Research On Power Stability Of Semiconductor Laser

Since the laser was discovered in 1960, its component, technology and application have been developing at the very high speed, and it has penetrated into all disciplines and the applicatory domain. As a kind of superior radiant source, the laser is widely used. At present lasers designed successfully several hundred kinds, with the output wavelength ranging from near ultraviolet to the far infrared, and the radial power ranging from several milliwatts up to ten thousand watts. According to the work matter, the lasers include the gas laser, the solid state laser, the dye laser, the semiconductor laser and so on.With the maturation of the semiconductor technology day by day, semiconductor laser is applied more and more widely in the fields of scientific research, industry, military, medical service because of its characteristic: High transferring efficiency, small size, light weight, the high reliability, direct modulation and so on. Like development and transformation from the original electron tube to the later transistor and the integrated circuit in the electronic technology domain in the past, the laser has played such an important role that other lasers can not substitute because of the position and the developmental tendency of the semiconductor laser in photoelectron domain. But as far application, one of the main problems is that its output power is not stable and the laser is easy to be destroyed because of transient circuit and voltage peak. In recent years, many researchers have been studying it. With the development of computer technology, the digital control, which is based on microcomputer, can solve effectively the problems of semiconductor laser on accuracy, stability, reliability. Therefore digital and intelligent control system must be the direction of development for semiconductor laser.The essay introduces a negative feedback loop control system for semiconductor laser; with the use of MSP430F167 single chip computer of 16 bits, lower power to control output power of semiconductor laser. First, output power of semiconductor laser is sampled by PD, and then the data sampled is sent into MSP430F167 single chip computer to process. Last the date processed compared with the value presupposed to adjust output of driving current. Driving current is transformed into analog by D/A transducer embed in MSP430F167 single chip computer to control semiconductor laser, So that the design can realize stable output power of semiconductor laser. At the same time, a series of protecting measures are adopted, e. g. slow-start soft design, slow-end soft design, current and voltage limited and so on.