Temporal response and first order volume changes during grating formation in photopolymers
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|Title:||Temporal response and first order volume changes during grating formation in photopolymers||Authors:||Kelly, John V.
Gleeson, M. R.
Close, Ciara E.
O'Neill, Feidhlim T.
Sheridan, John T.
|Permanent link:||http://hdl.handle.net/10197/3411||Date:||Jun-2006||Abstract:||We examine the evolution of the refractive index modulation when recording gratings in an acrylamide based photopolymer. A nonlocal diffusion model is used to predict theoretically the grating evolution. The model has been developed to account for both nonlocal spatial and temporal effects in the medium, which can be attributed to polymer chain growth. Previously it was assumed that the temporal effect of chain growth could be neglected. However, temporal effects due to chain growth and monomer diffusion are shown to be significant, particularly over short recording periods where dark ﬁeld amplification is observed. The diffusion model is solved using a ﬁnite-difference technique to predict the evolution of the monomer and polymer concentrations throughout grating recording. Using independently measured refractive index values for each component of the recording medium, the Lorentz-Lorenz relation is used to determine the corresponding refractive index modulation. The corresponding diffraction efficiency is then determined using rigorous coupled wave analysis. The diffraction efficiency curves are presented for gratings recorded using short exposure times, monitored in real time, both during and after recording. The effect of volume shrinkage of polymer on grating evolution is also examined. Both the nonlocal temporal response of the material and monomer diffusion are shown to inﬂuence refractive index modulation postexposure.||Funding Details:||Science Foundation Ireland
Irish Research Council for Science, Engineering and Technology
|Type of material:||Journal Article||Publisher:||American Institute of Physics||Copyright (published version):||2006 American Institute of Physics||Subject LCSH:||Refractive index
|DOI:||10.1063/1.2200400||Language:||en||Status of Item:||Not peer reviewed|
|Appears in Collections:||Electrical and Electronic Engineering Research Collection|
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