Blue-sensitive rewriteable holographic media

Abstract

An easily fabricated organic holographic media is presented that is rewriteable, sensitive to 407-nm light, and that exhibits high storage capacity, photosensitivity, and environmental robustness. Data written in this media is nonvolatile to readout with the blue write beam, and is only erased by irradiation with UV light. Over 50 holographic write/erase cycles have been demonstrated to date.

Low‐Distortion Holographic Data Storage Media Using Free‐Radical Ring‐Opening Polymerization

“…This conclusion is also manifested in the measured sensitivity of the two samples, where unadjusted sensitivity (i.e., reciprocal of energy density required to produce from 10 to 90% of maximum obtainable index contrast, measured in cm 2 J À1 [18] ) of the LS-CAS 1 sample is only 20% less than that of the comparative control sample, while the RI adjusted sensitivity (i.e., the product of maximum obtainable RI contrast and unadjusted sensitivity [18] ) is less than one fifth of the comparative control sample.…”

“…However, polymerization-shrinkage-induced distortion is a major hurdle for the reliable use of photopolymers, and is repeatedly referred to in the literature. [7,8,10,17,18] Shrinkage arises from the formation of covalent bonds between monomers during the polymerization process where previously van der Waals interactions existed. Common monomers such as methacrylates, acrylamides, and styrene undergo large polymerization shrinkages of 14-23% (Scheme 1A).…”

“…[24,25] However, the two major systems that are of current commercial interest, are the two-chemistry free radical polymerization materials (InPhase Technologies) [17,18] and cationic ringopening polymerization media (Aprilis/Dow). [26] Each system has strengths and limitations.…”

Characterization of volume holographic recording in photopolymerizable nanoparticle-(thiol-ene) polymer composites at 404 nm

“…[15][16][17] as well as of all-organic photopolymers. [18][19][20] Despite large Dn sat and high thermal stability of volume gratings recorded in (meth)acrylate-based NPCs, shrinkage was at best a few %, still larger than the required value (<0.5%) for HDS applications. 8 This is due to the fact that all these reported NPCs employed monomers capable of free radical mediated chain-growth polymerizations in which gelation takes place early in conversion since high-molecularweight polymer is formed immediately in the crosslinking polymerization process.…”

“…31,[34][35][36] Thanks to the recent development of highly coherent blue diode lasers for HDS, 37 it is possible to implement compact HDS systems in the blue (at and near the 405-nm diode laser line). 38,39 The use of a blue diode laser provides higher storage capacity in HDS, [18][19][20][37][38][39] but the effect of grating distortions due to shrinkage on degradation in readout fidelity may become more significant than the case with a green laser. Therefore, we are now in a position to develop bluesensitive thiol-ene based NPCs with large Dn and low shrinkage.…”