【作者】 范国芳；

【导师】 宁继平；

【作者基本信息】 天津大学 ， 物理电子学， 2007， 博士

【摘要】 高速波导声光调制器,由于具有开关速度快、体积小、插入损耗小、驱动功率低、机械稳定度高、设计灵活方便、便于集成等优点,成为全光纤调Q激光器中最佳的开关器件之一,而且这种调制器还可用在高速光通信领域中。本文对高速波导声光调制器进行了系统的研究,并且进行了掺镱全光纤激光器的实验研究。论文主要的工作重点和创新性为以下几个方面:1、建立了一套波导声光调制器设计理论,对声光调制器各设计参数、波导声光互作用的重叠积分、声波导、光波导、总体结构以及光纤与波导耦合等方面进行了研究。设计了一种新型高速波导声光调制器,其开关速度能进入70ns以内,超过目前国际上这一领域的水平。2、首次利用声表面波衍射模型来分析波导声光器件的带宽和衍射效率间的关系,得出了异于其他模型分析的结论。人们普遍认为:波导声光器件不可能同时获得大的带宽和高的衍射效率(利用耦合模理论模型),但是我们的理论模型发现在一定的条件下波导声光器件可同时获得大的带宽和高的衍射效率。3、提出了一种分析光波导的改进型光线近似法。基于光线近似法,结合有效折射率法,发展出改进型光线近似法,用来分析设计三维的单模光波导。与其他方法相比,该方法简单,不需要大量复杂的运算。4、提出了一种新的分析设计锥形波导的方法。该方法可以用来分析设计不同形状函数的锥形波导。与其他方法相比,该方法简单而又实用。5、首次发现,小的波导模场椭圆度并不总意味低的光纤与波导的耦合损耗。通过分析光纤与波导耦合损耗的根源,研究波导模场的椭圆度和不对称度对光纤与波导模场失配耦合损耗的影响,发现小的波导模场不对称度就意味着低的耦合损耗,但与普遍看法不一样的是小的波导模场椭圆度并不总是带来低的耦合损耗。6、掺镱全光纤激光器的实验研究。分别进行了连续掺镱全光纤激光器、声光调Q掺镱全光纤激光器、主被动混合调Q掺镱全光纤激光器以及自调Q掺镱全光纤激光器的实验研究。更多还原

【Abstract】 High-speed guided-wave acousto-optic modulator will be one of the best switching devices of the Q-switched all-fiber laser for their high speed, compact size, low insertion loss, excellent design flexibility, high mechanical stability, low driver power requirement and good integration. At the same time, it can be used in the high -speed optical communications.The paper is mainly focused on the research about the high-speed guided-wave acousto-optic modulator. And, the paper does the experimental research about the Yb³⁺- doped double-clad fiber laser.The main emphasis and innovation of the paper are as follows:1. The design theory of the waveguide acousto-optic modulator is presented. The research is investigated about the design parameters of the acousto-optic devices, the overlap integral, the acoustic waveguide, the optical waveguide, the whole structure design and the coupling between the fiber and the waveguide. A novel high-speed guided-wave acousto-optic modulator is designed and fabricated. The switching speed is within 70ns, which takes the lead in the world.2. The first analysis is presented, based on the diffraction of surface acoustic waves, of the relationship between the Bragg bandwidth and the diffraction efficiency in guided acousto-optic interactions. It has been found that the Bragg band width is not always inversely proportional to the acoustic aperture. It is possible to simultaneously get high diffraction efficiencies and large bandwidths for guided acousto-optic devices.3. A novel method is proposed to analyze optical waveguide, which we call the improved ray approximation method. The method is developed based on the ray- approximation method and the effective index method to design the single-mode 3-D optical waveguide. The method is simple and effective compared with other methods.4. A new method is provided to the taper waveguide. The method can be used to analyze and design the taper waveguide with the different form functions. The method is simple and practical compared with other methods.5. A detailed analysis is presented, about the coupling loss dependence on the waveguide mode eccentricity and symmetry between single-mode fibers and waveguides. A new conclusion is obtained that more symmetric waveguide mode leads to lower coupling loss, but less eccentric waveguide mode does not always mean low coupling loss, which depends on the waveguide mode depth.6. The experimental research of the Yb³⁺-doped double-clad fiber lasers. We do the experimental research about the CW Yb³⁺-doped double-clad fiber lasers, Q- switched Yb³⁺-doped double-clad fiber lasers, the active and passive Q-switched Yb³⁺ -doped double-clad fiber lasers and self-Q-switched Yb³⁺-doped double-clad fiber lasers, respectively.更多还原