What are light-emitting diodes (LEDs) primarily used for in opto-electronics?

Light-emitting diodes (LEDs) are primarily used to generate optical signals in opto-electronics. They are solid-state devices that emit light when an electric current passes through them. This characteristic makes LEDs exceptionally useful for a variety of applications, including lighting, display technology, and communication systems, where light signals need to be created.

The ability of LEDs to convert electrical energy into visible light with high efficiency is fundamental to their function. Unlike other devices in opto-electronics, which may focus on switching or detecting signals, the primary role of an LED centers around the generation of light itself. This property is exploited in applications like indicators on devices, LCD backlighting, and even in high-speed data transmission via optical fibers, where the emitted light serves as a medium for transmitting information.

In contrast, the other options focus on different functions that are not the primary role of LEDs. For example, while some devices do involve switching electrical signals or amplifying light signals, these functions are more characteristic of transistors and photonic amplifiers, respectively. Using LEDs primarily to detect electrical signals diverges from their main purpose and aligns more closely with the function of photodetectors.