What are the matters need attention to use the page-turning green laser pointer?
If the injection current is large enough, it will reverse the formation and thermal equilibrium carrier distribution, ie inversion. When the active layer of the carrier in the case of a large number of inversion, a small amount of spontaneous emission of photons at both ends of the cavity surface as arising from induced radiation reflected back and forth, resulting in frequency-selective resonant positive feedback, or to a frequency with a gain.What are the matters need attention to use the page-turning green laser pointer? When the gain is greater than the absorption loss, the PN junction can be sent from a good line of coherent light - laser, which is the simple principle of the laser diode. With the technology and process development, the actual use of the semiconductor laser diode has a complex multi-layer structure. There are two commonly used laser diodes: ① PIN photodiode. It received optical power generated photocurrent, there will be quantum noise. ② avalanche photodiode. It can provide internal amplification than PIN photodiode transmission distance, but the quantum noise even more. In order to get a good signal to noise ratio, optical detection devices to be connected behind the low-noise pre-amplifier and main amplifier.green laser pointer has been more and more widely used with the rapid development of technology. Semiconductor laser diode works, in theory, the same with gas lasers. Laser diode is essentially a semiconductor diode, according to the PN junction is the same material, the laser diode can be divided into homojunction, single heterojunction (SH), double heterostructure (DH) and quantum well (QW) 100mW green laser pointer diode. Quantum well laser diodes with low threshold current, the advantages of high output power, is the mainstream product market applications. Compared with lasers, laser diodes with high efficiency, small size, long life advantages, but its output is small (generally less than 2mW), linear poor, not very good color, its application in the cable television system is considerably limited, can not transmit more channels, high-performance analog signal. The page-turning green laser pointer has become a very important demonstrating instrument.Two-way optical receiver in the return module, uplink transmitter generally uses quantum-well laser diodes as light sources. Semiconductor 50mW blue violet laser pointer diodes used parameters are: (1) Wavelength: the laser operating wavelength, optical switches currently used for laser wavelength 635nm, 650nm, 670nm, 690nm, 780nm, 810nm, 860nm, 980nm and so on. (2) the threshold current Ith: the laser generates laser oscillation start current, low-power laser in general, its value is about tens of mA, with a strain multi-quantum well structure laser threshold current as low as to 10mA or less. (3) Working current Iop: the laser output power at rated drive current, the value for the design of laser driver circuit debugging more important. The page-turning 200mW green Laser Pointer has played a very important role in education. (4) vertical divergence angle θ ⊥: light-emitting laser diode PN junction in the vertical direction with open angle, generally about 15 to 40. (5) the level of divergence angle θ ‖: the light-emitting laser diode and PN junction in parallel with the direction of the opening angle, usually in 6 ~ 10 So. (6) monitor current Im: the laser tube at rated output power, in the current flowing PIN tube. Laser diode on a computer CD-ROM drive, laser printer print top low-power optoelectronic devices have been widely used.
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