Research On The Chromatic Dispersion Measurement Based On Microwave Photonics

With the development of long-haul and high-speed optical fiber communication technology, dispersion increasingly becomes a critical factor affecting the system performance. In the process of optical communication design, control and management of the dispersion value is even more important, while the dispersion effect can also be used for the generation of optical solitons in nonlinear fiber optics and super continuum spectrum generation. For these applications, the accurate dispersion measurement is particularly necessary and a variety of dispersion measurement methods have been proposed home and abroad, which have their own advantages, weakness and applicability.In this thesis, a novel dispersion measurement method is proposed and demonstrated based on microwave photonics, it can be used to measure the dispersion characteristic of optical fiber and other optical devices. In this method light with different wavelengths are simultaneously modulated by the same microwave signal and then transmit through the dispersive medium under test, the dispersion value of the test media at different wavelengths can be obtained by monitoring the changing interference microwave power after photodetector. The advantages of the proposed method include the following points:1. Phase noise induced from the different optical links can be avoided for the reference optical signal and the under test signal transmit in the same link in the measurement process;2. The dispersion curve in the scanning wavelength range can be easily obtained;3. The data process is simple, and both positive and negative dispersion value can be measured;4. It has more advantages for the measurement of large dispersion fibers, for it only need relative low modulating frequencies, and it has high accuracy.This thesis includes the following work:the dispersion measurement background is introduced at the beginning, and there is an overview of the general dispersion measurement methods; in chapter two principle of the microwave photonic dispersion measurement method is derived in detail and analyzed theoretically, and the measurable dispersion range and its influencing factors are given based on the instruments performance in our laboratory; the experimental verification of the proposed method is carried out in part three, and the dispersion value of25km single mode fiber(SMF),800m SMF and200m dispersion compensation fiber (DCF) are measured, meanwhile the repeatability and accuracy of this method is investigated, the results show that the repeatability measurement error can reach0.043ps/(nm·km), and the measurement accuracy can reach0.21ps/(nm·km), all the dispersion values are compared with data measured by the modulated phase shift method and the results are consistent; finally, the error source of the dispersion measurement is analyzed.