谐振式光子带隙光纤陀螺关键技术研究

发布时间：2018-08-11 12:40

【摘要】：谐振式光纤陀螺(Resonator Fiber Optic Gyro,R-FOG)以其良好的发展前景成为了人们研究的热点,其基本工作原理是通过检测谐振腔内由旋转产生的频率差,完成对旋转角速度的测量。在R-FOG中,通常采用窄带光源获得良好的谐振性能,而窄带光源的高相干性使得陀螺中的光学噪声大幅增强,严重影响了 R-FOG的性能。科研人员考虑采用多种措施对相关光学噪声进行抑制,然而效果都不是十分理想。空芯光子带隙光纤(Hollow-core Photonic-bandgap Fiber,HC-PBF)是一种新型的微结构光纤,由于其能够实现光波在空气纤芯内传输,且空气介质相比传统实芯纤芯(Si/SiO2)具有更优的光学特性,人们考虑将HC-PBF应用于R-FOG构建HC-PBF-ROG,从而降低相关噪声。尽管HC-PBF-ROG在误差抑制方面具有潜在的优势,然而目前仍存在一些问题:1.HC-PBF中,光波导尺寸直接影响传输特性。针对R-FOG进行光纤设计时,如何使得特定波段的光源入射光在传输时具有最优的传输特性有待研究。2.空芯光纤的损耗要大于传统单模光纤,影响了空芯光纤的应用,损耗主要是由表面模机制引起的;3.还没有针对R-FOG的特种HC-PBF研究进行,考虑到R-FOG的误差因素,特种HC-PBF的主要特性应包括更低的克尔非线性特性和瑞利散射特性,同时也应具有良好的保偏特性或单偏振特性;4.HC-PBF谐振腔内由于双本征偏振态之间相互串扰而产生的偏振波动噪声的问题;5.光纤陀螺系统中离散背向反射的问题。针对以上HC-PBF-ROG中存在的问题,本论文由HC-PBF结构设计入手,研究设计了新型的HC-PBF,对单偏振HC-PBF谐振腔中的偏振噪声和HC-PBF-ROG中的离散背向反射进行了研究,论文的主要研究内容如下:1.研究了 HC-PBF传输截止区间特性。利用平面波展开法对HC-PBF的光子带隙特性进行了分析,推导了空芯光纤的数值孔径,发现由于光子带隙的限制,HC-PBF中的数值孔径存在两个极值;进一步研究了不同占空比下的传输截止区间特性,发现占空比是影响中心波长比率和波长比率宽度的重要因素;利用HC-PBF传输截止区间,设计了针对1550nm光源的具有最低限制损耗的HC-PBF基本结构。2.研究了 HC-PBF的表面模损耗问题。利用全矢量有限元法对HC-PBF进行了数值计算,得到表面模在纤芯附近的强度分布,研究了 HC-PBF纤芯截切半径对表面模损耗的影响,研究结果表明,以融合截切方式引入19单元纤芯孔能够最有效地抑制表面模损耗,获得最优的纤芯传输功率。3.研究设计了单模单偏振态HC-PBF。基于谐振耦合的思想,设计了一种针对R-FOG的新型的双椭圆辅助孔HC-PBF,并对其各个传播模式的传输特性进行了分析,结果表明新型光纤在1550nm波段附近具有良好的单模单偏振特性;考虑到R-FOG中主要的误差因素,重点对双椭圆辅助孔HC-PBF中的克尔非线性特性和瑞利散射特性进行了分析,结果显示,与传统单模光纤相比,新型光纤具有极低的克尔非线性系数和瑞利散射损耗系数。4.全面分析了 HC-PBF-ROG中的克尔效应和Shupe效应。包括产生机理及目前主要的抑制措施等,分析结果表明,利用空芯光纤构建的HC-PBF-ROG,能够有效地、大幅地降低克尔效应对于陀螺性能的影响;Shupe效应误差在高精度R-FOG中也应加以考虑,HC-PBF-ROG中采用较低Shupe系数的空芯光纤,配合环形谐振腔较短的低光纤长度和合理的绕制手段,能够大幅降低陀螺中的Shupe效应误差5.研究了单偏振HC-PBF谐振腔中的偏振误差。建立了单偏振态HC-PBF谐振腔的传输矩阵,基于该传输矩阵,利用琼斯矩阵方法建立了单偏振态谐振腔的偏振噪声模型,在理论上对单偏振态HC-PBF谐振腔的偏振噪声进行了分析,结果表明单偏振态HC-PBF谐振腔能够有效抑制偏振波动误差。6.研究了 HC-PBF-ROG中的离散背向反射噪声。分析了 HC-PBF-ROG中的瑞利背向散射和离散背向反射,对离散背向反射进行了归纳分类,建立了完整的离散背向反射干涉光强模型,提出了在检测器耦合器悬空端加入相位调制的方法,分析了调制波形对离散背向反射的影响,通过对比分析,理论上通过设置合理的调制系数就能有效地抑制离散背向反射噪声。
[Abstract]:Resonator Fiber Optic Gyro (R-FOG) has become a research hotspot for its good development prospects. Its basic principle is to measure the angular velocity of rotation by detecting the frequency difference caused by rotation in the resonator. In R-FOG, narrow-band light source is usually used to obtain good resonance performance, while narrow-band light is used. The high coherence of the source greatly enhances the optical noise in the gyroscope, which seriously affects the performance of the R-FOG. Researchers consider a variety of measures to suppress the related optical noise, but the effect is not very satisfactory. Hollow-core photonic bandgap fiber (HC-PBF) is a new kind of micro-structure fiber. HC-PBF is considered to be used in R-FOG to construct HC-PBF-ROG because it can transmit light in the air core and the air medium has better optical properties than the traditional solid core (Si/SiO2). Thus the related noise can be reduced. Although HC-PBF-ROG has potential advantages in error suppression, there are still some problems: 1. In HC-PBF, the size of optical waveguide has a direct impact on the transmission characteristics. How to optimize the transmission characteristics of the incident light of a particular band in the design of R-FOG optical fiber remains to be studied. 2. The loss of hollow-core optical fiber is larger than that of traditional single-mode optical fiber, which affects the application of hollow-core optical fiber. The loss is mainly caused by the surface mode mechanism. 3. No special HC-PBF research has been carried out for R-FOG. Considering the error factor of R-FOG, the main characteristics of special HC-PBF should include lower Kerr nonlinearity and Rayleigh scattering, as well as good polarization-maintaining or single polarization characteristics. 4. HC-PBF resonator is produced because of cross-talk between two intrinsic polarization states. 5. Discrete backscatter in fiber optic gyroscope system. Aiming at the problems existing in HC-PBF-ROG, a new type of HC-PBF is designed in this paper based on the structure design of HC-PBF. The polarization noise in single polarized HC-PBF resonator and the discrete backscatter in HC-PBF-ROG are studied. The main research contents are as follows: 1. The transmission cut-off characteristics of HC-PBF are studied. The photonic band gap characteristics of HC-PBF are analyzed by plane wave expansion method, and the numerical aperture of hollow fiber is deduced. It is found that there are two extreme values of numerical aperture in HC-PBF due to the limitation of photonic band gap. The duty cycle is found to be an important factor affecting the central wavelength ratio and the wavelength ratio width. Using the transmission cut-off region of HC-PBF, the basic structure of HC-PBF with the lowest limiting loss for 1550nm light source is designed. 2. The surface mode loss of HC-PBF is studied. The full vector finite element method is used to calculate the number of HC-PBF. The strength distribution of the surface mode near the core is obtained. The influence of the cutting radius of the HC-PBF core on the loss of the surface mode is studied. The results show that the introduction of 19-element core holes in the fusion cutting mode can effectively suppress the loss of the surface mode and obtain the optimal core transmission power. 3. The single-mode single-polarization HC-PBF is designed. Based on the idea of resonant coupling, a novel double elliptical auxiliary hole HC-PBF for R-FOG is designed, and the transmission characteristics of each propagation mode are analyzed. The results show that the new fiber has good single-mode and single-polarization characteristics near 1550 nm band. The Kerr nonlinearity and Rayleigh scattering characteristics in-PBF are analyzed. The results show that the new fiber has very low Kerr nonlinearity and Rayleigh scattering loss coefficient compared with the traditional single-mode fiber. 4. The Kerr effect and the Shupe effect in HC-PBF-ROG are comprehensively analyzed, including the generation mechanism and the main suppression measures. The analysis results show that the HC-PBF-ROG constructed by hollow fiber can effectively reduce the influence of Kerr effect on the performance of gyroscope; the error of Shupe effect should be considered in high precision R-FOG, and the hollow fiber with lower Shupe coefficient should be used in HC-PBF-ROG to match the shorter ring resonator with lower fiber length and reasonable winding. The polarization error in a single polarized HC-PBF resonator is studied. The transmission matrix of a single polarized HC-PBF resonator is established. Based on the transfer matrix, the polarization noise model of a single polarized HC-PBF resonator is established by using Jones matrix method, and the single polarized HC-PBF resonator is theoretically resonated. The polarization noise of the cavity is analyzed, and the results show that the single polarization state HC-PBF resonator can effectively suppress the polarization fluctuation error. 6. Discrete backscattering noise in HC-PBF-ROG is studied. Rayleigh backscattering and discrete backscattering in HC-PBF-ROG are analyzed. The discrete backscattering is classified and the complete discrete backscattering is established. A method of adding phase modulation to the suspension end of detector coupler is proposed. The influence of modulation waveform on discrete backscatter is analyzed. By comparison and analysis, the discrete backscatter noise can be effectively suppressed theoretically by setting reasonable modulation coefficient.
【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】：2014
【分类号】：TN96

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