光子晶体光纤红外超宽带连续谱的研究

使用钛宝石飞秒激光器抽运一根长30 cm的光子晶体光纤,产生了从可见到近红外区的超连续谱,波长范围为465~2500nm,光谱展宽范围达到了2000nm以上,同时研究了超连续谱产生的机制.     

光子晶体光纤中超连续谱的形成及其影响因素

介绍了在光子晶体光纤(PCF)中产生超连续谱(SC)的发展现状及应用背景,从广义非线性薛定谔方程入手,讨论了超连续谱的形成机理.并从光子晶体光纤色散特性、脉冲参数等方面探讨了对超连续谱形成的影响,从而可以控制超连续谱的形成.     

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。     

高非线性光子晶体光纤中超连续谱产生的特性研究

利用数值方法求解广义非线性薛定谔方程,数值模拟了光脉冲在高非线性光子晶体光纤正常色散区超连续谱产生的演化,研究和分析了脉冲参数如峰值功率,脉冲宽度及初始频率啁啾对超连续谱形成的影响.结果表明,当脉冲峰值功率一定时,随着传输距离增大,超连续谱随之愈宽,平坦度愈好;随着脉冲峰值功率逐渐增大,超连续谱随之更宽,平坦度有所劣化.相反,脉冲宽度逐渐增大,超连续谱展宽范围减小,其平坦度也逐渐劣化;具有适当的正负啁啾脉冲,在高非线性光子晶体光纤传输中获得宽而平坦超连续谱.     

光子晶体光纤的超连续光谱及其应用

介绍了在光子晶体光纤(PCF)中产生超连续光谱的实验和理论研究成果以及超连续光谱在光学频率测量等方面的应用进展。     

光子晶体光纤产生紫外超连续谱的数值研究

提出了一种基于高非线性氟化镁光子晶体光纤产生紫外超连续光源的方法。采用分步傅里叶法求解光纤的非线性薛定谔方程,基于光子晶体光纤数值模拟了扩展到紫外波段的超连续谱的产生;通过分析光纤结构参量与泵浦光源参数对紫外超连续谱产生的影响,得出了光纤长度、色散参量以及泵浦脉冲峰值功率、初始脉冲宽度对超连续谱光谱宽度的影响规律。研究发现:当光子晶体光纤长度为8 cm、脉冲中心波长为450 nm、峰值功率为3.1 kW、初始脉冲宽度为40 fs时,可获得展宽至紫外的超连续谱,范围为279.6～769.0 nm。     

高非线性光子晶体光纤的研究及应用

文章介绍了高非线性光子晶体光纤的特点及产生高非线性特性的基本原理,分析了在高非线性光子晶体光纤中产生超连续光谱和慢光效应的机理和其应用,并给出了国内利用文章作者研制的高非线性光子晶体光纤进行超连续谱和慢光试验的结果.     

基于光子晶体光纤的超连续谱光源设计

为了运用光子晶体光纤高非线性效应技术获得超宽光谱,设计了一种基于光子晶体光纤的超连续谱光源,通过对光子晶体光纤进行塌孔处理后再熔接的方式,将高峰值功率的窄线宽脉冲光注入高非线性光子晶体光纤,利用光纤非线性效应实现了光谱展宽.实验结果表明,该超连续谱光源实现了光谱范围440～2400 nm,输出光功率为276 mW.     

光子晶体光纤的中红外超连续谱的产生与控制

设计了一种低损耗高非线性的碲化物PCF（光子晶体光纤）.采用分布傅里叶算法求解非线性薛定谔方程,数值模拟了基于PCF的中红外波段SC （超连续谱）的产生与控制.分析了PCF参量及泵浦光源参数对SC的影响,得出SC宽度和平坦度随PCF长度、色散参量以及泵浦脉冲峰值功率、初始宽度的变化规律.仿真结果表明,中心波长为2μm、脉冲峰值功率为20kW、脉冲宽度为100fs的泵浦光在PCF中传输15cm 时,SC谱宽可达1330-3450nm,且具有良好的平坦度.     

基于光子晶体光纤高质量超连续谱的优化设计

采用分布傅里叶方法模拟了光子晶体光纤超连续谱的产生,分析了超连续谱的产生机理与不同光子晶体光纤超连续谱的特点,分析结果表明,在正常色散区可以获得高质量超连续谱.优化光子晶体光纤结构,利用脉宽为100 fs、峰值功率为500 W的高斯脉冲通过10 m长的优化光子晶体光纤,在1 550 nm波段获得了宽度为210 nm、平坦度为3 dB的超连续谱.     

High nonlinear photonic crystal fiber and its supercontinuum spectrum

The high nonlinear photonic crystal fiber with pure silica core has been designed and fabricated, and the practical structure parameters of the fabricated fiber sample coincided precisely with the parameters we designed. The core diameter is 1.65 μm; the air hole diameter is 4.75 μm; the distance between the center of two holes is 5.35 gin; the zero dispersion wavelength of the fiber is 1120 nm; the dispersion at 800 nm is -88 ps.(nm.km)-1; and the nonlinear coefficient of this photonic supercontinuum emission with a smooth spectrum stretching from 450 to 1400 nm was attained by the injection of 30 fs Ti:sapphire laser pulses into 2 m-long high linear photonic crystal fibers, with an energy up to 5 nJ at a pulse repetition rate of 100 MHz and a central wavelength of 800 nm.     

Tapered photonic crystal fiber for supercontinuum generation in telecommunication windows

We numerically studied supercontinuum generation in a tapered photonic crystal fiber with flattened dispersion properties.The fiber was weakly tapered to have normal dispersion at wavelengths around 1.55 μm after a certain distance.We pumped 4 ps pulses with low peakpower and found that flatly broadened, wideband supercontinuum was generated in telecommunication windows.Furthermore, we also demonstrated the effects of tapered length and pulse width of the pump pulse on supercontinuum generation.     

充氩气Kagome空芯光子晶体光纤中超连续光谱产生的动力学研究

利用飞秒激光在充氩气的Kagome结构空芯光子晶体光纤中产生了高亮度宽带的超连续光谱.通过改变填充气体的气压以及输入激光的单脉冲能量可以对产生的超连续光谱进行控制.利用中心波长980 nm的飞秒脉冲作为抽运获得了光谱范围覆盖340~1 550 nm的宽带超连续光谱.通过基于载波的单向脉冲传输方程研究了超短脉冲在充氩气的Kagome光纤中产生超连续光谱的动力学过程.     

光子晶体光纤中非线性传输的数值研究

数值模拟了飞秒激光脉冲在光子晶体光纤中的非线性传输过程,详细计算分析了自相位调制（SPM）、脉冲内拉曼散射（ISRS）、自陡峭（SS）以及群速度色散（GVD）、三阶色散（TOD）、四阶色散(FOD)对脉冲传输和频谱的影响。结果表明,在反常色散区,脉冲内拉曼散射以及三阶、四阶色散对频谱的展宽和脉冲的平滑都有着重要作用;而自陡峭是使高阶孤子分量产生分裂衰变,对光谱的不对称展宽有一定影响。     

反常色散区抽运光子晶体光纤产生的超连续谱

为了研究反常色散区抽运光子晶体光纤产生的超连续谱,采用分步傅里叶方法数值模拟了飞秒激光脉冲在光子晶体光纤反常色散区中的非线性传输和超连续谱产生.结果表明,初始激光脉冲的峰值功率和脉冲初始啁啾对光子晶体光纤反常色散区产生超连续谱形状和带宽是有影响的.这些结论给光子晶体光纤中产生超连续谱提供了参考.     

All-optical regeneration based on highly nonlinear photonic crystal fiber

An all-optical regeneration based on selfphase modulation in a highly nonlinear photonic crystal fiber is proposed. The dispersion and nonlinearity properties of a series of photonic crystal fibers are analyzed, and the results show that the nonlinearity coefficient is closely related to the structure of the fiber.In this paper, the nonlinearity coefficient is increased by reducing the effective mode area, and a highly nonlinear photonic crystal fiber with a large air-filling fraction is used as nonlinearity medium in optical regeneration. The numerical results show that good optical regeneration results can be obtained by using a relatively short fiber length due to the high nonlinearity of the fiber. The input peak power launched into the photonic crystal fiber and the parameters of the filter have much influence on optical regeneration. To achieve good optical regeneration, those parameters need to meet certain requirements.Furthermore, the transfer characteristic of the regenerator is also discussed. By adjusting the input peak power and filter parameters, the regenerator can deal with input pulses of different pulse widths.     

Design of nonlinear photonic crystal fibers with ultra‐flattened zero dispersion for supercontinuum generation

The study reports on the design and performance of two air‐filled and two partial ethanol‐filled photonic crystal fiber (PCF) structures with a tetra core for supercontinuum generation. The PCFs are nonlinear with ultra‐flattened zero dispersion. Holes with smaller areas are used to create a tetra‐core PCF structure. Ethanol is filled in the holes of smaller area while the larger holes of cladding region are air‐filled. Optical properties including dispersion, effective mode area, confinement loss, normalized frequency, and nonlinear coefficient of the designed PCF structures are investigated via full vector finite difference time domain (FDTD) method. A PCF structure with lead silicate as wafer exhibits significantly better results than a PCF structure with silica as wafer. However, both structures report dispersion at a telecommunication wavelength corresponding to 1.55 μm. Furthermore, the PCF structure with lead silicate as wafer exhibits a very high nonlinear coefficient corresponding to 1375 W^?1 km^?1 at the same wavelength. This scheme can be used for optical communication systems and in optical devices by exploiting the principle of nonlinearity.     

多芯光子晶体光纤在国内高校的研究现状

多芯光子晶体光纤(Photonic Crystal Fiber,PCF)具有设计更灵活、大模场面积、显著的非线性效应以及纤芯耦合等优势.介绍了国内高校对多芯光子晶体光纤研究的状况,主要包括高功率超连续谱、高功率光纤激光器和光器件三个研究方向.同时,讨论了多芯PCF的可调结构参数.