What is the difference between ordinary light-emitting diodes and laser diodes?

- 2021-10-30-

What is the difference between ordinary light-emitting diodes and laser diodes?
Both light-emitting diodes and laser diodes are widely used in various fields such as automobiles, lighting, technology, military, engineering, and medical care. What is the difference between ordinary light-emitting diodes and laser diodes? The following editor of Shenzhen Guang Chuang Feng Technology Co., Ltd. will introduce it in detail from the aspects of light-emitting principle, architecture and efficiency.

Ordinary light-emitting diodes are also abbreviated as LED, LED is the abbreviation of Light Emitting Diode (light emitting diode). It is very common in our daily life. LED is a device that emits visible light when electrons and holes are recombined; and the LASER of the laser diode (LaserDiode) is the first of "Light Amplification by Stimulated Emission of Radiation (light amplification based on stimulated emission)". The abbreviation word composed of letters, laser diode is also called semiconductor laser, usually abbreviated as LD.

1: The difference in the principle of luminescence

LED uses the spontaneous emission of carriers injected into the active region to recombine light, while LD is recombined light-emitting by stimulated radiation. The direction and phase of the photons emitted by the light-emitting diode are random, and the photons emitted by the laser diode are in the same direction and in the same phase.

LEDs are widely seen in daily life, such as indicator lights for household appliances, and rear anti-fog lights for automobiles. The most notable feature of LED is long service life and high photoelectric conversion efficiency. In the PN junction of some semiconductor materials, when the injected minority carriers and the majority carriers recombine, the excess energy will be released in the form of light, thereby directly converting electrical energy into light energy. With reverse voltage applied to the PN junction, it is difficult to inject minority carriers, so it does not emit light. This kind of diode made by injection electroluminescence principle is called light-emitting diode, commonly known as LED.

LD is the English abbreviation of laser diode. The physical structure of laser diode is to place a layer of optically active semiconductor between the junctions of the light-emitting diode, and its end surface has a partial reflection function after being polished, thus forming an optical resonant cavity. In the case of forward bias, the LED junction emits light and interacts with the optical resonant cavity to further stimulate the emission of single-wavelength light from the junction. The physical properties of this light are related to the material. The working principle of semiconductor laser diode is theoretically the same as that of gas laser. Laser diodes are widely used in low-power optoelectronic devices such as CD drives on computers and print heads in laser printers.

2: Differences in principle, structure, and efficiency.

(1) The difference in working principle: LED uses the spontaneous emission of carriers injected into the active region to recombine light, while LD is recombined light-emitting by stimulated radiation.

(2) The difference in architecture: LD has an optical resonant cavity to make the generated photons oscillate and amplify in the cavity, while LED does not have a resonant cavity.

(3) The difference in efficiency: LED has no critical value characteristics, the spectral density is several orders of magnitude higher than that of LD, the output light power of LED is small, and the divergence angle is large.

Shenzhen Guang chuang feng Technology Co., Ltd. focuses on visible laser light source products and solutions. The services provided by the company include R&D, production and manufacturing of household laser engraving and industrial laser light sources. The business mainly covers laser diodes, laser modules, lenses, laser drivers, laser protective glasses and other fields. We look forward to your cooperation here!
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