半导体激光器电流调制实现短相干光源

Short coherent light source based on current modulation in semiconductor lasers

传统的干涉仪采用激光光源,由于激光的高相干性,在平行平板、棱镜等特殊光学元件测量时存在严重的串扰;LED、钨灯等光源因准直性较差、光强稳定性差和相干长度较短等特征,同样不适合作为特殊光学元件检测干涉仪的光源。短相干激光光源具有方向性好、亮度高和相干长度适中等优点,是特殊元件检测干涉仪的理想光源。针对短相干干涉仪对光源的需求,对通过电流调制半导体激光器光源的相干性进行了理论研究。研究结果表明,调制频率越高、调制强度越大,光源的相干长度越短;偏置电流越大,输出功率越高,相干性也会变好,不利于产生短相干光源。在此基础上,搭建并研制了一款短相干激光光源,该光源相干长度为80μm,光源的旁瓣抑制比下降为0.31,输出光功率可达30 mW,能够满足短相干测量对光源的要求。

Traditional interferometers use laser light source,because of the high coherence of laser,there are serious crosstalk in the measurement of parallel plate,prism and other special optical elements.Due to the characteristics of poor collimation,poor stability of light intensity and short coherence length,LED and tungsten lamps are also not suitable for the detection of interferometers with special optical elements.Short-coherent laser source has the advantages of good directivity,high brightness and moderate coher⁃ence length,and is an ideal source for detecting interferometers with special components.In order to meet the demand of short coherence interferometer,the coherence of current modulated semiconductor laser source is studied theoretically,the results show that the higher the modulation frequency and the greater the modulation intensity,the shorter the coherence length of the light source.The larger the bias current is,the higher the output power is,but the coherence will also be better,which is not conducive to the genera⁃tion of short coherent light source.On this basis,a short coherent light source verification system is built to verify the correctness of the relevant theories.A short coherent laser source has been developed,the co⁃herence length of the light source is 80μm,the sidelobe rejection ratio of the light source decreased to 0.31,the output power of the light source can reach 30 mW,which can meet the requirements of short co⁃herent measurement.