What functionality does an LED provide in opto-electronics?

In opto-electronics, the primary functionality of an LED (Light Emitting Diode) is to convert electrical energy directly into light. This process is based on the principle of electroluminescence, which occurs when electrical current passes through a semiconductor material, causing electrons to recombine with holes and release energy in the form of photons, which we perceive as light.

This capability makes LEDs invaluable in a wide range of applications, from display technologies and lighting solutions to indicators and various electronic devices. The efficiency and long lifespan of LEDs as light sources also contribute to their widespread use in modern electronic systems.

The other options relate to functionalities that are not applicable to LEDs. For instance, converting electrical energy into sound, amplifying electrical signals, or storing power do not describe the operation of an LED but rather pertain to other electronic components or systems.