What distinguishes Laser Diodes (LDs) from standard LEDs in terms of light emission?

Laser diodes (LDs) are unique because they emit coherent light, which means the light waves are in phase and have a very narrow frequency range. This coherence allows for a concentrated and focused beam of light, making LDs highly effective for applications such as data transmission, laser pointers, and optical CD/DVD players.

In contrast, standard light-emitting diodes (LEDs) emit incoherent light, which consists of multiple wavelengths and is not in phase. This results in a broader beam of light that is often less directed and less intense than the light produced by laser diodes.

Regarding spectrum emission, laser diodes tend to operate within a much narrower wavelength range than LEDs, which can emit a wider spectrum of colors. Additionally, size is not a defining characteristic as laser diodes can vary in size, and while many LDs may be more compact than some larger LEDs, this is not a fundamental difference.

Thus, the defining feature that sets laser diodes apart from standard LEDs is their ability to emit coherent light, making them suitable for specialized applications where precision and directionality are crucial.