Enhanced wavelength-sensitivity of volume holographic grating with dual-photoinitiation system in polymer-dispersed liquid crystal

ABSTRACT

We propose a method to improve the wavelength-sensitivity of a volume holographic grating by mixing dual-photoinitiation dopants, namely, rose bengal (RB)/N-phenylglycine (NPG) system and methylene blue (MB)/p-toluenesulfonic acid (PTSA) system, which enable the fabrication of gratings upon both green and red light illumination. The RB/NPG green light photoinitiation system is chosen in combination with the red-active MB/PTSA system because RB and MB absorb light near 567 and 665 nm independently. In this case, the holographic gratings, recorded in polymer-dispersed liquid crystal, can be fabricated simultaneously by two different visible laser lights with an output wavelength of 532 and 632.8 nm. The electro-optical performances of the gratings exposed upon 532 and 632.8 nm have been implemented: the diffraction efficiencies (DE) are 75% and 57% respectively when the exposure time is optimised to 2 min and 17 min; the threshold voltage is approximately 2.9 V/μm. The enhanced wavelength-sensitivity of holographic gratings allows for the storage of three-dimensional (3D) images on the same hologram plate, and these 3D images are easily reconstructed by both red and green light.

Graphical Abstract

KEYWORDS:

• Holographic optical elements
• photoinitiators
• liquid crystals
• polymers
• diffraction gratings

Acknowledgments

The authors gratefully acknowledge the financial support from the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province (18KJB510048), the National Natural Science Foundation of China (11704162) and the Ph.D. Teacher’s Research Project of Jiangsu Normal University (16XLR023).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province under Grant number 18KJB510048; the National Natural Science Foundation of China under Grant number 11704162; the Ph.D. Teacher’s Research Project of Jiangsu Normal University under Grant number 16XLR023.