Photopolymers are special polymeric materials that can be irradiated with light to form polymer structures. It is widely used in the fields of 3D printing, anti-counterfeiting and information storage. In today's relatively mature holographic storage technology, high-density volume holographic data storage requires storage materials with a high response rate, high effective storage density and optical transparency, and high signal-to-noise ratio, etc. For this reason, storage materials have been studied in various fields. Phenanthrenequinone (PQ)/poly(methyl methacrylate) (PMMA) materials are a choice for holographic storage. By modifying the polymer substrate of the lamellar PQ/PMMA holographic polymeric material, it is possible to reduce the generation of bubbles during the preparation of the material to increase the usable area of the material, and at the same time, it is also possible to improve the photoreceptor sensitivity to a certain extent, to increase the read/write speed of the material and to analyze the causes of the phenomenon using the first nature principle calculations.
This paper proposes a fabrication method for realizing all-optical AND and NOR logic gates based on polarization holography. During the recording process, two specially designed polarization holograms are recorded at the dual-region position of the polarization-sensitive material. During the reconstruction process, two reading waves in different directions are used as two input lightwaves. The background lightwave is added to the propagation direction of the two reconstructed waves, and the two reconstructed waves superimposed with the background lightwave are used as two output lightwaves. The light intensity of the two output lightwaves, together, defines the logic signal of the final output. The all-optical AND and NOR logic gates fabricated using this method have the advantages of simple structure, low cost, and fast response.
Volume holographic storage technology expands two-dimensional storage to multi-dimensional high-density storage, which can realize the advantages of large data storage capacity and fast data transmission speed. For holographic storage, material selection is very important. Photoinduced polymers are considered as one of the most promising holographic storage materials due to their high resolution, real-time recording and rapid preparation. Among them, phenquinone doped polymethyl methacrylate (PQ/PMMA) photoinduced polymer has negligible shrinkage rate, sensitivity to light polarization, anisotropy and other properties, and can be preserved for a long time, which is a good choice for holographic storage materials. However, due to the low solubility of PQ in methyl methacrylate (MMA), the diffraction efficiency and sensitivity of the material are still limited, which cannot meet the requirements of high speed writing of holographic stored data. In this paper, vinylpyrrolidone (NVP) monomer was introduced into PQ/PMMA photoinduced polymer system. Because PQ has better solubility in NVP, doping NVP monomer into the original system can increase the concentration of PQ from 1.0wt% to 1.2wt %. Compared with the basic PQ/PMMA materials with 1.0wt% PQ, the photosensitivity of the NVP-PQ/PMMA material are increased by 2 times (from 0.35 cm/J to 0.70 cm/J), and the diffraction efficiency are increased by 20%(from 57% to 77%). Finally, by using NVP-PQ/PMMA materials in collinear holography systems, holographic data storage can be achieved faster and with lower bit error rate than basic materials. In conclusion, the introduction of vinylpyrrolidone (NVP) monomer into PQ/PMMA photoinduced polymer system effectively improves the holographic properties of the material and has the potential to be an excellent holographic storage material.
Phenanthraquinone-doped poly (methyl methacrylate) (PQ/PMMA) photopolymers have been considered a promising holographic recording medium for polarization holography due to their neglectable shrinkage, controllable thickness, and photoinduced anisotropy. Past studies have demonstrated that the polarization properties of PQ/PMMA materials are caused by the anisotropy of the photosensitizer PQ molecules. In addition, when measuring the photobirefringence value of the PQ/PMMA material, we can obtain a curve of photobirefringence values that is positively correlated with time. We prepared a new photopolymer material based on PQ/PMMA material. Specifically, we introduced the photoinitiator Triethanolamine (TEA) on the basis of PQ/PMMA material. Then we use the experimental optical path to record two beams of the orthogonal polarization interference light. By measuring the polarization state of diffracted light and the photoinduced birefringence curve of the material, we found the negative photoinduced birefringence phenomenon in PQ/PMMA material for the first time.
The tensor polarization holography theory has predicated some phenomena and been verified by the experiments. In the theory, the parameters α and β represent the scalar and tensor coefficients of the photoinduced change in dielectric tensor respectively. The ratio of α to β, called the exposure response coefficient, is a key to manipulate the polarization state of reconstructed waves and deepen the understanding of tensor polarization holography theory. In this work, for the polarization-sensitive material, phenanthrenequinone-doped poly methyl methacrylate (PQ/PMMA), we analyze the effect of interference angle and the polarization states of signal wave on the initial exposure response coefficient when the reference wave is s-polarized in linear polarization holography.
This paper analyzed the security of random phase encryption holographic storage technology. Taking binary random phase as an example, the recorded hologram is continually readout by series guessing reference. The experiment showed that the correlation coefficient between readout information and the recorded information was firstly decreased and then increased when the phase correct ratio of guessing reference is increased from 0% to 100%. The recorded information can’t be readout at all when the phase correct ratio of guessing reference range from 40% to 60%. Since the guessing reference with phase correct ratio between 40% and 60% has occupied majority guessing cases, the recorded information can’t be cracked in most cases. This indicates the high security of the random phase encryption storage technique.
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