Research Of Driver And Temperature Controlsystem For Semiconductor Laser

With its high efficiency, small size, light weight, and low price，semiconductorlaser plays an irreplaceable role in the military, medical, industrial production,communications and other fields. Meanwhile, semiconductor laser is a sensitive device.Per mA of current change will result in0.01nm wavelength drift; per degree Celsiuschange in temperature will cause0.1nm wavelength drift. Moreover, the drive surge andelectrostatic will cause damages to the semiconductor laser. What’s more, the bulk andexpensive drivers make the commercial semiconductor lasers unfavorable for outdoorapplication. So it’s of great practical significance to design a semiconductor laser driver,with smaller size, lower cost, continuously adjustable injection current, higher currentstability, controllable temperature and perfect protection.Not only does this paper analyze the work principles and the characteristics ofsemiconductor lasers but also summarize a variety of external factors affecting itsstability. After the investigations on the current development of the semiconductor laserdriver, we study the main technical indicators of the semiconductor laser driver in thispaper. Based on these indicators, the semiconductor laser driver was designed.The semiconductor laser driver consists of the current driver and the temperaturecontrol. There are three steps in the design of electrical current driver. Firstly, thecurrent values are fed into the MCU from its keyboard. According to the linearrelationship of the current–voltage, MCU controls the output voltage of the DAC. Then,whether the MOSFET is on or off is controlled, and the conversion of voltage to currentis finished. Thirdly, the current is injected into the semiconductor laser. In this section,in order to stabilize the current output and reduce the homeostasis time, the circuitsemploy the principle of negative feedback and the PID algorithm to accomplish adouble closed-loop control. In addition, this driver includes lots of perfect protectionmeasures to prevent the impact of the power-on, static electricity, delay soft start, andexcessive current. In the temperature control part, the dedicated control chip LTC1923is used to control the temperature of semiconductor laser. Similarly, the temperaturetarget value from the keyboard is fed into the MCU. According to the relationship of the temperature-voltage, the MCU controls LTC1923to accomplish its task.We give the results at the end of this paper. The relationship between the outputcurrent and the setting voltage of the constant current driver is favorable.The accuracyof the output current is0.08mAand its stability reaches0.052%in an hour. Its accuracyis0.1℃and its stability is0.84%in an hour.They both meet the requirement.