A tilted long period grating imprinted on a commercial plastic optical fiber for liquid level sensing

摘要

In this paper, a corrugated surface tilted long period grating (LPG) is proposed for liquid-level sensing. The tilted LPGs are fabricated on commercial plastic optical fiber (POF) by a simple mechanical die-press-print method. The liquid-level sensing performances of the so-obtained non-tilted LPGs (with the tilted angle of 0°) and the tilted LPGs (with the tilted angle of 10-30°) are investigated, respectively. The results show that the tilted LPG exhibits a better sensing performance than that of the non-tilted LPG. When the LPG period is 300μm, the groove depth is 155μm, and the tilted angle is 20°, the highest sensitivity of 0.417dB/mm is obtained by measuring the liquid-level with the refractive index (RI) of 1.33. In addition, the influence of RI on the liquid-level sensing performance of the sensor is also studied. The results show that the sensitivity of sensor is increased as the RI of liquid increased from 1.33-1.43, and the highest sensitivity can reach to 0.454dB/mm when the RI of liquid is 1.43. The proposed sensor is a low-cost solution for liquid-level measurement and with the features of easy fabrication, high sensitivity, and continuous measurement.