光纤的声光特性研究-光学工程专业论文.docxVIP

、 ‘ 摘要摘要 摘要 摘要 本论文研究了光纤的声光特性，主要提出了一种新的声光调Q的方法，利用 换能器阵列进行连续声光衍射来实现调Q，并因此而设计了实验。 本文从声波和光波在介质中的耦合波方程出发，利用动量匹配和动量失配分析 了介质中的声光互作用规律，分析了声光正常布拉格衍射时的声光衍射效率。从 衍射效率的公式中可看出，增大超声波功率或者增大换能器的长度或者减少换能 器的宽度，都可增加声光衍射效率。因此实验要根据这几点来设计。 另外，为了验证实验的可行性，本文用ANSYS仿真软件做了一个简单的关于 光纤在声场中受力的仿真模型。在模拟中发现当声功率加很高时光纤的纤芯会发 生震裂的现象，因此，超声波功率又不能够加的太大。这样，合适的超声波功率 以及适当的超声换能器尺寸都必须做出严格的计算。 因此接下来，利用了传输线的马森等效电路理论，计算并结合实际情况确定了 压电换能器的结构、材料以及换能器的长度、宽度和厚度，以及各镀层的实际厚 度。 根据上述的工作以及对国内目前研究现状的分析，设计了实验方案。在实验过 程中，设计并制作了射频信号电路，并编写了控制软件，使整个实验实现自动化 控制。然后搭建了实验系统并测了数据，最后对实验结果进行了分析。 关键词：光纤声光耦合换能器声光调Q 电 ABSTRACTAB ABSTRACT AB STRACT By studying acousto·-optical characteristics of the optical fiber,a llew Q-·switched method is proposed and the correlative experiments ale designed． Began with acousto—optic interaction coupled wave equation and use the theory of the momentum match and mismatch between the polarization wave and the free waves of medium，acousto—optic interaction law and the diffraction efficiency formula is analysised．From the diffraction efficiency formula,it can be found that in order to improve diffraction efficiency,ultrasonic power and the length of transducer,and decrease of the width of transducer can be increased．Therefore，the experiment should be designed according to the points mentioned above． In addition,to verify the feasibility of the experiment,ANSYS simulation software was used to do a simple optical fiber in the sound field on the force of the simulation model．According to the model it could be found that when the acousto·power is increased to a higher number,then the fiber core is shattered and,therefore，ultrasonic power can not be added too much．Thus，appropriate ultrasonic power and the appropriate transducer size must be made strictly calculations． According to the transmission line of Mason equivalent circuit theory,the metallic membrane plating structure of piezoelectric transducer is deterrninated．Then,the length， width and thickness of piezoelectric transducer are calculated． Based Oil the abo