Finnish-Japanese Workshop on Functional MaterialsEspoo and Helsinki, Finland25-25.5.2009

Utsunomiya UnivesityCenter for Optical Research and Education

SURFACE RELIEF GRATING AND RETARDAGRAPHY:

Center for Optical Research and EducationToyohiko Yatagai

SURFACE RELIEF GRATING AND RETARDAGRAPHY: OPTICAL MANIPULATION OF AZOBENZENE POLYMER FILMS AND ITS APPLICATIONSFILMS AND ITS APPLICATIONS

OPTICAL FUNCTIONAL DEVICESUSING AZOBENZENE POLYMER FILM

Photoisomerization Photoisomerization

Surface relief grating Surface relief grating

R t d h di f ti l l i ti d Retardagraphy: recording of optical polarization and reconstruction of complex amplitude

Functional devices based on multilayer polymer thin filmfilm

PHOTOINDUCED MASS TRANSPORT

N nof b i tion photo me h ni l Nanofabrication, photo-mechanical devices

R

RLightTwo beaminterference

NN

R'

N N

C fLight orthermal

R'

Trans form

Cys form

Azobenzene

Photoinduced surface relief (PSR) formationP. Rochon et al., Appl. Phys. Lett., 66, 136 (1995)

POLARIZATION DEPENDENTPOLARIZATION DEPENDENT

50 μm 10 μm

MULTIPLE RECORDING GRATINGSMULTIPLE RECORDING GRATINGS

Orthogonal grating structureSurface relief grating

Hexagonal structure Blazed grating structure

RELEIF DEPTH CONTROLBY ELECTRIC FIELD

H iHomogeniousIllumination or heating

Heating +electric field applied

substrate

Heater

COMPUTER SIMULATION BASED ON VISCOUS FLUID MODEL

Navier-Stokes equation

Inertialt

Pressuret

Outer forceterm

Viscoustermterm term termterm

Continuity equationContinuity equation u: velocity vector

COMPUTER SIMULATION OF MASS TRANSFERCOMPUTER SIMULATION OF MASS TRANSFER

Nd:YAG Laser(532 nm)

Intensity:50 mW/cm2 :Electric Field

:Wave number:Wave number

1 μm

SUMMARY IN SURFACE RELIEF GRATING

Origin of mass transfer:・Origin of mass transfer:gradient of light intensitygradient of light pressuresurface tensionsurface tension

・SRG generation is mainly due toelectric dipole interaction with outer pelectric field.

PHOTOINDUCED BIREFRINGENCE

Opti l to ge medi pol i tion Optical storage media, polarization controllable devices

Optical recording technique forth t d f bi f i t bj t

Retardagraphythe retardance of a birefringent object

Liquid crystalspatial light modulatorMultivalued phase recordingwith a single laser beam

Large amount information recordingLarge amount information recording

PHOTOTRIGGEREDMOLECULAR REORIENTATION

Polarizationaxis

Molecular axis

axis

trans-azobenzeneAbsorption

AbsorptionRelaxation

cis-azobenzene Absorption

PHOTOINDUCED BIREFRINGENCEPHOTOINDUCED BIREFRINGENCEIrradiationareaarea

Polarization axis

Azobenzene-containing material

POLARIZATION HOLOGRAPHY:RECORDING

FF Signal beam (Right-circular pol.)

Reference beam(Left-circular pol )(Left-circular pol.)

Azobenzene film

POLARIZATION HOLOGRAPHY: RECONSTRUCTION

FFReference beam(Left-circular pol ) 0 order beam(Left-circular pol.) 0 order beam

(Left-circular pol.)Polarizationhologram

+1 order diffracted beam(Right-circular pol.)

hologram

(Right circular pol.)

POLARIZATION HOLOGRAPHY: RECONSTRUCTION

FF-1 order diffracted beam(Left circular pol )

Reference beam(Right-circular pol.)

(Left-circular pol.)

FPolarizationhologram F

0 order beam(Right-circular pol )(Right circular pol.)

JONES CALCULUSJONES CALCULUS

PRINCIPLE OF RECONSTRUCTIONPRINCIPLE OF RECONSTRUCTION

PRINCIPLE OF RETARDAGRAPHYPRINCIPLE OF RETARDAGRAPHY

yx

yx

zz

45 degree linear polarization45 degree-linear polarization

x-componenty-component

RecordingRecordinglaser

PRINCIPLE OF RETARDAGRAPHYPRINCIPLE OF RETARDAGRAPHY

yy

z

x

z

x

z

Phase difference

z

Phase difference(Polarization retardance)Elliptical polarization

x-componenty-componenty p

Recordinglaser

EXPERIMENTAL SETUPEXPERIMENTAL SETUP

OPTICAL RECORDINGBY RATARDAGRAPHY

SUMMARY IN RETARDAGRAPYSUMMARY IN RETARDAGRAPY

E l i f l i i h l hi h i i iExplanation of polarization holographic characteristics in photoinduced birefringent films

Complex amplitude of signal beam from an objectAmplitude: Retardance of photoinduced birefringencePhase: Principal axis of photoinduced birefringence

Complex amplitude of signal beam from an object

Application to phase-type optical recording by retardagraphy

Features of retardagraphyFeatures of retardagraphyRecording absolute retardance values using a single laser beamHigh 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 & PROPOSALSSUMMARY & PROPOSALSFunctional photo material:

A b lAzobenzene polumers

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)