DPL低噪声腔内倍频激光器及其应用的研究

【作者】 陈慧卿；

【导师】 陆祖康； 倪旭翔；

【作者基本信息】 浙江大学 ， 光学工程， 2003， 硕士

【摘要】 20世纪末数码技术得到了迅猛的发展，数码产品逐渐取代了传统的家用电器和测试仪器，如数码相机等。新的事物带来新的需求，数字彩扩系统就是在这样的背景下提出的。而激光以其特有的高饱和度、高精准度、高能量等优点，成为理想的曝光光源。特别是LD泵浦的蓝、绿固体激光器，具有寿命长、体积小、效率高等特点，已经在许多领域有着广泛的应用，如光存储、激光打印、光学信息传输、激光测距、激光医疗等方面。 本论文对LD泵浦的内腔倍频固体激光器及其在激光数字彩扩系统中的应用做了大量研究工作并取得一定的研究成果，此项目受到国家教委重点项目激光数字彩扩技术资助。 本文首先介绍了固体激光器多模运转的速率方程，结合二次谐波的产生方程，给出了内腔倍频固体激光器的动态方程。在此基础上模拟了谐振腔内光强的变化，指出影响“绿光问题”的根本原因，分析了主要因素对“绿光问题”的影响，为新方案的提出提供了理论依据。 文中提出一种新的方案，采用Nd：YVO₄／KTP组合，利用Nd：YVO₄晶体对偏振态的选择作用以及温度控制KTP晶体长度，实现双折射窄带滤波，强制激光器工作在单纵模的模式下。300mW的LD泵浦得到约5mw的绿光输出，对激光器进行了10 hour的连续监测，其输出功率噪声的不稳定性优于2％。 本文首次将Nd：YVO₄晶体应用于抑制激光噪声的补偿片法中，利用Nd：YVO₄晶体的线偏振特性，控制谐振腔内激光束的偏振方向，使多纵模均为线偏振，且偏振方向一致，从而减少了绿光输出中的波动现象。激光器工作在相互平行的多纵模模式下，在900mW的泵浦输入功率下得到倍频光功率为10.7mW，40小时连续输出光功率噪声＜1％。在此基础上对腔结构进一步优化，缩短腔长，得到更好的结果。在400mW的泵浦功率下得到8mW的绿光输出，在温度变化以及不同的泵浦功率输入下，功率噪声始终＜1％。更多还原

【Abstract】 At the end of 20 century,digital technology developed rapidly,and digital products take place of traditional products and instruments,such as digital camera etc.. New business brings new requires. Digital color developing and enlarging system is brought forward in that background. Laser beam is the perfect light source with high saturation,high precision and high power,to explore the printing paper. Especially in the field of the green and blue DPSSL(Diode pumped state-solid laser),intracavity doubled-frequency DPSSL has the advantages of long lifetime,compactness and high efficiency etc.. So it has had a wide variety of applications in the field of light storage,laser printer,optical information transmission,laser rangefinder and laser medical etc..We do many researches of intracavity doubled-frequency DPSSL and the application of laser digital color developing and enlarging system,and obtain some useful results. The paper is supported by the Significant Project of National Education Committee.At first,we introduced the velocity equation of DPSSL,which operates in the multi- longitudinal modes. Then,we give the dynamic equation of intracavity doubled-frequency DPSSL,when we take in the SHG(Second harmonious wave generation) equation. On the base of that,we simulate the light power of the intracavity doubled-frequency DPSSL. We point out the reason of "green problem",and analyze the influence of the main factors. It offers the theory of new precept to decrease the infection of "green problem" .Realizing the excellency of Nd:YV04 crystal,we use Nd:YV04/KTP firstly in our experimentation. The loss of light with different polarized orientation is different,when it through Nd:YV04 crystal. Utilizing the case and changing the thickness of KTP crystal bycontrolling temperature,we get a narrow light filter,so the cavity operates with single longitudinal mode. When the pumped light was 300mW,we gain the green light about 5mW. The noise is lower than 2% in 10 hours.An other time,we use Nd:YV04 crystal and compensator firstly. The loss of light with different polarized orientation is different,when it through Nd:YVO.i crystal. So it can select different linear polarized light. The compensator compensates the change of polarized light,and also controls the polarized orientation. In result,we get a cavity,with the orientations of the linear polarized multi- longitudinal modes are agree. The noise of green output reducing,the cavity is steady with multi-longitudinal modes operating. The laser give out 10.7mW green light,pumped 900mW. We observed it for 40 hours,the noise of green power is lower than 1%. We optimized the laser cavity later. The length of cavity is shortened by 5mm and the result of experiment is pleased. When the pumped light was 400mW,we gain the green light about 8mW.更多还原