基于长周期光栅的有机聚合物高速电光调制器

TN761 2004064380 基于长周期光栅的有机聚合物高速电光调制器=A novel electro-optic polymer modulator based on long period fiber gratings[刊,中]/董小伟(北京交通大学光波技术研究所.北京(100044)),裴丽…∥光学技术.—2004,30(3).—289-291,295 结合长周期光栅的特性和有机聚合物的优点,首次提出了一种新型的基于长周期光栅的有机聚合物高速电光调制器结构。应用多层光波导理论,分析计算了聚合     

长周期光纤光栅傅里叶模式耦合理论

建立了长周期光纤光栅傅里叶模式耦合理论.在分析同向模式耦合时,发现了同向耦合模式的振幅系数间存在傅里叶变换关系.推导了长周期光纤光栅的同向耦合谱和透射谱的通用表达式.该理论是用傅里叶变换分析得出长周期光纤光栅折射率微扰的空域谱,再对该空域谱进行模式同向耦合分析,从而得到长周期光纤光栅光谱特性的通用表达式.根据该理论模拟分析了长周期光纤光栅在不同长度和微扰幅值时的光谱特性,与传统耦合模理论进行了对比分析.结果表明,该长周期光纤光栅傅里叶模式耦合理论具有简单、精确和高效的特点,与实际长周期光纤光栅的透射谱特性一致.应用该理论可分析无过耦合的任意轴向折射率微扰分布的长周期光纤光栅光谱特性.     

长周期光纤光栅折射率传感器的结构优化

为了提高长周期光纤光栅对环境介质折射率的传感灵敏度,提出一种长周期光纤光栅的周期和包层半径的结构优化.基于长周期光纤光栅的耦合模理论,分析了长周期光纤光栅的周期和包层半径的大小分别与环境介质折射率传感灵敏度的关系,讨论了长周期光纤光栅的周期和包层半径对折射率传感的影响以及控制光栅周期与包层半径对折射率传感的重要性.为使...     

级联长周期光纤光栅光谱特性研究

级联长周期光纤光栅作为长周期光纤光栅的一个特殊形式,具有许多特殊性质。本文研究了级联长周期光纤光栅理论以及其光谱随级联光纤长度和光栅强度变化的特性,并与实验结果进行了比较,为级联长周期光纤光栅传感和设计级联长周期光纤光栅器件提供了依据。     

长周期光纤光栅温度稳定性分析及其改善

利用模式耦合理论推导出长周期光纤光栅(LPG)温度特性的一般关系式;通过测试周期为400～600μm的长周期光纤光栅的温度特性,确定了芯内导模与被耦合的不同包层模间的热光系数差,并结合长周期光栅温度特性关系式总结出长周期光栅温度灵敏度与光栅周期和耦合包层模阶次的对应关系;在理论与实验的基础上,提出了改善长周期光栅温度稳定性的方法。     

长周期光纤光栅的理论分析及实验验证

采用简化的三层光纤模型,从模式理论和耦合模理论出发,分析了长周期光纤光栅的耦合特性及功率透射谱,给出了长周期光栅的主要特性参数。利用计算机建模,采用Matlab软件对实用的SMF 28单模光纤加以特定的光栅折射率调制参数进行数值计算,并采用振幅掩模法刻写长周期光纤光栅进行实验验证,计算结果与实验结果相吻合。     

长周期光纤光栅谐振波长与曝光量的变化关系

利用波动干涉理论推导了长周期光纤光栅的光栅方程. 利用色心模型和Kramers-Kronig原理，得到了长周期光纤光栅的中心谐振波长与曝光量的变化关系的理论公式，并进行了实验研 究. 理论和实验结果都表明，长周期光纤光栅的中心谐振波长与曝光量的关系按多项e负指 数之和规律变化，其变化率受到模板占空比的控制；另外，长周期光纤光栅的中心谐振波长 与模板占空比成反比关系. 关键词： 长周期光纤光栅 谐振波长 模板占空比     

长周期光纤光栅谐振波长的横向负载特性分析

在考虑波导效应、弹光效应等因素后,详细地理论分析了长周期光纤光栅(LPFG)的横向负载传感特性,包括谐振波长漂移及谐振峰分化后的双峰间距与横向负载、光偏振的关系,模拟计算了单模光纤长周期光栅的横向负载传感特性.理论分析和计算结果表明,长周期光纤光栅谐振波长随横向负载的漂移量和方向与光源的偏振方向有关,加载方向偏振光的谐...     

模式耦合理论在圆周对称长周期光纤光栅建模中的应用

长周期光纤光栅是不同于光纤Bragg光栅的一种光纤光栅器件 ,根据模式耦合理论 ,长周期光纤光栅表现为前向传播的纤芯导模和同向的各阶次包层模式之间的耦合。分析研究了长周期光纤光栅轴向的模场变化。忽略轴向的模式耦合以及包层模式之间的相互耦合作用 ,并认为折射率指数的调制只存在于纤芯中 ,建立了简化的长周期光纤光栅数学模型。对圆周对称轴向均匀型长周期光纤光栅谱特性进行了仿真 ,其结果与实验结果基本吻合 ,表明了简化的数学模型的合理性     

光子晶体光纤及在光纤光栅中的应用

从光子晶体光纤(PCF)与普通光纤在光纤结构上的差异出发，简要分析PCF的导光原理与单模特性，并探讨基于PCF的光纤光栅的稳定性，基于聚合物填充多孔光纤的长周期光纤光栅的温度调谐性能，以及纯结构性非光敏纤芯长周期光子晶体光纤光栅的原理。从一个方面说明了光子晶体光纤的潜在应用。     

A Novel Electro-Optic Polymer Modulator Based on Long Period Fiber Gratings

A novel high-speed electro-optic (EO) polymer modulator based on long period gratings (LPG) is designed. Using the theory of multi-cladding optical waveguide, we achieved relationship between modulate voltage and LPG’s resonant wavelength.     

A quantitative analysis of an athermal design for a long period grating based tunable filter

In this paper, a quantitative analysis of an athermal design for a unique all-fiber tunable filter based on the combination of a single resonant band long period grating (LPG) with an electro-optic polymer second cladding layer is presented. The single resonant band LPG is used to select the resonant wavelength, which can be tuned by changing the refractive index of an electro-optic polymer second cladding layer via external electric field. Although the basic operational principle and implementation of this unique tunable filter have been previously reported, this paper is focused on the quantitative analysis of the athermal design, which may significantly enhance the practicability of the proposed tunable filter.     

级联长周期光栅光谱特性

利用传输矩阵法分析了级联长周期光栅的光谱特性,讨论了级联处光纤的长度、位置以及包层模损耗系数对级联长周期光栅光谱的影响,并对级联长周期光栅和相移长周期光栅的光谱进行了比较。结果表明两者光谱存级联光纤长度较小或级联位置靠近光栅两端时具有较强的一致性,而在级联处光纤较长并且级联位置在中间时,两者表现出截然不同的光谱特性;在不考虑其他损耗的情况下,如果只改变级联处光纤长度,级联长周期光栅总量守恒;此外,当级联长周期光栅在级联处光纤包层模损耗系数较大时,级联长周期光栅的光谱等效于两个长周期光栅光谱的非相干叠加,从而为长周期光栅增益均衡器的优化设计和制作提供了一个简便有效的方法。     

Theory and practice of long-period gratings: when a loss becomes a gain

Losses of cladding modes are part of the mechanism of operation of a long-period grating (LPG) when it is used as an optical filter. We present a LPG computer simulation that accounts for these losses. On the basis of this simulation, we show that losses result in qualitatively different LPG spectral behavior. There is an optimal loss value that provides sidelobe-free, 100% power transfer from the core to the cladding mode for a uniform LPG. We obtained a simple equation that relates this optimum lose value to the LPG length and the cross-coupling coefficient. Based on the results, we propose new approaches to LPG design in a fiber as well as in waveguide platforms for fiber-optic communication and sensor applications. A design of a LPG reconfigurable filter is suggested.     

液化石油气中二甲醚含量快速测定方法研究

二甲醚(DME)掺入液化石油气(LPG)中能加速储气罐橡胶密封圈的老化,存在严重安全隐患,直接危害消费者安全和利益,国家明令规定禁止向LPG中掺入二甲醚等化学品作为液化气商品出售,因此实现LPG中DME含量的快速分析极其重要。提出一种快速测定LPG中DME含量的新方法,解决了液化气成分快速测量技术难题。实验设计和制造了一套精确配制DME液化气溶液的装置和一套基于近红外光谱技术快速测定LPG的分析系统。该分析系统耐压3.5 MPa,可方便与高压钢瓶连接,实现了液化气直接快速测量。收集了市场上LPG-1(胺前液化气),LPG-2(焦化液化气),LPG-3(脱硫醇后液化气)LPG-4(沧炼催化液化气)共四种液化石油气,采集其近红外光谱作为背景子空间,采用称重法配制DME浓度范围1.0%～45.0%。采用斜投影算法从LPG溶液近红外光谱中提取出不同浓度LPG溶液中DME纯信号,使用DME纯信号强度I与浓度c建立标准曲线,其线性相关系数为0.999 4。外部验证结果表明,方法相对误差小于2.0%。该方法具有操作简单,快速、无需建模等优点。     

长周期光纤光栅温度和应力传感特性研究

本文报道了长周期光纤光栅(LPG)温度和应力传感特性的实验研究结果,测得LPG的温度和应力灵敏系数均高于光纤布喇格光栅(FBG)灵敏系数的典型值,在11～80℃和0～100gf的温度和应力测量范围内,温度和应力响应曲线具有较好的线性.基于同一LPG不同透射波长具有不同温度和应力灵敏度的特性,实现了温度和应力的单光栅同时测量.     

相移长周期光纤光栅的光谱特性及其在光分插复用器中的应用

从耦合模理论出发,动用传输矩阵法对相移长周期光纤光栅（ＬＰＧ）的传输光谱进行了数值计算,着重分析了相移个数、切趾函数的发言为对光机特性的影响,在分析及联长周期光纤光栅传输特性的基础上,提出了一种新型的基于相移长周期光纤光栅的光分插复用器的结构设计方案。     

Simultaneous spectral recovery of long-period grating sensor array using optical time-division multiplexing

A novel sensor network based on optical time-division multiplexing (OTDM) is proposed and demonstrated for simultaneous sensing of long-period grating (LPG) sensor array with overlapping spectra. A star network is configured by pairing a circulator with each of the LPG sensors. Experiments are conducted by measuring the changes of surrounding refractive index at different sensors, which show excellent agreement between the demultiplexed and pristine transmission spectrum of the LPG sensors.     

Deep-notch, ultracompact long-period grating in a large-mode-area photonic crystal fiber

An extremely short long-period grating (LPG) with strong resonance has been developed in a large-mode-area photonic crystal fiber (PCF) by use of the heat source of a CO2 laser. We believe that such a LPG in pure silica PCF is the first example to be obtained with the point-by-point technique. The fabrication method is simple and repeatable. The resulting LPG has 8 periods, written by a CO2 laser, within a 2.8-mm length of fiber, which yields a deep notch of core-cladding mode coupling of -31.5 dB at the telecommunication wavelength of 1529.2 nm, with a FWHM of approximately 0.7 nm. The principal advantages of this LPG are that it is practical, cost effective, and compact.     

A cheap and practical FBG temperature sensor utilizing a long-period grating in a photonic crystal fiber

A whole temperature sensor in one package utilizing a fiber Bragg grating (FBG) made in a conventional single-mode fiber and which uses a long-period grating (LPG) made in a photonic crystal fiber is proposed and experimentally demonstrated. The function of the interrogation is that the wavelength change of the FBG with environmental temperature is transferred to the intensity of the output via the LPG. Utilizing the temperature-insensitivity of the LPG in the PCF, the interrogation is stable and enables a cheap and practical temperature measurement system with a wide dynamic range.