Wavelength-switching fibre laser based on multimode fibre Bragg gratings

A multimode fibre Bragg grating (MMFBG) based wavelength-switching erbium-doped fibre laser is reported. With a simple singlemode fibre to MMFBG structure, a novel wavelength-selection technique is developed to achieve the wavelength-switching by changing the mode coupling condition in the multimode fibre. 31 discrete lasing wavelengths are obtained over a wide wavelength range.     

Reflectively tapped fibre optic transversal filter using in-fibreBragg gratings

A novel optical transversal delay line signal processor based on the use of in-fibre Bragg grating reflectors as tapping elements is presented. The requirements on reflectivity mismatch are analysed, and this is accurately controlled using postprocessing techniques. Results on frequency discriminator filters using reflectively tapped optical transversal filter structures demonstrate uniform and level responses >20 GHz with notch depths >44 dB     

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     

基于F-P滤波器光纤光栅解调系统

提出并实验演示了一种基于F-P可调滤波法对光纤光栅波长解调的新方案,利用参考光栅温度与其反射波长关系来检测传感光栅的波长移动量,该解调方法成本低.实验结果证明:采用此方法的解调系统波长测量精度达到5pm以上,有很高的稳定性,具有实际应用价值.     

Moving fibre/phase mask-scanning beam technique for enhancedflexibility in producing fibre gratings with uniform phase mask

A new and flexible technique for producing photorefractive fibre gratings with a uniform phase mask is demonstrated. By slowly moving the fibre relative to the mask as the writing beam is scanned, wavelength shifts, pure apodisation and phase-shifted gratings can be achieved     

基于包-全法的红外滤光片光学参数测量方法

为了研究准确性更高的复杂多层膜光学参数测量方法,测量实际镀制红外带通滤光片的光学参数,对红外滤光片研制过程的设计优化与工艺的改进具有重要的指导作用。首先,在研究传统薄膜光学参数光谱测量方法的基础上,提出了包-全法,并研究了该方法的基本思想、物理模型以及优化算法;其次,设计制备了2 000~8 000 nm谱段内膜料单层膜和高透射率、宽截止中波带通红外滤光片,通过对比测量单层膜光学参数反演计算光谱与实测光谱的差异,验证了包-全法测量膜料单层膜光学参数的准确度及有效性,依据测量结果确定了膜料色散关系,甄别了膜层工艺的优劣;最后,采用包-全法与全光谱拟合反演法对红外滤光片的光学参数作了对比测量验证。结果证明:该方法能够准确测量红外滤光片的光学参数,测量结果可用于指导修正设计与工艺之间的匹配性,进而研制了性能更好的红外滤光片。     

基于锁模光纤激光器的光学频率梳

基于锁模光纤激光器的光学频率梳是一种新型的光梳发生器。介绍了其产生的基本原理,分析了以射频标准、光频标准以及高次谐波与铯原子跃迁频率标准比较等方法对重复频率,进行精密控制,抖动在10μHz以内;以及采用基频倍频自参考法、2f-3f干涉法等对偏移频率8进行精确测定和稳定性控制,其稳定性达到10mHz。报道了国内外基于锁模光纤激光器的光学频率梳最新研究进展情况,并简单介绍了其在时间、长度精密测量以及与光频有关的科研生产领域中的应用,展望了未来的发展方向。     

一种基于采样布拉格光栅的梳状滤波器解决方案

基于采样布拉格光纤光栅,设计出一种多通道数梳状滤波器,所设计的梳状滤波器可应用于光纤通信中的波分复用（WDM）系统。在光栅中引入一种非连续线性啁啾阶梯式结构,并且在采样内,使折射率调制深度符合汉明分布,设计出一个具有26个通道、通道间隔25GHz的梳状滤波器,它能够产生具有平顶、陡峭边沿以及高透射率的多个相同的通带,可用作多通道光分插复用器,广泛应用于WDM系统。     

基于梳状滤波器的光纤甲烷传感器的研究

采用基于Sagnac的保偏光子晶体光纤(polarization-maintaining photonic crystal fiber,PM-PCF)滤波器,将宽带光源精确匹配甲烷气体在近红外波段的几个吸收线谱.设计出一个简单合理的多反射气室,使得光源和甲烷气体之间能够充分相互作用,提高了系统的灵敏度.同时,在测量甲烷气体浓度时,加入乙炔气体作为干扰,通过实验验证了该方案能够有效减缓交叉气体的灵敏度.     

Temperature-immune and intensity-referenced pressure sensor based on strain-induced quadratic-chirped fibre bragg grating

A technique for temperature-immune pressure measurement using a strain-induced quadratic-chirped fibre Bragg grating by differential optical power detection is demonstrated. Linear pressure measurement up to 20 kPa with a resolution of 0.05 kPa and thermal stability less than 2% full-scale for a temperature range from 0 to 80degC are achieved using pin photodiodes detection, without any temperature compensation     

Dual-wavelength single-longitudinal-mode erbium-doped fibre laser based on fibre bragg grating pair and its application in microwave signal generation

A simple dual-wavelength single-longitudinal-mode erbium-doped fibre laser is proposed by incorporating a fibre Bragg grating pair, which is used as a Fabry-Perot filter with two ultra-narrow (~0.12 pm) transmission bands. Stable dual-wavelength single-longitudinal-mode lasing with a wavelength spacing of ~0.08 nm is achieved at room temperature. By beating the dual-wavelengths at a photodetector, a microwave signal at 9.616 GHz is demonstrated with a frequency stability better than 1 MHz and a spectral width less that 10 kHz.     

Optical fiber gas sensor based on self-assembled gratings

The electrostatic self-assembled monolayer synthesis process is used to fabricate gas sensors by building up grating sensor elements on the ends of multimode optical fibers. These novel sensors can be designed to operate in the transmission windows of standard optical fibers and implemented using specific reference wavelengths to normalize the output signals. Experimental results for such sensors designed to detect dichloromethane gas are presented     

Multiwavelength all-fiber ring laser using side-polished fiber comb filter and mechanically formed long-period fiber gratings

Multiwavelength all-fiber lasers to be operated at room temperature are demonstrated. A side-polished fiber comb filter and mechanically formed long-period fiber gratings (LPFGs) are used to generate colasing operation. By using the band suppression characteristics of the LPFGs to prevent the gain cross-saturation effect, simultaneous lasing of four-wavelength peaks is obtained.     

基于光子晶体光纤Sagnac环梳状滤波器的设计

提出了由两段高双折射光子晶体光纤构成的Sagnac环滤波器,利用Jones矩阵理论对所提出的Sagnac环滤波器的传输函数进行了理论推导,并分析了光子晶体光纤双折射大小、两段光子晶体光纤的长度,以及偏振控制器的偏转角度对滤波器透射光谱特性的影响,并以此为基础设计出平顶梳状交错滤波器。此类滤波器在密集波分复用系统中有着广阔的应用前景。     

Tunable all-optical incoherent bipolar delay-line filter usinginjection-locked Fabry-Perot laser and fibre Bragg gratings

A novel tunable all-optical incoherent bipolar delay-line filter scheme is proposed. It utilises the cross-intensity modulation characteristic of an injection-locked Fabry-Perot laser and the reflection characteristic of a delay line composed of a sequence of tunable fibre Bragg gratings. Bipolar transversal filters are experimentally demonstrated and their filter performance agrees well with theoretical calculation     

基于光纤Bragg光栅的Fabry-Perot滤波器特性的分析

在分析光纤Bragg光栅Fabry-Perot(F-P)腔特征的基础上,提出了光纤Bragg光栅F-P滤波器的数学模型.利用传输矩阵法对光纤Bragg光栅F-P腔进行了理论分析.通过Matlab仿真工具数值模拟光纤Bragg光栅F-P滤波器的光谱,并对其特性进行了详细分析,得出了决定滤波器传输特性的相关参量及其影响规律.根据光纤Bragg光栅F-P腔的相位谐振条件,推导了光纤光栅F-P腔的腔长与光纤Bragg光栅常数之间的关系,从而为研制基于光纤Bragg光栅的F-P滤波器提供了依据.     

光栅错位光程差对马赫-曾德尔型光插分复用器性能的改善

在结合BG和马赫-曾得尔干涉仪(MZI)型OADM的结构上,提出在MZI两臂上的BG之间引入错位光程差,实现旁瓣抑制和邻道串扰改善.同时讨论了定向耦合器耦合系数和错位光程差的偏差对器件性能的影响.     

Transverse strain sensing based on optical fibre Solc filter

We present an optical sensor based on Solc filter to measure the transverse strain. The Solc filter is made of highly birefringent fibre by twisting its optical axes back and forth in equal sections. When a polarised light goes through the sensor, a periodic transmission response is obtained with a certain free spectra range (FSR) determined by the modal birefringence and the section length. The transverse strain can be measured by the shift of FSR from the transmitted response as the transverse stress changes the birefringence. More importantly we find that the measurement of transverse strain is free from the influence of temperature. We theoretically analyse the sensor model and simulate it by Jones Formalism. It is found that the sensitivity can achieve 7.14 pm/με. The influence of section length, wavelength of light source, modal birefringence and number of sections on the sensitivity is also investigated.     

基于光子晶体光纤长周期光栅的传感器研究

详细研究了光子晶体光纤长周期光栅(LPG-PCF)的应力和温度特性,利用成功制作的温度不敏感PCF-LPG,实现了两种结构简单光纤传感器.在温度不敏感应力传感器中,PCF-LPG作为温度不敏感的应力传感头,当以波长为1553nm的分布反馈(DFB)激光器为入射光源、用分辨率为0.001dB的光功率计测量时,PCF-LP...     

Simultaneous measurement of temperature and strain based on arc-induced long-period fibre gratings

A study on arc-induced long-period fibre gratings (LPFGs) revealed that their strain sensitivity depends on the electric current of the arc discharge. Based on that property, a sensor scheme comprising two concatenated LPFGs was implemented for discrimination of temperature and strain effects. This sensor presented resolutions of /spl plusmn/0.1/spl deg/C//spl radic/Hz and /spl plusmn/35 /spl mu//spl epsiv///spl radic/Hz, respectively.