Question

An optical transmitter can generate optical signal with power of 0dBm. The signal is transmitted in an optical fiber with attenuation coefficient α=0.2dB/km. What is the output power after the signal is transmitted over 100km in this fiber? Assume the power loss only comes from fiber attenuation, and no coupling loss. Use the unit of dBm.

Answer 1

The output power after the signal is transmitted over 100km in the optical fiber is -20 dBm.

Step-by-step explanation:

To calculate the output power after the signal is transmitted over 100km in the optical fiber, we need to consider the attenuation coefficient of the fiber. The attenuation coefficient is given as α=0.2dB/km. To calculate the output power, we need to subtract the power loss due to attenuation from the initial power of 0dBm. The power loss can be calculated using the formula:

Power Loss (dB) = α x Distance (km)

Substituting the values into the formula, we get: Power Loss = 0.2 dB/km x 100 km = 20 dB.

To calculate the output power, we subtract the power loss of 20 dB from the initial power of 0 dBm:

Output Power = Initial Power - Power Loss = 0 dBm - 20 dB = -20 dBm.