Linear Birefringence and Linear Dichroism Coupled Optical Anisotropy of Magnetic Fluids by External Magnetic Fields

The optical anisotropy of magnetic fluids, including linear birefringence and linear dichroism simultaneously, under externally applied magnetic fields is investigated in this work. Analytical expressions to describe the polarization properties (direction of main polarization and degree of polarization) of the transmitted elliptically polarized light after the optically anisotropic magnetic fluids are obtained by theoretical derivation. Numerical examples are presented to examine the relationship between the polarization properties and the combined (coexistence of linear birefringence and linear dichroism) optical anisotropy. Applications to photonic devices based on the combined and "pure" (linear birefringence only) optical anisotropy are demonstrated. The notable discrepancy between the two cases at slightly high magnetic fields indicates that it is usually improper to ignore the linear dichroism for some applications.