Finnish-Japanese Workshop on Functional Materials Espoo and Helsinki, Finland 25-25.5.2009 Utsunomiya Univesity Center for Optical Research and Education Center for Optical Research and Education Toyohiko Yatagai SURFACE RELIEF GRATING AND RETARDAGRAPHY: SURFACE RELIEF GRATING AND RETARDAGRAPHY: OPTICAL MANIPULATION OF AZOBENZENE POLYMER FILMS AND ITS APPLICATIONS FILMS AND ITS APPLICATIONS
OPTICAL FUNCTIONAL DEVICES USING AZOBENZENE POLYMER FILM Photoisomerization Photoisomerization Surface relief grating Surface relief grating Retardagraphy: recording of optical polarization and R t d h di f ti l l i ti d reconstruction of complex amplitude Functional devices based on multilayer polymer thin film film
PHOTOINDUCED MASS TRANSPORT Nanofabrication, photo-mechanical N nof b i tion photo me h ni l devices R Two beam R Light interference N N R' Light or N N thermal C Cys form f R' Trans form Azobenzene Photoinduced surface relief (PSR) formation P . Rochon et al. , Appl. Phys. Lett., 66 , 136 (1995)
POLARIZATION DEPENDENT POLARIZATION DEPENDENT 50 μ m 10 μ m
MULTIPLE RECORDING GRATINGS MULTIPLE RECORDING GRATINGS Orthogonal grating structure Surface relief grating Hexagonal structure Blazed grating structure
RELEIF DEPTH CONTROL BY ELECTRIC FIELD H Homogenious i Illumination or heating Heating +electric field applied substrate Heater
COMPUTER SIMULATION BASED ON VISCOUS FLUID MODEL Navier-Stokes equation Viscous Outer force Inertial Pressure term term term term t term t term Continuity equation Continuity equation u : velocity vector
COMPUTER SIMULATION OF MASS TRANSFER COMPUTER SIMULATION OF MASS TRANSFER Nd:YAG Laser (532 nm) Intensity:50 mW/cm 2 :Electric Field :Wave number :Wave number 1 μ m
SUMMARY IN SURFACE RELIEF GRATING ・ Origin of mass transfer: Origin of mass transfer: gradient of light intensity gradient of light pressure surface tension surface tension ・ SRG generation is mainly due to electric dipole interaction with outer p electric field.
PHOTOINDUCED BIREFRINGENCE Optical storage media, polarization Opti l to ge medi pol i tion controllable devices Retardagraphy Optical recording technique for th the retardance of a birefringent object t d f bi f i t bj t Liquid crystal spatial light modulator Multivalued phase recording with a single laser beam Large amount information recording Large amount information recording
PHOTOTRIGGERED MOLECULAR REORIENTATION Molecular axis Polarization axis axis trans- azobenzene Absorption Absorption Relaxation Absorption cis- azobenzene
PHOTOINDUCED BIREFRINGENCE PHOTOINDUCED BIREFRINGENCE Irradiation area area Polarization axis Azobenzene-containing material
POLARIZATION HOLOGRAPHY: RECORDING F F Signal beam (Right-circular pol.) Reference beam (Left-circular pol ) (Left-circular pol.) Azobenzene film
POLARIZATION HOLOGRAPHY: RECONSTRUCTION F Reference beam (Left-circular pol ) (Left-circular pol.) 0 order beam 0 order beam (Left-circular pol.) Polarization hologram hologram +1 order diffracted beam (Right-circular pol.) (Right circular pol.)
POLARIZATION HOLOGRAPHY: RECONSTRUCTION F -1 order diffracted beam (Left circular pol ) (Left-circular pol.) Reference beam (Right-circular pol.) F F Polarization hologram 0 order beam (Right-circular pol ) (Right circular pol.)
JONES CALCULUS JONES CALCULUS
PRINCIPLE OF RECONSTRUCTION PRINCIPLE OF RECONSTRUCTION
PRINCIPLE OF RETARDAGRAPHY PRINCIPLE OF RETARDAGRAPHY y y x x z z 45 degree linear polarization 45 degree-linear polarization x -component y -component Recording Recording laser
PRINCIPLE OF RETARDAGRAPHY PRINCIPLE OF RETARDAGRAPHY y y x x z z z z Phase difference Phase difference (Polarization retardance) Elliptical polarization x -component y -component p y Recording laser
EXPERIMENTAL SETUP EXPERIMENTAL SETUP
OPTICAL RECORDING BY RATARDAGRAPHY
SUMMARY IN RETARDAGRAPY SUMMARY IN RETARDAGRAPY Explanation of polarization holographic characteristics in E l i f l i i h l hi h i i i photoinduced birefringent films Complex amplitude of signal beam from an object Complex amplitude of signal beam from an object Amplitude: Retardance of photoinduced birefringence Phase: Principal axis of photoinduced birefringence Application to phase-type optical recording by retardagraphy Features of retardagraphy Features of retardagraphy Recording absolute retardance values using a single laser beam High robustness
MULTILAYER STRUCTURE BY SIPN COARTING R. Katouf, T. Yatagai and S. Umegaki: Photonics & Nanostructure, 3 , 116(2005).
MULTILAYER STRUCTURE BY SIPN COARTING R. Katouf, T. Yatagai and S. Umegaki: Photonics & Nanostructure, 3 , 116(2005).
SUMMARY & PROPOSALS SUMMARY & PROPOSALS Functional photo material: A Azobenzene polumers b l Photoisomerization Surface relief grating: hologaphy & functional gratings Photo induced bifringence: retardagrapy optical memory & Photo-induced bifringence: retardagrapy, optical memory & polarization devices ( polarization grating for LS devices) Optical multi-layer structure: functional modulator Collaboration: Joensuu University (Design of functional devices)
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