Implementation of uniform diffraction efficiency of partially overlapping holograms in photopolymers based on the photopolymerization of a free radical

Wei Song,Shiquan Tao,Qianli Zhai,Dayong Wang

doi:10.1117/1.oe.52.4.045801

Wei Song, Shiquan Tao + Show 2 more

Open Access

https://doi.org/10.1117/1.oe.52.4.045801

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Abstract

The exposure schedule model for uniform diffraction efficiency is extended to be suitable for the partially overlapping multiplexing method. The proposed model is based on solving an optimization problem. Fifty holograms were multiplexed using the exposure schedule calculated with the extended model. The material used in the experiment is based on the photopolymerization of a free radical. By comparing the intensity of the reconstructed images during recording with that readout after recording, the calculated exposure schedule is verified to be effective to realize the uniform diffraction efficiency for the multiplexing holographic storage.

Highlights

Holographic storage is a potential data recording technology because of its high storage capacity and fast data rate.[1]
We have proposed a simplified model for grating formation in photopolymers based on the first-harmonic diffusion model[18] and extended the work to a calculation model for exposure schedules applicable to holographic recordings with common-volume multiplexing methods in single-monomer photopolymers.[19]
The exposure time for the sequentially recorded holograms is rising smoothly except for the 51st. It is reasonable because the diffraction efficiencies of the former 50 holograms are compensated in dark reaction and uniform postexposure (UPE) processes after holographic recording

Summary

Introduction

Holographic storage is a potential data recording technology because of its high storage capacity and fast data rate.[1]. In the dual-monomer photopolymer, the two kinds of monomers participate in the polymerization independently,[7] without influence on each other, during holographic writing, dark reaction, and postexposure In this way, the final refractive index modulation of the grating, ΔnðtÞ), should be expressed as. (1)–(3) and can be calculated with the polymerization time constant τP1, τP2, the diffusion time constant τD1, τD2, and the saturation index modulation ΔnSAT1, ΔnSAT2, respectively These parameters can be obtained by the data-fitting method with dark reaction and holographic writing experiments. Equations (1)–(5) together with all necessary parameters fitted from experimental data constitute the fundamentals of our exposure schedule model

Exposure Schedule Model for Partially Overlapping Multiplexing

Experiment of Multiplexing Storage

Conclusion