Broadband gradient refractive index planar lens based on a compound liquid medium

We have proposed a new method to achieve gradient refractive-index (GRIN) optics via a compound liquid medium. By adjusting the composition of the liquid medium, the refractive index of the compound liquid was tuned in a very broad range from 1.58 to 5.15. The liquid medium also exhibited weak frequency dependence. Based on these properties, we designed a liquid GRIN planar lens and experimentally demonstrated the feasibility of this approach. The beam deflection of the lens was controlled by adjusting the distribution of the refractive-index of the lens. By changing the composition of the compound liquids in different cells of the lens framework, different spatial gradually varied refractive index profiles have been achieved. The proposed liquid planar lens has shown a good directive property at different receiving angles and demonstrated a broadband performance between 12GHz and 15GHz. This method results in a rapid and flexible realization of gradient refractive index structures by using liquid medium.