This is some more in depth information on how the physics work in this use case:

Light is electromagnetic radiation, made up of perpendicular vibrations of electric and magnetic fields. Natural materials usually only affect the electric component – this is what is behind the optics that we’re all familiar with such as ordinary refraction.

But metamaterials can affect the magnetic component too, expanding the range of interactions that are possible.

The metamaterials used in attempts to make invisibility cloaks are made up of a lattice with the spacing between elements less than the wavelength of the light we wish to ‘bend’.

The silk-based cloak recently announced uses’split-ring resonators’ – concentric pairs of rings with splits at opposite ends. 10,000 gold resonators were initially attached to a one-centimetre-square piece of silk.

Wow!  We can’t wait for more advancements and applications in this area of study.

thanks to physics.org for the great info