半导体激光器特性参数测量系统的设计研制

【作者】 郭少华；

【导师】 王广济；

【作者基本信息】 天津工业大学 ， 物理电子学， 2005， 硕士

【摘要】 随着半导体激光器的制作工艺的完善和成本的降低,半导体激光器已被广泛应用于光纤通信、测量技术、激光测距、微细加工、激光雷达成像、医疗、生物工程等技术领域,在这些领域中,使用者对半导体激光器的各项性能指标越来越加关注。目前市场上的能够测量半导体激光器的特性参数的仪器种类很多,但从测量种类、测量精度上有所不同,此类产品中,国外产品占多数,测量精度相对较高,但价格昂贵,只有专业厂家肯花钱配备此类产品,而对于一般用户,则由于价格太高而较难推广,因此这些限制了人们对半导体激光器的进一步认识,因此如何开发出既使用方便,又能较准确测量半导体参数的设备,具有重大意义。 半导体激光器的一般特性包括阈值特性、光谱性质、光强分布、输出功率和转换效率、激光器的温升和热阻等。 目前对半导体激光器常见性能参数的测量,国内的测量方法,有的采用独立测试的手段,有的采用中科院半导体所的自动测试系统,这些系统测量精度较高,但系统庞大,操作复杂,测量周期长,使用价格昂贵,而且由于测量周期长,容易对器件造成损伤。目前国外的此种测量仪器,大多外形小巧简洁,携带方便,且仪器所能测量的半导体激光器的种类较多,测量精度高、操作简单,测量周期短,不易损伤器件,但是此类仪器却价格昂贵,很多公司和研究结构只得望洋兴叹。因此现在市场上的此类测量仪器很难推广其使用,这样便严重限制了人们对半导体激光器的研究和开发应用。 针对这样的市场情形,我们以较低的成本研制了半导体激光器特性参数测量装置,它能够方便、准确地测量激光器的这些重要参数,并根据测得的电压—电流特性曲线和光功率—电流特性曲线对器件的质量和性能作出评价。半导体激光器是一种阈值器件,当注入电流低于阈值时,输出光功率很小(荧光输出);当电流达到阈值以上时,输出光功率迅速增大(激光输出);LD的工作电流不能超过额定电流。在使用半导体激光器时,它的工作电流一定要大于阈值电流才能输出激光;同时工作电流也应小于额定电流,否则容易烧坏激光器。 本系统首先完成了对几种典型半导体激光器的特性参数的测量,包括伏安特性,功率—电流特性等,该测量系统由以单片机为核心的输入输出电路组成,系统工作时,半导体激光器在恒流源驱动下,通过调节电路参数,使激光器工作在不同的工作点上,然后将各工作点的电压值通过A/D采样和转换后送入单片机,经过处理后的数据显示在液晶上。 由于开发时间较短,我们没有来得及作上位机的程序,但在测量装置上留有通讯串口,以备将来扩展之用。下位机的测量软件采用C语言编程实现,程序中对光功率值的获得采取多次采样求平均值的方法,功率、管压降、驱动电流等数值都实时显示在测量系统的液晶屏上,数据处理采用曲线拟合的办法,用数学工具MATLAB6.5完成拟合和曲线作图,最终描出光滑的特性曲线,使对半导体激光器的特性一目了然,进而判断出激光器的性能情况。 我们测量激光器的参数,目的是更好的使用它,因此,我们设计的测量装置不仅能够对激光器的参数进行测量,同时还可以把激光器作为应用产品来应用。光纤通信是对激光器的最有代表性的应用,因此我们就以此为背景,同时更多还原

【Abstract】 With the development of technics, It is getting more perfect in manufacturing LD and getting more cheaper in cost of it, LD has been widely used in many field such as optical fiber communication, measurement technic, distance measurement by laser, micro-machining, radar imaging by laser, medical treatment, bioengineering and so on, in these field, users are getting more care about the feature of LD. There are many devices that can measure the idiocratic parameter of LD at the present time, but these devices are different on the LD varieties that can be measured and precision that the device can reach. In this kind of product, the products that occupy great proportion is foreign product, and its measurement precision is higher, but it has higher price. Only the professional company is able to equip this kind of measurement device, but to general user, because of its higher price the device can not be used widely, so it limits our research on LD greatly. So it is becoming more significantly to develop an new device that can is not only precise in measurement but also easy to use.The general parameter of LD is include threshold feature, optical spectrum feature, optical intensity distribution, output power and conversion efficiency, temperature and thermal resistance and so on.At the present day, in domestic field, there are some way on the measurement of LD’s parameter , one of them is called ’testing independently’, another way to measure is through the use of ’automatic testing system ’in CAS, and these testing system has the high testing precision, but the system are very huge in size, difficult to operate, has a long testing period, and are higher in price, and it is easy to hurt the LD because of its long testing period. This kind of device that made by foreign country, largely are small in size, easy to carry, has a more short testing period, and not easy to hurt the LD, but this kind of foreign device is too costly to buy them to some company and research institution. So these kinds of device is very difficult to used widely and then it limit the research and development on the LD greatly.According to the present market condition, we develop an new device successfully with lower cost, it can measure the important parameter of LD precisely and our device is easy to use, we can get the idiocratic curve of LD by processing the data we got from our testing devive, such as voltage-current curve,optical power-current curve, also we can evaluate the performance of LD we have tested according the curve we got.Semiconductor Laser is a kind of device which is only work above some value. It has two important parameters, which are threshold and power-current characteristic, it will be very useful to measure this two parameter curve, this will help you understand semiconductor laser very much. When the current driving LD is lower than threshold current, the optical power outputted will be a few, and the output light now is called fluorescence; When the driving current reaches threshold current, the output optical power will increase rapidly ,and now the output light is laser. The work current of LD can not be in excess of rated current. So we know if we need laser, the driving current in LD must be in excess of threshold current, but at the same time, the value of the work current should be below that of rated current, or LD will be destroyed easily.Firstly our device can measure parameter of some representative LD, include Voltage-Current Feature, Optical Power -Current Feature and so on, our system are made up of input-output circuit based on microchip system. When the system is on work, under the driving of power whose current is invariance, the LD can work atdifferent point through adjusting parameter of circuit, then sample these different work point and convert analog voltage to digital data, that is doing A/D convert, and put these data into cpu, after the process of cpu, the data will be displayed on crystal screen.Because the short development time, we have to time to write the program on PC part, but we have finished更多还原