Gallego Sergi, Márquez André, Méndez David, Marini Stephan, Beléndez Augusto, Pascual Inmaculada
Departamento Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, 03690 San Vicente del Raspeig, Alicante, Spain.
Appl Opt. 2009 Aug 1;48(22):4403-13. doi: 10.1364/ao.48.004403.
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.
光聚合物是用于制造衍射光学元件（DOE）的有吸引力的材料。我们评估了基于聚乙烯醇/丙烯酰胺的光聚合物存储低空间频率衍射元件的可能性。我们在材料中记录了不同空间频率的光栅，并通过测量透射和反射级次作为曝光的函数来分析材料的行为。我们研究了光聚合物的两种不同组成，一种有交联剂，一种没有交联剂。两种组成所达到的衍射效率值使该材料适合记录具有长空间周期的DOE。假设基于费米 - 狄拉克函数的分布，我们对衍射强度（高达八阶）进行拟合以获得所记录光栅的相位分布。该分析表明，在周期性相位分布中有可能实现大于2π弧度的相移且具有陡峭边缘。在反射测量的情况下，我们获得了有关表面轮廓的信息，这表明它具有平滑的形状且具有极大的相位调制深度。
