Integrated Chromatic And Modal Dispersion Measurement Using Microwave Photonic Techniques

Since the capacity limit of single-mode fiber,in recent years,space division multiplexing system has become a hot research.Mode division multiplexing is a major method of space division multiplexing,namely the use of a single mode fiber with orthogonal transmission modes to carry different channels of information.However,since the dispersion characteristics of few-mode fiber affects the overall performance of the transmission system,it is particularly important to characterize and test its modal dispersion(differential group delay)and in-mode dispersion(chromatic dispersion),which will have a crucial importance for implementation complexity of MIMO algorithm in receiver and dispersion compensation algorithm in long-distance transmission coherent optical communication.Measurement methods of modal dispersion and chromatic dispersion include interferometry,delay method and microwave photonics and other technology.However,there is no can take into account the research acquiring the modal dispersion and chromatic dispersion simultaneously.This article is based on sweep technology of microwave photonics technology,carried out an integrated measuring system of few-mode fiber dispersion characteristics,customized high-precision,simple,integrated dispersion measurement program.This paper presented theoretical and experimental research will focus on the following aspects: 1.A measurement system based on the spatial offset coupling model is proposed to measure the dispersion parameters in the few-mode fiber at the same time.The theoretical analysis is done and the measuring system is set up.The performance and details of the system are analyzed.The experimental results are given and the measurement accuracy and the deficiency are discussed.2.In order to solve the existing problems of spatial offset coupling model,we built a system with free-space photodetector,and carried out experiments and data processing to get the integrated measurement of modal dispersion and chromatic dispersion.At the last,we discussed the measurement accuracy and advantage.3.The dispersion curves based on the time-of-flight method are obtained,and the reliability of the two microwave photonics measurement methods is further verified.