The circuit control of china laser pointer is APC line

The volt-ampere characteristics of GaAs laser diodes with the same general, also has a one-way conductivity, as shown. Positive use of the laser system, the resistance depends on the crystal resistance and contact resistance, although resistance is not, but the work current, can not ignore its impact. The semiconductor laser gain is equal to loss, began to produce the laser injection current density is called the threshold current density. 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. If one end of the cavity on the silver-plated film, increasing the reflectivity of infrared light, can further reduce the threshold. The circuit control of china laser pointer is APC line.
Within a certain range, the cavity length, the lower threshold, below is the experimentally measured homojunction GaAs laser threshold current density Jth and the reflectivity of the cavity length L and R curves. Temperature threshold current of great influence, measured by the temperature change when the threshold current density curve can be seen in the 100K below the threshold value and the temperature is less, l00k above, the threshold increases with the cube of T. Therefore, the semiconductor laser should work at low temperature or room temperature. The following figure shows the spatial distribution of the semiconductor laser beam. Map coordinates of selected plane parallel to the y-axis and the end, z-axis perpendicular to the plane with the knot. Located at the junction plane direction of the laser half-power width, perpendicular to the junction plane direction of the beam width, the fundamental mode beam width. 120mW of power of china laser pointer can be customized.
Where, for the end zone horizontal dimension, as the laser wavelength. And perpendicular to the junction plane direction of the beam width. Where, d is the thickness of the active region, usually greater than lm, approximately in accordance with the narrow width of single-slit diffraction angle calculated. In fact realistic, but very far with the actual, you can not use the source divergence angle of the calculation method to calculate. As the short cavity semiconductor lasers, laser direction is poor, especially in the end of the vertical plane, a large divergence angle, up to 20 ° ~ 30 °. In the end of the horizontal plane, the divergence angle of about several times. The figure is a GaAs laser emission spectra, which Figure (a) is below the threshold of the fluorescence spectrum, spectral width is generally several tens of nanometers, Figure (b) is the injection current to or greater than the threshold value of laser spectroscopy, spectral width of a few tenths of nanometers. What are the differences between red raychina laser pointerand green raychina laser pointer?
Although the semiconductor laser spectral width is much narrower than the fluorescence, but because of their special electronic structure, stimulated recombination radiation in the conduction band and valence band, therefore the gas and solid-state lasers than the much wider, and more at room temperature wide, up to a few nanometers. Monochromatic visible laser diode is poor. With the emergence of new devices, has improved, such as distributed feedback semiconductor laser linewidth, only about 0.1nm. Semiconductor laser operating wavelength varies with the structure. For example, for double heterojunction lasers, you can change the A1GaAs material in the A1 content, resulting in 0.751m ~ 0.92 m wavelength range of the laser, and the most widely used wavelength is 0.85m. The table will introduce the difference between the blue raychina laser pointer and green raychina laser pointer.
In recent years, due to the development of optical fiber manufacturing technology in the 1.0m ~ 1.8m in, especially in the 1.3 m ~ 1.55 m wide transmission loss is very low, so as to promote fiber-optic communications, people are working on long-wavelength lasers. For example, indium gallium arsenide (InxGal-xAs) laser (0.87 m ~ 1.7 m), antimony, gallium arsenide (GaAsl-xSbx) laser (0.4 m a 1.4 m), indium gallium arsenide phosphate (InxGal-xAsl-yPy ) laser (0.92m ~ 1.7m). Which, quaternary compound InGaAsP more used, the choice of x, y relationship, usually y = 2.16 (1-x). On the whole, the biggest distinguishes between these two types of green ray green laser pointer lie in their technology.