The interface of usa green laser pointer is USB interfaces

Here is the general introduction to    green laser pointer     .
The α fc with the initial carrier concentration N (on GaAs material doped) have the following relationship: α fc = 0.5 × 10? 17 N, when the doping concentration in active region 1018 cm? 3 below, α fc constant unchanged at 10cm? 1, and reached 10 cm, the absorption coefficient with increasing doping concentration. Of α fcx have the same relationship, so the active area and 18? 3 waveguide region is not doped. To optimize the thickness of the cladding, reducing the laser cladding thickness can reduce the thermal resistance, in order to reduce the carrier leakage, it must ensure that the waveguide layer with a bandgap difference, if the carrier is too small will lead through waveguide layer leak, so that the quantum efficiency and lower the temperature characteristics. 3.2 for a single tube core chip design and its structural parameters are launching aperture and cavity length, decided to launch a single die aperture output 3.2.1 the structural parameters of single-die design of power, usually in the 50-500? M between the cavity length and width of the spectral gain and, generally 600-1200? m between, single-tube core structure diagram shown in Figure 3.2.   green laser pointer    could be used as laser pointers shooting into targets.
Figure 3.1 Schematic diagram of a single die in the high-power semiconductor lasers, high-through-plated film and antireflection film against, not only can reduce the threshold current and improve the quantum efficiency of the laser and electro-optical conversion efficiency, but also can improve the optical-cavity surface-damage threshold value, protect the cavity surface, to prevent oxidation and enhance reliability. Before the cavity surface reflectivity R f to be optimized to achieve the best value to ensure the threshold current density and external quantum efficiency η d, etc. in the appropriate range. Threshold current density J th can be expressed as 8-cavity surface-reflectance laser: laser-cavity surface-reflectance Rr after as high as possible to reduce useless power consumption. Yanbian University undergraduate thesis J th = J0 η α i (1? Γ) α c 1 1 1 () ln () ηα g Rr R f Γηα g Γηα g L-type (3-2) external differential quantum efficiency ηd the following equation ηd? 1 = ηi? 1 (1 2α i L) ln (Rr R f)? 1 type (3-3) where: ηi, α i, L, Γ, d, respectively, for the internal quantum efficiency, internal loss factor, cavity long, the limiting factor, the active region thickness, η, J 0 is a constant related to the gain.    green laser pointer      adopts RF technology.
From (3-11) can be seen, J th with Rr R f decreases, to obtain low threshold current density, demands for higher reflectivity. However, equation (3-12) shows that external quantum efficiency versus Rr R f decreases. To obtain the maximum output power, Rr R f there is an optimum value. Experimentally optimized to ensure Rr> 0.95 when, R f value of 0.8. Constitute a multi-media material refractive index difference of two larger, the higher the reflectivity of the film, so for high-refraction of Si materials. Calculations show that, as reflectance coating to meet the requirements of greater than 95%: S / L / H / L / H / L / H / L / H / A (where: L is the optical thickness of 200nm of Al2O3, H is the optical thickness of 200nm of Si, S is a smooth, A is the environment). For the first cavity surface, with different optical thickness of Al2O3, the rest can be of different reflectivity. The interface of usa green laser pointer is USB interfaces.
Optical thickness of 232nm, reflecting the remaining 5%; optical thickness of 263nm, the remaining reflectivity of 11%; optical thickness of 288nm, the remaining reflectivity of 18%. 3.2.2 Continuous high-power semiconductor laser array is the array elements the main structural parameters (including emission aperture, cavity length, width and shape of the isolation groove) design design, the structure of adjacent cells on the inhibition of coupling between the horizontal, to avoid cross amplification reduce efficiency. As the laser is a high-power devices, and electro-optical conversion efficiency of the active region is very sensitive to temperature, reduce the device series resistance is particularly important. Cavity surface-coating process using electron beam evaporation station, optimizing the cavity surface reflectivity, increased output power and efficiency. 3.3 Reliability design for various applications of semiconductor lasers, semiconductor laser reliability and life is very important.    green laser pointer      can show office files via the projector.