Which type of diode requires a higher voltage power supply and more complex circuitry than PIN diodes?

The Avalanche Photodiode (APD) is designed to operate under a high voltage bias, often requiring several hundred volts to achieve its internal gain mechanism. This phenomenon occurs due to the avalanche breakdown effect, where the incoming photons can cause a chain reaction that produces multiple charge carriers, significantly amplifying the signal.

The complexity of the circuitry for APDs arises from their need for precise voltage control and biasing circuits to maintain their operational characteristics. They often include additional components to regulate the voltage and manage the high electric fields within the device.

In contrast, a laser diode is designed for light emission and operates at a lower bias compared to an APD, while a Pin diode is primarily used for RF applications and does not require such high voltages. A basic silicon diode operates at relatively low voltages and is simpler in design.

Thus, the requirement for a higher voltage power supply and more complex circuitry distinctly characterizes the APD among the choices provided.