No mention of how this works.. It's called "birefringence": > The recently developed 5D optical storage technique uses birefringence as an extra degree of fre

No mention of how this works.. It's called "birefringence": > 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. from https://www.5dmemorycrystal.com/technology https://www.5dmemorycrystal.com/technology