Reduction of transmission spectrum shift of long-period fibergratings by a UV-preexposure method

We examined the photosensitivity and stability in an ultraviolet (UV)-preexposure method that locks the photosensitivity of refractive index by hydrogen loading in the fabrication of long-period fiber gratings (LPFGs). Photosensitivity and stability comparisons are made between the UV-preexposure method, a typical hydrogen-loading method, and a UV-exposure method without hydrogen loading. The UV-preexposure method can enhance the photosensitivity to induce effective refractive index modulations up to 1.6×10^-4, which is sufficient for fabricating LPFGs in a practical manner under the hydrogen-loading condition at a relatively low pressure of 2.9 MPa. The sensitivity is preserved in terms of the length of time at least over 10 000 h. The spectrum changes after the completion of the LPFG writing are more stable than under the typical hydrogen loading. Therefore, the proposed UV-preexposure method is one of the most useful techniques for fabricating precise and stable fiber gratings, because there are no free hydrogen molecules in the fiber when the fiber gratings are written     

Study of the photosensitivity at 193 nm and comparison withphotosensitivity at 240 nm influence of fiber tension: type IIa aging

The photosensitivity in germanosilicate fibers at 193 nm is studied and compared with that at 240 nm. As previously shown, it is found that, without hydrogen sensitization, the initiation of the phenomenon is a one-photon process for a high germanium content fiber and a two-photon process for a low germanium content fiber. However, when the low germanium content fiber is previously loaded with hydrogen, it is observed that the photo-induced index change initial growth rate varies linearly with the fluence, invoking a one-photon process. It is shown that external strains applied to the fiber strongly influence the mechanisms of the photosensitivity at 193 nm. Finally, an aging study is carried out     

Sm~(+2)/Sm~(+3)掺杂铝硅基玻璃光纤的光敏特性研究

用2W多线输出功率的氩离子激光器照射Sm－2／Sm－3掺杂铝硅基玻璃光纤能产生5．1×10－3％的永久性折射率变化。通过测定LP11模截止波长的偏移能检测该光纤的光敏特性，同时在可见光区域能观察到宽消感应吸收带。Sm掺杂光纤光敏特性是由多光子增强的Sm+2离子消感应吸收过程所致。     

Sm~(+2)/Sm~(+3)掺杂铝硅基玻璃光纤的光敏特性研究

用2 W多线输出功率的氩离子激光器照射Sm~（+2）/Sm~(+3)掺杂铝硅基玻璃光纤能产生0.005 1％的永久性折射率变化。通过测定LP_(11)模截止波长偏移能检测该光纤的光敏特性,同时在可见光区域能观察到宽消感应吸收带。钐掺杂光纤光敏特性是由多光子增强的Sm~(+2)离子消感应吸收过程所致。     

光纤相位光栅（布喇格光栅）的制作

讨论了光纤的光敏性，并着重综述了光纤相位光栅（布喇格光栅）的制作方法。     

Fiber Bragg grating technology fundamentals and overview

The historical beginnings of photosensitivity and fiber Bragg grating (FBG) technology are recounted. The basic techniques for fiber grating fabrication, their characteristics, and the fundamental properties of fiber gratings are described. The many applications of fiber grating technology are tabulated, and some selected applications are briefly described     

掺Ge/B光纤紫外光敏性研究

本文分析了掺Ｇｅ／Ｂ比掺Ｇｅ光纤具有较高紫外光敏性的原因,并通过实验研究了氢载对掺Ｇｅ／Ｇ光纤紫外光敏性的影响。研究结果表明氢载可以提高掺杂Ｇｅ／Ｂ光纤的光敏性,而且它在氢载前后都存在曝光饱和点。     

Photosensitization of standard fibers with deep UV laser radiation

A strong and permanent ultraviolet photosensitivity enhancement was locked into standard optical fiber pre-treated with above-bandgap 157-nm F/sub 2/-laser radiation. Below-bandgap 248-nm irradiation of the pre-treated fiber yielded fiber Bragg gratings (FBGs) with an index contrast of 6.5 /spl times/ 10/sup -4/, a value four-fold larger than that available in 16% Ge-doped photosensitive fiber. The F/sub 2/-laser photosensitivity locking was 300 times more effective than with KrF-laser pre-treatment in terms of the accumulated fluence required to lock in a similar refractive index change. Accelerated FBG aging tests equivalent to 25 years at 70/spl deg/C revealed a less than 2% reflectivity decay in both 157- and 248-nm pre-treated fibers, which is sufficient to eliminate the postannealing step typically required in hydrogen-loaded fibers. The large photosensitization and the superior thermal stability of both 248- and 157-nm pre-treated fibers are associated with a new Si-H bond absorption feature at 1387 nm, which appears only during the FBG formation step.     

高掺锗紫外光敏光纤的研究

由于紫外光纤光栅的快速发展和广泛应用,迫切需要一种具有高紫外光敏性的特种光纤,使之更容易、更快速地在光纤拉丝时在线写入紫外光栅,研究发现高掺锗光纤能较好地满足其要求。通过采用ＭＣＶＤ光纤生产工艺研制出了纤芯折射率达４％ 的光纤,并用它成功的写出了紫外光纤光栅     

相位掩模法红外飞秒激光刻写光纤光栅技术

掺Tm3+光纤激光器在工业、医疗、科技及军事领域具有重要应用前景.光纤布拉格光栅(FBG)是构成光纤激光器的重要元件.但掺Tm3+光纤不具备光敏性,利用紫外脉冲激光很难在其中刻写FBG,即使采用增敏技术提高其光敏性,获得的FBG的折射率调制量也很小,尚不能满足应用要求,阻碍了掺Tm3+光纤激光器全光纤化的发展.以相位掩...     

光子晶体光纤的研究和应用

研究了光子晶体光纤的基本原理、基本特性以及其目前的研究进展,最后对光子晶体光纤的应用如光敏性、栅、色散特性等做了介绍。     

Strong fiber Bragg grating fabrication by hybrid 157- and 248-nmlaser exposure

A permanent 248-nm photosensitivity response was locked into hydrogen-loaded standard telecommunication fiber by uniform 157-nm F₂-laser pre-exposure. Strong (>30 dB) fiber Bragg gratings were efficiently generated after hydrogen out-diffusion, improving the thermal stability. The 157-mn radiation produced weakly absorbing Si-OH and Ge-OH absorption bands at 1.39-μm     

Design of a sinc-sampled fiber Bragg grating fabricated in high birefringence fiber

In this paper we design a new kind of sinc-sampled fiber Bragg grating which is fabricated in high birefringence fiber (HBF). The sampled grating has two sets of reflection spectra along two perpendicular polarization directions. The grating’s channel number can be doubled approximately by designing the refractive index difference between the fast and slow axes of the fiber, which enhances the utilization ratio and reduces the claim for photosensitivity of the fiber. The group delay characteristics are theoretically studied and side-lobes are depressed by apodization as well to get the optimized spectra. The results show that the comb-like spectra of the grating have promising applications in both multi-wavelength polarized fiber lasers and fiber sensing networks.     

基于紫外写入PCFBG的实验研究

光子晶体光纤Bragg光栅（PCFBG）是构建光子晶体光纤激光器的重要部件。利用高压载氢增敏技术和紫外聚焦加扫描写入法在光子晶体光纤上成功制作出了1058nm波段的Bragg光栅。同时结合理论模型,对PCFBG的性能进行了实验研究,并对光栅写入过程中存在的一些现象进行了分析。     

Photosensitivity Studies of Sm 2/Sm 3 Doped Aluminosilicate Fiber

ＰｈｏｔｏｓｅｎｓｉｔｉｖｉｔｙＳｔｕｄｉｅｓｏｆＳｍ＋２／Ｓｍ＋３ＤｏｐｅｄＡｌｕｍｉｎｏｓｉｌｉｃａｔｅＦｉｂｅｒ￥ＺｈｕＹｉ－Ｎｉａｎ（ＳｈａｎｇｈａｉＥｌｅｃｔｒｉｃＣａｂｌｅＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅ，Ｓｈａｎｇｈａｉ２０００９３，...     

Playing with fire and fibers

Annealing optical fibers has made the optical-fiber current sensor practical for monitoring and diagnostics by utility companies. To produce an annealed-fiber coil for this application, the annealing process must be held within time and temperature bounds or devitrification and OH absorption will degrade coil performance. Annealed-fiber devitrification can produce other useful fiber components, such as a fiber depolarizer and increased photosensitivity for FBG production     

聚合物光纤光栅制备进展

聚合物光纤光栅不仅具有体积小、质量轻、柔软、成本低等诸多优点，还因聚合物自身的特性而具有灵敏度高、响应范围宽、生物兼容性等优良特性。首先梳理了聚合物光纤的光敏性机理，概述了聚合物光纤光栅制备的刻蚀光源和方法；其次根据聚合物光纤的组成材料，概述了多种聚合物光纤光栅的制备进展和性能指标，包括聚甲基丙烯酸甲酯、环烯烃共聚物TOPAS、透明无定物氟聚合物CYTOP和聚碳酸酯。总之，目前聚甲基丙烯酸甲酯聚合物光纤光栅的研究占主导，而基于新型材料的聚合物光纤光栅因自身独特的优势也逐渐受到重视。     

Optical Fiber Index Taper–Theoretical Analysis and Experiment Demonstration

We discuss theoretical analysis of optical fiber taper with its refractive index gradually changing alone its propagation axis caused by photosensitivity. The numeric results for two different taper shapes in step-index fiber show that the couplings of fundamental mode to the reflected mode and to high-order modes is relatively small provided the change is gradual. The fundamental mode has the capability of excellent transmission that can adjust itself adiabatically to the refractive index change. The experiment demonstrates its effectiveness for optical interconnection with different mode-fields     

硫化物光纤及其功能器件的应用

本文概述了９０年代初兴起的硫化物光纤的独特性能、目前的发展状况及可能的应用前景;针对硫化物光纤实用化中的关键技术进行了分析,并对硫化纤的光敏机理作了一定的探讨。由于具有优于石英光纤的特点,硫化物光纤及其人器件具有广阔的应用前景。     

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