Improved thermal stability of volume holograms recorded in nanoparticle–polymer composite films

Abstract

We examine thermal distortions of volume holograms recorded in (meth)acrylate photopolymers doped with SiO(2) or ZrO(2) nanoparticles. A holographic method is used to evaluate the temperature-induced Bragg-angle detuning of recorded volume holograms as a result of thermally induced refractive index and dimensional changes. It is found that the incorporation of inorganic nanoparticles into photopolymer leads to the effective suppression of these thermal changes, thereby extending the range of operating temperatures for their use in photonic applications.

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

“…The drastic improvement of thermal stability of recorded volume gratings was also confirmed. 7 Measured values for Dn sat and S exceeded the required minimum values of 5 Â 10 À3 and 500 cm/J, respectively, for HDS media. 8 Following our first demonstration of volume holographic recording in methacrylate-based NPCs incorporating TiO 2 nanoparticles, 3 acrylate-based NPCs incorporating similar and other inorganic nanoparticles (e.g., nanozeolites, semiconductor quantum dots, and LaPO 4 ) 9-13 as well as inorganic species introduced at a molecular level 14 were also reported.…”

A Review of the Optimisation of Photopolymer Materials for Holographic Data Storage

“…Tomita et al [66] examined thermal distortions of volume holograms recorded in (meth)acrylate photopolymers doped with SiO 2 or ZrO 2 nanoparticles. A holographic method was used to evaluate the temperature-induced Bragg-angle detuning of the recorded volume holograms as a result of thermally induced refractive index and dimensional changes.…”

Stoichiometric thiol-ene ratio dependence of refractive index modulation and polymerization shrinkage in holographic nanocomposite materials

“…The dispersion of 25 vol.% silica nanoparticles having the lower refractive index (1.46) would lead to large Δn since the refractive index of the thiol-ene monomer mixture is between 1.52 and 1.53 in the solid phase [8][9][10]. In addition, silica nanoparticles would provide better thermal stability of a recorded hologram than the case of using organic nanoparticles [9,10] since the coefficient of linear thermal expansion for inorganics is much smaller than that for organics and the sign of the thermo-optic coefficient dn/dT is opposite between inorganics and organics [7]. To sensitize in the green, we employed a titanocene organo-metallic complex, Irgacure 784 (Ciba), in combination with benzoyl peroxide, BzO 2 (Aldrich), as a visible initiator/sensitizer system [13].…”

“…The inclusion of nanoparticles increases the refractive index modulation Δn and the material sensitivity S that exceed the required minimum values of 5×10 −3 and 500 cm/J, respectively, for holographic data storage materials [6]. At the same time the mechanical and optical stability (polymerization shrinkage and thermal expansion/refractive index changes [7]) of recorded volume holograms in NPCs can be improved. However, polymerization shrinkage of holograms recorded in NPCs was of the order of 1% that was still larger than the required criterion of 0.5% [6].…”