Designing the refractive indices by using magnetic fluids

Magnetic fluid is a type of colloid consisting of magnetic nanoparticles dispersed in liquid carriers with the aid of surfactants and Brownian motion. Thus, the optical properties of magnetic fluids can be manipulated through the careful selection of magnetic particles and carriers. In this work, we give an example by designing a refractive index by using magnetic fluids composed of various carriers and particles, around 1.465 at 1.557 μm wavelength, which plays an important role in optical fiber communication. In addition, we also show how to achieve a desired flexibility in the tunable refractive index with externally varying fields by adopting suitable magnetic fluid films. These results reveal the feasibility of developing index-match or index-tunable devices using magnetic fluids.