slide1 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Ludmila Nikolova Central Laboratory of Optical Storage and Processing of Information Bulgarian Academy of Sciences PowerPoint Presentation
Download Presentation
Ludmila Nikolova Central Laboratory of Optical Storage and Processing of Information Bulgarian Academy of Sciences

Loading in 2 Seconds...

play fullscreen
1 / 18

Ludmila Nikolova Central Laboratory of Optical Storage and Processing of Information Bulgarian Academy of Sciences - PowerPoint PPT Presentation


  • 369 Views
  • Uploaded on

POLARIZATION HOLOGRAPHY AND LIGHT INDUCED STRUCTURES IN PHOTOANISOTROPIC MATERIALS. Ludmila Nikolova Central Laboratory of Optical Storage and Processing of Information Bulgarian Academy of Sciences. What is polarization holography?.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Ludmila Nikolova Central Laboratory of Optical Storage and Processing of Information Bulgarian Academy of Sciences' - lotus


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

POLARIZATION HOLOGRAPHY

AND LIGHT INDUCED STRUCTURES

IN PHOTOANISOTROPICMATERIALS

Ludmila Nikolova

Central Laboratory of Optical Storage and

Processing of Information

Bulgarian Academy of Sciences

slide2

What is polarization holography?

The polarization of the interference field is modulated

The intensity is constant

Photoanisotropic materials

slide3
INORGANIC

-AgCl emulsions

- Alkali halide crystals

- Chalcogenide layers

- Photochromic glasses

ORGANIC

-Thriphenylmethane,

xanthene, etc. dyes in

solid matrices

-Azobenzene polymers

- bacteriorhodopsin

Photoanisotropic materials

slide4

Azobenzene polymers

izomerization

reorientation

amorphous

Photoinduced effects

liquid-crystalline

  • -Linear anisotropy
  • - Circular anisotropy
  • Surface relief
slide5

Photoinduced processes

in azobenzene polymers

slide7

Application of polarization holography for novel optical elements

- polarization holographic gratings

The polarization pattern

The properties of the grating

I+1 + I-1 = const.

Measuring the S3 parameter

slide8

A spectrophotopolarimetric scheme

The optical scheme

The instrument matrix

PHG - polarization diffraction grating

DG – conventional diffraction grating

LDS – linear diode sensors

K1 = I0/I1; k2 = I0/2I2;;

K3 = I0/2k3; k4 = I0/Ik4

slide9

Photopolarimeter for one wavelength

Measurement of the photoinduced anisotropy of fluorescein

in a solid matrix

F

PP

Ar 00

He-Ne 450

,

The optical set-up

,

The changes in the Stokes

parameters

D par = lg(-(S0 + S2))

D ort = lg(-(S0 - S1))

Δn = λδ/2πd

δ= arctg (S3 /S2)

,

The changes in the optical

constants of a film of

fluorescein in a solid matrix

slide10

A first version of the spectral device

Spectral range: 500 – 1500 nm,

determined by the polarization grating

Polarization selectivity of the grating

The diffraction efficiency of the polarization grating

Photoinduced dichroism and birefringence in MR/PMMA

slide11

Observation of photoinduced

circular anisotropy in

liquid - crystalline azopolymers

( holographic method )

The polarization pattern

Dependence of the diffraction efficiency

on the probe beam azimuth

slide12

Observation of photoinduced

circular anisotropy in

liquid - crystalline azopolymers

( polarimetric method )

The optical set-up

The photoinduced optical rotation

slide13

Light-induced polarization rotation

in previously ordered amorphous azopolymers

The optical set-up

The induced polarization rotation

slide14

Self-induced rotation of the polarization ellipse

The rotation of the azimuth

in amorphous samples

The optical scheme

The rotation of the azimuth in

liquid-crystalline samples

Output/input ellipticity

slide15

θ

Understanding the phenomenon

Ө

Rotation of the polarization

ellipse in anisotropic media

slide16

Photoinduced chirality in amorphous azopolymers

Gradually rotation of

the optical axis

One macroscopic chiral structure

slide17

Light propagation through

photoinduced chiral structures

- The eigenmodes are elliptical

Output azimuth

Output ellipticity

slide18

Photoinduced chirality

in liquid-crystalline azopolymers

The initial structure

of the polymer –

many domains with

different axes

The photoinduced effect –

many microscopic

chiral structures

Photoinduced

optical activity

Light controlled polarization rotators