The last decades have witnessed intensive attentions focused
on the transformation optics, as well as the transformation acoustics, which have paved the way for the design of
metamaterials with unprecedented flexibility in controlling and guiding waves.
This results in various conceptual devices with wave-manipulation
functionalities, such as invisibility and illusion cloaks, field rotators, and omnidirectional absorber. Among these fascinating designs, the field
rotator is an important one which can be attributed as a special kind of
illusion cloak, with the capability of
making the object inside it appears like a rotated one. Moreover, it belongs to
a few of those designs that can be experimentally implemented, but only for
electromagnetic waves and liquid waves.