No mention of how this works..<p>It's called "birefringence":<p>> The recently developed 5D optical storage technique uses birefringence as an extra degree of freedom – the property of a medium whereby its refractive index varies depending on the polarization and direction of incident light. Birefringence generated by the orientation and size of optical nano-gratings offers two extra dimensions, providing much higher storage capacities.<p>from <a href="https://www.5dmemorycrystal.com/technology" rel="nofollow">https://www.5dmemorycrystal.com/technology</a>