The Investigation Of High Power Laser Thermal Characteristic And The Invent Of Thermal Resistance Analyzer

Semiconductor lasers are optoelectronic devices, it is of great significance in the field of photonics, wide range of applications including laser printers, optical sensorsand optical communications. In recent years semiconductor lasers are developing more and more rapidly and its power is also growing. As an efficient energy the application of semiconductor laser also extends to medical, military and other fields. Packaging structure of semiconductor laser device is quite important for temperature rise and thermal resistance, which directly determines the range of semiconductor devices’ spectrum and laser light conversion efficiency. With increasingly high power in laser devices, heat dissipation is becoming an important bottleneck. As a result, it is very necessary to optimize the packaging structure, and also be of significance for the future development of semiconductor lasers. thermal resistance Analyzer measure the thermal resistance of the high power laser, by using PN junction voltage variation with temperature relationship. Thermal resistance measurement instrument through the issuance of the project, combined with the structure function method, can clearly distinguish the laser to a heat transfer path on each layer of heat resistance, and the result of measurement with infrared thermal imaging by comparison. the method can realize the measurement of the thermal resistance of high power laser.Studying on thermal characteristics of semiconductor lasers with electrical method, this paper mainly includes the following work:Independently complete the research and development of high power laser thermal analyzer, including logic design, circuit design and implementation section. The logic design part is based on FPGA, asynchronous serial communication protocol, the modules include serial receive module, serial port module, the baud rate generator module, a control module, and ultimately the serial data transformed into parallel executable command to complete the communication with the PC, then realizing the current control and switch control of thermal resistance circuit, achieving the real-time acquisition of the measured voltage and current feedback devices to the PC. In this way, we can achieve the purpose of real-time monitoring.The realization of resistance instrument hardware circuit design mainly includes current circuit design, test current circuit design, switch circuit design and acquisition amplifier circuit design. FPGA transfers serial digital signal from PC into DAC recognition, then Digital Analog Converter provides constant voltage, the constant current output by current circuit and test current circuit. Turning on the current to control the heating time of measurement device by switching circuit. Shut off high-power working current when the temperature of tested device rises to the steady state, switch to small current that does not affect the temperature rise, then the voltage signal acquired by the acquisition circuit is transmitted to the computer for processing.Based on the method of optical power measurement, measure the laser thermal resistance when it is emitting light or not emitting by electrical method. Utilizing the principle of thermal resistance, convert thermal resistance into temperature, calculate the optical power by the temperature rise, then the light conversion efficiency can be calculated by optical power and total power. At last, the experiment was verified by infrared method, Infrared test instrument measures the temperature rise while the measurement of thermal resistant.The results of this study are conducive to improving the level of technical indicators and test equipment for commercial semiconductor laser device thermal resistance in China. It has important theoretical significance and application value in the field of thermal resistance measurement of semiconductor laser.