Multi-Parameter Sensors Based on Optical Reflective Coupler Probe

Abstract

We propose and demonst rate multi-parameter sensors based on optical reflective coupler probe (ORCP), for detection of liquid level, temperature, and refractive index (RI). Single-mode fiber ORCP (S-ORCP), few-mode fiber ORCP (F-ORCP) and multi-mode fiber ORCP (M-ORCP) are fabricated by adiabatically tapering and weak fusion technology. The highest liquid level sensitivity is 363.64 nm/mm, achieved by the M-ORCP, with detection limit of as low as 0.06 μm. In addition, multi-parameter measurement of liquid level, temperature and RI can be achieved by the M-ORCP, with temperature and RI sensitivities of −0.327 nm/°C and 7859.27 nm/RIU, respectively. With the merits of high sensitivity, stability, and compact half-coupler probe structure, the proposed ORCP sensors of ∼ cm length can measure the liquid level range of ∼3 mm, which have broad application prospects in the fields of fuel storage and chemical liquid level measurement, especially for chemical reagents, biological tissue liquids and flammable and explosive liquids.

Keywords

• Liquid level sensor
• multi-parameter
• optical reflective coupler probe
• low detection limit