Therefore, junction conduction band and valence band top to achieve particle (electron) inversion conditions are N area and P area of the quasi-Fermi level difference is greater than the band gap width. This must only be able to do in the highly doped, semiconductor lasers, and this was also the difference between the general semiconductor devices. In the P-N junction with appropriate large positive voltage, so that when the reverse occurs junction particles, if the energy to meet the (5-4) photons by junction type, you can achieve stimulated emission of light. The above calculation is only a rough analysis, rigorous mathematical model for semiconductor lasers, see the monograph. The report will describe the fault status of green laser pointer in details.
Figure (5-28) shows a GaAs laser structure. It is the core of p-n junction. p-n junction of the two ends are the natural crystalline lens surface by Slice open, called the cleavage plane, the two extremely smooth surface, can be directly used as a parallel to the reflecting mirror to form cavity. Upper and lower electrodes applied forward voltage, so that junction produces double degeneracy of the band structure and laser current. Laser can be output from the side of the cleavage plane, but also by both sides of the output. Lasers produce a prerequisite for addition to the laser reverses particles also need to meet the threshold condition, that is, two-way optical resonator magnification is greater than 1, or to meet the gain coefficient given in Chapter II (2-36) is in Here is a semiconductor laser cavity internal losses, the crystal cleavage plane between the two lengths, and for the cleavage surface reflectivity. The company will try to reduce the cost and expense of green laser pointer .
Where is the junction area of electronic life, and its inverse is equal to the energy levels between the Einstein spontaneous emission coefficient, the value for the inversion. Active area of the semiconductor laser population inversion is difficult to determine the value, but it can be linked with the operating current. At low temperatures, assuming a certain time interval, the total number of injected electron laser with the same time occurred the same number of electron and hole recombination to achieve balance, and there were crystal where the width and the thickness of the active area. Into (5-8), we get through the role of the area where the current density. With (2-36) type and is approximately 1 /, threshold current density can be an approximate expression for the. GaAs laser diode volt-ampere characteristics and the same, also has a one-way conductivity. The green laser pointer workshop is holding a lecture to introduce importance of safety of green laser pointer workshop.
Figure (5-29) below. Positive use of the laser system, the resistance depends on the crystal body resistance and contact resistance, the resistance was not much, but the operating current density, can not ignore its impact. Factors affecting the threshold: the greater the concentration of doped crystals, the smaller the threshold value; the smaller the cavity loss, the smaller the threshold value; within a certain range, the cavity length, the lower threshold; temperature on the threshold great influence on the current value of the semiconductor laser should work at low temperature or room temperature. Homojunction semiconductor laser threshold current density is high. Of (3 × 104 ? 5 × 104) A/cm2. Such a high current density, the device will heat. Therefore homojunction semiconductor laser at room temperature only the low repetition rate (a few tens of KHz KHz) under pulsed operation. The machining process of green laser pointer is important to enhance quality of green laser pointer .
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