| With the development of fiber and optical components,all kinds of new type of fiber have begun to emerge.Multicore fibers because of its advantage,such as high level of integration,compact structure and low cost,not only are widely used optical switch,wavelength division multiplexer,optical filters and other optical devices,but also used in the field of optical communication and optical fiber sensing.The fiber sensors based on multicore fibers have advantages of the high level of integration,resistance to electromagnetic interference,small volume and low cost.Due to the fiber sensors based on multicore fiber usually need optical coupling,it is very important to research the couple technology of the multicore fiber.In this topic,we have studied the fabrication method and characteristics of the multicore fiber coupler based on the thermal diffusion coupling method,and manufacturing method and characteristics of the twin-core fiber sensor based on the thermal diffusion coupling method.In this paper,we theoretically analyze and experimentally research the multicore fiber coupler based on the thermal diffusion coupling method.First of all,the transmission properties and the coupling characteristics of the twin-core fiber coupler based on the thermal diffusion coupling method are detailedly analyzed according to coupled mode theory.Then,Beamprop module of the optical simulation software Rsoft is used to build the model of twin-core fiber coupler based on thermal diffusion coupling method and analyze the simulation results of twin-core fiber coupler,and the results verify the correctness of the design.Afterward,using the multicore fiber made by our own laboratory,we fabricated multicore fiber couplers with the thermal diffusion technology.And the stress,temperature,and the refraction index and bending properties of the multicore fiber couplers were studied.We theoretically analyze and experimentally research the integrated twin-core and side-hole fiber Michelson interferometer based on the thermal diffusion coupling method.First,we introduced the fabrication method and interference principles of the Michelson interferometer based on the twin-core and side-hole fiber.Secondly,we theoretically analyze and experimentally research the bending properties of the Michelson interferometer based on the twin-core and side-hole fiber,according to the asymmetric distribution of the two cores ofthe used twin-core fiber,the interferometer can be used as the bending sensor which bend direction can be identifiable.Third,according to the characteristic that the output waveform power of the Michelson interferometer based on twin-core and side-hole fiber will shift with the change of the axial stress applied to the fiber,we used the Michelson interferometer based on twin-core and side-hole fiber to measure stress,the theoretical simulation and experimental research had confirmed that the Michelson interferometer based on twin-core and side-hole fiber can be used as the stress sensor.Forth,according to the characteristic that the output waveform power of the Michelson interferometer based on twin-core and side-hole fiber will shift with the change of the twist applied to the fiber,we used the Michelson interferometer based on twin-core and side-hole fiber to measure twist,the theoretical simulation and experimental research had confirmed that the Michelson interferometer based on twin-core and side-hole fiber can be used as the twist sensor.Last,theoretical research proves that the change of environmental temperature cause the shift of the output waveform of the Michelson interferometer based on twin-core and side-hole fiber,so the interferometer is used to measure the change of the temperature,and the experimental results showed that the interferometer can be used as a temperature sensor. |
