The SMS Fiber Structure Based Devices And Its Application Study

As laser device and low-loss optical fiber come into being, the optical fibercommunication and fiber optic sensing become a reality. And they have a big advance innearly three decades. Multimode fiber has a wide range of application in fiber optic sensing,integrated optics and in the future’s fiber to the premise (FTTP). The single mode–multimode-single mode (SMS) fiber structure, which is an important part of multimode fiberdevices, has attracted a lot of attention in recent years. In this case, the SMS fiber structurebecomes a research hotpot gradually. Therefore, the study of SMS fiber structure devices hasimportant theoretical value and actual application value.In this paper, we design a variety of SMS fiber structure based devices after further studyof the function and application of SMS fiber structure devices. Moreover, we verify thefeasibility of these devices from the perspective of theoretical and experimental. First of all,the development and applications of optical devices is introduced, especially focused onresearch status and actual application state of SMS fiber structure devices.The SMS fiber structure based refractometer is studied in detail. The modes stimulated inmultimode fiber are analyzed by using the end-coupling theory and tested by experiments.The factors that affect the sensitivity of refractometer are analyzed. On this basis, the sensor isoptimized and the optimization program is verified successfully by simulation studies andexperimental tests.A strain based tunable band-rejection filter is designed by us through the study of SMSfiber structure. The analysis of the feasibility of such a filter is realized by use of beampropagation method simulation. The simulation results go well with experiment results.The coupled equations are derived for the first time when the single mode fiber splice tomultimode fiber with off-axis. A numerical analysis is also carried out by use of MATLABsoftware. We study different modes excited in multimode fiber under different off-axis. Andwe focus on the temperature and strain response of such a SMS fiber structure with off-axisfusion. The off-axis SMS fiber structure achieves two parameters of temperature and strainsensing at the same time through experimental tests.At last, the reflection spectrum of SMS FBG structure is analyzed in detail by use ofcompound coupled theory. We analyze the characteristic of SMS FBG structure under the condition of off-axis and co-axis welding by comparing. The potential application ofmulti-parameter sensing for off-axis welding SMS FBG is carried out by theoretical analysis.On the basis of predecessors’ research, we propose to write long period grating in multimodefiber of SMS fiber structure by use of metal-curing adhesive for the first time. Thecharacteristics of the SMS LPG are studied experimentally and good results are achieved.