1. An optical signal at a specific wavelength has lost 55 percent of its power after traversing 7.0 km of fiber. What is the attenuation in dB/km of this fiber?
2. A continuous 40-km-long optical fiber link has a loss of 0.4 dB/km.
(a) What is the minimum optical power level that must be launched into the fiber to maintain an optical power level of 2.0 auW at the receiving end?
(b) What is the required input power if the fiber has a loss of 0.6 dB/km?