Magnetic field measurement device based on Sagnac interferometer

The invention discloses a magnetic field measurement device based on a Sagnac interferometer. The magnetic field measurement device comprises a light source, a 2*2 optical fiber coupler, a magnetic field sensing probe, an optical spectrum analyzer and a single mode fiber, wherein one end of the magnetic field sensing probe is connected with one port of the 2*2 optical fiber coupler through the single mode fiber, the other end of the magnetic field sensing probe is connected with the other port, on the same side with the port connected with the magnetic field sensing probe, of the 2*2 optical fiber coupler through the single mode fiber, a Sagnac ring structure is formed, and two ports on the other side of the 2*2 optical fiber coupler are connected with the light source and the optical spectrum analyzer respectively. Light given out by the 2*2 optical fiber coupler is divided into two beams of light, the two beams of light are transmitted in opposite directions, the phase difference between the two beams of light is sensitive to changes of an external magnetic field, changes of a Sagnac output spectrum of an optical fiber are caused by changes of the external magnetic field through interference of a Sagnac output end, and sensing measurement of magnetic field intensity can be achieved through measurement of changes of the output spectrum. The conical coreless optical fiber and a film are adopted for the magnetic field sensing probe, and in the range interval, the magnetic field sensing probe has the advantages of being high in linearity and sensitivity, simple, exquisite and the like.