Spatial-phase-modulation-based study of polyvinyl-alcohol/acrylamide photopolymers in the low spatial frequency range.
Photopolymers are appealing materials for the fabrication of diffractive optical elements (DOEs). We evaluate the possibilities of polyvinyl-alcohol/acrylamide-based photopolymers to store diffractive elements with low spatial frequencies. We record gratings with different spatial frequencies in the material and analyze the material behavior measuring the transmitted and the reflected orders as a function of exposition. We study two different compositions for the photopolymer, with and without a cross-linker. The values of diffraction efficiency achieved for both compositions make the material suitable to record DOEs with long spatial periods. Assuming a Fermi-Dirac-function-based profile, we fitted the diffracted intensities (up to the eighth order) to obtain the phase profile of the recorded gratings. This analysis shows that it is possible to achieve a phase shift larger than 2pi rad with steep edges in the periodic phase profile. In the case of the measurements in reflection, we have obtained information dealing with the surface profile, which show that it has a smooth shape with an extremely large phase-modulation depth.
Gallego
Sergi
S
Departamento Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, 03690 San Vicente del Raspeig, Alicante, Spain. sergi.gallego@ua.es
Márquez
André
A
Méndez
David
D
Marini
Stephan
S
Beléndez
Augusto
A
Pascual
Inmaculada
I
D020106:Acrylamide / Q000737:chemistry*; D000465:Algorithms; D003432:Cross-Linking Reagents; D004867:Equipment Design; D008962:Models, Theoretical; D016011:Normal Distribution; D055096:Optical Devices; D055095:Optics and Photonics; D010777:Photochemistry / Q000379:methods; D011108:Polymers / Q000737:chemistry; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors
D003432:Cross-Linking Reagents; D011108:Polymers; D020106:Acrylamide; D011142:Polyvinyl Alcohol