Fig. 1. Schematic diagram of the proposed magnetic field sensor.

Fig. 2. (a) Optical microscope image of the cross-sectional morphology of SMF and TCF, including the dimensions of the elliptical TCF cores and the splicing point between SMF1 and TCF. (b) Schematic diagram of the femtosecond laser micromachining system. The insert image shows an optical microscope image of the drilled microchannel through Core2.

Fig. 3. Transmission spectra of the pristine TCF and TCF with a microchannel filled with either air or an MF.

Fig. 4. Schematic diagram of magnetic field response measurement.

Fig. 5. Variation of the fringe dip wavelength with respect to an applied magnetic field, divided into sluggish area, high-sensitive area, low-sensitive area, and saturated area.

Fig. 6. (a) Transmission spectral evolution with an increasing applied magnetic field in the linear response region from 5 to 9.5 mT. (b) Variation of the fringe dip wavelength and dip intensity with respect to an applied magnetic field.