Polarisation selective all-fibre Fabry-Perot filters with superimposed chirped Bragg gratings in high-birefringence fibres

Periodic highly birefringent filters with 50 and 100 GHz free spectral range and finesse of up to 20 are demonstrated. With a polarisation peak separation of 25 GHz, the polarisation crosstalk was measured to be less than -16 dB.     

基于重叠写入啁啾光栅的Fabry-Perot腔的研究

以两段重叠写入的啁啾光栅作为反射面,构成光纤光栅Fabry-Perot(FP)腔.分别采用施加应力法和移动相位掩模板法,在同一段光纤中重叠写入啁啾光栅形成FP腔.使用啁啾量为1 nm的相位掩模板进行实验,两种方法曝光后的重叠啁啾光栅都可以形成明显梳状透射光谱.使用移动相位掩模板法,透射光谱的自由光谱范围(FSR)可达0...     

Compact all-fiber add-drop-multiplexer using fiber Bragg gratings

A novel compact all-single-mode fiber add-drop-multiplexer for dense wavelength-division-multiplexing systems is demonstrated. The device consists of a polished fiber coupler with identical Bragg gratings within the interactive length. The multiplexer operation has been theoretically analyzed and calculated transmission and reflection spectra are given. A fabricated prototype device shows good performance, but suffers from a high-insertion loss of 7 dB, which is due to the long but imperfect coupling region and can be drastically reduced in principle. A return loss >30 dB, coupling efficiency=99%, and bandwidth at FWHM /spl Delta//spl lambda/=1.2 mn was measured.     

Design of all-optical integrators and differentiators using Fabry-Perot filters based on fiber Bragg gratings

All-optical networks are the solution to overcome the speed limitation of electronic circuits. The basic and important components for all-optical circuits and optical signal processing are the integrator and differentiators. In photonics, there are many research, developments and implementations are going on in the area of above equivalents of fundamental devices that form basic building blocks in electronics signal processing. Here we are proposing a simple and cost-effective method to implement the optical differentiator and integrator using passive narrowband Fabry-Perot filters based on fiber Bragg gratings. Their high-speed performances are tested with Gaussian, Double Gaussian and Phase-Shifted Gaussian pulses.     

High-finesse large band Fabry-Perot fibre filter with superimposedchirped Bragg gratings

Filters with 100 GHz free spectral range (FSR) and finesse up to 16 are demonstrated over the 1525 to 1583 nm band. The photoinduced birefringence results in a polarisation-dependent spectral response. Finesse and FSR uniformity are addressed     

啁啾光纤光栅的制备研究进展

对连续啁啾光纤光栅和阶跃啾光纤光栅的制备研究情况做了概述,并对各种制备方法的特点进行了简要分析。     

An all-fiber dense wavelength-division multiplexer/demultiplexerusing photoimprinted Bragg gratings

A wavelength multiplexing/demultiplexing device is fabricated and used to drop/insert a single wavelength channel from/into a multiple wavelength transmission link with 100 GHz channel-spacing at 1550 nm. The device consists of an all-fiber Mach-Zehnder interferometer with photoinduced Bragg gratings. The following performances were measured: extraction/coupling efficiency =99.4%, excess loss <0.5 dB, adjacent channel-isolation >20 dB, and return loss >23 dB     

基于重叠多光栅的动态应变传感特性研究

利用重叠多光纤布拉格光栅(FBG)反射谱的时间同 步性,实现了动态或静态应变信号的高速传感与解调。给出了基于光纤F-P 可调谐滤波器(FFP-TF)的重叠多FBG解调系统及其时域重构的实现方法,重叠多FBG在FFP- TF 三角波扫描电压与动态应 变信号测量时产生时域上等间隔分布的传感脉冲,解调系统采用质心法硬件解算并结合平滑 滤波的方法可满足速度与解调精 度的同时测量需要。在重叠双FBG与500Hz FFP-TF扫描速率条件下 可产生2kHz的传感脉冲,动态应变信号的测量 带宽相对于单FBG解调系统提高了4倍,静态条件下的波长偏移小于±4pm。给出了影响重叠多FBG动态应变信号解调结果失真度的影响因素。     

Group-delay-tailored chirped fiber Bragg gratings using a tapered elastic plate

A new method to induce a strain gradient on a fiber Bragg grating is described. The method can be used to generate arbitrary strain distributions along the fiber. The objective of the method was to apply strain to a fiber grating that is attached on an appropriately tapered elastic plate. Using this method, linearly/nonlinearly chirped fiber gratings were prepared. Various group delay slopes were obtained depending on the plate shape and the applied strain. In addition, the repeatability could be maintained by adopting a feedback control method for the strain adjustment.     

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.     

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。     

Accelerated-aging studies of chirped Bragg gratings written in deuterium-loaded Germano-silicate fibers

Accelerated-aging studies of chirped Bragg gratings written in deuterium-loaded germano-silicate fibers were carried out using isothermal and continuous isochronal anneal methods. The master aging curve obtained from the isothermal decay is explained using the Arrhenius-rate-model-based equation. An empirical polynomial function was used to fit the continuous isochronal anneal data. The estimated attempt frequency (n) values from the two anneal methods were found to agree well within error. Further, the model-based calculations were found to predict postanneal long-term behavior of the gratings extremely well. Implications of the two anneal methods to accurately predict the thermal stability of chirped fiber Bragg gratings are discussed in light of rapid and reliable qualification of different types of gratings written in different fibers.     

Fabrication and characterization of bandpass filters based onconcatenated chirped fiber gratings

Practical, low-loss (<2 dB), fiber Bragg grating single-passband transmission filters have been realized with >30 dB out-of-band rejection over ~25 mm spectral widths. The approach adopted is based on the concatenation of two or more tailored broadband chirped gratings fabricated with low short-wavelength loss to maximize the rejection and stopband width in a filter with ~1 nm passband. The effect of thermal aging for similar complex structures is considered in the context of three different fiber types: standard telecommunication, high germania (Ge)-doped and boron/germania (B/Ge)-codoped. It is shown that while hydrogenated B/Ge-codoped fiber exhibits excellent photosensitivity, the resulting decrease in guiding strength and thermal stability may make germania-doped fiber the more attractive choice     

基于光纤F-P滤波器的全光纤水汽拉曼激光雷达系统的设计与分析

提出并设计了一套基于光纤F-P滤波器的可见波长域全光纤水汽拉曼激光雷达系统,实现对大气水汽和气溶胶的精细探测。讨论了光纤F-P腔内损耗和腔镜反射率对F-P透射谱的细度、峰值透过率以及带宽的影响,得到腔内损耗在小于3%的情况下,光纤F-P滤波器具有较高的峰值透过率（>0.5）和较窄的谱线带宽(<0.9nm)。通过结合光纤带通滤波器和二级级联光纤F-P滤波器的参数设计,在三个独立的光通道中分别实现水汽拉曼信号（660nm）、氮气拉曼信号(606nm)和米瑞利信号(532nm)的窄带宽、高透过率严格滤波,并获得对杂散光的高抑制率。通过系统仿真,对各散射信号强度分布、水汽廓线和探测信噪比进行了数值仿真计算,验证了系统方案的可行性。     

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.     

利用啁啾光纤光栅的色度色散补偿方案的研究

本文针对高速率光传输系统中的色度色散问题,利用啁啾光纤光栅,设计了后置补偿、前置补偿和混合补偿三种方案并实现了320k。的G．652光纤单信道40Gbit/s的无中继传输,仿真实验结果表明：较之后置补偿和前置补偿,混合补偿具有最好的色散补偿性能。     

啁啾光纤光栅中偏振模色散的研究

首先介绍了不同种双折射率差Δn的光纤制成的啁啾光纤光栅中偏振模色散现象 ,然后说明了光栅中偏振模色散的大小与 Δ n的相关性 ,并阐述了对用于色散补偿作用的啁啾光纤光栅中偏振模色散的消除 (补偿 )方法 ,最后指出利用啁啾光纤光栅中大的偏振模色散对高速光通信系统传输线路中偏振模色散的补偿方法。     

Large-band periodic filters for DWDM using multiple-superimposed fiber Bragg gratings

The tight specifications of dense wavelength division multiplexing (DWDM) filters are challenging for any available technologies. In this letter, periodic transmission filters based on superimposed chirped fiber Bragg gratings are designed to have flat amplitude response and nearly constant in-band group delay. These filters should prove to be useful as interleavers and mux/demux filters in DWDM systems.     

Custom design of long chirped Bragg gratings: application togain-flattening filter with incorporated dispersion compensation

We present and experimentally demonstrate simple relationships between the refractive index modulation, the chirp-rate or dispersion and the transmission loss through, and reflection of, chirped Bragg gratings, and apply them to the design of a new type of gain flattening filter with incorporated dispersion compensation     

啁啾光纤光栅色散补偿方案研究

设计了利用啁啾光纤光栅(CFG)对10Gbit／S光信号进行色散补偿的仿真模拟系统,该模拟系统研究了5种不同的色散补偿方案对系统误码率的影响,选出了最佳的一种补偿方案,模拟研究了入纤光功率对系统误码率的影响,结论是在保持光探测器接收功率不变的条件下,入纤光功率越高,误码率越大．对于最佳色散补偿方案,入纤光功率为6dBm时既能保证较高的传输功率又有较好的误码性能。