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 ~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 indus tries, and down-hole monitoring, etc.