啁啾和切趾函数可调的光纤光栅的扫描写入法

使用均匀相位模板和244nm倍频氩离子连续激光器,采用扫描写入法,制作了啁啾和切趾函数可调的光纤光栅。扫描器由微机控制。通过软件编程可动态高速扫描 速度及曝光量,操作简便、调整的灵活余地大。已在载氢的标准单模光纤上制作出了具有反射率、 高边模抑制比、平顶和不同带宽要求的光纤光栅。     

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.     

A novel dual-wavelength fiber Bragg grating and its application in fiber ring laser

A novel method for fabricating dual-wavelength fiber Bragg gratings (FBGs) by using one phase mask is developed. The method is based on a double-exposure technique. Our technique lends itself to writing gratings with controllable reflectivity and separation of two Bragg wavelengths. A grating with two equal transmission peaks of 20.25 dB is obtained by this method and the separation of the two Bragg wavelengths is about 0.8 nm. With the grating, we demonstrate a dual-wavelength erbium-doped fiber ring laser whose interval of the two peaks is 0.8 nm. The laser's peak powers can get 3.1 mW above and have a good stability.     

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     

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。     

Dispersive properties of planar polymer Bragg gratings

We report on the first dispersion study performed on planar Bragg gratings for WDM systems. The gratings are produced in low-loss single-mode polymeric waveguides and have a remarkable amplitude response (reflectivity >99.99%, suppressed out-of-band features). The phase response study shows that the dispersion that they introduce in a system (<100 ps/nm) is lower than that typical of fiber Bragg gratings     

用遗传算法从时延特性重构光纤光栅参数

提出了采用遗传算法(GA)结合传输矩阵法从需要的时延特性对光纤光栅进行参数重构的方法。该方法以时延为目标函数,由光纤光栅参数,包括光栅长度、折射率调制、光栅周期和光栅啁啾,组成种群中的待优化的个体,经过若干代遗传得到最优结果。用实值编码遗传算法实现了对均匀光纤光栅、啁啾光纤光栅和切趾啁啾光纤光栅参数的重构。数值仿真结果表明该方法对光纤光栅的时延特性参数重构十分有效。由斜率为100ps/nm,最大时延为300ps,中心波长为1555.2nm的理想线性时延特性重构出切趾啁啾光纤光栅的参数。此方法可以有效地从时延信息中提取光纤光栅参数,能够应用在利用光纤光栅时延特性的光控相控阵天线设计中。     

Minimization of phase errors in long fiber Bragg grating phase masks made using electron beam lithography

Centimeter-long fiber Bragg grating phase masks having several thousand periods are fabricated using electron beam lithography and require the stitching together of many electron beam writing fields. Two techniques are used to minimize the effect of phase errors arising from the stitching process. Fiber Bragg gratings with more than 99.9% reflectivity are photoimprinted using the phase masks and near perfect spectral response is obtained in spite of stitching errors.     

Fiber Bragg gratings with suppressed cladding modes made in SMF-28 with a femtosecond IR laser and a phase mask

High reflectivity fiber Bragg gratings (FBG) with strong cladding mode suppression were written in standard telecom fiber (SMF-28) with femtosecond 800-nm laser pulses and a phase mask. No special fiber photosensitization or fiber design was required. Induced index modulations were created by two-beam interference from the phase mask in both the core and cladding region, which resulted in cladding-mode coupling loss <0.1 dB for a high reflecting -30 dB in transmission FBG.     

带状光纤多波长阵列光栅刻写工艺研究

为了实现一次性在八芯带纤上不同波长阵列光纤光栅刻写,采用专门设计的带纤夹具夹持光纤,使用电控位移平台对带状光纤整体施加拉力,利用相位掩膜工艺对光纤逐根曝光,采用扫描写入的方法进行汉明切趾,仅用单一相位模板就实现了八芯带纤上不同波长阵列布喇格光纤光栅刻写。刻栅过程由电脑编程控制,中心波长、波长间隔以及切趾方式可以灵活调整。结果表明,获得的光栅其3dB带宽为0.2nm、波长间隔为0.5nm、波长偏差小于50pm、反射率达到80%~85%。此种带状光纤多波长阵列光栅刻写工艺是完全可行的。     

DBR掺饵光纤激光器的功率特性研究

本文主要研究ＤＢＲ掺饵光纤激光器的功率特性。通过对光纤Ｂｒａｇｇ光栅的光谱特性和激光器的传播方程的分析,得到了阈值泵浦光功率、掺饵光纤长度、Ｂｒａｇｇ光栅反射率与激光器输出光功率之间的关系。与近期报道的实验数据进行了比较,结果十分吻合。     

线性啁啾光纤布喇格光栅反射谱的数值模拟

为了研究线性啁啾光纤布喇格光栅的特性,并进一步把它用于光纤激光器上,介绍了线性啁啾光纤布喇格光栅的耦合模理论,采用4阶Runge-Kutta法和传输矩阵法结合控制变量法,对线性啁啾光纤布喇格光栅反射率与啁啾系数、半峰全宽与光栅长度、反射率与直流纤芯折射率改变量之间的关系进行了数值模拟。结果表明,线性啁啾光纤布喇格光纤可以展宽带宽。基于这个结论,提出了利用线性啁啾光纤布喇格光栅作为光纤激光器腔镜,使输出谱线展宽,从而可作为宽带光源使用的方案。     

基于多子群竞争进化规划算法的光纤光栅设计

从光栅传输矩阵分析法出发,提出了一种基于多子群竞争进化规划算法的光纤Bragg光栅(FBG)设计方法,进而设计了用于滤波的均匀FBG和用于色散补偿的啁啾FBG(CFBG)的结构参数.结果表明,本文设计方法可直接确定FBG的结构参数,在不同的设计精度要求下所设计的FBG分析曲线与目标曲线吻合很好,所采用算法具有比传统的进化规划算法快几10倍的收敛速度和更好的稳定性.     

纵向应力法制作双波长布喇格光栅

介绍了一种用一个均匀相位模板制作双波长布喇格光栅的方法;对这种方法制作的双波长布喇格光栅进行了理论分析,用矩阵分析法,对其进行了数值模拟.采用了移动曝光技术,通过调节所加应力的大小、光栅长度及曝光次数可以控制两个布喇格波长的间隔和反射率;写制了一个双波长光栅,两个透射峰均为19.5 dB,两个布喇格波长的间隔为0.78 nm.     

Spectral investigation of multimode fiber Bragg grating based external-cavity semiconductor lasers

The output spectra of external-cavity semiconductor lasers (ECSLs) formed by using different antireflection (AR) coated laser diodes (LDs) with multimode fiber Bragg gratings (MMFBGs), are studied systematically. It is found that the side mode suppression ratio (SMSR) of the output spectra of ECSL is dependent on the relative position of the Bragg wavelength and the intracavity modes of the LD, and this effect is more apparent when the reflectivity of AR coating of LD is increased. Numerical simulations are provided to explain the experimental observations. Furthermore, the requirements of wavelength locking of ECSLs with MMFBGs are found to be different from those with single-mode fiber Bragg gratings (SMFBGs). The conditions of wavelength locking of the MMFBG-based ECSLs in terms of gain margin between the material gain peak and the gain corresponding to the selected Bragg wavelength, reflectivity of AR coating of LD and reflectivities of the Bragg wavelengths of MMFBG are comprehensively investigated, and compared with the experimental results.     

光栅致双折射引起偏振相关损耗的理论分析

应用耦合模理论,给出均匀布拉格光纤光栅在考虑光栅致双折射时的透射与反射系数的解析式,按照测量偏振相关损耗(PDL)的确定性与非确定性两种方法,推导出了均匀布拉格光纤光栅中偏振相关损耗的解析公式。理论分析表明,该公式能够准确分析弱双折射光纤或者各向同性光纤上写入的均匀布拉格光纤光栅的偏振相关损耗特性,同时数值模拟高双折射光纤上写入的均匀布拉格光纤光栅偏振相关损耗特性,得到的结果也与已有实验曲线相近。     

New technique to accurately interpolate the complex reflection spectrum of fiber Bragg gratings

We demonstrate theoretically a new method to accurately interpolate the complex reflection spectrum of fiber Bragg gratings with a finite length at any desired frequency resolution. The required sampling resolution is significantly smaller than can be expected by directly using the sampling theorem for obtaining a low-error characterization of the reflection spectrum. A further decrease in the required sampling resolution by a factor of two is obtained by sampling both the complex reflection and the complex transmission functions. The new reconstruction technique may enable to significantly reduce the time needed to characterize fiber Bragg gratings and to interrogate fiber Bragg sensors.     

Fiber grating spectra

In this paper, we describe the spectral characteristics that can be achieved in fiber reflection (Bragg) and transmission gratings. Both principles for understanding and tools for designing fiber gratings are emphasized. Examples are given to illustrate the wide variety of optical properties that are possible in fiber gratings. The types of gratings considered include uniform, apodized, chirped, discrete phase-shifted, and superstructure gratings; short-period and long-period gratings; symmetric and tilted gratings; and cladding-mode and radiation-mode coupling gratings     

利用均匀光纤光栅进行色散补偿的数值分析和实验研究

介绍了利用均匀光纤光栅的透射色散特性进行色散补偿的机理 ,对其色散补偿效率作了数值模拟 ,并进行了利用均匀光纤光栅补偿色散的实验。通过与传统的啁啾光纤光栅色散补偿方案比较 ,得知利用均匀光纤光栅的透射色散特性进行色散补偿是一种行之有效的色散补偿方案