Which of the following is true regarding dense wavelength division multiplexing (DWDM) systems?

Dense Wavelength Division Multiplexing (DWDM) systems involve the simultaneous transmission of multiple data streams over a single optical fiber by using different wavelengths (or channels) of laser light. The use of these systems introduces complexities in monitoring, maintaining, and troubleshooting the network, primarily due to the number of channels and the tightly packed wavelength allocations.

The assertion that DWDM systems create the need for an optical spectrum analyzer is accurate because this specialized test equipment is essential for analyzing the multi-wavelength signals transmitted through the fiber. An optical spectrum analyzer allows operators to observe the different wavelengths in use, check their power levels, and ensure that there is no interference or crosstalk between the channels. This is crucial for optimal performance, reliability, and to diagnose any potential issues within the network.

In contrast, the other options may misrepresent the complexities and requirements associated with DWDM systems. For instance, while it may seem that DWDM systems could operate without additional test equipment, the reality is that most installations, especially in complex networks, will benefit significantly from tools like the optical spectrum analyzer. Additionally, while DWDM is known for its ability to provide high capacities over long distances, it is typically considered to be more expensive than Coarse Wavelength Division Multip