Dynamics of peristrophic multiplexing in holographic polymer-dispersed liquid crystal

Abstract

In this article, we derive a two-dimensional nonlocal diffusion model utilising finite difference time domain method, which describes the dynamics of how multiple holographic gratings are formed in a polymer-dispersed liquid crystal film for peristrophic multiplexing storage. This model takes into account the diffusion processes of both the free monomer and the liquid crystal molecules, and the polymerisation kinetics in the overlapped regions of multiple holographic gratings. We have experimentally found out that there exists a bounce in the diffraction efficiency for multiplexed gratings at relatively low-exposure intensities, which is undesirable for recording the equal-strength holograms. Instead, the equal-strength holograms can be stored under relatively high-exposure intensities. To predict the occurrence of bounce, the temporal evolutions of the refractive index modulation are estimated and then verified by the experimental results. The appropriate holographic exposure intensity for recording the equal-strength hologram is suggested.

Keywords:

• holographic gratings
• peristrophic multiplexing
• PDLC
• diffraction efficiency
• diffusion equations

Funding

This work was sponsored by 973 Program [grant number 2013CB328804]; NSFC [grant number 61307028], NSFC [grant number 61205183], [grant number 2013ZJ_0206]; Science and Technology Commission of Shanghai Municipality [grant number 11JC1405300], [grant number 13ZR1420000]; Fundamental Research Funds for the Central Universities [grant number XDJK 2011C047], and in part by Minhang Talent Program.