Self-Enhancement of Scalar and Vector Holographic Gratings in Azobenzene Molecular Glassy Films

作     者：Andris Ozols Valdis Kokars Peteris Augustovs Dmitrijs Malinovskis Kaspars Traskovskis Elmars Zarins Girts Ivanovs 

作者机构：Faculty of Electronics and Telecommunications Riga Technical University Riga Latvia Faculty of Material Science and Applied Chemistry Riga Technical University Riga Latvia 

出 版 物：《Optics and Photonics Journal》 (光学与光子学期刊（英文）)

年 卷 期：2014年第4卷第6期

页      面：143-152页

学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学] 

主　　题：Self-Enhancement of Holograms Light Polarization Holographic Gratings Azobenzene Molecular Glasses 

摘      要：Self-enhancement (SE) effect of scalar and vector holographic gratings (HG) recorded in three different azobenzene molecular glassy films is experimentally studied in both transmission and reflection modes at 532 and 633 nm. The maximal SE factor (the ratio of diffraction efficiency to its initial value) SEF = 42 has been achieved. It is shown that the model of complementary HG can be applied also in scalar transmission thin HG case to explain coherent SE. The possibility of vector HG coherent SE in transmission mode is experimentally demonstrated for the first time (SEF = 4.3). The possibility of coherent HG SE in reflection mode is also established for the first time (SEF = 21). HG recording processes as well as coherent SE processes are found to be independent in transmission and reflection modes being determined by volume and surface relief HG, respectively. The permittivity gradient mechanism is proposed to explain the coherent SE of surface relief HG. Both HG recording and coherent SE efficiencies strongly decrease when HG period is decreased from 2 mm to 0.5 mm. No relaxational SE effect is found. Coherent SE effect in molecular glasses is found to be weaker than in inorganic materials.