An effective broadband optical ‘cloak’ without metamaterials

An effective optical ‘cloak’ consisting of lenses was developed. Experiments show that it works well at multi-frequencies or in broadband in the visible range. The intensity distributions of the input beam and the output beam are almost the same, and the distortion of the wavefront of the output beam is negligible. This kind of ‘cloak’ is very simple and can be achieved with very low cost. Also, a theoretical explanation was given using theory of curvature sensing.