Quality Testing System Of Semiconductor Lasers On The Basis Of The Virtual Instrument Technology

The development of semiconductor lasers bring the improvement to thewhole industry of photoelectron. With the boarding of application fields, thetechnical of semiconductor lasers improve fast. There are two importantreasons. First, it has lots of merits, such as high efficient of photoelectricconversion ,and covers large wave range, long operating life, modulationdirectly, small capacity, light weight and cheapness. Second, the combinationof practical application and the development of lasers. At present,semiconductor lasers are widely used in optical fiber communication, opticalsensor, information memory, medical treatment, and pumping solid lasers.Especially the high power semiconductor lasers is compelling used inoptical fiber amplifier and pumping source of solid lasers. So the quality of thehigh power semiconductor and reliability is become a hotspot among scientificworkers.The capacity and quality are decreasing day by day, the technicalpercentage is increasing, and intellectual technology develops rapidly. Thoughthe reliability is also strengthen, with the lack of communication betweensystem workers and designers of advanced device, the reliability and quality ofproducts are limited. This paper in the view of system workers to formulate thetask in the process of LDs examination about reliability and quality.It becomes more important in advanced technology fields. Then, it is veryimportant to measure the performance of LDs exactly and conveniently and toassess the quality and reliability of LDs. At present, the usual method ofscreen is electric aging in which all devices are aged with a constant power ora constant current under high temperature and then the early failed devices areselected. In the aging, the reliable devices are also subject to screening, and thelifetime of devices is affected because of the hot and electric hurt. It can causebatches of devices damage when some accidences happen, for instance, the outof control system or power cut. On the other hand, electric aging is notsensitive for latent defects, for example, some devices after electric agingscreening are usually found fail rapidly. Thus, the urgent problems are how toanalyse the factors which affect the device reliability, and how to select theunqualified devices with a fast, nondestructive and conveniently method.This paper puts forward to the reliability testing system of semiconductorlasers. The system uses virtual instruments instead of the analyzer, so the costof the system is reduced. We use PCI6014 data acquisition produced byNational Instruments company,it is a data acquisition with high accuracy ofA/D and D/A.The language of Visual C++.NET in Measurement Studio used bycompiling software is designed and developed for virtual instrument by theAmerican National Instrument Company. It is a graphic program software fordata acquiring,apparatus controlling,data analyzing and data expression. Itamplifies the user's ability of making the own apparatus system on thecomputer with high efficience and economic hardware equipments. VisualC++ it includes all kinds of functions,whereby making compiling workingconvenient,quick, the interface of the compiled software well-looking, similarto the practical instrument.We measured many AlGaAs/GaAs high power QW semiconductor laserswith electric derivative technique, analyzed the relation between the electricderivative parameters m, h, b and the reliability of devices. The value m ofInGaAsP/InP's normal character is between 2.2~3.0. The value m ofGaAs/GaAlAs's normal character is between 1.8～2.5. The value b ofInGaAsP/InP's normal character is below 60mv. The value b ofGaAs/GaAlAs's normal character is below 50 mv. The value h of InP 'snormal character is between 10~25mv. The value h of GaAs/GaAlAs 'snormal character is between 20~40mv.We find that there usually exist peaks in the electric derivative curveand optic derivative curve of high power semiconductor laser, these two kindsof peaks are related properly The peaks with opposite direction have notevident relation with the reliability of device, while the peaks with samedirection are usually related to the inner defects, carrier leakage andcurrent leakage, so, the device with same direction peaks is usuallyunreliable one. The number of the peaks increase after aging which reflectsthe degradation of device. According to the research, it indicates the stressand damage of the tube core, dirt on the chamber are the main reasons ofdegradation of device. Besides, the inappropriate operating in the testingprocess could also accelerate the degradation. To strengthen the reliabilityof device, we do researches to reduce the Ith by several means.We discuss the quality testing system of semiconductor lasers on thebasis of the virtual instrument technology could measure the character line ofLDs accuracy. Such as the line of C-V characteristic of the threshold currentIth, the sloping efficiency Es,the differential resistance RS,the characteristicjunction parameter m, the intercept b and the junction voltage saturation h.We measured many high-power semiconductor lasers, and the resultsreally show the performance of the devices. We can exactly and convenientlyassess the quality and reliability of the devices by the electrical derivative andits parameter. Besides, this system is easy to operate and the system discussedby this paper has extensively applying value.