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Investigation of the diffusion processes in a self-processing acrylamide-based photopolymer system
Izabela Naydenova1, Raghavendra Jallapuram, Robert Howard
1Centre for Industrial Engineering Optics, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland. izabela.naydenova@dit.ie
Applied Optics
|May 18, 2004
Summary
Two diffusion processes impact acrylamide photopolymer grating formation. Monomer diffusion enhances modulation, while polymer/radical diffusion reduces it, potentially limiting high-frequency response.
Area of Science:
- Photopolymerization dynamics
- Holographic materials science
- Optical data storage
Background:
- Acrylamide-based photopolymers are crucial for holographic applications.
- Optimizing high-spatial-frequency response is key for advanced applications.
- Understanding diffusion is vital for controlling photopolymerization.
Purpose of the Study:
- Investigate diffusion processes in dry acrylamide photopolymers.
- Determine the impact of diffusion on refractive-index modulation.
- Identify factors limiting high-spatial-frequency response.
Main Methods:
- Transmission holographic grating dynamics were monitored.
- Diffusion coefficients were measured at short exposure times.
- Refractive-index modulation was analyzed.
Main Results:
- Two diffusion processes with opposing effects on refractive-index modulation were identified.
- Monomer diffusion (D0 = 1.6 x 10^-7 cm²/s) increases modulation.
- Polymer/radical diffusion (D0 = 6.35 x 10^-10 cm²/s) decreases modulation.
Conclusions:
- A secondary diffusion process negatively impacts refractive-index modulation.
- This secondary diffusion may explain poor high-spatial-frequency response.
- Observed diffusion processes are faster than in high-performance photopolymers.