Fig. 1. Schematic diagram of light polarization modulation of the D-shaped fiber based on the magneto-optical dichroism of MF.

Fig. 2. Images of the polished surface of D-shaped fibers (a) A and (b) B. The widths of the polished surfaces are dA=124.2μm and dB=123.5μm.

Fig. 3. Optical images of MF films on the fabricated D-shaped fiber taken by a metalloscope (Leica DM4M). (a) shows the liquid MF film. (b) is solidified MF film in the absence of the magnetic field. MF films in (c) and (d) are solidified in magnetic fields. The arrows show employed magnetic field directions.

Fig. 4. Schematic diagram of the experimental setup for light polarization modulation and detection.

Fig. 5. U1(t) and U2(t) versus the sampling point of the DAQ card. (a) and (b) are for D-shaped fiber A. (c) and (d) are for D-shaped fiber B.

Fig. 6. Light polarization modulation when the surface widths of the D-shaped fiber are (a) 124.2 μm and (b) 123.5 μm. The magnetic field is 42 mT. The MF is diluted with water according to the volume ratio of 1:5.

Fig. 7. D-shaped fiber light polarization modulation when the magnetic field is 42 mT, the polished surface width of the D-shaped fiber is 124.2 μm, and the MF is diluted with water according to the volume ratio of 1:2.

Fig. 8. D-shaped fiber light polarization modulation when the magnetic field is 88 mT, the polished surface width of the D-shaped fiber is 124.2 μm, and the MF is diluted with water according to the volume ratio of 1:2.