Research Of The Key Technologies Of Ultrahigh Dynamic Range OTDR

OTDR?Optical Time Domain Reflectometry?is a device used to analysis the quality of optical fiber by detecting the power of Rayleigh back-scattering light based on distributed optical fiber sensing.The quality of service of the optical network can be badly effected if an event such as the break or bend of the optical fiber happens.In order to ensure the quality of service of optical network,finding and processing events quickly in fiber in tens or hundreds of kilometer is necessary.OTDR is a kind of device that can analysis the quality of optical fiber efficiently.Dynamic range is one of the key technical indicators of OTDR.The distance that OTDR can detect is limited because of fiber loss and noise.The larger the dynamic range is,the farther the OTDR can detect.OTDR with 50dB dynamic range is realized in this thesis by using synchronous 2^nd order Raman amplifier and pulse coding method.The main content of the thesis includes:?1?Theories,background knowledge and technology indicators of OTDR are described briefly.Some exist technologies are also introduced.?2?The schemes of using synchronous 2^nd order Raman amplifier and pulse coding method are proposed to gain the SNR?Signal to Noise Ratio?.The solution has been realized and proved to be effective.An OTDR with 50dB dynamic range has been realized.?3?The solution of using 2D wavelet denoising method to decrease the power of noise in results is proposed to improve the signal to noise ratio.