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The details about the modulation property of the magnetic-fluid-based fiber-optic evanescent field modulator are studied in this article. Experiments show that it needs some time for the outgoing light from the modulator to reach the final steady value when the external magnetic field is turned on or off (called the relaxation property of the modulator). Two exponential functions are employed to fit the experimental data of the falling and rising relaxation processes in order to achieve the falling and rising response times. By this method, the magnetic field dependent falling and rising response times are gained. The physical mechanisms of the relaxation property of the modulator are discussed qualitatively. [ABSTRACT FROM AUTHOR]

A compact air-gap Fabry-Pérot fiber interferometer using magnetic fluids as the constituent material is constructed. The proposed structure possesses high sensitivity to magnetic field and is eligible for probing the tiny magnetic-field-induced volume variation of magnetic fluids. The underlying physical mechanisms for the magneto-volume variation are clarified in detail. The shift of the interference spectrum with magnetic field is employed for the magnetic field sensing applications. The highest sensitivity of magnetic field sensing for our experimental structure can reach 117.3 pm/mT when the sensing head is set at 45° azimuthal angle (with respect to the magnetic field direction). [ABSTRACT FROM AUTHOR]

A method for suppressing the field-induced agglomeration of magnetic particles in a magnetic fluid is proposed in this letter. After the magnetic fluid is doped with nonmagnetic silica particles, the field-induced agglomeration effect is weakened, and this suppressing effect is expressed by the measured birefringence magnitude and the simulation results of the agglomeration parameter. The optical properties of this system such as the optical transmission and response time are analyzed. With this method, the quality of the magnetic-fluid-based optical devices might be improved. [ABSTRACT FROM AUTHOR]

Birefringent effect dependent on magnetic intensity and wavelength in a water-based Fe3O4 magnetic fluid over the wavelength range of 400–700 nm is studied in this letter. The results are compared with the theory proposed by Llewellyn [J. Phys. D 16, 95 (1983)], in which the optical anistropic properties of the magnetic fluid due to the aggregation of the particles at a relatively low density is suggested. It is shown that the degree of aggregation corresponds to the value of the axial ratio of the aggregated particles. So does the magnitude of the birefringence. [ABSTRACT FROM AUTHOR]