What differentiates a laser from an LED?

The correct choice emphasizes that lasers have very specific energy levels during their transitions, which is a fundamental characteristic that distinguishes them from LEDs. In a laser, the process of stimulated emission takes place, where electrons transition between two precise energy levels, leading to coherent light that is typically monochromatic (single wavelength) and phase-aligned. This coherence and the precise energy levels are what primarily make lasers capable of producing highly focused and powerful beams of light.

In contrast, LEDs do not operate through stimulated emission but rather through spontaneous emission, which involves a range of energy levels as electrons transition between various levels in the semiconductor material. This results in the emission of light over a broader spectrum of wavelengths, leading to incoherent and less focused light output.

The other choices do not accurately reflect fundamental differences:

• Lasers can operate at a variety of power levels, and their operational power can be high, particularly in applications such as cutting or medical procedures.

• While both LEDs and lasers may utilize dopants, the concentration of dopants in LEDs does not directly differentiate their operation from lasers.

• Lasers, as mentioned earlier, are characterized by a narrow wavelength output, contrasting with the broader emission spectrum typically associated with LEDs.

This understanding of energy transitions and coherence is crucial for