光纤光学器件的飞秒激光制备及其性能研究

发布时间：2018-05-25 23:32

本文选题：熊猫光纤Bragg光栅 + 飞秒激光加工　；参考：《吉林大学》2017年硕士论文

【摘要】：基于光纤材料的光学元器件,越来越受到大家的关注。光纤波导作为光学和光通信领域的一员,有着诸多优势,比如对光信号有着极强的束缚作用,尺寸小,质量轻等,给光纤波导的广泛应用提供了条件。根据制备时的预制棒的不同,光纤有很多种类,有着不一样的作用。近些年来,人们通过在光纤上进行修饰,或者结合激光制备方法在其中刻写结构,在传感和光学集成等领域,大大扩展了光纤的应用背景。在本文中,我们尝试着在特殊光纤中刻写光栅结构,并对其传感特性进行探索研究。我们采用的是飞秒激光直写技术进行刻写,经过对实验参数的不断摸索,在熊猫型光纤的纤芯处成功刻写了光纤布拉格光栅(以后统称:光纤Bragg光栅)。另外,我们尝试着将光学菲涅尔波带片结构跟光纤波导材料结合起来,在大芯径的多模光纤的纤芯处进行制备,得到了光纤菲涅尔波带片。经过实验,初步观察到了结构稳定,聚焦效果明显的光纤元器件。总结发现,本文主要有两个方面的内容:一、应用飞秒激光直写技术,刻写熊猫型光纤Bragg光栅。该方法借鉴了飞秒激光刻写单模光纤Bragg光栅的制备过程,经过不断调整实验参数发现,当飞秒激光的工作波长为λ=nm800,重复频率为f=100Hz的情况下,将脉冲能量调整为50nJ,可以在熊猫型光纤上制备出光纤Bragg光栅,此条件下制备出的光栅反射谱最好。经过对其反射谱的观察,有双峰反射谱,利用特殊的双峰结构,可以在传感领域有所作为。文中,初步对其温度、轴向应力进行传感探测,并对其双峰的灵敏度进行研究。二、应用飞秒激光直写技术,在大芯径多模光纤内部刻写光纤菲涅尔波带片。首先,根据飞秒激光与光纤材料相互作用的机理,论证了在大芯径多模光纤中进行激光加工的实验可操作性。然后,根据菲涅尔波带片的特征公式,设计出合理的结构。然后,通过对实验加工参数的摸索发现,当飞秒激光的工作波长为λ=nm800,重复频率为f=2.5kHz的情况下,通过光路中再加一块倍频晶体,得到λ=nm400的加工激光,将脉冲能量调整为48nJ,可以在多模光纤中加工出光纤菲涅尔波带片。用光学显微镜对其加工出的结构进行观察,发现这种条件下的结构比较完美。然后,通过观测系统,对其聚焦特性进行研究,聚焦效果明显。说明了,通过飞秒激光直写技术在大芯径多模光纤中制备出了功能性光学器件,效果良好。
[Abstract]:Optical components based on optical fiber materials have attracted more and more attention. As a member of the field of optics and optical communication, fiber waveguide has many advantages, such as strong binding to optical signal, small size and light mass, which provides conditions for the wide application of optical fiber waveguide. According to the preparation of the precast rod, there are many kinds of optical fiber, has a different role. In recent years, the application background of optical fiber has been greatly expanded by modifying the optical fiber, or combining the laser preparation method to write the structure in it, and in the field of sensing and optical integration. In this paper, we try to write the grating structure in a special fiber and study its sensing characteristics. We use femtosecond laser direct writing technique to write FBG (fiber Bragg grating) at the core of panda fiber. In addition, we try to combine the optical Fresnel band plate structure with the fiber waveguide material to prepare the fiber core of the large-diameter multimode fiber, and obtain the fiber Fresnel band plate. Through the experiment, the optical fiber components with stable structure and obvious focusing effect have been observed. It is found that there are two main contents in this paper: first, using femtosecond laser direct writing technology to write panda fiber Bragg gratings. This method draws lessons from the fabrication process of single-mode fiber Bragg gratings by femtosecond laser. It is found that when the working wavelength of femtosecond laser is 位 nm800 and the repetition rate is f=100Hz, the experimental parameters are adjusted continuously. When the pulse energy is adjusted to 50nJ, the fiber Bragg grating can be fabricated on the panda fiber, and the reflection spectrum of the grating is the best under this condition. Through the observation of its reflection spectrum, there is a double peak reflection spectrum, and the special double peak structure can be used in the sensing field. In this paper, the temperature and axial stress are detected and the sensitivity of the two peaks is studied. Secondly, femtosecond laser direct writing technique is used to write Fresnel band plate in large core diameter multimode fiber. Firstly, according to the mechanism of the interaction between femtosecond laser and fiber material, the feasibility of laser processing in large-core multimode fiber is demonstrated. Then, according to the characteristic formula of Fresnel band plate, a reasonable structure is designed. Then, the experimental processing parameters are explored. When the working wavelength of femtosecond laser is 位 nm800 and the repetition rate is f=2.5kHz, the processing laser of 位 nm400 is obtained by adding a double frequency crystal in the optical path. When the pulse energy is adjusted to 48nJ, the Fresnel band plate can be fabricated in multimode fiber. The structure was observed by optical microscope and it was found that the structure was perfect under this condition. Then, through the observation system, the focusing characteristics are studied, and the focus effect is obvious. The results show that functional optical devices are fabricated by femtosecond laser direct-writing technique in large core diameter multimode optical fiber with good effect.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN253

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