A cascaded symmetrical dual-taper Mach-Zehnder interferometer structure based on guided-mode and leaky-mode interference is proposed in this paper. Firstly, the interference spectrum characteristics of interferometer has been analyzed by the Finite Difference-Beam Propagation Method (FD-BPM). When the diameter of taper waist is 20 μm–30 μm, dual-taper length is 1 mm and taper distance is 4 cm–6 cm, the spectral contrast is higher, which is suitable for sensing. Secondly, experimental research on refractive index sensitivity is carried out. A refractive index sensitivity of 62.78 nm/RIU (refractive index unit) can achieved in the RI range of 1.3333–1.3792 (0%~25% NaCl solution), when the sensor structure parameters meet the following conditions: diameter of taper waist is 24 μm, dual-taper length is 837 μm and taper distance is 5.5 cm. The spectrum contrast is 0.8 and measurement resolution is 1.6 × 10−5 RIU. The simulation analysis is highly consistent with experimental results. Research shows that the sensor has promising application in low RI fields where high-precision measurement is required due to its high sensitivity and stability.
This paper proposes and experimentally demonstrates a non-invasive pressure measurement method based on magneto-mechanical effects. The relative permeability-stress curve is obtained using the J-A force magnetic coupling model, then imported into a finite element simulation model based on the coupled multiphysics of mechanical mechanics and static magnetics. The magnetic variations versus the pressure changes at the periphery of a pressure vessel are obtained through simulations and multi-channel magnetic measurement experiments. The proposed method shows good linearity in the range of 0-3 MPa, and is more sensitive for smaller, thinner vessels. Overrange measurement can lead to saturation. Measurement points need to be carefully chosen in order to achieve the highest sensitivity and precision. The highest sensitivity achieved is 1.314 ×10 −5 T MPa −1 , and the readily available sensitivity is about 5.0 ×10 −6 T MPa −1 . The precision in many cases is better than 0.1 MPa. The repeatability errors for the three components are about 2.7% of the full scale when referred to the most sensitive component. The measurement fluctuation over 48 h is 0.1 MPa when referred to the readily available sensitivity.
This paper optimizes the conditions for the formation of slow light produced by coupled fiber ring resonators. Investigated parameters include the number of rings, ring length, splitting ratio of couplers, and ring losses. The optimized parameters included two rings in the resonator, equal length of the rings, and splitting ratios of 90:10 and 50:50 for the couplers. Under these conditions, a slow light delay time of 32.0668 ns was achieved, which corresponds to a group velocity of 3.43 10 7 m/s.
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