Inscription high-fringe visibility Fabry-Perot etalon in fiber with a high numerical aperture objective and femtosecond laser

In this paper, a femtosecond laser micromachining system to fabricate a microfiber Fabry-Perot (F-P) cavity, and a real-time system to monitor interferometric intensity of F-P cavity have been developed. The relationships of fringe visibility of an F-P cavity on parallelism and surface roughness are analyzed and discussed. In order to eliminate the slope of the cutting section coming from the focusing optics, precompensation and double machining are introduced. The fringe visibility of a F-P interferometric sensor which exceeds 15 dB has been realized.