光纤中涡旋光束的产生与调控研究

发布时间：2018-01-08 09:10

本文关键词：光纤中涡旋光束的产生与调控研究　出处：《中国科学技术大学》2016年博士论文　论文类型：学位论文

【摘要】：相位是光的重要特性之一,涡旋光束具有螺旋形波前结构、光强呈环形分布、确定的轨道角动量、存在着相位奇点等,其在光学信息传输、光学微操纵、显微成像、激光微加工等领域中得到广泛的应用。目前光纤中涡旋光束的产生方式和传输特性的研究是涡旋光束很重要的研究方向之一,通常采用热熔机械扭曲或应力等加工手征光纤、光子晶体光纤等来产生涡旋光束,但这些方法只能制作长周期螺旋光纤光栅,且它们的制作方法复杂、效率低下。本论文在前期工作的基础上,提出采用紫外光单面曝光技术,制得螺旋形光纤光栅的方案,此方案可以实现涡旋光束的产生以及它们轨道角动量的调控。除此之外我们也提出了利用光纤模式耦合器产生涡旋光束的方法，并设计了一种新型的三芯结构的光纤耦合器,系统分析了它的耦合特性。本轮文主要研究内容有下列几点：1.基于螺旋光纤光栅,高阶涡旋光束产生和调控的研究。利用单面刻写光纤光栅的技术,我们提出了刻写螺旋光纤光栅的方案。系统分析了螺旋光纤光栅的耦合特性,并研究了利用螺旋光纤光栅产生高阶涡旋光束,模拟了以下涡旋光束轨道角量子数的转换：0→±1,±1→0，，0→±2,0→±3,其最大耦合效率达到97%。我们证明了通过增加光纤中的模式数,螺旋光纤光栅可以产生更高阶的涡旋光束。除此之外我们还研究了螺旋光纤光栅的耦合特性跟光纤的材料吸收因子、最大折射率调制深度和光纤光栅长度的关系。2.在螺旋光纤光栅刻写的基础上,我们提出了正交错位刻写光纤光栅的方案,这大大减小了螺旋光纤光栅刻写的难度,此方法可以直接利用目前的掩模板刻写技术。接着我们模拟了此正交错位刻写的光纤光栅可以产生±1阶的涡旋光束。并研究了此正交错位光纤光栅在非正交及错位有一定误差的情况下产生涡旋光的情况,发现也能够产生一定的涡旋光束。3.系统研究分析了目前常用的光纤耦合器的耦合特性,并设计了一种新型的三芯结构的光纤融耦合器,利用此耦合器可以产生涡旋光束。并以0→±1和0→±3涡旋光束的产生为例,设计了两种光纤耦合器,此耦合器除能够产生涡旋光束外,光场的偏振形式也能够得到控制。在理论分析的基础上,实验上搭建了两个双芯耦合器并联产生涡旋光的装置,并取得了一定的结果,实验结果跟理论模拟一致。本论文的主要创新点：1.研究了单面刻写光纤光栅过程中,光纤中模场的分布情况跟光纤刻写方向间的关系,系统分析了光纤横向折射率非对称光纤光栅的耦合特性跟光纤材料吸收因子、最大折射率调制量以及光纤光栅饱和长度间的关系。再次基础上提出了一种螺旋刻写光纤光栅的方案,并且模拟了利用螺旋光纤光栅能够产生高阶涡旋光束。2.在螺旋刻写光纤光栅的基础上,提出了正交错位刻写光纤光栅的方案,并模拟了涡旋数是1和-1的涡旋光束的产生。在此基础上分析了正交错位光纤光栅的耦合特性,并研究了正交错位光纤光栅在非正交及错位有一定偏差的情况下,也能够产生一定的涡旋光束,表面此正交错位光纤光栅具有较强的适用性。3.研究了少模光纤耦合器的耦合特性,设计了一种新型的三芯结构的光纤耦合器,利用此耦合器我们能够产生高阶涡旋光束,并分别模拟了0→±1和0→±3涡旋光束的产生,此耦合器能够产生除了圆偏振特性的涡旋光束外,也能够产生线偏振的涡旋光束,实现了自旋角动量和轨道角动量的同时输出。
[Abstract]:The phase is one of the important characteristics of light, vortex beams with spiral wave front structure, intensity of circular distribution, determine the orbital angular momentum, there exist phase singularities, the optical information transmission, optical micromanipulation, micro imaging, has been widely used in the field of laser micro processing. The current research method and transmission characteristics the vortex beam in the optical fiber is one of the very important research direction of the vortex beam, usually by mechanical stress or distorted melt processing chiral optical fiber, photonic crystal fiber to generate vortex beam, but these methods can only be made of long period fiber grating spiral, and their complex production methods, based on the low efficiency. On the previous work, the single UV exposure technology, prepared spiral fiber grating scheme, this scheme can realize the vortex beam produced and their orbital angular momentum In addition to this regulation. We also propose a method for generating vortex beam by using optical fiber coupler mode, and designed a fiber coupler three core structure model, system analysis the coupling characteristics of it. The content of this paper mainly studies the following points: 1. based on the spiral fiber grating, high-order vortex beam generation and control. Using a single fiber Bragg grating inscription technology, we put forward the scheme of fiber grating writing spiral system. Analyze the coupling characteristics of spiral fiber grating, and studied using spiral fiber grating high-order vortex beam, simulated the transformation of vortex beam orbital angular quantum number: 0 to + 1. + 1 - 0,0 - 2,0 + to + 3, the maximum coupling efficiency reached 97%. we show that by increasing the number of modes in optical fiber, optical fiber grating spiral vortex beam can produce higher order. We also research in addition The spiral fiber grating coupling with fiber material absorption factor, the maximum refractive index modulation depth and length of fiber grating based on the relationship between.2. spiral fiber grating inscribed, we propose orthogonal dislocation fiber Bragg grating inscription scheme, which greatly reduces the difficulty of helical fiber grating writing, this method can be directly used at present the mask writing technology. Then we simulate the optical fiber grating. The orthogonal dislocation can produce + 1 order vortex beams. And makes a research on the orthogonal vortex dislocation fiber grating has a certain error in non orthogonal and dislocation of the situation, that can also produce of vortex beam.3. system analysis of certain the current commonly used optical fiber coupler coupling characteristics, and designed a fiber coupler into three core structure model, using this coupler can generate vortex Beam. And in 0, 0, + 1 and + 3 vortex beam as an example, the design of two kinds of fiber coupler, the coupler can the generation of vortex beam, the polarization form of light field can be controlled too. On the basis of theoretical analysis, experimental device was built two dual core and coupler and students vortex, and achieved certain results, the experimental results with theoretical simulation. The main innovations of this dissertation: 1. research on the single fiber Bragg grating inscription process, the relationship between the fiber mode field distribution and optical fiber curves between the direction of the optical fiber system, analysis of the transverse refractive index of asymmetric optical fiber grating the coupling characteristics of fiber materials with absorption factor, the maximum amount of fiber grating refractive index modulation and the saturation length between the relationship. Based on a spiral fiber Bragg grating inscription, and simulated by using the spiral fiber grating can Have a high order vortex beam based on spiral.2. fiber Bragg grating inscription, proposed orthogonal dislocation fiber Bragg grating inscription scheme, and the simulation of vortex vortex beam number is 1 and -1 is produced. Based on the analysis of coupling properties of orthogonal dislocation fiber grating, and studied the orthogonal grating has certain deviation dislocation in the case of non orthogonal and dislocation, also can produce a vortex beam, the coupling characteristics of the surface of the fiber grating with.3. orthogonal displacement applied on the few mode optical fiber coupler, optical fiber coupler design a three core structure model, using this coupler we can generate high order vortex beam, and simulate 0 to + 1 and 0 + 3, the vortex beam, this coupler can produce circular polarization characteristics except vortex beam, the vortex beam can generate linear polarization, realizes the self The simultaneous output of angular momentum and orbital angular momentum.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN253

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