What type of LED has relatively narrow spectral widths, high output power levels, and performs at high modulation rates?

The type of LED that exhibits relatively narrow spectral widths, high output power levels, and the capability to perform at high modulation rates is the edge-emitting LED. This design allows for a more efficient light output as the light is emitted from the edge of the semiconductor material rather than from a surface. Consequently, edge-emitting LEDs can achieve higher levels of power output because they benefit from larger active areas within the semiconductor structure.

The narrow spectral width is critical for applications requiring precise wavelength emissions, such as in fiber optic communications, where signal integrity is paramount. This characteristic also contributes to the ability to modulate the light at high rates, making edge-emitting LEDs well-suited for high-speed data transmission.

In contrast, surface-emitting LEDs typically have broader spectral widths and lower modulation speeds, making them less effective for high-performance applications. Standard LEDs, while versatile, do not usually achieve the output power levels or modulation rates associated with edge-emitting designs. Quantum dot LEDs are an emerging technology with their unique attributes but do not primarily focus on the high modulation rates and output levels like edge-emitting LEDs do.