Laser Diode (Laser Diode), referred to as LD, the physical structure of the laser diode is a layer of light-emitting diode junction placed between the light-emitting diode with a layer of light-active semiconductor, the end face of which is polished with partial reflection, thus forming an optical resonance cavity.
And LED is short for light-emitting diode, made of compounds containing gallium (Ga), arsenic (As), phosphorus (P), nitrogen (N), etc.. When the electron-hole complex can radiate visible light, and thus can be used to make light-emitting diodes.
In the case of forward bias, the LED junction emits light and interacts with the optical resonance cavity, which further excites the emission of a single wavelength of light from the junction, the physical properties of which are material dependent. Semiconductor laser diodes work on the same principle as gas lasers in theory. Laser diode is widely used in the CD-ROM drive on the computer, laser printer in the print head and other small power optoelectronic devices.
The difference in light-emitting principle
LED using the carrier injected into the active area of spontaneous radiation compound luminescence, laser diode LD is excited radiation compound luminescence. Light-emitting diode issued by the direction of photons, phase is random, laser diode issued by the photons is the same direction, the same phase.
LED is the abbreviation of Light Emitting Diode (Light Emitting Diode), LED applications are widespread, such as the indicator lights of household appliances, automotive rear anti-fog lights, etc..
The most significant feature of LEDs is their long service life and high photoelectric conversion efficiency. The original under the PN junction in some semiconductor materials, the injection of a few carriers and most carriers compound will release the excess energy in the form of light, thereby directly converting electrical energy into light energy. pn junction plus reverse voltage, a few carriers difficult to inject, so no light. This use of injected electroluminescence principle to produce the diode called light-emitting diodes, commonly known as LED.
LD is the abbreviation for laser diode, the physical architecture of the laser diode is placed between the junctions of the light-emitting diode with a layer of photoactive semiconductor, its end face polished with partial reflection, thus forming an optical resonance cavity.
In the case of forward bias, the LED junction emits light and interacts with the optical resonance cavity, which further excites the emission of a single wavelength of light from the junction, the physical properties of this light are material dependent.
Semiconductor laser diodes work on the same principle as gas lasers, in theory. Laser diodes are widely used in small power optoelectronic devices such as CD-ROM drives on computers and print heads in laser printers.
In the working principle, architecture and efficiency of the difference
① working principle: LED is the use of injected into the active area of the carrier spontaneous radiation compound luminescence, and LD is excited radiation compound luminescence.
② architecture: LD has an optical resonant cavity, so that the photons generated in the cavity oscillation amplification, LED no resonant cavity.
③ effectiveness: LED no critical value of the special, spectral density than the LD several orders of magnitude higher, LED sink light power is small, the divergence angle is large.