Determination of scattering mean free path in magnetic nanoparticle suspensions

Understanding the mechanisms of light scattering and diffraction in random media is of great importance for random lasers, and can play a vital role in the efficient use of materials for optoelectronic devices and magneto-optical applications. Here, the effect of dynamic properties of dispersed magnetic (Fe 3 O 4 ) nanofluids with different concentrations on the Gaussian laser beam passing through them was investigated, which involved the roles of magnetic field strength and response time factors. The results obtained showed that each of these two factors has a clear effect on the re-diffusion and distribution of nanoparticles (NPs), forming a layer of chains with different sizes. Moreover, it was found that the Fe 3 O 4 NPs can be focused at the point of interaction with the laser beam. The transmittance of the laser beam decreased as a function of the magnetic field strength and response time until reaching a critical point, followed by changing the transmittance for a certain period of time until reaching a second critical point. Different laser beam shapes were achieved under the influence of the investigating factors, significantly changing the resulting scattering mean free path (SMFP). This variation behavior of SMFP can be used in many applications, including random lasers and light radiation.