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应用等效折射率模型研究光子晶体光纤 总被引:11,自引:4,他引:7
应用等效折射率模型研究了光子晶体光纤(PCF)的传播特性.介绍了光子晶体光纤的等效折射率模型.通过求解标量波动方程得到了光子晶体光纤包层基空间填充模的模式折射率,利用阶跃光纤的理论来研究光子晶体光纤的导模特性.应用此模型对不同结构光子晶体光纤包层区的等效折射率与波长的关系进行了讨论.包层区等效折射率与芯子的折射率差随波长的增加而增大,并由此阐述了光子晶体光纤的单模特性.数值分析得到光子晶体光纤的基模的模式折射率,并由此研究了光子晶体光纤的波导色散与结构参量的关系.分析表明,光子晶体光纤的波导色散随空气孔孔距的变化符合Maxwell方程的比例性质.空气孔的相对孔径对波导色散有重要的影响.这些分析表明光子晶体光纤具有可以灵活设计其色散特性的潜在应用前景. 相似文献
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利用模式理论和传输矩阵法,对基于包层空气孔排布为正八边形对称结构的光子晶体光纤光栅(PCFG)的模式截止特性以及谐振特性进行了研究,得出了此种光子晶体光纤光栅的模式截止条件和可传导的模式,并利用得到的模式截止条件,提出利用相位匹配条件设计相应的光纤光栅周期来得到满足需要的谐振波长,同时给出了谐振峰的反射谱图。研究表明,通过合理选择此种光子晶体光纤光栅的结构参数,可以实现需要的单模传输以及定制波长处的主谐振峰的谐振。所研究的基于包层空气孔排布为正八边形对称结构的锗掺杂光子晶体光纤光栅有望更好地应用于光子晶体光纤光栅传感领域。 相似文献
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利用全矢量平面波展开法对三角形排布孔包层-圆纤芯结构的光子晶体光纤的光子带隙特性进行了数值模拟,对比研究了传统光子晶体光纤(空气-石英纤芯结构)和全固态光子晶体光纤(非空气-石英纤芯结构)的光子带隙(导模)与结构参数(包层孔直径dclh、包层孔间距和包层孔填充比f)的关系,设计出了一组合适的结构参数(纤芯直径dco=5.3 m,包层孔材料的折射率nclh=1.65,dclh=1.0 m,=2.0 m,f=0.7),可以使相应的全固态光子晶体光纤工作在1 550 nm的现代光通信波长上,且光子带隙可以达100 nm. 相似文献
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研究了正十边形对称结构光子晶体光纤布拉格光栅(PCFBG)特性,分析了不同空气孔层数以及不同占空比对布拉格光栅反射谱的影响.在此基础上,对正十边形光子晶体光纤光栅的传感特性进行了研究.研究表明:随着温度的增加,该光纤光栅的反射谱谐振波长明显向长波方向偏移;随着应力的改变,光纤光栅的反射谱谐振波长变化趋势不明显.该光栅具有对温度敏感,对应变不敏感的特点.这种空气孔排列为正十边形对称结构的光子晶体光纤光栅有望应用在光子晶体光纤光栅的传感领域中. 相似文献
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Chenxi Lin Wei Zhang Yidong Huang Jiangde Peng 《Lightwave Technology, Journal of》2007,25(12):3776-3783
Narrow bandwidth and large group velocity (vg) dispersion are two fatal limitations of slow light in Bragg fibers. In this paper, by introducing a well-designed defect layer into the cladding of the Bragg fiber, the modal characteristics are modified by the coupling between the core mode and the defect mode. The defect location mainly determines the coupling strength and, thus, exerts a strong influence on vg and dispersion. The defect thickness mainly determines the resonant wavelength of the defect waveguide and, thus, the wavelength where the modal coupling takes place. Consequently, the two limitations of the slow-light propagation in the Bragg fiber are overcome through proper optimization of the defect parameters. Around 1550 nm, a slow-light bandwidth up to 90 nm is achieved at an average vg of c/5 (c is the light velocity in a vacuum) under N = 2, whereas an average vg of c/10 is achieved with a bandwidth of 20 nm under N = 5. On the other hand, the slow-light propagation of vg = 0.074c with both zero dispersion and zero dispersion slope is achieved, which is able to support applications requiring a subterahertz bandwidth of optical pulse. All of the fiber designs ensure sufficient low losses and good optical field distribution. The results are helpful in developing various Bragg-fiber-based slow-light devices. 相似文献
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The mode theory is the main way to study the propagation characteristics of light in fiber so far, but it is not suitable for analysis of light in duct. By using ray-tracing method, the rotary propagation characteristics of light in multimode-single mode-multimode (MSM) fiber structures are analyzed in this paper. Firstly, the light ray in fiber can propagate around an inscribed circle, and the central axis of this fiber is the propagation axis. Secondly, the radius of the inscribed circle is decided by both incident angle and incident position, and its variation is between 0 and RM, where RM is the radius of the multimode fiber. Lastly, the bigger the ratio of core and cladding diameter is, the higher the propagation efficiency is. 相似文献
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Bending effects in biconically tapered single-mode fibers 总被引:1,自引:0,他引:1
Biconically tapered single-mode fibers were fabricated, and their characteristics were studied experimentally. The optical throughput was measured as the fiber was being pulled to produce the required radial profile. The tapered single-mode fiber was bent in a simple fixture, and the optical throughput was measured as a function of the bending angle. It is seen that the bending resulted in very strong oscillations of the optical power as the bend angle was varied. At the point when the light in the core was minimal, the cladding region was bright, indicating that the light has moved to the cladding. The propagation characteristics of the tapered single-mode fiber subjected to bending are analyzed using a stepwise approximation. A simple sensor based on this principle is discussed 相似文献
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针对超强能量密度的飞秒脉冲很难在传统光纤中传输的情况,设计了一款用于高功率飞秒脉冲传输的空心单模Bragg光纤。首先基于一维光子晶体的光子禁带特性选择了制作空心Bragg光纤的材料,接着利用光学软件FDTD Solutions分析了光纤各结构参数对光纤模式的影响,并对传输特性进行了分析。随后,通过在光纤包层中引入缺陷层的方法对其进行了进一步的优化,有效调控了该款光纤的色散曲线分布。经全带宽扫描可知,该款空心Bragg光纤单模传输的带宽达100 nm,完全满足了100 fs光脉冲的传输要求。 相似文献
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基于倾斜光纤光栅的温度不敏感振动传感器 总被引:1,自引:0,他引:1
提出了一种基于倾斜光纤光栅与多模光纤相结合的温度不敏感振动传感器,其振动传感头是在倾斜光纤光栅与单模光纤之间加入一小段多模光纤所组成。倾斜光纤光栅的反射光谱有布拉格模和包层模两部分组成,其中多模光纤的作用是将倾斜光纤光栅反射包层模耦合到单模光纤的基模。倾斜光纤光栅包层模对外界振动很敏感,通过传感器的包层模平均输出功率完成对外界振动物理量测量。由于采用强度解调的方式,可以大大降低传感器装置的复杂性。实验表明:当传感器温度从20 ℃上升到70 ℃时,传感器的输出平均光功率均方根误差为0.01 μW,其反射光谱平均输出功率影响很小,故可以避免外界温度对测量结果的影响。 相似文献
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通过引入缺陷和色散介质方法,调控光子的运动状态,研究一种〔A(BC)〕m结构负折射率光子晶体的TE波和TM波的传输特性和色散特性,得到两种模的色散特性随入射角变化而变化规律,并且其带隙比普通光子晶体的大,而透射带要窄。通过运用传统计算电磁场与电磁波传播的FDTD方法及PML边界条件来仿真〔A(BC)〕m结构光子晶体光纤... 相似文献
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Zhong-Yuan Sun Zhi-Jun Yan Kai-Ming Zhou Qi-Zhen Sun Abdulyezir Ayomipo Badmos Lin Zhang 《电子科技学刊:英文版》2015,13(4):328-342
We have UV-inscribed fiber Bragg gratings (FBGs), long-period gratings (LPGs), and tilted fiber gratings (TFGs) into mid-IR 2m range using three common optical fiber grating fabrication techniques (two-beam holographic, phase mask, and point-by-point). The fabricated FBGs have been evaluated for thermal and strain response. It has been revealed that the FBG devices with responses in mid-IR range are much more sensitive to temperature than that in near-IR range. To explore the unique cladding mode coupling function, we have investigated the thermal and refractive index sensitivities of LPGs and identified that the coupled cladding modes in mid-IR range are also much more sensitive to temperature and surrounding medium refractive index change. The 45 tilted fiber gratings (45-TFGs) as polarizing devices in mid-IR have been investigated for their polarization extinction characteristics. As efficient reflection filters and in-cavity polarizers, the mid-IR FBGs and 45-TFGs have been employed in fiber laser cavity to realize multi-wavelength 2 m Tm-doped CW and mode locked fiber lasers, respectively. 相似文献