Tunable refractive index of magnetic fluids and its applications

Magnetic fluid is a type of colloid consisting of magnetic nano-particles dispersed in a liquid carrier with the aid of surfactants and Brownian motion. Thus, the optical properties of magnetic fluids can be manipulated through careful selection of magnetic particles and carriers. In this work, we give an example by designing a refractive index around 1.465 at 1.557 μm wavelength with magnetic fluids composed of various carriers and particles, that could play 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.