共查询到20条相似文献,搜索用时 992 毫秒
1.
We have computed the contribution of UV-light-induced densification to the refractive-index modulation of fiber Bragg gratings. Our results confirm that, for strong gratings written in Ge-doped silica fibers with 248-nm UV light, density changes account for a major part of the photosensitivity effect. 相似文献
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Multiwavelength Raman-fiber-laser-based long-distance remote sensor for simultaneous measurement of strain and temperature 总被引:2,自引:0,他引:2
We propose a simple and flexible multiwavelength Raman-fiber-laser-based long-distance remote-sensing scheme for simultaneous measurement of strain and temperature by use of fiber Bragg gratings. By combining two uniform fiber Bragg gratings with a tunable chirped fiber grating, we readily achieve simultaneous two-channel sensing probes with a high extinction ratio of more than approximately 50 dB over a 50-km distance. When strain and temperature are applied, lasing wavelength separation and shift occur, respectively, since the two uniform fiber Bragg gratings have identical material composition and different cladding diameters. This allows simultaneous measurement of strain and temperature for long-distance sensing applications of more than 50 km. 相似文献
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We present a novel and simple technique for obtaining transversal filters with negative coefficients by using uniform fiber Bragg gratings. We demonstrate a wide tuning range, good performance, low cost, and easy implementation of multitap filters in an all-optical passive configuration in which negative taps are obtained by use of the transmission of a broadband source through uniform Bragg gratings. 相似文献
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光纤光栅传输矩阵研究 总被引:5,自引:0,他引:5
利用模耦合理论给出并分析了一般坐标系下相移布喇格光纤光栅中的传输矩阵及其特性,所给出的传输矩阵具有分段不变性,而且不能被分解为一个矩阵和一个相移矩阵的乘积.利用该传输矩阵可以研究均匀、相移、啁啾、超结构等光纤光栅及光栅的级联等.计算了相移光栅的反射谱和相移量的关系,以及两个光栅级联时的反射谱.结果表明,同样相移量时的反射谱和已有文献不同,两个光栅级联时,也不同于已有文献,各自的谐振波长与光栅的级联没有关系. 相似文献
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Fabrication of long-period fiber gratings by focused irradiation of infrared femtosecond laser pulses 总被引:9,自引:0,他引:9
We have fabricated long-period fiber gratings by use of a novel technique using focused irradiation of infrared femtosecond laser pulses. We investigate the thermal stability of the fabricated fiber gratings. The values of the loss peak wavelength and the transmittance of the fiber gratings after heat treatment below 500 degrees C are the same as initial values before heat treatment. The fiber gratings that were fabricated by this technique have a high resistance to thermal decay. We propose that this technique will be useful for fabrication of fiber gratings with a superior aging characteristic. 相似文献
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We compare and analyze the filter properties of transmission-type volume holographic gratings, especially the dispersion characteristics for uniform and chirped gratings. It is theoretically and experimentally shown that the dispersion characteristics can be controlled by introducing one-dimensional chirping to the volume grating in a photorefractive crystal. The filter response including output power and dispersion comes from a combined effect of the spatial spectra of the grating structure, input beam, and output-coupling fiber mode. Filter responses can be designed by controlling these parameters for optical communication applications. 相似文献
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JosÉ Capmany Daniel Pastor Beatriz Ortega Jose Luis Cruz Miguel V. AndrÉs 《Fiber and Integrated Optics》2013,32(4):483-494
Some of the work that has been recently carried outjointly by the Optical Communications Group of the Universidad Politécnica de Valencia and the Optical Fibre Group of the Universidad de Valancia on the applications of fiber Bragg gratings to microwave photonics is described. The paper investigates separately some applications of linearly chirped fiber Bragg gratings (LCFBGs) and uniform fiber Bragg gratings (UFBGs). 相似文献
10.
S. V. Varzhel’ V. V. Zakharov G. N. Vinogradova A. V. Veniaminov V. E. Strigalev 《Optics and Spectroscopy》2013,114(1):116-119
Experimental results on visualization of type II fiber Bragg gratings induced in a birefringent fiber with an elliptical stress cladding are presented. The gratings are recorded by a single pulse of an excimer KrF-laser by means of the phase-mask method. Images of the gratings are obtained in a bright field using contrasting techniques such as differential interference contrast and dark field. It is shown that single-pulse recording forms several type II Bragg gratings in the optical fiber. The spatial profile of these gratings corresponds to the phase mask period. Microcracks due to which type II gratings are induced are localized both on the boundaries between the fiber core and claddings surrounding it and at some distance from them. 相似文献
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理论分析了利用高频CO2激光脉冲在不同类型光纤中写入长周期光纤光栅(LPFG)时光纤包层和纤芯发生折射率改变的机理和计算方法.结果表明,残余应力释放、快速固化、光纤致密化和熔融变形是高频CO2激光能成栅的主要原因,但采用不同的写入方法、不同的激光写入能量在不同的光纤类型上制作光栅时各种机理的重要性不同.利用长周期光纤光栅对构成的M-Z干涉仪实验测量了高频CO2激光以不同辐射能量在光纤不同作用位置所引起的光纤纤芯或包层的折射率平均变化量,并通过实际制作光栅的过程来初步验证光纤折射率的变化情况.CO2激光与光纤相互作用机理的分析和实验研究为利用这种方法制作折变型全光纤器件提供了实验制作的基础和完善工艺的方法.
关键词:
光纤器件
长周期光纤光栅
2激光脉冲')" href="#">CO2激光脉冲
折变 相似文献
12.
Dynamic arbitrary waveform shaping in a continuous fiber 总被引:1,自引:0,他引:1
We present a low-loss dynamic waveform shaping technique for high-repetition-rate signals by independent phase and amplitude control of spectral lines in a continuous fiber. Our system employs uniform fiber Bragg gratings to separate the spectral lines and provides independent amplitude and phase control for each line via an in-line polarization controller and an in-line fiber stretcher, respectively. Several distinct waveforms are experimentally demonstrated by manipulating five spectral lines with a spectral resolution of 0.12 nm and a temporal resolution of 17 ps. Better temporal resolution can be achieved by increasing the bandwidth through additional spectral lines. 相似文献
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We report here for the first time to our knowledge the formation and characterization of non uniform long and ultralong period reversible optical fiber gratings. Study of the spectral response of LPFGs with periods exceeding one millimeter is scarce. The Non uniform LPFG with periods exceeding one millimeter is practically induced in communication grade single mode fiber, and then apodization and chirping effects are experimentally characterized. The spectral response is then compared with spectral response of uniform grating. 相似文献
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提出了一种结构新颖的Sagnac干涉仪,分析计算了所含光纤光栅分别为均匀Bragg光栅和线 性啁啾光栅时的透射响应,得到了均匀光栅Sagnac环的解析解,发现含均匀光栅时可得到间隔均匀的通带结构,而含啁啾光纤光栅时只能得到间隔非均匀的通带结构.这两种结构都可 能有应用价值,前者可用在密集波分复用系统中,后者可用在光纤传感领域中.实验制作了 两种通带间隔不同的、通带数分别为8和16的多通带滤波器,实验证实了理论计算得到的结果.
关键词:
光纤光栅
Sagnac干涉仪
光学滤波器 相似文献
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Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains. 相似文献
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Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains. 相似文献
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A new exposure scheme for fabricating apodised fiber Bragg gratings by the use of a uniform phase mask and a Gaussian beam laser is demonstrated. Average refractive index is kept nearly constant along the grating to derive a side lobe suppression of 20 dB in the shorter wavelength. This scheme allows the writing of truly apodized fiber Bragg gratings. 相似文献
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A new and simple mathematical formulation that is employed to analyze numerically coupled-mode equations modeling uniform
and non-uniform gratings in optical fiber is investigated. This method would be straightforward and thus beneficial to solve
multimode coupled equations in comparison with a previously used fundamental matrix method, and the Runge--Kutta algorithm.
The new formulation proposed in this study is applied to calculate transmission and reflection spectra of core mode and higher-order
cladding modes of acoustically induced superstructure modulation caused by microbending through fiber Bragg gratings (FBGs).
Co-directional and contra-directional couplings based on acoustically induced modulation in FBGs have been discussed for a
variety of induced coupling coefficients. 相似文献
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M. J. Erro M. A. G. Laso T. Lopetegi D. Benito M. J. Garde M. Sorolla 《Fiber and Integrated Optics》2000,19(4):311-325
A way to model and test fiber gratings and fiber grating-based systems in the microwave range is proposed. The method rests on the equivalence relationship found between a fiber grating and a one-dimensional microstrip photonic bandgap structure that consists of a periodic pattern of circles etched in its ground plane. The equivalence assures that the frequency-response of the fiber grating is an upshifted replica of the corresponding frequency to its equivalent microstrip device. Both apodized and nonapodized uniform fiber gratings have been considered and the feasibility of the proposed method has been shown in simulation and measurement. 相似文献
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We have developed a simple method to analyze the growth process of fiber gratings (FGs) in the core of photorefractive optical fibers. It is based on the exponential saturation model and it takes into account the type of photosensitive fiber used, the exposure times, and the incident optical power. The photorefractive fiber has been characterized by two parameters: the saturation photoinduced refractive index change and the saturation energy, which can be obtained experimentally. We carry out a numerical investigation for the growth process of a uniform FG. The experimentally observed phenomena of shifting the Bragg optical frequency with exposure times and the appearance of higher-order Bragg resonances are predicted and discussed. 相似文献