多波长啁啾光纤光栅叠栅的数值分析和设计

为了研究多波长啁啾光纤光栅叠栅的反射和时延特性,提出多波长啁啾光纤光栅叠栅的耦合模理论方法,得到波长间隔Δλ=1.6nm的4波长和8波长的啁啾叠栅的反射谱和时延特性的数值分析结果,并设计了波长间隔Δλ=0.4nm的8波长的啁啾叠栅,数值分析结果与实验结果非常一致.结果表明,多波长啁啾光纤光栅叠栅的耦合模理论是可靠的,可用来分析其各种特性,此方法对多波长啁啾叠栅的设计和制作具有重要的参考价值.     

基于传输矩阵法的纵向啁啾体光栅衍射特性

为了研究纵向啁啾体光栅的光谱衍射特性,采用传输矩阵方法进行了分析,研究了光栅的厚度、折射率调制系数和啁啾波长范围对纵向啁啾体光栅中心衍射效率的影响。结果表明,随着光栅厚度的增加,中心衍射效率随之增大;随着光栅折射率调制系数的增大,中心衍射效率也随之逐渐增加;而随着啁啾波长范围的增大,纵向啁啾体光栅的中心衍射效率则逐渐减小。此研究结果对大尺寸啁啾体光栅的设计制作有一定的参考价值。     

Investigation on reflection spectr a of chirped and phase-shifted fiber Bragg gratings

The characteristics of chirped and phase-shifted fiber Bragg gratings have been investigated by the use of transfer matrix formulation. While the characteristics of a chirped and phase-shifted fiber Bragg grating are the same as those of non- chirped one in some important aspects, both the reflection and transmission windows of a chirped and phase-shifted fiber Bragg grating can be broadened in a wide range. Therefore, chirped and phase-shifted fiber Bragg gratings will have applications in WDM or DWDM optical communication systems. The work in this paper can be used to design the new devices based on chirped and phase-shifted fiber Bragg gratings.     

Finite Beams in Reflective Volume Bragg Gratings: Theory and Experiments

We present a theoretical model to describe finite beams incident on reflective volume Bragg gratings. We also give experimental results that verify our model. From these results, we identify certain properties of reflective volume Bragg gratings, such as beam waist, incidence angle and beam profile, that have direct impact on the design of laser cavities that include such gratings. We also show how these gratings can act as spatial mode filters.     

Efficient design of spatially symmetric Bragg gratings for add/drop multiplexers

A simple and fast numerical procedure is presented for designing spatially symmetric Bragg gratings with no need for iteratively solving the coupled mode equations. Using a unique relation between the phase and the amplitude of the reflection spectra valid for spatially symmetric gratings, the grating spectra are suitably optimized to fit given specifications. At the end of the design process an inverse-scattering algorithm determines the spatial structure of the corresponding Bragg grating. This method is particularly useful for the design of add/drop multiplexers, where symmetry can be a crucial prerequisite.     

双体光栅外腔二极管激光器光谱特性研究

为了研究双体布喇格光栅外腔二极管激光器的衍射特性,采用一块体布喇格光栅与一块横向啁啾体布喇格光栅组成双体布喇格光栅,理论分析了组合前后体布喇格光栅的衍射特性,实验研究了双体布喇格光栅外腔二极管激光器的输出光谱特性。结果表明,在双体布喇格光栅外腔反馈的作用下,可以实现双波长同时输出,通过横向移动横向啁啾体布喇格光栅,可以在保持其中一个中心波长不变的情况下,使另外的一个波长在800nm~815nm的范围内线性调谐。此研究为基于双体布喇格光栅实现双波长输出的大功率二极管激光器提供了实验指导。     

光孤子在高斯变迹光栅中传输特性的数值分析

为了研究光纤光栅中布喇格孤子的传输特性,基于耦合波理论采用有限差分法在孤子传播速度与传输距离无关的条件下,数值模拟了布喇格孤子在高斯变迹光纤光栅中的传输以及孤子之间的相互作用,得到一些有意义的结果。结果表明,输入功率和初始脉宽等初始条件的不同将导致孤子峰值强度的周期变化;具有初始频率啁啾时布喇格孤子在传输过程中被展宽(正啁啾)或被窄化(负啁啾),并始终受到高斯变迹光栅的制约。当输入两个孤子时,它们之间的相互作用对其相对相位和相对振幅参量敏感。     

光栅色散渐减和损耗对布拉格孤子传输的影响

运用有限差分法数值模拟了布拉格孤子在光纤光栅中的传输,计算和分析了光栅色散与光栅损耗对布拉格孤子传输的影响.结果表明,光栅色散渐减使脉冲的峰值增大,光栅损耗使脉冲展宽,两者对布拉格孤子在光纤光栅中的传输具有互补性,即两者对布拉格孤子的传输作用相反.在一定的情况下,两者使布拉格孤子在光纤光栅中稳定地传输.     

Design of polarization-insensitive Bragg gratings inzero-birefringence ridge waveguides

Addresss the problem of designing polarization-insensitive Bragg gratings in zero-birefringence ridge waveguides. It is known that the reflection spectrum of a Bragg grating is be polarization-independent if both the phase-matching condition and the coupling coefficient are polarization-independent. While the use of a zero-birefringence waveguide can guarantee a polarization-independent phase-matching condition, it does not in general lead to a polarization-independent coupling coefficient. Our theoretical analysis indicates, however, that a strictly polarization-independent coupling coefficient is not essential for the achievement of a polarization-insensitive Bragg grating. Our detailed calculations on both corrugation and phase gratings in zero-birefringence ridge waveguides reveal some general design principles. Our results should be useful for the design of a wide range of Bragg-grating-based waveguide devices     

一种重构多信道布拉格光栅的混杂算法

由于光纤光敏性的限制,当信道数N变得很大时,采用幅度取样方式制作多信道光栅将变得非常困难.通过相位取样来制作多信道光栅被证明是一种能有效降低峰值折变量的方法.提出一种采用逆散射技术和优化策略的混杂算法有效地设计多信道光栅.由遗传算法进行优化,得到每一个信道相应的相位因子的最优值,改进了多信道光栅复杂的反射谱.再由Layer-peeling算法为依据引入了相位因子后的频谱响应重构光栅.通过对信道间相对相位的优化,制作这种多信道光栅所需的峰值折变量降低为单信道光栅的√N倍.经过数值仿真,得到8信道光栅的峰值折变量大约为单信道光栅的√8倍.     

Fabrication of High Quality Broadband Type IIA Chirped Fiber Bragg Gratings

Chirped fiber Bragg gratings have found many applications in optical communication and sensing systems. High quality filters based on chirped fiber Bragg gratings with reflection bandwidth of 2.6 and 32nm and high reflectivity are demonstrated experimentally with 2 and 4cm long phase masks, respectively. These filters with flat reflection band and high reflectivity are achieved by writing type IIA chirped Bragg gratings.     

光纤光栅反射波长移动研究

提出并实验了一种探测光纤光栅波长移动的新方法。该方法用一组与各个传感光纤光栅的参数对应相同的光纤光栅作为滤波元件,用抖动倍频的方法跟踪传感光纤光栅的反射光谱的峰值点,同时采用高分辨率的光栅尺作为系统的读出设备,彻底消除了压电陶瓷的非线性性及滞后性带来的误差,从而得到高精度的测量结果。     

光纤光栅反射波长移动研究

提出并实验了一种探测光纤光栅波长移动的新方法.该方法用一组与各个传感光纤光栅的参数对应相同的光纤光栅作为滤波元件,用抖动倍频的方法跟踪传感光纤光栅的反射光谱的峰值点,同时采用高分辨率的光栅尺作为系统的读出设备,彻底消除了压电陶瓷的非线性性及滞后性带来的误差,从而得到高精度的测量结果.     

线性啁啾光纤光栅变迹函数的研究

文中利用传输矩阵法对我们构造的四种变迹函数所描述的线性啁啾光纤光栅的光学特性进行了数值计算,并与常用的高斯型变迹线性啁啾光纤光栅的最佳光学特性进行了比较和分析,得出了一些有意义的结论,为设计和制作合适的线性啁啾光纤光栅用作色散补偿器提供了一定的理论依据。     

折射率非线性调制的双重光纤光栅特性

利用耦合模理论 ,系统分析了双重光纤光栅在折射率深度调制或非线性调制情况下的光谱特性。结果发现 ,在折射率非线性调制情况下 ,双重光纤光栅具有规则的多波长反射特性 ,同时 ,其反射光谱中的二次谐波也变得非常强 ,因此 ,它是一种实现多通道波分复用器、分插复用器及多波长激光器等的潜在技术。     

Long-phase error-free fiber Bragg gratings

Stitching errors in the phase mask degrade the spectral response of fiber Bragg gratings fabricated with the phase mask technique. We successfully fabricated a stitching error-free phase mask and applied it to the fabrication of fiber Bragg gratings (FBGs). The gratings have no observable excess sidelobes in the reflectivity and show excellent wavelength selectivity     

变迹光纤光栅中布拉格孤子相互作用特性的数值研究

在耦合模理论基础上,运用有限差分法分别数值模拟了布拉格孤子在抛物线平方变迹和高斯变迹光纤光栅中的相互作用。结果表明,同振幅孤子对在不同变迹光纤光栅中的相互作用特点都具有一定的规律性。在高斯变迹光纤光栅中,合适选择相对相位和相对振幅等参数可以使两个不同振幅孤子的相互作用表现为排斥作用,而在抛物线平方变迹光纤光栅中两个不同振幅孤子相互作用较复杂。     

Dispersion of optical fibers with far off-resonance gratings

We derive analytic expressions for the quadratic and cubic dispersion of optical fiber Bragg gratings, at frequencies far from the Bragg condition, where the usual coupled-mode theory (CMT) fails. We use these to design fibers that have no quadratic dispersion at a particular wavelength, but find that the cubic dispersion then increases. We also show that it is possible to design a fiber link with vanishing average quadratic and cubic dispersion by combining a length of standard fiber and a length of dispersion compensating fiber with an off-resonance grating     

利用均匀光纤光栅进行色散补偿

概述了光纤光栅的基本性质 ,介绍了均匀光纤光栅进行色散补偿的机理以及作者在这方面进行的工作 ,并与传统的啁啾光纤光栅色散补偿做了比较。从而得知 ,利用均匀光纤光栅的传输色散特性进行色散补偿是一种更行之有效的色散补偿方法。