||In this dissertation we proposed a Fabry-Pérot fiber interferometer based on a polymer microlens structure on the endface of a single-mode fiber. We can simply attach a fixed mass of polymer at the fiber end to form a microlens structure due to the surface tension effect. As the light wave propagates to the interfaces of SMF/polymer and polymer/air, we can obtain two reflective light beams with different optical paths to form the reflective interference spectrum. Besides, as the curvature of radius of the microlens structure increases, the average spacing of the interference fringe becomes larger in the same wavelength range.|
We have demonstrated the sensing applications of the microlens-based Fabry-Pérot fiber interferometers for temperature, surrounding refractive index, and pressure. The temperature sensitivity between 25℃ to 65℃ is 634pm/℃ for the 126.14μm microlens-based fiber interferometer. As we increase the surrounding refractive index from 1.33 to 1.4071, the 78.82μm microlens-based fiber interferometer shows a 6.38dB peak intensity difference, and the refractive index sensitivity is -82.26dB/RIU. In addition, the measured pressure sensitivity for the 75μm microlens-based fiber interferometer is 89pm/psi. We have also compressed the microlens structure by a movable object and found that the average spacing of the interference fringe becomes larger. As a result, our fabricated microlens-based Fabry-Pérot fiber interferometers can be utilized as useful sensors.