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1.
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
2.
A novel scheme is proposed to transform a Gaussian pulse to a millimeter-wave frequency modulation pulse by using an apodized Moiré fiber Bragg grating in radio-over-fiber system. The relation between the input and output pulses is analyzed theoretically by Fourier transformation method and the requirements for the proposed fiber grating are presented. An apodized Moiré fiber Bragg grating is designed and its characteristics are studied. It is shown that the proposed device is feasible, and the new scheme is believed to be an effective solution for the generation of millimeter-wave sub-carrier in future radio-over-fiber systems. 相似文献
3.
利用矩阵分析法,针对两个相同光栅构成的光纤布拉格光栅法布里-珀罗(F-P)腔滤波器进行理论分析。数值模拟分析了光栅长度变化对光栅以及F-P腔滤波器反射特性的影响,指出光栅长度增加对反射特性影响的优缺点,分析利用常用切趾函数对光栅进行切趾,减小由于光栅长度增加导致反射谱的的旁瓣增大,对组成的F-P腔滤波器的反射特性的优化,得到了光栅切趾对F-P腔滤波器的反射特性的影响规律。对于在实际应用中制作出性能优良的光纤布拉格光栅F-P腔滤波器有一定的参考价值。 相似文献
4.
Nuran Dogru 《Optics Communications》2006,260(1):227-231
Mode-locking characteristic of hybrid soliton pulse source (HSPS) utilizing linearly chirped raised-cosine flat top apodized fiber Bragg grating (FBG) is investigated by using coupled-mode equations. It is found that the fundamental repetition frequency range of HSPS is significantly extended by using linearly chirped raised-cosine flat top apodized FBG instead of linearly chirped Gaussian apodized FBG. The range of repetition frequencies over which proper mode-locking is obtained is 2-3.3 GHz with linearly chirped raised-cosine flat top apodized grating whereas this range is 2.1-2.95 GHz with linearly chirped Gaussian apodized grating. 相似文献
5.
体光栅光谱合成技术是获得高功率激光输出的一种有效途径,体光栅衍射旁瓣是影响合成光束数目的主要因素。采用了Hamming切趾技术对体光栅旁瓣进行抑制,建立了Hamming切趾体光栅的折射率分布模型,分析了Hamming切趾体光栅的衍射特性,给出了Hamming切趾体光栅光谱合成效率公式,分析了切趾光栅对光谱合成效率的影响。计算结果表明:体光栅切趾后有效减小了体光栅对相邻合成光束的衍射损耗,切趾后,在20 nm的带宽内,谱合成光束的数目由13束增加为20束,谱合成效率达75.3%,光谱合成功率提高为切趾前的1.5倍。 相似文献
6.
Abstract This article presents a theoretical study of the dispersion properties of the asymmetrically apodized fiber Bragg gratings. It is shown that the dispersive behavior of these gratings may be changed from normal to anomalous, depending on the apodization function and the grating strength. The asymmetrical Bessel functions were chosen in order to demonstrate these properties of the gratings. The application of this effect in a dispersion-less Fabry-Pérot fiber cavity formed by two asymmetrically apodized fiber Bragg gratings is discussed. 相似文献
7.
We propose a flexible method for fabricating complex fiber grating structures based on sequential writing for fiber gratings with polarization control of the UV source beam. Pure apodized as well as arbitrary phase-shifted fiber Bragg gratings (FBGs) can be fabricated in a single scan. Experimental examples of raised-cos2 apodized and dispersionless FBG filters are given to demonstrate the feasibility of this method. 相似文献
8.
We theoretically and numerically demonstrate that a single fiber Bragg grating – conveniently apodized and of uniform period – operated in reflection can perform an arbitrary-order fractional integration of an input optical waveform. Analytical expressions were found relating the fractional integration order with the apodization profile of the fiber Bragg grating. This simple device shows a good accuracy calculating the fractional time integral of the complex field of arbitrary input optical waveforms. 相似文献
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10.
Longhi S Marano M Laporta P Svelto O Belmonte M Agogliati B Arcangeli L Pruneri V Zervas MN Ibsen M 《Optics letters》2000,25(19):1481-1483
Pulse-train multiplication based on the temporal Talbot effect in a linearly chirped fiber Bragg grating has been experimentally demonstrated. A 40-GHz repetition-rate, nearly transform-limited 10-ps duration optical pulse train at 1.533 mum has been obtained from a 2.5-GHz mode-locked Er- Yb:glass laser by use of a 100-cm-long linearly chirped apodized fiber grating. 相似文献
11.
Scalar diffraction theory is applied to analyze the intensity distribution in the fiber core during fiber Bragg grating (FBG) fabrication using an apodized phase mask. The averaged diffraction field distribution in fiber core was calculated as a function of optical fiber position. The results show that in a case of apodized FBGs fabrication, averaged field intensity profile, and thus refractive index changes in fiber core have complex form. Moreover, it was shown that the influence of optical fiber position behind the phase mask on average intensity distribution in fiber core decreases with increasing of its diameter. 相似文献
12.
Incorporation of a fiber Bragg grating to improve the efficiency of a 1580-nm-band tunable fiber ring laser 总被引:1,自引:0,他引:1
An efficient and tunable 1580-nm-band erbium-doped fiber ring laser is achieved by injection of amplified spontaneous emission in a conventional band by a fiber Bragg grating into the gain medium. The insertion of the fiber Bragg grating reduces the lasing threshold to 25%. The tuning range is 1560-1610 nm; the side-mode suppression ratio is better than 65 dB. 相似文献
13.
Asymmetrically apodized linearly chirped fiber Bragg gratings (FBGs) are shown to have highly linearized time-delay response. In simulations of a five-stage, 5-cm grating-based dispersion compensation system, asymmetrically apodized FBGs are shown to give over 60% reduction in the energy scattered from the main pulse body, 16 ps?60 ps pulses propagated over 800 km, as compared to a symmetrically apodized grating of similar length, strength, and bandwidth. 相似文献
14.
All-optical AND gate based on coupled gap-soliton formation in a fiber Bragg grating 总被引:2,自引:0,他引:2
We experimentally demonstrate an all-optical AND gate based on coupled gap-soliton formation in an apodized fiber Bragg grating. A switching contrast of better than 17 dB is obtained with an incident pulse peak power of 2.5 kW. 相似文献
15.
In this paper, a simple label eraser employing Gaussian apodized fiber Bragg grating (FBG) for all optical label swapping (AOLS) networks is proposed. Relying on the analysis of the payload through multi-stage erasers, this kind of eraser significantly improves the cascadability in comparison with the traditional fiber-loop mirror (FLM) eraser. The influences of the residual labels on the intermediate swapping node labels through the eraser are also investigated. It is shown that the power penalty is only less 1 dB when the optical power ratio of residual label to the new label signal arrives at -8 dB. The influence is negligible due to the sharp notch filtering effect of the Gaussian apodized FBG. 相似文献
16.
SHU Xuewen SHI Wei JIANG Shan HUANG Dexiu 《Chinese Journal of Lasers》2000,9(4):319-324
1 Introduction Fibergratingsareprovedtobeoneofthemostimportantrecentdevelopmentsinthefieldofopticalfibertelecommunicationsandsensing .Theyarelikelytohaveapplicationintwomainareas:dispersioncompensationinlong haulfibernetworks[1,2 ]andwavelengthroutinginw… 相似文献
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Simultaneous strain and temperature sensor based on the numerical reconstruction of polarization maintaining fiber Bragg gratings 总被引:2,自引:0,他引:2
C. Caucheteur F. Lhomm K. Chah M. Blondel P. Mgret 《Optics and Lasers in Engineering》2006,44(5):411-422
When a short-length fiber Bragg grating is inscribed into a polarization-maintaining fiber, the resonant peaks produced by birefringence can overlap. In this case, the discrimination between strain and temperature effects is only possible by means of polarization control devices, i.e. a linear polarizer and a polarization controller. To avoid this complexity and the measurement errors that it involves, we propose a novel demodulation technique based on the numerical reconstruction of the grating physical parameters. Our technique evaluates the grating parameters from the amplitude spectrum by means of the coupled-mode equations. The convergence tool used to search the solutions is the Nelder–Mead simplex algorithm. The method is tested on uniform and apodized Bragg gratings and a very good accuracy is reported. The method is finally applied to a 2 mm-long uniform polarization-maintaining grating in order to simultaneously measure longitudinal strain and temperature. 相似文献
19.
A temperature distribution sensing system based on the reflection spectrum of a 70 mm apodized chirped fiber Bragg grating has been demonstrated. Reflection variations created by the Fabry-Perot effect due to the intra-grating wavelength shift are presented. By fitting a parametric transfer matrix model of the grating response to measured spectra, the temperature change, position and width of a localized temperature change are obtained. This system is particularly attractive of its simplicity, high spatial resolution and ability in measuring a non-monotonic distribution. Experiments to measure two localized heating regions along the grating indicate that the technique is promising for measuring more complex temperature profiles. 相似文献
20.
Owing to the second-order fiber Bragg grating possessing narrower reflectivity bandwidth than first-order, an all-fiber spectroscopic filter with several second-order fiber Bragg gratings and optical fiber couplers in the visible region is designed to extract interest rotational Raman spectra. Considering the inference fringe visibility of inscribing fiber Bragg grating and the fiber core index dispersion effect, numerical simulations are made by the improved mathematical model based on an exponential photorefractive dynamic, and its simulative results show better agreement with the experimental data. We propose an all-fiber spectroscopic configuration, which could balance lidar sensitivity against signal-to-noise ratio for optimizing remote sensing performance by fiber Bragg gratings serially. Simulative results show that the thumb principle for fabricating second-order fiber Bragg grating is the increasing gratings length, and that this all-fiber spectroscope can achieve >70 dB suppression to elastic scattering and efficiently extract the rotational Raman signal for profiling atmospheric temperature. 相似文献