Page 13 - Photoreactive Organic Thin Films

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14 Surface-Relief Gratings on Azobenzene-Containing Films
OSVALDO N.OLIVEIRA,JR.,LIAN LIJAYANT KUMAR, AND SUKANT K.TRIPATHY

14.1 Introduction 430
14.2 Processes of SRG Formation 432
14.2.1 Light-Driven Mass Transport 436
14.2.2 Ablation, Photobleaching, and Photodegradation 440
14.2.3 SRGs on LC Polymers 443
14.3 Theoretical Models 446
14.3.1 Free Volume Model 446
14.3.2 Field-Gradient Force Model 446
14.3.3 Mean-Field Theory Model 448
14.3.4 Model of Viscous Mass Flow 451
14.3.5 Diffusion Model 452
14.3.6 Model Using Jones Matrix Formalism 453
14.3.7 Comments on the Models 453
14.4 Factors Influencing the Formation of SRGs 454
14.4.1 Plasticization 454
14.4.2 Importance of the Dye and Degree of
Azofunctionalization 455
14.4.3 Polarization Dependence 456
14.4.4 Dependence on the Molecular Weight 458
14.4.5 SRG Inscription Requiring Thermal Treatment 459
14.4.6 Single-Beam Experiments 460
14.4.7 Dependence on the Beam Intensity 461
14.4.8 Main Chain and Conjugated Azopolymers 463
14.4.9 Film Architecture—SRGs Recorded on Organized Films and
Gels 464
14.4.10 Post-writing Evolution and Erasure Characteristics 468
14.5 Open Questions and Challenges for the Near Future 472
14.6 Possible Applications 473
14.6.1 Holography Applications 4 74
14.6.2 Liquid Crystal Anchoring 475
14.6.3 Waveguide Couplers 476
14.6.4 Intricate Surface Structures 477
14.6.5 Electro-Optic Devices and Second Harmonic
Generation 479
14.7 Final Remarks 480

15 Dynamic Photocontrols of Molecular Organization and Motion
of Materials by Two-Dimensionally Arranged Azobenzene
Assemblies
TAKAHIRO SEKI AND KUNIHIRO ICHIMURA

15.1 Introduction 487