一种具有高二阶非线性椭圆芯中空光纤

提出并制造一种新颖的椭圆芯中空光纤,采用热极化方法使其具有高二阶非线性,可用作相位调制器。该光纤在300℃温度、大于1×108 V/m强电场和9cm有效电极长度条件下热极化30min后,产生大的线性电光相移。基于双椭圆芯中空光纤构建一种纤内马赫-曾德尔干涉仪,通过观察干涉条纹的移动来评估相移,最终得到1.16pm/V的高二阶非线性系数和0.52pm/V的线性电光系数。该技术具有简单、灵活的特点,可以用来制作高电光系数器件,降低制作成本,并能进一步提高全光纤器件的集成度。     

Highly Active Second-Order Nonlinearity from Sol-Gel Processed Poled Silica and Germanosilicate Thin Film

Poled silica and germanosilicate thin films are prepared with typical sol-gel processing. Second-order nonlinearity about one order of magnitude larger than that of quartz crystal is realized. Substrate effect and dopant effect on the nonlinearity are discussed.     

Mechanism Study for Thermal/Electric Field Poling of Fused Silica

On the basis of the experimental reports, the mechanism of the second-order susceptibility ⁽²⁾ for the thermal/electric field poling of fused silica is analyzed, and expressions for ⁽²⁾ are detailedly derived and numerically calculated for the first time. By comparison the theoretical value of ⁽²⁾ with the experiment results, we propose that the effective ⁽²⁾ is created via both the interaction of the intense electric field with the third-order susceptibility ⁽³⁾ and the dipole orientation. The theoretical results show that, in the differently applied voltage, the dipole orientation and ⁽³⁾ play different role in the formation of ⁽²⁾. This theory successfully explains some experiment results.     

光纤光栅外腔分布布拉格反射激光器中的波长转换

报道了一种新型的基于光纤光栅外腔分布布拉格反射激光器的波长转换技术，获得了８ｎｍ的波长转换间隔，对注入信号的灵敏度、转换信号之间的反相特性等进行了测量研究。讨论了波长转换的机理和该技术的特点和优点。     

石英光纤中二次非线性级联波长转换的理论分析

提出了利用周期性热及电场诱导D型光纤光栅的二次非线性级联(χ⁽²⁾∶χ⁽²⁾),实现在波分复用网中波长转换的方法,并进行了理论分析.推导出χ⁽²⁾ ∶χ⁽²⁾的耦合模方程,得出了小信号条件下转换产生光波的场强振幅和 功率,以及转换效率η的解析式,该式与数值计算相吻合.解析式和数值结果都表明,在近 似满足相位匹配条件下,η与抽运光功率平方、光栅总长度L和二次非线性系数d的四次方分 别成对数关系.计算结果表明,这种光纤光 关键词： 石英光纤 二次非线性 级联 波长转换 光纤光栅 诱导     

色散位移光纤中零色散波长纵向分布对四波混频转换效率的影响

研究了色散位移光纤零色散区域附近的四波混频特性 ,讨论了当零色散波长彼此不同的多段光纤连接起来后对四波混频效率的影响。理论计算结果表明 ,在信号光和抽运光波长间隔较小的区域 ,各光纤对四波混频过程都有贡献 ,且互相调制 ,并出现增益现象 ,有着很复杂的效率图。     

准相位匹配级联二阶非线性全光波长转换研究

对基于级联和频差频非线性效应铌酸锂光波导新型全光波长转换器进行了理论研究。这种新型波长变换器需要两束抽运光源,它将输入的抽运光波长置于信号光波段窗口的两边,抽运光波长与信号光波长相近容易实现最佳耦合又不会占用信号波段,而且具有偏振不敏感的优点。从建立级联和频差频铌酸锂光波导全光波长转换器的理论模型出发,给出了波导中光相互作用的耦合模方程;利用逐步法详细推导了耦合模方程的解,得出了物理意义清晰的转换光功率表达式,分析了非线性晶体相互作用长度、抽运光功率对转换效率的影响,为级联和频差频铌酸锂光波导全光波长转换器优化设计提供了理论依据。     

Experimental Study of Single- and Multicast Wavelength Conversion at 10 Gb/s Exploiting Four-Wave Mixing in Highly Non-Linear-Photonic Crystal Fiber with Widely Tunable Conversion Range

Abstract

Optical networking applications require the use of all-optical wavelength converters with input and output wavelength tenability as well as large numbers of multicasting channels. This article demonstrates the single-to-multiple wavelength conversion via multiple four-wave mixings between a 10-Gbit/s return-to-zero signal and several continuous waves co-propagating in a dispersion-flattened highly non-linear photonic crystal fiber. For single-to-single channel wavelength conversion, a wide conversion range of 31 nm is achieved with the optimal conversion efficiency of ?21.4 dB. By employing several continuous-wave probe lights, tunable single-to-dual and single-to-triple channel wavelength conversions are experimentally demonstrated, respectively. Moreover, the dynamic characteristics of the designed wavelength converter are studied under the conditions of variable input powers, polarization mismatch, and different lengths of the highly non-linear-photonic crystal fiber. The system is transparent to both bit rate and modulation format. This is very useful for engineering design and applications of optical-fiber-based wavelength converters in future ultra-high-speed photonic networks.     

热及电场诱导石英光纤的电光系数

利用多载流子模型及单轴对称和光激励机理,从理论上计算了经热及电场诱导后的石英光纤的电光系数γ与D型光纤的距离d、诱导时间t和外加电压V的关系。结果表明,尽量缩短d并在适当时间内诱导,能有效提高电光系数;电光系数与外加电压近似平方根关系：γ33与γ13的比值非常接近3。理论结果与实验报道相当一致。     

Theoretical Research on Sensitivity for Resonance Wavelength of Long Period Fiber Grating

In a long period fiber grating(LPFG), the forward-propagating guided mode in the core is coupled to a number of co-propagating lossy cladding modes at resonance wavelengths. Sensitivity of resonance wavelength against temperature, axial strain, and external refractive index is modeled in this paper. Schemes for temperature compensation and enhanced wavelength tuning of LPFG are proposed and analyzed. Experiments show accordant results with simulations. Temperature coefficient of the LPFG compensated by means of axial strain is below 1.8 nm/100℃. For the LPFG with polymer recoating layer, the enhanced tuning range is more than 70 nm.     

Theoretical Research on Sensitivity for Resonance Wavelength of Long Period Fiber Grating

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基于和频与差频级联的全光单光子波长变换

基于周期极化铌酸锂波导,提出了一种采用和频产生与差频产生级联的全光单光子波长变换方案.在海森堡绘景下,通过非线性变换过程的哈密顿量求解了目标单光子信号的湮灭算子,进而根据变换前后的光子数算符之比得到了单光子波长变换的效率.分析了和频产生过程以及差频产生过程中单光子的转换效率与泵浦功率之间的关系,证明了存在最佳泵浦功率使得量子态能够完全转移.数值分析结果表明,当上变换(和频产生)泵浦光功率为65 mW、下变换(差频产生)泵浦光功率为150 mW时,由1550 nm到1530 nm的单光子波长变换可达到61％的转换效率.给出了级联单光子波长变换的实验装置,包括周期极化铌酸锂波导、泵浦激光、准单光子信号源、滤波等光学元器件、单光子探测器和同步线路.     

波长转换受限条件下的最优组播波长分配算法

扩展了静态组播路由和波长分配问题,引入了范围受限的波长转换器,改进了优化目标,新的优化目标为整个组播连接使用的波长转换器数目最少,同时保证源节点到每个组播成员的路径上使用的波长转换器数目均小于指定值.利用动态规划,在两种连接建立策略下对问题进行了求解,所得解可用于衡量启发式组播波长分配算法的优劣.     

基于光子晶体光纤四波混频效应的波长转换研究

研究了光子晶体光纤中的四波混频效应及其波长转换.采用长度为25 m的高非线性色散平坦光子晶体光纤,当泵浦功率为19.8 dBm时,得到100 nm的转换带宽和－20 dB的最大转换效率.实验结果表明,当信号功率低于四波混频阈值时,两路不同波长的信号同时输入产生的四波混频效应互不影响.     

Characteristics of the Wavelength Converted Signal in Wavelength Conversion Based on Cross-Gain Modulation

An analytical theory describing the frequency chirp characteristics of the wavelength converted signal in wavelength conversion based on cross-gain modulation (XGM) in semiconductor optical amplifier (SOA) is derived. By computation, we can see that low input pump power, high probe power, small line-width enhancement factor and low unsaturated single-pass gain of the SOA are favorable for reducing the frequency chirp of the wavelength converted signal. The analytical results have significance in understanding and designing wavelength converters.     

双抽运光纤光参变放大的全光多波长变换与码型转换

利用强度调制的数据信号光作为一路抽运光,与另一路直流或者正弦强度调制抽运光组合可以在双抽运光纤光参变放大过程中实现全光多波长变换或者在全光多波长变换的同时实现码型转换.理论上,从信号增益的角度分析了波长转换与码型转换的原理.实验上演示了2.5Gb/s的非归零(NRZ)码信号的全光多波长转换与到归零(RZ)码信号的转换.多波长转换实验表明:双抽运条件下的光参变过程可以实现多波长转换并得到正、反码的输出,还同时对信号有一定的再生作用.码型转换后信号的占空比为30%,消光比也得到提高.     

全光波长变换器消光比特性的理论研究

半导体光放大器（SOA）是具有优良非线性效应的光子器件,在光开关、波长变换、光逻辑运算中有重要的应用。从SOA载流子的速率方程和耦合波方程出发,建立了基于SOA的交叉增益调制波长变换理论模型,并利用分段模型分析方法,对SOA的交叉增益调制波长变换的消光比特性进行了详细的研究。研究结果表明,适当增大信号光功率、减小探测光功率并选择合适的波长差和SOA长度,可以有效地提高传输信号的消光比。     

用于光纤光栅解调的波长敏感光纤耦合器

为了拓宽光纤耦合器的使用范围,开发光纤耦合器的新功能,采用熔锥技术制作波长敏感耦合器,该耦合器在分光的同时对波长敏感。通过耦合理论验证实验结果,实验数据与理论值相符合。实验中得到波长灵敏度最大值为17.86%/nm的耦合器。采用拉锥工艺制作波长敏感耦合器工艺简单,耦合比峰值对应波长控制易于实现。该耦合器可用于光纤光栅布拉格波长漂移解调。令待解调光纤光栅布拉格波长与耦合器波长灵敏度最大值对应的波长一致,当波长发生漂移时,耦合器输出耦合比发生变化。自制的波长敏感耦合器实现了对布拉格波长为1566.71 nm光纤光栅波长漂移的解调,波长漂移1.80 nm,耦合比变化20.34%。此种解调方式具有光路简单,易于与光纤匹配的优点,可以应用在大型建筑中光纤光栅的健康监测。     

半导体激光器实现波长转换的理论模型分析

作为自动交换光网络中的核心器件，全光波长转换器的研究是目前的热点。提出了基于半导体激光器实现波长转换的理论模型，采用小信号分析方法，利用速率方程求解了波长转换的频率调制响应特性。并初步研究了不同半导体激光器工作电流、码速、输入信号光功率、增益吸收系数条件对波长转换性能的影响。这对于优化基于半导体激光器的全光波长转换器有一定的参考价值。