用于光动力的微结构光纤理论研究

发布时间：2018-10-15 12:01

【摘要】：微结构光纤作为一种新型特种光纤,其拥有许多独特特性,不光在光通讯领域延续着传统光纤的道路,在光纤传感领域也开始得到广泛应用。近来,光动力研究逐渐兴起,它主要探讨物质在复杂光环境下的力学动态特性,进而延伸至实际应用领域,例如生命科学、集成光学等应用领域。基于延展微结构光纤应用范围,发展新型光纤传感器件的实际应用需求,开展基于微结构光纤的光动力技术研究显得尤为重要。本文从光波导内部或外部光场变换角度出发提出了三类微结构光纤器件。这三类光纤器件通过改变光纤外部形状或内部结构,对入射光进行光强相位调制,从而生成特殊光场,而这些特殊光场主要用于信号传输或对微小物体进行微操控。本文主要完成的工作有:1.开展基于四芯光纤光镊探针的微粒光动力研究。(1)首次提出了具有横向双光镊和轴向双光镊的两种四芯光纤光镊探针,对光纤制备、光源注入、纤芯光束路径改变等内容进行了较系统的研究。该光镊探针是通过微加工技术使光纤端头形状发生改变,从而使纤芯光束出射路径发生改变,并最终形成两个不同位置的光势阱捕获点。(2)通过光束传输法,角谱等理论仿真了不同光纤形状的外部光束组合光场。(3)基于几何光束追迹模型计算微粒在组合光场中的受力情况,并通过朗之万运动方程计算了微粒在液体介质中的运动特点以及基于双光镊探针的横向振荡、轴向推拉特性,其中主要包括微粒周期驱动频率调制、幅度调制变化特性。结果表明基于四芯光纤光镊探针的微粒周期驱动本质是一个低频运动过程,在保证可用幅度情况下,频率不会高于100Hz。2.开展特种艾里光纤研究以及相关微粒力学特性研究。(1)基于耦合模理论探讨了艾里光纤内部高斯场与艾里场的周期转换机制。(2)首次提出具有自定义对称艾里函数分布的多芯对称艾里光纤,并基于光束传输法计算了该光纤的出射场,探讨了出射场对波长的响应特性。结果表明其出射场的中央主瓣会分裂成多个离轴主瓣,整个光束仍具有自由加速特性以及自愈特性,而无衍射特性较弱。而波长调制会造成光束自由加速性变化从而造成主瓣落点不同。(3)首次提出了具有环形艾里函数分布的对称环形芯艾里光纤,并计算了出射场对波长的响应特性,还仿真计算了微米尺度的粒子在对称环形芯艾里光纤出射场下的力学特性。结果表明该艾里光纤具有对称环形艾里场,可在长距离范围内保持无衍射传输,自由加速特性则会形成自聚焦点,可用于微加工或微粒捕获。微粒在出射场作用下还可进行输运。3.开展了表面等离子激元光纤研究以及相关微粒力学特性研究。(1)首次提出了基于金纳米管和金纳米线的表面等离子激元光纤。(2)基于有限元法计算了基于金纳米管和金纳米线的表面等离子激元光纤具有的模式数。结果表明在金纳米结构整体尺寸微小时,光纤一般只具有两个纤芯传输模式,分别为短程模和长程模。但色散特性分析表明,当管壁足够小时金纳米管结构光纤模式数会增多。(3)重点对长程模的传输损耗特性和模场宽度进行了分析,结果表明该结构光纤的长程模传输距离在极端情况可传输三十毫米,而模场宽度与传输距离并不呈简单的反比关系。壁厚d的大小对传输距离和模式宽度都具有调制作用。(4)仿真分析了纳米微粒在表面等离子激元光纤端面处的受力情况,结果表明纳米粒子会受到较大捕获力作用,会把纳米微粒拉向金纳米结构,且最终弹射脱离。不同微粒所受力会有差异,在微流场配合下可以实现微粒分选等用途。综上所述,本论文展开的新型微结构光纤(或光纤外形结构)研究扩展了微结构光纤的应用领域。由于微结构光纤可集成度高、成本低廉等优点,使得其极具应用潜力。而基于光纤的微粒光动力研究,则是通过新型光纤出射场对外部微小微粒进行操控或信息传感,对生命科学,光纤传感等实际应用领域发展都具有十分重要的意义。
[Abstract]:As a new type of special optical fiber, micro-structured optical fiber has many unique characteristics. It not only continues the traditional optical fiber road in the field of optical communication, but also has been widely used in the field of optical fiber sensing. Recently, optical power research has gradually emerged. It mainly discusses the dynamic characteristics of materials under complex light environment, and then extends to practical application fields, such as life science, integrated optics and other fields of application. Based on the application range of extended micro-structured optical fiber and the development of the practical application requirement of a new type of optical fiber sensor, the research of optical power technology based on micro-structured optical fiber is very important. In this paper, three kinds of micro-structured fiber optic devices are proposed from the angle of optical waveguide internal or external optical field. These three types of fiber optic devices modulate the intensity phase of incident light by changing the external shape or internal structure of the optical fiber, thereby generating special optical fields, which are mainly used for signal transmission or micromanipulation of small objects. The main tasks are as follows: 1. The research of particle optical power based on four-core optical tweezers probe was carried out. (1) Two kinds of four-core optical tweezers probe with transverse double optical tweezers and axial double optical tweezers are put forward for the first time, and the contents of optical fiber preparation, light source injection and fiber core beam path change are systematically studied. According to the optical tweezers probe, the shape of the end of the optical fiber is changed through the micro-processing technology, so that the light exit path of the fiber core beam changes, and finally, two light potential well capture points with different positions are formed. (2) External beam combined optical field of different optical fiber shapes is simulated by beam transmission method and angular spectrum theory. (3) calculating the stress condition of the particles in the combined light field based on the geometric beam tracking model, calculating the motion characteristics of the particles in the liquid medium through the Langevin motion equation, and the axial push-pull property based on the transverse oscillation and the axial push-pull characteristics of the double optical tweezers probe, which mainly comprises a particle period driving frequency modulation and an amplitude modulation variation characteristic. The results show that the particle cycle drive based on the four-core optical tweezers probe is a low-frequency motion process, and the frequency is not higher than 100Hz when the available amplitude is guaranteed. The research on special Airy fiber and the research on the mechanical properties of relevant particles were carried out. (1) On the basis of the coupled-mode theory, the periodic conversion mechanism between the inner Gaussian field and the Airy field in the Airy fiber is discussed. (2) A multi-core symmetric Airy fiber with self-defined symmetric Airy function distribution is proposed for the first time, and the light exit field of the fiber is calculated based on the beam transmission method, and the response characteristics of the emission field to the wavelength are discussed. The results show that the central main lobe of the exit field is split into a plurality of off-axis main lobes, the whole beam still has the free acceleration characteristic and the self-healing property, but the diffraction characteristic is weak. and the wavelength modulation can cause the light beam to freely change so as to cause the falling point of the main lobe to be different. (3) For the first time, the symmetric ring-core Airy fiber with the distribution of the ring-shaped Airy function is put forward, and the response characteristics of the emission field to the wavelength are calculated, and the mechanical properties of the micro-scale particles in the symmetric ring-core Airy fiber exit field are also simulated. The results show that the Airy optical fiber has a symmetric ring-shaped Airy field, which can maintain no diffraction transmission over a long distance, and the free acceleration characteristic will form a self-focusing point, which can be used for micro-machining or particle capture. the particles can also be transported under the action of an ejection field. In this paper, the research on surface plasmon excitation and the research of relevant particle dynamics are carried out. (1) The surface plasmon excitation fiber based on gold nanotubes and gold nanowires was proposed for the first time. (2) Based on the finite element method, the pattern number of the surface plasmon fiber based on gold nanotubes and gold nanowires is calculated. The results show that when the whole size of the gold nano-structure is small, the optical fiber generally only has two fiber core transmission modes, and is a short-range die and a long-range die, respectively. However, the dispersion characteristic analysis shows that the number of fiber modes of the gold nanotube structure increases when the tube wall is small enough. (3) The transmission loss characteristics and the mode field width of the long-range model are analyzed. The results show that the long-range mode transmission distance of the structured optical fiber can be transmitted by 30 mm in extreme cases, while the mode field width and the transmission distance are not in a simple exponential relationship. the wall thickness d has a modulation effect on both the transmission distance and the mode width. (4) The stress condition of nano-particles at the end face of the surface plasmon excitation is simulated and analyzed. The results show that the nano-particles will be subjected to larger capture force, the nano-particles can be pulled to the gold nano-structure, and finally ejected. the force of different particles can be different, and the application of particle sorting and the like can be realized under the cooperation of micro-flow fields. In conclusion, the new micro-structured optical fiber (or fiber shape structure) in this paper expands the application field of micro-structured optical fiber. The micro-structured optical fiber has the advantages of high integration degree, low cost and the like, so that the micro-structured optical fiber has great application potential. And based on the optical fiber-based particle photodynamic research, it is very important to control the micro-particles in life science, fiber sensing and other practical applications through the control or information sensing of the new optical fiber exit field.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN253

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