Hongsheng Chen at Zhejiang University in China and an international circle of friends have created large-scale invisibility cloaks that work over the entire optical spectrum but can cloak in several directions at once.
Most animals cannot detect phase changes in light. Abandoning the requirement of phase preservation for natural light cloaking opens the door to hide large-scale living creatures.
They have built
1. square cloak with 90 degree symmetry, meaning it hides objects from view in the north, south, east and west directions.
2. A hexagonal cloak which hides in six directions.
A cloak that can hide living creatures from sight is a common feature of mythology but still remains unrealized as a practical device. To preserve the phase of wave, the previous cloaking solution proposed by Pendry et al. required transforming electromagnetic space around the hidden object in such a way that the rays bending around it have to travel much faster than those passing it by. The difficult phase preservation requirement is the main obstacle for building a broadband polarization insensitive cloak for large objects. Here, we suggest a simplifying version of Pendry’s cloak by abolishing the requirement for phase preservation as irrelevant for observation in incoherent natural light with human eyes that are phase and polarization insensitive. This allows the cloak design to be made in large scale using commonly available materials and we successfully report cloaking living creatures, a cat and a fish, in front of human eyes