Microstructure of Reflection Holographic Grating Inscribed in an Absorptive Azopolymer Film

TL;DR

This paper investigates the microstructure of reflection holographic gratings in absorptive azopolymer films, revealing surface relief formation and polarization-dependent properties influenced by optical absorption.

Contribution

It provides a detailed analysis of the internal polarization structure and surface microstructure of reflection holograms in azopolymer films, including theoretical insights.

Findings

Surface relief forms even in reflection configuration

Polarization grating structure depends on optical absorption

Reflection polarization grating exhibits periodic elliptic polarization modulation

Abstract

Microstructure of reflection holographic grating fabricated via a photo-isomerization process in an absorptive azopolymer film is analyzed. A surface relief formation takes place on the film surface even in the reflection holographic configuration. The polarization-dependent diffraction efficiency and the polarization analysis reveal that the polarization grating structure inside the film strongly depends on the amount of optical absorption experienced by the two writing beams. Theoretical analysis shows that the reflection polarization grating, while mimicking a cholesteric liquid crystal structure, is composed of elliptic polarizations with the ellipticity going through a periodic modulation.