WDM is a technology that is achieved using a multiplexer to combine wavelengths traveling through different fibers into a single fiber. The space between the individual wavelengths transmitted through the same fiber are the basis for differentiating the CWDM and DWDM.
CWDM- Coarse wavelength division multiplexing. WDM systems with fewer than eight active wavelengths per fiber. DWDM – Dense wavelength division multiplexing. WDM systems with more than eight active wavelengths per fiber.
CWDM is defined by wavelengths. DWDM is defined in terms of frequencies. DWDM’s tighter wavelength spacing fit more channels onto a single fiber, but cost more to implement and operate. CWDM match the basic capacities of DWDM but at lower capacity and lower cost. CWDM enable carriers to respond flexibly to divers customers needs in metropolitan regions where fiber may be at a premium. The point and purpose of CWDM is short-range communications. It uses wide-range frequencies and spreads wavelengths far apart from each other. DWDM is designed for long-haul transmission where wavelengths are packed tightly together. Vendors have found various techniques for cramming 32, 64, or 128 wavelengths into a fiber. DWDM system is boosted by Erbium-Doped Fiber Amplifier, so that to work over thousands of kilometers for high-speed communications.
The cost difference between CWDM and DWDM systems can be attributed to hardware and operational costs. Despite the superiority in terms of cost of DWDM laser with respect to the CWDM DFB laser chilled provide cost effective solutions for long haul and metro rings large capacity demanding. In both applications, the cost of DWDM system is set off by the large number of customers who use this system. Except for encapsulation, the DWDM laser for stabilizing the temperature with a cooler and a thermistor, it is more costly than an uncooled laser coaxial CWDM.
The energy requirements for DWDM are significantly higher. For example:DWDM laser temperature stabilized through coolers integrated modules encapsulation, These devices together with the associated PIN and the control circuit consumes approximately 4 W of power per wavelength monitor. However, an uncooled CWDM laser transmitter consumers about 0.5w. The transmitter of 8 channel CWDM system consume about 4W of power, while the same functionality in a DWDM system can consume up to 30W. As the number of wavelengths in DWDM systems with increased transmission speed, power and thermal management associated with them becomes a critical issue for the designers.
Because DWDM doesn’t span long distance as its light signal isn’t amplified, which keeps costs down but also limits maximum propagation distances. Manufacturers may cite working ranges of 50 to 80 kilometers, and by signal amplifiers to achieve 160 kilometer. CWDM supports fewer channels and that may be adequate for carrier who would like to start small but expand later when demand increases.