Transformation based diffusive-light cloak for transient illumination

In this work we design an unidirectional invisibility cloak for a diffusive-light medium based on transformation optics, which provides a broadband, passive and polarization-independent performance and can conceal macroscopic objects. Unlike the other cloaking designs based on scattering cancellation or transformation optics, our design can work under transient illumination, which is crucial in many applications, like time-of-flight imaging or high-speed communication systems. We demonstrate that this technique can also be applied to achieve a multidirectional performance with a polygonal cloak. Moreover, we propose and analyze a simpler design of unidirectional cloak based on a layered stack of two isotropic materials. The performance of the designed cloaks is numerically analyzed in transient regime and the successful concealment of the object is confirmed.