新型光子晶体光纤近零平坦色散的研究

文章作者设计了一种新型的光子晶体光纤(PCF),在纤芯引入了一个小空气孔形成缺陷,并改变第一层空气孔的直径.采用平面波法研究了该PCF的色散特性,结果表明,该光纤能够得到比传统的PCF更低、更平坦的色散曲线;通过优化该光纤的结构参数,可以设计在1 350～2 010 nm波长范围内近于零的平坦色散PCF,其色散变化△D＜0.5 ps/(km·nm),在1 320～2 040 nm波长范围内色散斜率变化△D<,slope>＜0.02 ps/(km·nm<'2>).     

基于FDTD方法的光子晶体光纤色散特性分析

基于电磁场时域有限差分法(FDTD)计算光子晶体光纤(PCF)的方法, 分析了运用该方法时需要注意的一些问题, 特别是关于晶格位置、晶格上各个电磁场分量的分布以及完全匹配层(PML)中在边界处的电磁场的处理。以此为理论依据分析了一种纯石英材料双层芯PCF, 对这种光纤的传输特性进行了详细的数值模拟。通过调整光纤的结构参数, 设计出大负色散值的宽带色散补偿光子晶体光纤(DCPCF)。数值模拟结果显示在1530～1565 nm波长范围内其色散值在-400和-600 ps/(km·nm)之间变化, 达到了具有相同有效模面积的普通色散补偿光纤(DCF)的5倍。在整个C波段可以有效补偿长度25倍以上的标准单模光纤(SMF), 其色散剩余量在±1.0 ps/nm·km以内。该种结构的PCF对于制作高增益和宽带色散补偿于一体的集中式光纤放大器具有十分重要的意义。     

全固高非线性低色散斜率光子晶体光纤设计

提出了利用掺氟同心圆环的光纤结构来提高光子晶体光纤(PCF)的非线性,所需控制的参量仅有两个。设计了三种具有高非线性、低色散斜率和低限制损耗的全固光子晶体光纤。这三种光纤分别具有正常色散、双零色散点和零色散点恰好在1.55 μm波长处的色散曲线特性。所设计的零色散点恰好在1.55 μm波长处的光子晶体光纤色散斜率值为5.12×10-4 ps/(km·nm2),这比传统的高非线性光纤的色散斜率小了2个数量级。同时,该光纤在1.55 μm波长处的非线性系数为31.5 W-1·km-1,限制损耗为9.62×10-5 dB/km。     

C波段色散补偿光子晶体光纤的研究和设计

设计了一种新颖结构的双层芯色散补偿光子晶体光纤。此光纤在整个C波段具有高负色散特性。通过合理选取双层芯光纤的外层芯层数,同时优化孔间距和空气孔直径,设计的光纤在C波段的色散值在-520ps/(km.nm)和-390ps/(km.nm)之间近似线性变化,残余有效色散系数近似为零,相关色散斜率(RDS)在0.0032nm-1的色散补偿光纤,其RDS值与标准单模光纤匹配,有效模场面积优于常规色散补偿光纤,可以对其长度30倍以上、用于宽带传输的标准单模光纤进行良好的色散和色散斜率补偿。     

平坦色散高非线性光子晶体光纤的研究与制备

运用改进的全矢量有效折射率法(IFVEIM),研究了光子晶体光纤结构(PCF)参数改变时,光纤的色散系数、有效模场面积和非线性系数随波长的变化规律,深入地分析了光纤可调节的色散平坦特性和高非线性特性.课题组自行设计了一种在900nm附近具有低平坦色散高非线性特性的光子晶体光纤.并且在改进工艺的基础上,采用包层孔充气挤压法对其进行了制备,虽然制得的光纤各参数未达到设计值,但其在800～1000nm的波段内色散值仅为0.75ps/km/nm,非线性系数值则达到了30(W/km)-1,这在当前规则结构的纯硅光子晶体光纤中已经较高.     

基于组合包层的微结构光纤的色散特性

为了获得微结构光纤的平坦色散特性,设计了一种圆形排列的微结构光纤,其包层由周期分布的空气孔构成,通过有限元数值分析法对该微结构光纤基模的色散特性进行了数值仿真,研究了色散和纤芯圆孔尺寸以及波长的关系。结果表明:内外空气孔间距和直径对微结构光纤的色散曲线都有影响,但内包层大孔间距和第一圈小空气孔的直径对色散曲线的走向起决定作用。在内圈空气孔直径为3.1μm,其他空气孔直径为1.0μm,内圈空气孔中心间距为5μm,其他空气孔中心间距为4μm时,光纤在1.3μm波长的色散为19.5ps/(nm·km),在1.6μm波长的色散为26.5ps/(nm·km),在1.3～1.6μm波长范围内,其色散值变化范围为7ps/(nm·km)。     

Design for photonic crystal fibers with high nonlinearity and flattened dispersion for self-frequency shift of Raman soliton

A new concept of photonic crystal fiber (PCF) with high nonlinearity and flattened dispersion was designed. The PCF structure is indeed a hexagon lattice. The bigger air holes in the outer rings are used to confine the light field into the core region for enhancing the nonlinearity. The flattened dispersion can be achieved by adjusting the diameters of six smaller air holes in the first ring, and six micro air holes are inserted between smaller air holes for higher nonlinearity and the better flattened dispersion. By optimizing the size of the smaller and micro holes, the PCF can reach to high nonlinearity of 23.3 W⁻¹ · km⁻¹ and the low dispersion of 51.32 ps/(nm·km) with the fluctuation range of 0.98 ps/(nm·km), which is within the wavelength range of 1 400 nm to 1 900 nm. The designed PCF can be used in important applications in realizing the Raman soliton self-frequency shift (RSSFS).     

Dispersion-flattened Bragg photonic crystal fiber for large capacity optical communication system

A novelty dispersion ultra-flattened Bragg photonic crystal fiber (PCF) has been fabricated in this paper.The fiber is composed of compound cores and periodical claddings with 11 coaxial rings.It has flattened dispersion of 8.54±1.3 ps-(nm· km)-1 in the communication wavelength range of 1460-1625 nm.Its dispersion slope alters from -0.0428 to 0.0392ps·nm-2·km-1.The low attenuation of 0.52 dB/km and low bending loss of 0.09 dB at 1550 nm of the fiber are also achieved.The Bragg PCF has enormously potential application in the fields of dense wavelength division multiplexing systems because of its superior dispersion properties and easy splicing performances.     

一种新型高双折射光子晶体光纤的特性研究

设计了一种新型结构的光子晶体光纤,建立了对应的数学模型并采用全矢量有限元法对该结构的模场强度、有效折射率、双折射、色散特性和限制损耗进行了分析。研究表明,该光纤在1 550nm处可以获得高达7.66×10-3的双折射和低至12ps/(nm·km)的色散值,同时在800～1 600nm波长范围内,始终保持1.498×10-6 dB/m以下的极低限制损耗,可用于制造极低色散值的保偏光纤。     

A novel ultraflattened dispersion photonic Crystal fiber

A novel four-ring photonic crystal fiber (PCF) structure with two different air-hole sizes is proposed with nearly zero ultraflattened dispersion characteristics. Through optimizing only three geometrical parameters, two air-hole diameters, and one hole pitch, the ultraflattened zero dispersion PCF can be efficiently designed. As an example, a four-ring PCF with flattened dispersion of /spl plusmn/0.25 ps/km/nm from 1.295- to 1.725-/spl mu/m wavelength is numerically demonstrated. The corresponding design procedures for the novel PCF are also presented in this letter.     

高非线性光子晶体光纤及其超连续谱研究

文章作者设计并制造了一种纯硅芯高非线性光子晶体光纤,该光纤纤芯直径为1.65 μm,空气微孔直径为4.75 μm,孔中心间距为5.35 μm,零色散波长为1 120 nm,800 nm波长的色散为-88 ps/(nm·km).将能量为5 nJ、重复频率为100 MHz、中心波长为800 nm的30 fs的钛蓝宝石激光脉冲耦合入2 m长的该高非线性光子晶体光纤中,得到了450～1 400 nm宽波段范围内的超连续光谱.     

平坦色散高非线性光子晶体光纤的制备与实验

运用改进的全矢量有效折射率法(IFVEIM),课题组自行设计了一种在900 nm附近具有低平坦色散高非线性特性的光子晶体光纤.并且在改进工艺的基础上,采用中心抽真空挤压法对其进行了制备.虽然所制得光纤的结构参数与理论设计值存在一定的偏差,但其在所研究波段内色散值仅为0.5 ps/km/nm,非线性系数值则达到了35(W*km)-1,这在当前规则结构的纯硅光子晶体光纤中已经很高.最后,我们对其进行了非线性实验测试,其在400～1 400 nm的波段范围内展现出了宽平坦的超连续谱.     

高非线性液芯光子晶体光纤中超连续谱的产生

提出了一种实现高非线性光子晶体光纤(PCF)的新方法,即在空芯光子晶体光纤(HC-PCF)的纤芯空气孔中填充高折射率、高非线性折射率的液态物质三氯甲烷、甲苯、二硫化碳等。利用全矢量有限元方法分析了这种液芯光子晶体光纤的模式分布及色散性质,分析得出其零色散波长可在800 nm左右调节,因此可使中心波长800 nm的钛宝石飞秒脉冲激光在这种光子晶体光纤的反常色散区传输,有利于超连续谱的产生。而且由于填充后光子晶体光纤具有较高的非线性系数,较小功率的脉冲激光就可在几毫米长的这种液芯光子晶体光纤中得到频谱范围大于1000 nm的超连续谱。     

Design and optimization of photonic crystal fibers for broad-band dispersion compensation

Design of photonic crystal fibers (PCFs) for application of broad-band dispersion compensation is investigated by using an improved design model based on combination of a rigorous vector solver for modal properties and a scaling approach for dispersion characteristics. The newly designed PCF is shown to exhibit large normal dispersion up to -474.5 ps/nm/km, nearly five times of conventional dispersion compensating fibers, and compensate conventional single-mode fibers within /spl plusmn/0.05 ps/nm/km over a 236-nm wavelength range. Furthermore, the design model and methodology can be applied to design other dispersion-based devices such as dispersion flattened fibers and dispersion shifted fibers.     

新型色散平坦光子晶体光纤设计与分析

研究了一种新改进的折射率导光光子晶体光纤的色散性能。研究表明当纤芯空气孔的孔径小于包层空气孔孔径时, 光子晶体光纤仍然通过全内反射（TIR）导光。采用全矢量平面波展开法分析光子晶体光纤的色散特性, 并设计了波长为1360 nm到1730 nm时, 色散值在-10±0.5 ps/（nm·km）之间的色散平坦光子晶体光纤, 其色散斜率在波长为1370～1740 nm时可达±0.01 ps/nm2/km。     

Research on the stability of nearly zero flattened dispersion of photonic crystal fibers

To analyze the stability of nearly zero flattened dispersion, the dispersion deviations for three kinds of PCFs are calculated when the hole diameters deviate from their designed values. Numerical results show that around the wavelength of 1.55 μm, the dispersion deviations of both the PCF with three-fold symmetry core and the PCF with hexagonal lattice are much less than that of the PCF with different hole diameters in different rings. Therefore, the stabilities of nearly zero flattened dispersion of the first two kinds of PCFs are much better than that of the last one. Considering the confinement loss, the PCF with three-fold symmetry core is preferable to practical use.     

基于光子晶体光纤的宽带色散补偿光纤的设计

采用矢量光束传输法(VBPM)对小纤芯光子晶体光纤(PCF)的色散特性进行了数值分析,研究发现通过调节光子晶体光纤的结构参数可以灵活的对其色散补偿值进行调整,能够实现C L波段(1 530～1 565 nm)的宽带色散补偿功能,并且对标准单模光纤的色散斜率有很好的补偿.在∧=1.0μm,d/∧=0.7时,1 550 nm处的色散值可以达到-339.1 ps/(km×nm),相关色散斜率(RDS)可以达到0.003 2 nm-1,能够有效的对标准单模光纤进行色散斜率补偿.     

Tailoring Dispersion and Confinement Losses of Photonic Crystal Fibers Using Hybrid Cladding

We present a hybrid cladding photonic crystal fiber (PCF) for shaping nearly zero ultraflattened dispersion and low confinement losses in a wide range of wavelengths. The finite difference method with anisotropic perfectly matched boundary layer is used to investigate the guiding properties. It has been shown theoretically that it is possible to obtain nearly zero ultraflattened dispersion of ${hbox{0 }} pm {hbox{0.25}} ~{hbox{ps}}/{hbox{nm}}/{hbox{km}}$ in a wavelength range of 1.44 to 2.0 $ mu{hbox{m}}$ with low confinement losses less than 0.005 dB/km within the entire band of interest from a five-ring hybrid cladding PCF.      

New High Nonlinear and Dispersion Flattened Photonic Crystal Fiber

A new high nonlinear dispersion flattened photonic crystal fiber is proposed. This fiber has three-fold symmetry core. The doped region in the core and the big air-holes in the 1-st ring can make high nonlinearity in the PCF. And the small air-holes in the 1-st ring and the radial increasing diameters air-holes rings in cladding can be used to turn the dispersion properties of the PCF. We can achieve the optimized optical properties by carefully selecting the PCF's structure parameters. A PCF with flattened dispersion is obtained. The dispersion is within ±0.8 ps·nm-1·km-1 from 1.50 μm to 1.62 μm. The nonlinear coefficient is about 12.645 6 W-1·km-1, the fundamental mode area is about 10.257 9 μm2 and the birefringence is about 3.086 96×10-5 at 1.55 μm. This work may be useful for effective design and fabrication of dispersion flattened photonic crystal with high nonlinearities.     

近零平坦色散三包层光子晶体光纤的设计

为了使光子晶体光纤（PCF）在钛宝石飞秒激光器的工作波长0.80 m 和光通信窗口1.55 m 处获得宽的近零超平坦色散,使用了三包层六角空气孔环结构设计来代替普通的单包层结构。应用了改进的有效折射率法对该三包层PCF 进行了数值模拟。结果表明:三包层PCF 的色散随结构参数的微小变化而有较大的变化,因此通过对PCF 结构参数的合理调节,分别实现了在0.800.02 m 和1.550.15 m 波长范围内近零、平坦色散（色散范围0.5 ps/（kmnm）,色散斜率范围0.02 ps/（kmnm2）的结构设计。这对于光通信系统及研究飞秒激光在PCF 中的传输特性,拓展飞秒激光的研究和应用都具有重要意义。