Teachers nowadays can turn pages of the screen at anywhere they stand by operating the green laser pointer

Gain coefficient and inversion of the relationship also depends on the resonant cavity of the work material t complex – complex junction electron lifetime t = 1/A21 △ n – inversion value of three semiconductor lasers The threshold current three, the threshold current of semiconductor lasers in 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 a positive balance when the threshold current density J to J formed after the laser threshold Numerical Example: GaAs P-N junction lasers homojunction and a heterojunction semiconductor lasers, homo-junction gallium arsenide (GaAs) laser characteristics 1. V characteristics: the same with the diode also has a single electrical wizard, as shown in Figure (5-29) as shown in 2.Teachers nowadays can turn pages of the screen at anywhere they stand by operating the    200mW green Laser Pointer  . threshold current density: Many factors affect the threshold volt-ampere characteristics of the laser is clearly to reduce the threshold value of J is the key to improving the level of the semiconductor, the study found that people J threshold and the following factors: (1) and the specific structure of the laser and the preparation process is closely related to a value different devices vary widely; (2) J threshold α1 / L, the threshold current density and the cavity length L inversely proportional; (3) J threshold and the close relationship between temperature; (4) J threshold and the reflectivity r1r2, usually two reflecting surfaces are natural cleavage plane, so r1 = r2 = 0.32.The first generation of  green laser pointer   has become the mainstream of daily application. When the cavity length transfer short, if 1/2L overall than a small or close to, a film will end gold-plated anti-J was significantly lower threshold, but when the cavity length L is long, J to reduce the threshold is not very clear. 3 direction: Figure (5-30) gives the spatial distribution of the semiconductor laser beam diagram, because the semiconductor laser cavity short, so the direction of the laser beam than other typical lasers a lot worse, and because the thickness of very thin active region, active region of width many times larger than the thickness, so in the direction perpendicular to the junction and the junction are parallel to the direction of beam divergence is asymmetric, the former to a large multiple of 4 spectral characteristics: Figure (5-31 ) is a GaAs laser emission spectra which Figure (a) is below the threshold of the fluorescence spectrum, spectral width is generally a few hundred angstroms, Figure (b) is the injection current to or greater than the threshold value of laser spectroscopy, spectral wide and tens of angstroms.What is the safe class of the   50mW blue violet laser pointer  ? Figure (5-30) Schematic diagram of the spatial distribution of the laser beam lasing spectral linewidth of GaAs compared to solid and gas lasers width, which is generated due to the semiconductor laser, the particle distribution is not reversed in the two between discrete energy levels, but in the conduction and valence bands within each band contains a number of levels, which makes recombination of photon energy has a wide energy range due to the gain line width, monochromatic emission spectrum would be worse. the actual structure of the laser emission spectrum is very complex, and spectral width broadens with increasing injection current, generally from a few tenths of nanometers to a few nanometers range. Meanwhile, the semiconductor laser spectral change with temperature when the temperature rises, the peak wavelength of the laser to the long-wave direction.What is the circuit control of a remote normal   100mW green laser pointer ? Laser series resistance of the forward current general homojunction laser power efficiency at room temperature only There are a few percent should be possible to improve the power efficiency decreases resistance.
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