共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
J. Canning 《Laser \u0026amp; Photonics Reviews》2008,2(4):275-289
Although mainstream grating writing, more often than not using single photon excitation of germanosilicate based defects with CW 244 nm light, remains the key technology for complex devices it is now being complemented by a whole host of processes which can enhance and tailor the properties of both conventional and not‐so‐conventional fibre Bragg gratings. Further, processes for writing of gratings in non‐germanosilicate fibres have also continued to develop and include multi‐photon excitation directly into the band edge of the glass. It is now possible to custom tailor a gratings property based on the application and the nature of production as well as custom tailor the grating writing process to suit the type of fibre and application. Examples and suggestions where these can benefit sensors and lasers are outlined. 相似文献
3.
A photonic crystal fibre Brillouin laser based on fibre Bragg grating Fabr-Perot cavity is presented. A highly nonlinear photonic crystal fibre 25 m in length is used as Brillouin gain medium and fibre Bragg grating Fabry-Perot cavity is chosen in order to enhance the laser conversion efficiency and suppress the higher-order Stokes waves. The laser reaches the threshold at input power of 35 mW, and the experimental laser conversion efficiency achieves 18% of the input power of 140 mW and does not show higher-order Stokes waves. A photonic crystal fibre Brillouin laser with shorter fibre length and lower threshold is experimentally realized. 相似文献
4.
Theoretical study and optimization of a high power mid-infrared erbium-doped ZBLAN fibre laser
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Based on the rate equations describing the erbium-doped fluoride glass(ZBLAN) fibre lasers with different pumping configurations being taken into account,this paper presents theoretical calculations related to the dynamic population density and the operation performance of a high power mid-infrared all-fibre erbium-doped ZBLAN fibre laser.It shows that the ground-state absorption,excited-state absorption and energy-transfer-upconversion processes co-exist and produce a population balance,causing the laser to operate stably at a continuous wave state.A good agreement between the theoretical results and recent experimental measurement is obtained.Furthermore,the laser structure parameters including fibre length,reflectance of output fibre Bragg grating and pumping configurations are quantitatively optimised to achieve the best performance.The results show,as expected,that the slope efficiency of the fibre laser can be improved significantly through optimisation,which then provides an important guide for the design of high-performance mid-infrared erbium-doped ZBLAN fibre lasers. 相似文献
5.
6.
High‐temperature tensile cell for in situ real‐time investigation of carbon fibre carbonization and graphitization processes
下载免费PDF全文
![点击此处可从《Journal of synchrotron radiation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Michael Behr James Rix Brian Landes Bryan Barton Gerry Billovits Eric Hukkanen Jasson Patton Weijun Wang Denis Keane Steven Weigand 《Journal of synchrotron radiation》2016,23(6):1379-1389
A new high‐temperature fibre tensile cell is described, developed for use at the Advanced Photon Source at Argonne National Laboratory to enable the investigation of the carbonization and graphitization processes during carbon fibre production. This cell is used to heat precursor fibre bundles to temperatures up to ~2300°C in a controlled inert atmosphere, while applying tensile stress to facilitate formation of highly oriented graphitic microstructure; evolution of the microstructure as a function of temperature and time during the carbonization and higher‐temperature graphitization processes can then be monitored by collecting real‐time wide‐angle X‐ray diffraction (WAXD) patterns. As an example, the carbonization and graphitization behaviour of an oxidized polyacrylonitrile fibre was studied up to a temperature of ~1750°C. Real‐time WAXD revealed the gradual increase in microstructure alignment with the fibre axis with increasing temperature over the temperature range 600–1100°C. Above 1100°C, no further changes in orientation were observed. The overall magnitude of change increased with increasing applied tensile stress during carbonization. As a second example, the high‐temperature graphitizability of PAN‐ and pitch‐derived commercial carbon fibres was studied. Here, the magnitude of graphitic microstructure evolution of the pitch‐derived fibre far exceeded that of the PAN‐derived fibres at temperatures up to ~2300°C, indicating its facile graphitizability. 相似文献
7.
This paper reviews recent progress in the nascent field of semiconductor optical fibres, from the fundamentals through to device demonstration. The incorporation of semiconductor materials into both the step‐index and microstructured fibre geometries provides a route to introducing new optoelectronic functionality into existing glass fibre technologies. Herein, the various fabrication methods that have been developed as of to date are described, and their compatibility with the different semiconductor materials and fibre designs discussed. Results will be presented on the optical transmission properties of several fibre types, with particular attention being paid to the observation of nonlinear propagation in silicon core fibres. Finally, some speculation regarding the future prospects and applications of this new class of fibre will be provided. 相似文献
8.
The measurement of micro-displacement or bending using a long-period fibre grating (LPG) in a self-referenced fibre optic intensity sensor is presented. The sensing head is based on a LPG whose attenuation peak changes as a function of its micro-displacement or bending and the fibre optic intensity sensor is referenced in frequency. Two other LPGs were used as rejection filters, located at the output of the optical source to shorten its spectral width. The implemented experimental set-up is described and, the results are presented being considered the measurement range and the intrinsic resolution. 相似文献
9.
Idowu David Ibrahim Tamba Jamiru Emmanuel R. Sadiku Williams Kehinde Kupolati Stephen C. Agwuncha Gbenga Ekundayo 《Composite Interfaces》2016,23(1):15-36
There has been a growing interest in the utilization of sisal fibres as reinforcement in the production of polymeric composite materials. Natural fibres have gained recognition as reinforcements in fibre polymer–matrix composites because of their mechanical properties and environmental friendliness. The mechanical properties of sisal fibre-reinforced polymer composites have been studied by many researchers and a few of them are discussed in this article. Various fibre treatments, which are carried out in order to improve adhesion, leading to improved mechanical properties, are also discussed in this review paper. This review also focuses on the influence of fibre content and fabrication methods, which can significantly affect the mechanical properties of sisal fibre-reinforced polymer composites. 相似文献
10.
A multi-wavelength microsphere laser system, using a chirped fibre Bragg grating and a microsphere resonator as wavelength-selective elements and a high dopant erbium doped fibre as the gain material, has been successfully demonstrated. The multi-wavelength generation of the laser system arises from both the microsphere whispering gallery mode selection and from the additional Raman scattering inside the microsphere cavity when the erbium laser is operating at resonance with the whispering gallery modes. Through an appropriate design and fabrication of a microsphere and of a fibre taper, a selective multi-wavelength fibre laser has been realized when the pump power is above threshold required. The laser output lines created have shown much narrower linewidths than those from conventional fibre lasers and these characteristics are particularly suitable for the range of sensor applications envisaged in the work. 相似文献
11.
研究了基于半导体光放大器(SOA)和双段级联取样光纤光栅构成的新型结构多波长激光器.设 计了取样光纤光栅,计算了其反射谱,模拟了多波长激光器的输出光谱.基于自行制作的SOA 和取样光纤光栅,进行了多波长激光器的实验研究,得到了间隔为0.8nm、输出功率不平坦 度小于1.0dB的11个波长输出.理论和实验两个方面都可以验证:与基于普通取样光栅的多波 长方案相比,基于双段级联取样光栅的方案能改善输出谱平坦度,并可提高可激射波长数.
关键词:
半导体光放大器
取样光纤光栅
多波长激光器 相似文献
12.
多层介质膜光栅是高功率激光系统的关键光学元件.为了满足国内强激光系统的迫切需求, 在大口径多层介质膜光栅的研制过程中,建立了单波长自准直条件下的衍射效率测量方法及其误差分析. 结果表明误差主要由探测器的噪声和测试人员的差异产生,对衍射效率测试精度的影响是±1%. 在此基础上,将光栅衍射效率及其分布测量技术应用于光栅制作工艺中, 作为大口径光栅无损检测的一种手段,如判断光栅掩模是否能进行离子束刻蚀、 离子束刻蚀的在线监测和是否需要再刻蚀,从而实现对大口径多层介质膜光栅离子束刻蚀过程的定量、 科学控制,提高了离子束刻蚀光栅制作工艺的成功率.利用上述技术,已成功研制出多块最大尺寸为 430 mm× 350 mm、线密度1740线/mm、平均衍射效率大于95%的多层介质膜光栅. 实验结果表明,该方法操作简单、测量快速准确,不必检测光栅微结构. 为大口径多层介质膜光栅研制的无损检测工程化奠定了基础. 相似文献
13.
F.J. McAleavey J. O'gorman J.F. Donegan J. Hegarty G. Mazé H. Poignant 《Optical and Quantum Electronics》2001,33(2):151-164
A wavelength tunable all fibre laser which utilizes Tm3+-doped fluoride fibre as a gain mechanism emitting around a wavelength of = 2.3 m is reported. Tm3+-doped fluoride fibre was coupled to a fibre Bragg grating inscribed in silica. This laser was evaluated by employing it as a wavelength tunable source in a methane gas optical sensor. A minimum gas detectivity of 100 ppm m limited by the ability to prepare low concentrations of gases was achieved. Emission wavelength control was implemented by thermally tuning the grating, although this method may prove to be too slow and cumbersome for practical use. A model describing the coupling between the silica fibre Bragg grating and the Tm3+-doped fibre was developed and integrated with a fibre laser model. This theoretical framework was used to examine the optimum silica and fluoride fibre parameters to achieve the maximum coupling between the fibres, with the aim of further reducing the fibre laser threshold. 相似文献
14.
15.
A long-period grating written in the SMF-28 fibre was heat treated at 1000 °C for 15 days. The spectrum of the grating shifted to longer wavelengths and the resonances depth decreased as a result of structural relaxation. The background loss increased considerably for times longer than 200 h, and this loss is caused by devitrification of the fibre. 相似文献
16.
A fabrication process for distributed multi-point fibre optic sensors based on cladding luminescence is presented. Fibres which have had their cladding removed are coated using a rig which pneumatically dispenses an epoxy phosphor mixture whilst the syringe is being moved axially along the length of the rotating fibre. The new coatings have uniform thickness on the fibre both radially and axially as well as having the same dopant density throughout the coating. A cross-sectional micrograph of a coated fibre is shown as well as the thickness distribution along the fibre. 相似文献
17.
Temperature or strain induced adjustable-chirp characteristics of uniform fibre grating with tapered metal coating
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Temperature and strain characteristics of uniform fibre grating with
tapered metal coatings have been analysed theoretically, by which
adjustable chirp characteristics of such gratings are shown.
Electroplating is adopted to fabricate such gratings, and the tapered
metal coating is obtained by gradually drawing the fibre grating out
of the solution during the process of electroplating. The gradually
changing cross-sectional area of the metal coating is calculated by a
newly suggested numerical method. By combining the theoretical and
numerical simulation analyses, the gratings' characteristics are
given at various temperatures and strains. The results obtained using
such a method are also testified by experiments. 相似文献
18.
Numerical investigation of slow solitons in Bragg gratings with a hyperbolic tangent apodization
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper numerically and analytically investigates the formation and propagation motion of optical soliton in the Bragg grating.We choose the fibre Bragg grating with hyperbolic tangent apodization in the middle section in order to obtain slower solitons.Optical fibre soliton but not Bragg grating soliton is used as input pulse in the discussion,which is much more approximate to the light source for the practical purpose.We discuss in detail the effects of the soliton’s velocity with some parameters in the process of transmission.The results show that by choosing special parameters,one can make the soliton slow-down with a little distortion and energy decay and obtain tunable time-delay on a small scale. 相似文献
19.
基于线性啁啾光纤布拉格光栅的色散补偿原理,探讨了不同的准高斯型耦合系数函数曲线对色散补偿特性的影响,建立使该光栅色散补偿曲线既具有高色散系数和宽带特点,同时对边峰还有相对的抑制能力的设计思想。文中讨论了相关参数对色散补偿曲线的影响。 相似文献