基于非对称双芯光子晶体光纤的宽带定向耦合器研究

A novel broadband directional coupler based on an asymmetric dual-core photonic crystal fibet(PCF)is proposed.The asymmetry in the fiher is introduced by the enlargement of one air-hole in dual-core PCF.Numerical investigation demonstrate that broadband directional coupling with spectral width as large as 370 nm and polarization-dependent loss and uniformity lower than 0.2 and 0.5 dB,respectively,can be achieved.In addition,the proposed fiber shows large tolerance to the variation of the fiber parameters.In particular,the fiber length allows at least 10%derivation from the proposed fiber length of 7.7 mm.     

弹光调制非线性光程差干涉信号的快速反演

为了提高弹光调制中非线性光程差干涉信号的光谱反演效率,采用非均匀快速傅里叶变换算法对弹光调制相位非均匀采样干涉信号反演光谱进行了仿真,得到1024点反演速率较直接计算提高20倍,平均误差达到0.87%的结果。结果表明,该算法可实现弹光调制干涉信号的快速、高精度反演,给硬件实现弹光调制反演光谱提供了一定的参考依据。     

An asymmetric dual-core single-polarization single-mode photonic crystal fiber coupler

A vectorial finite element method (VFEM) is adopted to investigate the novel single-polarization single-mode (SPSM) photonic crystal fiber (PCF) coupler which has asymmetric dual-core and two lines of enlarged air holes. It is demonstrated that the SPSM region of the designed fiber can be more than 250 nm wide with a set of optimized air-hole parameters and the width of the SPSM region could change slightly by fine adjustment of the inner large air holes. The coupling length between the odd and even x-polarization modes is also investigated through fine-tuning the large and small air-hole diameters.     

非对称双芯光子晶体光纤的温度传感特性研究

设计了一种基于非对称双芯光子晶体光纤的温度传感结构,在光子晶体光纤的一个纤芯中填充液体乙醇作为温敏介质,利用双芯光纤的定向耦合效应,通过检测定向耦合器的中心波长实现对温度的测量。用虚轴光束传播法分析光子晶体光纤基模的有效折射率与温度的关系,结果表明设计的光纤结构具有良好的温度传感特性,在-20～70 ℃范围内的温度检测灵敏度达3.73 nm/ ℃。用光束传播法仿真LP01模的传输特性,表明当光纤长度为耦合长度的0.5至1.5倍时,对于同一温度,传输光谱中主极大对应的波长保持恒定,传感器具有较大的制作容差。     

A novel polarization splitter based on octagonal dual-core photonic crystal fiber

A novel polarization splitter based on octagonal dual-core photonic crystal fiber(O-D-PCF) is proposed. The impacts of several fiber parameters on the coupling characteristics of the polarization splitter are investigated by full-vectorial finite element method(FV-FEM) in detail. Through optimizing the fiber configuration, a 4.267-mm-long polarization splitter with a bandwidth of 37 nm is achieved, and its extinction ratio(ER) is as high as 81.2 d B at the wavelength of 1.55 μm. Compared with the hexagonal dual-core photonic crystal fiber(H-D-PCF) based polarization splitter, both ER and bandwidth of the O-D-PCF based one are effectively improved.     

混合导光双芯光子晶体光纤及分束器

设计了一种基于全内反射和光子带隙效应两种导光机制的混合导光双芯光子晶体光纤,以耦合模式理论为基础,利用全矢量有限元法和平面波展开法分析了其有效折射率和耦合长度特性。数值分析结果表明:通过改变光纤中大空气孔直径及孔间距,可以调节耦合长度的大小,通过改变高折射率柱直径以及高折射率柱的有效折射率,可以调节耦合长度大小及耦合长度极大值的位置。利用所设计的混合导光双芯光子晶体光纤制作的偏振分束器,其长度为5.2 mm,在31 nm带宽范围内,分光比小于-30 dB;在60 nm带宽范围内,分光比小于-20 dB。     

双芯光子晶体光纤Mach-Zehnder干涉仪及其应力特性

利用自制的双芯光子晶体光纤(D-PCF)与单模光纤(SMF)熔接,并在熔接点塌陷空气孔,提出了一种新型的D-PCF马赫-曾德干涉仪(MZI).利用图像提取法和有限元方法,分析并计算了实际拉制出的D-PCF支持的光纤模式.经过分析发现,这种新型光纤干涉仪的主要干涉模式是环芯模式,不同于传统光纤干涉仪的干涉模式.实验观测了...     

Synthesis of polarization-independent splitters based on highly birefringent dual-core photonic crystal fiber platforms

The objective of this letter is to introduce and numerically investigate the operation of a novel type of polarization-independent splitter based on highly birefringent dual-core photonic crystal fiber (PCF), which allows wavelength multiplexing at 1.3 and 1.55 /spl mu/m. The design procedure follows a rigorous synthesis algorithm based on exact equations for describing the wavelength decoupling mechanism and on full-vector finite element as well as beam propagation methods for accurate modeling of PCFs. Typical characteristics of the newly proposed PCF splitter are coupling length of 9.08 mm and available optical bandwidths defined at a level of -20 dB of 5.5 and 2 nm around 1.3 and 1.55 /spl mu/m, respectively.     

双芯光子晶体光纤耦合器模型优化研究

为了优化双芯光子晶体光纤耦合器的耦合性能,采用改变两纤芯间空气孔的结构和孔内折射率的方法,得到了双芯光子晶体光纤耦合器的优化模型。基于光束传播法数值分析出两纤芯间空气孔尺寸以及孔内注入材料折射率的变化对双芯光子晶体光纤耦合器的耦合性能的影响。结果表明,由于光纤的整体结构不变,使得光纤损耗系数保持不变;减小双芯间的空气孔孔径或增大孔内折射率都会使耦合器的耦合长度减小,两不同偏振方向的耦合长度差异减小,损耗减小;双芯间空气孔内折射率可调性强,使得光纤耦合器的耦合性能有易调节的优点,为设计双芯光子晶体光纤耦合器的优化模型提供了理论支持。     

Design and characteristics of a novel narrow-band filter with the dual-core photonic crystal fiber

A novel narrow-band filter based on the dual-core doped photonic crystal fiber is proposed. By optimizing structure parameters of the photonic crystal fiber, the index curves of the fundamental modes for the two cores are crossed at 1.55 μm and the wavelength-selective coupling is achieved. The characteristics of the filter are numerically simulated by the full-vector beam propagation method. And the simulation results show that the coupling length and the bandwidth of the filter are 16.4 mm and 9 nm at −3 dB loss, respectively. It demonstrates the advantages of the filter with a small size, a low transmission loss and the narrow-band width.     

色散补偿双芯光子晶体光纤的数值研究

为了解决光纤通信系统中的色散补偿问题,提出一种新型的用于色散补偿的双芯光子晶体光纤,其构成材料是纯石英和空气,即在常规光子晶体光纤基础上变化包层第1圈和第3圈空气孔、增大了结构参量变化的自由度。采用平面波展开法对其色散补偿特性进行了数值研究,并模拟了包层结构参量与色散之间的关系,计算得出这种光纤的色散可以达到-1956.327ps·nm-1·km-1,能够补偿超过自身长度100倍的普通单模光纤。结果表明,双芯光子晶体光纤在色散补偿方面具有很大潜力,在未来光通信系统中将发挥重要作用。     

Switchable-multi-wavelength fiber laser based on dual-core all-solid photonic bandgap fiber

In this paper, we propose and demonstrate a switchable multi-wavelength fiber laser based on a dual-core all-solid photonic bandgap fiber (PBGF) comb-like filter. The transmission properties of the dual-core all-solid PBGF are theoretically and experimentally investigated. Then the fiber ring laser based on the PBGF is realized and its wavelength-selective mechanisms are studied. By adjusting the polarization controller (PC), the number and location of the laser wavelength can be tunable.     

Asymmetric elliptical-hole dual-core photonic crystal fiber with enhanced pressure sensitivity

We propose an asymmetric elliptical-hole dual-core photonic crystal fiber (AE-DC-PCF) for hydrostatic pressure sensing. The transmission spectra of the AE-DC-PCF under hydrostatic pressure and the relationship between pressure sensitivity and the minor axis ratio at different elliptical ratios have been calculated. Our results show that the AE-DC-PCF has higher pressure sensitivity than that of conventional dual-core photonic crystal (DC-PCF) fiber which has the circular-hole. Based on a 10 cm fiber, the pressure sensitivity of the AE-DC-PCF as high as 50.6 pm/MPa were achieved at 1.55 μm, which is higher than the pressure sensitivity obtained from conventional DC-PCF (32.2 pm/MPa).     

高双折射双芯光子晶体光纤偏振分束器

设计了一种基于双折射效应的新型矩形纤芯光子晶体光纤偏振分束器,通过在矩形晶格结构的光子晶体光纤的每个纤芯中引入一对椭圆来增加结构的双折射。应用全矢量有限元法（FEM）分析了双芯光子晶体光纤中结构参数对双折射和耦合长度特性的影响,数值模拟了该偏振分束器的性能。结果表明:增大椭圆率可以在增大结构的双折射的同时减小耦合长度,并且该分束器在工作波长为1.55 m、传输长度为282 m 的光纤中能够实现偏振状态的隔离,消光比达到最小值-45.42 dB,并且在1.507~1.596 m、带宽为89 nm 的范围内消光比小于-10 dB。     

一种基于光子晶体光纤的光纤旋转连接器设计

光纤旋转连接器因其具有传输带宽大、电磁兼容良好、体积小、寿命长等优点,有逐渐取代传统电滑环进行相对旋转平台间信息传输的趋势.提出一种利用大模场光子晶体光纤直接耦合的新型光纤旋转连接器的设计方案,耦合理论分析表明其不仅满足低插入损耗,而且具有结构简单、体积小、加工和装配精度要求相对较低等优点.大模场光子晶体光纤的无截止波长单模传输和低非线性传输特性使它能更有效地与WDM技术相结合提高传输容量,具有更广阔的应用.     

非对称光子晶体光纤中的双折射和色散

采用矢量电磁波多极子方法,对两种类型的非对称光子晶体光纤——小微孔对称性破缺光纤和大微孔对称性破缺光纤,进行数值计算和模拟研究,得出了非对称光子晶体光纤能实现较高双折射,其拍长可达1mm量级的结论。此外还分析了小微孔对称性破缺光纤的色散,并和实验结果进行了比较,两者较为一致。     

Experimental study of dual-core photonic crystal fibre

The authors report the fabrication and characterisation of photonic crystal (`holey') fibres in which multiple cores are created by filling in selected air-holes with glass. The guidance mechanism is modified total internal reflection. Using a tunable diode laser, the inter-core coupling is investigated as a function of air-hole spacing     

Coupling characteristics of the high-polarization dual-core photonic crystal fiber with mixing air holes

A high-polarization dual-core photonic crystal fiber (PCF) with mixing air holes is designed. The full-vector finite element method and coupled-mode theory are used to investigate the birefringence, coupling length, dispersion characteristics, normalized power and extinction ratio of this fiber. Numerical investigations demonstrate that by changing the structural parameters of the fiber, the birefringence is up to 1.48×10-2 at 1.55 μm, the coupling lengths are 79 μm and 94 μm for x-polarized and y-polarized modes, the fiber has two zero dispersion points, and the dispersion is very flat at the ultra-wide waveband scope from 0.7 μm to 1.7 μm.     

Design of a bending-insensitive single-mode photonic crystal fiber

We present a design of a bending-insensitive single-mode photonic crystal fiber (PCF) based on the existence of a triangular core formed by three neighboring air holes missing in the center of the fiber, and two cladding layers of air holes with different diameters. By optimizing the design parameters, the designed PCF with bending-insensitive characteristics can match the requirements of fiber to the home applications very well. Simulation results show that the designed PCF has an effectively single-mode operation, a small bending loss below 0.15 dB/m for the bending radius of 5 mm, as well as a stable effective mode area of 80 μm² whatever the designed PCF is straight or bent, which can connect well with conventional single-mode fibers (SMFs).