The effect of PQ concentration on holographic data storage in PQ/PMMA material

Phenanthraquinone-doped polymethyl methacrylate (PQ/PMMA) photopolymers with excellent characteristics of simplicity for manufacture, negligible photo-induced volume shrinkage, low cost, and high resolution for holographic data storage. In this paper, we explored the phenomenon of different PQ concentrations of PQ/PMMA photopolymers on collinear holography system. By designing a set of control experiments with different PQ doping ratios of 0.5%, 0.7%, 0.9%, 1% and 1.1% (1% means the ratio of monomer, thermal-initiator and photo-initiator are Methyl methacrylate:2,2'- Azobis(2-methylpropionitrile): PQ=100:1:1). And the Bit Error Rate (BER) of the reconstructed image using different PQ/PMMA photopolymers were measured, and we found that, at the value of the BER of 0.05, the material of 1% PQ/PMMA can last a longer time than other different PQ concentrations from 0.5% to 0.9% of PQ/PMMA at a recording beam intensity exposure. The 1.1% PQ/PMMA and the 1% PQ/PMMA can achieve the BER of 0.05 at the same time, but the 1.1% PQ/PMMA only last half time of the 1% PQ/PMMA. Furthermore, the diffraction efficiency has an obvious increase with the increase of the PQ concentrations from 0.5% to 1.0% of PQ/PMMA (from 10% to 60%), while it tends to decrease as the PQ concentration continues to increase to 1.1% due to the poor solubility. In summary, from the BER and holographic grating diffraction efficiency result, we got the optimal concentration of PQ in the PQ/PMMA photopolymer is 1%, and the current study is very meaningful for the use of PQ/PMMA in collinear holography data storage.