Erasable optical data storage

Other dye-based technologies evaluated for optical data storage include photo-chromic dyes for rewritable systems and azo dyes for holographic data storage. Spirobenzothiopyran dyes such as (40) absorb in the red/near-IR in their colored form and are suitable for erasible optical data storage [34]. Dyes for holographic data storage, such as (41), are similar to those used in nonlinear optics [35] (see below). 

Han YK, Ko BS. Synthesis of new erasable optical data storage polymers and their applications. Opt Mater 2003 21(l-3) 621-5. 

Scheme 4 Proposed optical data storage system based on optical switching of enantiomers, a) Writing with circularly polarized light (CPL), b) reading with linear polarized light (LPL) and erasing with unpolarized light (UPL).

A photorefractive polymer consisting of DMNPAA, TNF, ECZ, and PVK has been used for erasable/rewritable three dimensional bit optical data storage under two-photon excitation. A three dimensional bit density of 5 Gbits/cm(3) is achieved by pulsed beam illumination at an infrared wavelength of 800 nm in the recording process. 

D. Day and M. Gu. Use of two-photon excitation for erasable-rewritable three-dimensional bit optical data storage in a photorefractive polymer. Opt. Lett., 24(14) 948-950, July 1999. 

With the further development of new photo-erasable materials and advances in polymer film base technology a successful future for optical data storage seems assured. 

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