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Study On Slow Light And Temperature Sensing Via Stimulated Brillouin Scattering In Optical Fibers

Posted on:2012-04-05Degree:MasterType:Thesis
Country:ChinaCandidate:H B LiFull Text:PDF
GTID:2178330335466976Subject:Electronic Science and Technology
Abstract/Summary:PDF Full Text Request
In the present communication system, optical-electric conversions are applied in many places, which limits the improving of communication speed seriously. Implementing all-optical communication is a dream of human on communication technology. In all-optical communication, all-optical buffer technology is a difficult problem. Slowing down the speed of light, i.e., slow light technology, is the key of actualizing all-optical buffer.Since slow light was implemented by Electromagnetically Induced Transparency, there are many ways of achieving slow light, such as Coherent Population Oscillation, Optical Parameter Amplifier, Stimulated Raman Scattering, etc. But most of those ways have many shortcomings, such as particular temperature, particular materials, particular wavelength, and incompatible with current communication system, etc. With incomes of room temperature, arbitrary wavelength, simple equipments, compatible with current communications system, Stimulated Brillouin scattering (SBS) via fibers becomes a research hotspot of slow light.In this paper, the coupling equations of SBS are solved numerically with Characteristics formula and fourth-order Runge-Kutt formula. We get some conclusions as follows:1. We first proposed a way of restraining pulse broadening by modulating the injected stokes pulse. The influence of shape of injected stokes pulse on SBS slow light is studied, considering the following factors of stokes pulse respectively: parameter m, duration and power. The results from our numerical calculation shows that increasing parameter m befittingly can restrain the increase of broadening factor. So far as time delay is concerned. With increase of parameter m, the average intensity of stokes pulse increases accordingly, resulting in reduce of max time delay. Because the larger power pulse has smaller saturation gain, its maximum time delay is smaller accordingly. Likewise, the pulse with shorter duration has less energy and attains larger saturation gain, resulting in larger relative time delay.2. By ameliorating conventional equipment of implementing slow light, a new distributed temperature sensing system is designed. A new idea of measuring temperature is proposed by measuring the power of output stokes pulse. Two designed plan of photonic crystal fiber are compared. To achieve the precision of 1 o C, the power measurement equipment only needs 40 dB dynamic range. Whereas,the equipment of the traditional frequency detection must reach 80dB dynamic range. Finally, some influencing factors of system accuracy are discussed. And some relevant solutions are described.Selecting the pretty shape of stokes pulse can overcome the shortcoming of higher time delay with higher broadening factor, which provide a preference for design of all-optical buffer and has an actual value. Comparing with traditional detecting Brillouin shift, this project of distributed temperature sensing overcomes the shortcomings such as weak signal, easy to disturb and difficult to measure. In spite of there are some problem with this project, it has higher theoretic precision and the possibility of applications.
Keywords/Search Tags:fiber, slow light, stimulated Brillouin scattering, time delay, broadening factor, photonic crystal fiber, temperature sensor
PDF Full Text Request
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