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Fabrication and performance of efficient thin circular polarization gratings with Bragg properties using bulk photo-alignment of a liquid crystalline polymer
- Publication Year :
- 2018
-
Abstract
- Thin circular polarization gratings, characterized by high diffraction efficiency and large, up to 42°, diffraction angles were created by polarization holography for the first time. The high efficiency of the gratings is the result of the specific properties of a photo-crosslinkable liquid crystalline polymer and a two-step photochemical/thermal processing procedure. A diffraction efficiency of up to 98% at 532 nm has been achieved for gratings with periods of 700 nm. In contrast to polarization gratings with larger periods these gratings exhibit Bragg properties. So one beam is either transmitted or diffracted depending on the direction of the circular polarization of the incident light, whereas the maximal diffraction efficiency is achieved only at the proper incident angle. The f abrication procedure consists of holographic exposure of the film at room temperature which provides the photo-selective cycloaddition of cinnamic ester groups. Upon subsequent thermal annealing above Tg bulk photo-alignment of the LC polymer film occurs enhancing the optical anisotropy within the grating. The holographic patterning provides high spatial resolution, the arbitrary orientation of the LC director as well as high optical quality, thermal and chemical stability of the final gratings. Highly efficient symmetric and slanted circular polarization gratings were fabricated with the proposed technique.
- Subjects :
- Diffraction
polarization holography
Fabrication
Materials science
Physics and Astronomy (miscellaneous)
Holography
Physics::Optics
General Physics and Astronomy
photo-crosslinkable liquid crystalline polymer
02 engineering and technology
Grating
Diffraction efficiency
01 natural sciences
law.invention
010309 optics
law
0103 physical sciences
Circular polarization
business.industry
General Engineering
021001 nanoscience & nanotechnology
Polarization (waves)
Ray
polarization gratings
Optoelectronics
diffraction efficiency
0210 nano-technology
business
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....6ab17a881084eaf7fb4cc8a85f587ecc