Which of the following statements is true about APDs compared to PIN diodes?

The statement that APDs amplify the signal is true, as Avalanche Photodiodes (APDs) are designed to provide internal gain through a process known as avalanche multiplication. When a photon strikes the APD, it generates an electron-hole pair. Due to the high electric field present within the device, this pair can generate additional pairs, leading to an increase in the number of charge carriers. This intrinsic amplification of the optical signal makes APDs particularly advantageous in low light conditions, where they can effectively enhance the detection of weak signals.

In contrast, PIN diodes do not have this amplification capability; they are primarily used for direct conversion of light into electrical signals without increasing the intensity of the signal. This fundamental difference in functionality gives APDs an edge in applications requiring higher sensitivity and signal integrity. Thus, the amplification feature of APDs is a key factor that supports their use in various optical communication technologies.