Miniature Fiber-Optic Tip High Pressure Sensors Micromachined by 157 nm Laser

Two miniature all-fiber in-line tip pressure sensors fabricated by 157 nm laser are demonstrated. First, a sensor without any reflective coating been tested for pressure response in the range of 0-60 MPa, showing a sensitivity of similar to 0.01 rad/MPa, a linearity of 99.998%, and a long-term stability of +/- 0.04 MPa, respectively. For improving the sensor stability, sensor with high reflective coating is also demonstrated for comparison, which shows a long-term stability of less than +/- 0.02 MPA. Tolerance of the sensitivity of the sensors for 60 Mpa measurement range is +/- 5% for ten samples. These sensors could find important applications in automotive and aerospace industries, and down-hole monitoring, etc.