Although LED and LD have only one letter difference, they are two different kinds of products.http://www.new-lights.com
1、What is LED?
LED is the abbreviation of Light Emitting Diode (LED). Widely seen in daily life, such as home appliances, lights, cars, defensive lights, fog lamps, etc.. The most notable feature of LED is its long service life and high photoelectric conversion efficiency. Under the original PN junction of some semiconductor materials, the injected minority carriers combine with the majority carriers to release the excess energy in the form of light, thereby converting the electric energy directly into light energy. PN junction plus reverse voltage, the minority carrier is difficult to inject, so it does not emit light. The diode, produced by injection electroluminescent principle, is called light-emitting diode, commonly known as LED.
2、What is LD?
LD is the abbreviation of English laser diode, laser diode physical architecture is the placement of a layer with optical activity in the semiconductor light emitting diode junction, the surface polished with a partially reflective function, thus forming an optical resonant cavity. In the case of forward bias, the LED junction emits light and interacts with the optical resonant cavity, thereby further stimulating the single wavelength light emitted from the junction, which is related to the physical properties of the material. The working principle of semiconductor laser diode is the same as that of gas laser. Laser diodes have been widely used in computer compact disk drives, laser printers, and printed small power optoelectronic devices.
The differences between the two in principle, structure and effectiveness.
|（1）the difference in the principle of operation: LED is the use of injected active region of the carrier spontaneous radiation compound luminescence, and LD is stimulated radiation composite luminescence.（2）the difference in Architecture: LD optical resonator, so that the photon generated in the cavity oscillation amplification, LED no resonant cavity. （3）performance difference: LED no threshold characteristics, the spectral density is higher than LD several orders of magnitude LED export light power, divergence angle. In conclusion, compared to LD, LED has its own characteristics: there is no critical value characteristics, there is no noise, stable configuration type and without temperature control, long service life, high yield, low price.