in a single fiber and the AWG, once its routing is defined, is responsible for sending each wavelength to the ONU that must receive the information .

There are some components that are essential for the implementation and operation of WDM, of which we can highlight:

WDM-PON is divided into two most common types: CWDM (Coarse Wave Division Multiplex) and DWDM (Dense Wavelength Division Multiplexing).

CWDM technology is a technology that has the advantage of being low cost and easy to manufacture; its use is most significant in metropolitan networks. The distance between channels used in this system is 20 nm, using a spacing window between 1271 and 1611 nm, and supports up to 18 channels per fiber (the number of channels depends on the type of fiber used), each channel can reach up to 2, 5 Gbit/s. This technology can reach rates of 20 to 45 Gbit/s depending on the number of light colors (channels), with a range of up to 80 km. Its main disadvantage compared to DWDM is the limited number of channels.

DWDM technology is characterized by being high-cost and difficult to manufacture, and is most commonly used in places requiring greater network infrastructure, as they have a higher transmission capacity than the CWDM system. The distance between channels in this system can vary from 0.8 nm (100 GHz), 0.4 nm (50 GHz) and 0.2 nm (25 GHz), supporting up to 320 channels per fiber with a wavelength of 0 nm, each channel can reach up to 10 Gbit/s, DWDM uses a window spacing of 1525 nm to 1620 nm. To achieve this number of channels per fiber, the laser used must be more stable and must also have precise temperature control to avoid wavelength dispersion. This technology can work with transmission rates of 400 Gbit/s to 3.2 Tbit/s (varying according to the number of fiber channels), with a range of up to 1500 km, using amplifiers.

Conclusion

Thinking about the future is looking at WDM-PON as a promising alternative. This technology has the ability to improve the efficiency of optical networks by transmitting multiple signals at different wavelengths simultaneously along a single optical fiber. This means we have greater data transmission capacity, which allows us to have greater bandwidth and better network performance.
This technology still has room to evolve and is expected to be improved to allow a significant increase in transmission speed, greater energy efficiency, and lower implementation and maintenance costs.

XPONSHOP can supply Huawei WDM, Access Nwtwork equipment and provide tech support. If you have GPON OLT/ONT questions or project inquiry, please email us at sales@xponshop.com