Biomolecular optical storage

A new application of bacteriorhodopsin (BR) in optical storage is presented. BR is used as the active layer of a Write-Once-Read-Many (WORM) storage which may be easily applied to a wide variety of substrates. The recording process uses polarization-sensitive two-photon absorption. As an example for this new BR application an ID-card equipped with an optical recording strip is presented. The capacity is about 1 MB of data per card. The recording density used currently is 125 kB/cm² which is far from the optical and materials limits but allows operation with cheap terminals. Data are stored in pages of 10 kB each. A special optical encryption procedure, which is first described here, allows to protect the stored data from unauthorized reading. The molecular basis of this process is described. A special property of BR in this application is that by biomolecular design storage, photochromism and traceability of the material are combined in a single molecule. BR introduces a new quality of storage capability for applications with increased security and anti-counterfeiting requirements.