Invisibility cloaks of light, which used to be confined to the imagination,have now been turned into a scientific reality, thanks to the enablingtheoretical tools of transformation optics and conformal mapping. Inspired bythose theoretical works, the experimental realisation of electromagneticinvisibility cloaks has been reported at various electromagnetic frequencies.All the invisibility cloaks demonstrated thus far, however, have relied onnano- or micro-fabricated artificial composite materials with spatially varyingelectromagnetic properties, which limit the size of the cloaked region to a fewwavelengths. Here we report realisation of a macroscopic volumetricinvisibility cloak constructed from natural birefringent crystals. The cloakoperates at visible frequencies and is capable of hiding three-dimensionalobjects of the scale of centimetres and millimetres. Our work opens avenues forfuture applications with macroscopic cloaking devices.
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