LAUSR

Abstract A new C-type micro-structured grating structure was proposed for simultaneous measurement of depth and temperature in seawater. Because wedge-shaped defects got introduce, high birefringence was excited at fiber core of grating. Thermo sensitive materials filled in micro pores to improve the sensitivity of temperature. Then we established a mathematical model of birefringence effect in C-type structure. This work analyzed stress distribution in all directions under two disturbances. In pressure and temperature environment, reflection peaks in two-polarization states separated with a large offset. Two characteristic parameters:λB, y − λB, x, λB, y + λB, x were proposed for corresponding measurement. Structural parameters got optimize for better performance. Calculated output signals had high sensitivity and linearity under pressure range of 0–10 MPa and temperature range of 0–40 °C. λB, y − λB, x mainly responded to pressure, which got sensitivity −1.709 nm/MPa. While temperature mainly influenced λB, y + λB, x and the obtained temperature sensitivity was 1.054 nm/°C. This structure would have a great potential application due to the mature demodulation technique of grating signal.