Sensitivity improved tapered optical fiber sensor for dissolved oxygen detection

Abstract

A new method to improve the sensitivity of a fiber-based dissolved oxygen sensor by enhancing the evanescent field on the surface of optic fiber has been proposed and verified. The finite difference beam propagation method was used to simulate the transmission of light into the fiber. According to the simulation results, the evanescent field intensities of the step type fiber and tapered fiber were analyzed. Subsequently, a tapered fiber and step type fiber were fabricated. The layer-by-layer self-assembly process was used to place the fluorescent dye onto the surface of fiber. The reversibility, stability, response time, and temperature characteristics of the tapered fiber sensor were characterized. The experimental results show that the sensor has good repeatability, stability and temperature stability, with a response time of approximately 88 s for a change in dissolved oxygen concentration from 0 to 15 mg/L. The experimental measurements showed that the sensitivity of the tapered fiber dissolved oxygen sensor is 1.3-fold higher for dissolved oxygen concentrations from 0 to 15 mg/L compared to the step type fiber device.

Keywords:

• Dissolved oxygen
• finite difference beam propagation method
• layer-by-layer self-assembly
• optical fiber sensor
• tapered optical fiber

Additional information

Funding

This work was supported by the Fundamental Research Funds for the Central Universities under Grant N180402023 and N172002001; the Monitoring, Prediction and Scientific Research Project of the Seismological Bureau of China under Grant 1606X; the Spark Program of Earthquake Science and Technology under Grant XH13005Y; Key Research and Development Program of Shandong Province under Grant 2017GHY215010; and the Applied Basic Research Program of Qingdao under grant 17-1-1-99-jch.