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Time : 2015-04-07 11:38Source :analogtechnologies Author : Analog Click :

Laser diode is mainly made up of semiconductor materials, thus it is also called semiconductor laser, with features such as high conversion efficiency, wide band range, long service life, direct modulation capability, compact size, light weight and low cost, etc.

Like most of lasers, laser diode has the same working principle, i.e. stimulated emission. The difference is that the electrons of the laser diode are distributed in different energy states of different energy bands, while the particles of other lasers are distributed in different energy states of active media. Therefore, there is a difference in particle numbers inversion.

Laser diode current

There are two critical diode currents: threshold current and transparency current. The former stands for the forward current when reaching the threshold gain and the latter refers to the injection current when the stimulated radiation is the same as absorbing  below the threshold value. At this time, the material absorbs no net photon, which can be seen as transparent. When the current is below the threshold current, the output of the diode is spontaneous radiation, with low power, like LED. When the current is more than threshold current, and cavity gain reaches threshold gain, laser oscillation forms.

In order to properly drive the laser diode, a laser driver is needed. Nowadays, compact size laser driver is more and more popular among electronic engineers

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