With the development of intelligent manufacturing and precision instruments, the demand for small stress monitoring is more and more big, the wings of the aircraft stress monitoring, for example, casting, welding and forming the residual stress in the process of monitoring, stress monitoring of electronic instrument circuit board, micro mechanical device to perform an action monitoring, micro bionic structure mechanics monitoring, etc. Optical fiber sensor is a flexible sensor, with light weight, small volume, electromagnetic interference resistance, water resistance, high temperature resistance, corrosion resistance and other unique advantages, has a wide range of applications in micro stress monitoring. How to design and fabricate high performance fiber optic stress sensor with smaller detection limit has become the research focus of this kind of sensor.

  A length of 4.5 mm hollow core fiber and single-mode fiber were spliced by fusion splicer to form a long distance micro-cavity, and then the end of another single-mode fiber was pulled into a suspended cone structure by laser splicer discharge tapering method, and a quartz microbubble with a diameter of 75 microns and a thickness of 200 nanometres was connected to the end of the suspended cone by UV glue curing. Finally, the suspended cone is inserted into the hollow fiber, the distance between the quartz microbubble and the hollow fiber-single-mode fiber interface is 14 microns, and the other side of the suspended cone is spliced with the hollow core fiber inlet through laser discharge. On one side of the quartz microbubble, the end face of the single-mode fiber and the two sides of the quartz microbubble form three FP reflection surfaces, and the reflected light beam can form three-beam FP interference in the fiber. By using this structure, the difference between the length of micro-cavity and interference can be increased, and the sensitivity can be greatly improved. Moreover, the interference quality can be effectively improved by using three-beam interference, and the characteristic peak Q value can be greatly increased by using multi-beam interference enhancement.

  This new fiber optic sensor requires very high-accurancy of fusion splicing.The usual arc fusion splicer may not meet this splicing requirement. A laser splicer maybe the solution. Shinho fiber communication is keeping R&D on the specialty fiber fusion splicer to meet all kinds of applications for specialty fibers.We will bring you the answer for this case very soon.

  The sensor has great application potential in such fields as aerospace, precision instruments and bionic engineering. In addition, the sensor Shi Yingwei bubble and hanging cone in connection with UV glue has a good win min feature, the sensor spectral reflectance in two different types of interference fringes will produce different response to temperature, using filter method respectively to extract the two kinds of interference fringes, monitoring the respective characteristic peak wavelength, still can use double parameters sensing matrix strain and temperature of the synchronous detection, Further expand sensor functions.