The correct answer is: A. Smaller than
The 3dB optical bandwidth is always smaller than the 3dB electrical bandwidth. This is because the optical signal is attenuated as it travels through the fiber, while the electrical signal is not. The attenuation of the optical signal causes the 3dB optical bandwidth to be smaller than the 3dB electrical bandwidth.
The 3dB electrical bandwidth is the frequency at which the power of the electrical signal has decreased by 3dB, or 0.707 times its original value. The 3dB optical bandwidth is the frequency at which the power of the optical signal has decreased by 3dB, or 0.707 times its original value.
The attenuation of the optical signal is caused by the interaction of the light with the fiber material. The light is scattered by the impurities in the fiber material, and this scattering causes the light to lose energy. The amount of attenuation is dependent on the length of the fiber and the type of fiber material.
The 3dB optical bandwidth is always smaller than the 3dB electrical bandwidth because the optical signal is attenuated as it travels through the fiber. The attenuation of the optical signal causes the 3dB optical bandwidth to be smaller than the 3dB electrical bandwidth.