Measurement of the extinction coefficients of magnetic fluids

Abstract

A novel spectral transmittance approach for measuring the extinction coefficient of magnetic fluids is proposed. The measuring principle and accuracy of the approach are analysed. Experiments are conducted to measure the extinction coefficient of magnetic fluids with different particle volume fractions. The relative uncertainty of experimental data is less than 1.8%. The experimental results indicate that the extinction coefficient of magnetic fluids increases with increase of the volume fraction of suspended magnetic nanoparticles and the optical properties of the particle material have a significant effect on the extinction coefficient of the magnetic fluids.

A Highly Sensitive Intensity-Modulated Optical Fiber Magnetic Field Sensor Based on the Magnetic Fluid and Multimode Interference

“…The intensity attenuation is mainly caused by the evanescent field absorption coefficient of the MF. According to the evanescent field absorption theory in a multimode fiber [24], the change of is approximately in the order of 10 1 , and its influence on the intensity attenuation is not negligible, whereas because the change of is only of the order of 10 −3 , the wavelength shift on the transmission spectrum caused by the MMI is almost constant. Figure 8 is an enlarged view of dip (A) and peak (C).…”

“…When an external magnetic field is applied to the MF, the magnetic particles form the agglomeration and then chainlike clusters. The chain-like cluster of particles changes the extinction coefficient of MF, which determines the attenuation coefficient [23,24]. The intensity attenuation is mainly caused by the evanescent field absorption coefficient of the MF.…”

“…where is the evanescent absorption coefficient of the {LP 0 } mode with relation to the refractive index and the attenuation coefficient [24,25]. Figure 4 shows the calculated transmission spectrum of the SNS structure under different magnetic fields when the NCF length is 59.8 mm.…”

Complex refractive index of concentrated magnetic fluids

“…The influence of the magnetic field makes it possible to change the refractive index of a magnetic fluid and it gives prospects for the creation of magnetically tuneable optical devices. [5,6].…”

Terahertz Faraday rotation in a magnetic liquid: High magneto-optical figure of merit and broadband operation in a ferrofluid

“…In a normally isotropic ferrofluid, an external magnetic field parallel or orthogonal to the polarization plane of a propagating electromagnetic wave can induce linear (Voigt) or circular (Faraday) birefringence, respectively. Faraday rotation (FR) in ferrofluids, for example, has been demonstrated in the visible, 3,4 near-infrared, 5,6 and mid-infrared 7 regimes. Here, we investigate FR at the terahertz (THz) frequencies.…”