Ultrasensitive magnetic sensor using giant Faraday rotation

The present invention is a high-precision magnetic field sensor system relates to materials for use in this system. The sensor system measures the magnetic field with inorganic and / or organic magneto-optically active material such as a polymeric material, comprises an interferometer using the Faraday rotation. It is preferred polymeric material is a film. Polymeric material comprises Faraday rotation effect, an optical characteristic that sensitive to the magnetic field. Further, the present invention provides a sensor head structure comprising the polymeric material. The sensor head may comprise an optical fiber and a mirror. In particular, the present invention provides a fiber Sagnac interferometer for measuring the rotation of the polarization plane of the light. The present invention is capable of applying a passive phase bias to detect the magnetic field, to provide a Sagnac interferometer using a fiber or mirror. The present invention has the following three main embodiments of the. 1. Detection materials: polymers containing superparamagnetic nanoparticles shown conjugated polymers such as polythiophene, and / or a huge Faraday rotation. 2. Magnetic field probe comprising a composite material (e.g., film-like) of the polymer or polymer and nanoparticles. 3. Sensor: The sensor which Sagnac interferometer and the magnetic field probe is combined with the optical fiber.