Label-Free Optical Fiber Glucose Biosensor Based on Two-Mode Interference

A label-free glucose biosensor has been proposed and demonstrated in this article based on a tapered two-mode fiber (TTMF) sandwiched between two single-mode fibers (SMFs). The tapering technique helps excite the LP11 mode in TTMF, forming uniform interference fringe containing the LP01 and LP11 modes. The experimental results show that the sensor's sensitivity increases, as the TTMF waist diameter decreases, and at the TTMF diameter of 13.12 mu m, the maximum glucose sensitivity can reach 0.112 nm/mg/mL, while the temperature sensitivity is as low as 16.43 pm/degrees C. With compact structure, label-free sensing capacity, and ease fabrication, this proposed biosensor has bright application prospect in the fields of food safety, disease diagnosis, and clinical analysis.