DWDM technology multiplexes the tight spectral spacing of a single optical fiber carrier in a given fiber to take advantage of the transmission performance that can be achieved. DWDM wavelength spacing is very tight, because the closer the spacing is, the more channels per fiber will be reused, and thus the higher the bandwidth. The international telecommunication union (ITU) g. 694.1 standard regulates the nominal wavelength interval of DWDM system. Each channel was spaced three ways: 0.4nm(50Ghz), 0.8nm(100Ghz), and 1.6nm(200Ghz).
The most important advantage of CWDM is the low cost of equipment. Because of the wide wavelength interval of CWDM system, the requirement for the technical index of laser is low, so the structure of laser is greatly simplified and the yield is improved. In addition, the power consumption and physical size of CWDM system are much smaller than DWDM system. In addition, CWDM light modulation adopts non-cooling laser and electronic tuning. DWDM USES a cooling laser and temperature tuning. Temperature tuning is difficult and expensive to implement because of the unevenness of temperature distribution over a wide wavelength range. CWDM avoids this difficulty, thus significantly reducing the cost. Currently, the cost of CWDM system is generally only 30% of DWDM. As the name implies, sparse wavelength division multiplexing (RWDM) is a close relative of dense wavelength division multiplexing (DWDM). There are two main differences between them. Firstly, CWDM carrier channels are widely spaced. CWDM modulating laser USES non-cooling laser, while DWDM USES cooling laser. Temperature tuning is used for cooling laser and electronic tuning is used for non-cooling laser. Temperature tuning is difficult and expensive to implement because of the unevenness of temperature distribution over a wide wavelength range.
CWDM avoids this difficulty, because it significantly reduces the cost, the cost of the whole CWDM system is only 50% of DWDM.CWDM provides a high access bandwidth at a very low cost and is suitable for point-to-point, Ethernet, SONET ring and other popular network structures. It is especially suitable for short distance, high bandwidth and point-intensive communication applications, such as network communication within or between buildings. CWDM and PON (passive optical network) are particularly worth mentioning.
PON is an inexpensive, point-to-multipoint optical fiber communication method. By combining with CWDM, every single wavelength channel can be used as a PON virtual optical link to realize broadband data transmission between the center node and multiple distribution nodes. What are the differences between thick wavelength division multiplexer (CWDM) and dense wavelength division multiplexer (DWDM)? take the fast optical fiber as an example to compare the main band spacing and band 2 differences.
Wavelength division multiplexing (WDM) refers to the use of laser signal multiplexing to send multiple beams of different wavelengths simultaneously on a single optical fiber. Each optical signal has its own wavelength, and they are usually concentrated in the range of 1500nm to 1600nm, which is called the WDM ribbon. Optical signals are modulated by data (text, speech, video, etc.) and transmitted in its own color band. WDM supports existing network bandwidth expansion without the need to add additional fiber optic cables, and can save fiber installation costs, significantly reducing the operational capacity costs of metropolitan and wide area networks. WDM can also implement solutions that cannot be implemented without increasing the number of optical fibers.
First, on the one hand, FDM is generally used to describe old multiplexing systems that process electrical signals, while WDM refers to newer multiplexing systems that process optical signals.
Secondly, on the other hand, in the FDM system, each frequency multiplexing represents the multiplexing of models from a single transmitting source, while one of the main applications of WDM is the multiplexing of optical fiber synchronous network (SONET) signals. Each SONET signal can transmit multiple signals from multiple sources through time division multiplexing (TDM) technology. Therefore, in the application of timing, WDM technology will generally combine TDM and FDM technologies to achieve higher bandwidth utilization.