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Analysis of light diffraction by azobenzene-based photoalignment layers

Analysis of light diffraction by azobenzene-based photoalignment layers
Analysis of light diffraction by azobenzene-based photoalignment layers
Photoalignment materials, such as the azobenzene-based PAAD series studied here, are becoming increasingly important in liquid crystal-based optical devices and displays. Yet their properties and, in particular, their response to light, are still not fully understood. We investigate, experimentally and theoretically, the photoinduced birefringence, the order parameter and the formation of surface relief gratings, as well as the diffraction caused by them. We show that some of the azobenzene PAAD materials are suitable for the formation of surface relief gratings with high modulation depth, while others exhibit strong photoinduced birefringence. The two effects are inversely correlated: the stronger the surface relief grating is, the weaker is photoinduced birefringence. Analytical formulas based on the Raman-Nath approximation and numerical simulations of Maxwell’s equations are used to quantify the diffraction caused by the induced diffraction gratings, showing excellent agreement between theory and experiment.
Optical gratings, Surface relief gratings, azo dyes, liquid crystal, photoalignment
1094-4087
29495-29506
Berdin, Alex
eebc5fa3-c440-4ac6-bb4a-172954be13bd
Gill, Jordan Ronald Ewan
308dc268-ffc7-411b-80ec-761e3c0e55bc
Perivolari, Eleni
a65ec857-cf22-497d-bdb4-66fb449751d3
Kauppo, Joel
ed71b2f7-e65e-48f1-b673-176ec0033a03
Apostolopoulos, Vasileios
8a898740-4c71-4040-a577-9b9d70530b4d
D'Alessandro, Giampaolo
bad097e1-9506-4b6e-aa56-3e67a526e83b
Kaczmarek, Malgosia
408ec59b-8dba-41c1-89d0-af846d1bf327
Priimagi, Arri
177ae988-ea03-42cc-8d0b-961274e183e3
Berdin, Alex
eebc5fa3-c440-4ac6-bb4a-172954be13bd
Gill, Jordan Ronald Ewan
308dc268-ffc7-411b-80ec-761e3c0e55bc
Perivolari, Eleni
a65ec857-cf22-497d-bdb4-66fb449751d3
Kauppo, Joel
ed71b2f7-e65e-48f1-b673-176ec0033a03
Apostolopoulos, Vasileios
8a898740-4c71-4040-a577-9b9d70530b4d
D'Alessandro, Giampaolo
bad097e1-9506-4b6e-aa56-3e67a526e83b
Kaczmarek, Malgosia
408ec59b-8dba-41c1-89d0-af846d1bf327
Priimagi, Arri
177ae988-ea03-42cc-8d0b-961274e183e3

Berdin, Alex, Gill, Jordan Ronald Ewan, Perivolari, Eleni, Kauppo, Joel, Apostolopoulos, Vasileios, D'Alessandro, Giampaolo, Kaczmarek, Malgosia and Priimagi, Arri (2022) Analysis of light diffraction by azobenzene-based photoalignment layers. Optics Express, 30 (16), 29495-29506. (doi:10.1364/OE.464278).

Record type: Article

Abstract

Photoalignment materials, such as the azobenzene-based PAAD series studied here, are becoming increasingly important in liquid crystal-based optical devices and displays. Yet their properties and, in particular, their response to light, are still not fully understood. We investigate, experimentally and theoretically, the photoinduced birefringence, the order parameter and the formation of surface relief gratings, as well as the diffraction caused by them. We show that some of the azobenzene PAAD materials are suitable for the formation of surface relief gratings with high modulation depth, while others exhibit strong photoinduced birefringence. The two effects are inversely correlated: the stronger the surface relief grating is, the weaker is photoinduced birefringence. Analytical formulas based on the Raman-Nath approximation and numerical simulations of Maxwell’s equations are used to quantify the diffraction caused by the induced diffraction gratings, showing excellent agreement between theory and experiment.

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Accepted/In Press date: 18 June 2022
Published date: 1 August 2022
Additional Information: Funding Information: Engineering and Physical Sciences Research Council (ES/T502029/1); Academy of Finland PREIN Flagship Programme, No. 320165 and P-Cap project No.324353.
Keywords: Optical gratings, Surface relief gratings, azo dyes, liquid crystal, photoalignment

Identifiers

Local EPrints ID: 469031
URI: http://eprints.soton.ac.uk/id/eprint/469031
ISSN: 1094-4087
PURE UUID: f397e2ea-d57f-49d6-bb3b-e09b171deb3e
ORCID for Vasileios Apostolopoulos: ORCID iD orcid.org/0000-0003-3733-2191
ORCID for Giampaolo D'Alessandro: ORCID iD orcid.org/0000-0001-9166-9356

Catalogue record

Date deposited: 05 Sep 2022 16:55
Last modified: 06 Sep 2022 01:41

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Contributors

Author: Alex Berdin
Author: Jordan Ronald Ewan Gill
Author: Eleni Perivolari
Author: Joel Kauppo
Author: Arri Priimagi

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