Humidity and temperature induced changes in the diffraction efficiency and the Bragg angle of slanted photopolymer-based holographic gratings

Abstract

This work explores the humidity and temperature response of volume phase slanted gratings recorded in photopolymers with varied chemical composition. Acrylamide and diacetone acrylamide were used as monomers and triethanolamine and N-phenylglycine were used as photoinitiators. The study demonstrates that the response of photopolymer-based holographic gratings to relative humidity (RH) and temperature (T) can be tuned by alteration of the photopolymer composition. Humidity and temperature response of the holograms has been characterized by recording Bragg selectivity curves of transmission gratings and by monitoring the position of the maximum intensity in the spectral response of reflection gratings. Investigation of the humidity response in the range of 20-90 % RH reveals that photopolymers containing triethanolamine are more responsive to moisture than photopolymers containing N-phenylglycine and display significant sensitivity to relative humidity above 40 %. Full reversibility of humidity induced changes in gratings recorded in diacetone acrylamide-based photopolymer is confirmed at RH  60 %. Exposure to RH  70 % leads to irreversible changes in these gratings. The temperature response of slanted transmission gratings was investigated in the temperature range of 20-60 0 C. Exposure of the photopolymer layers containing triethanolamine to elevated temperature was found to cause layer shrinkage due to desorption of absorbed water. Sealed layers containing triethanolamine, however, demonstrated swelling due to the effect of thermal expansion. The photopolymer layers containing N-phenylglycine were found to be unresponsive to temperature changes below 30 0 C and have sensitivity to temperature above 30 0 C.

Holographic sol–gel monoliths: optical properties and application for humidity sensing

“…In spite of their advantages, reversibility of humidity indication requires high temperature treatment, so their applicability is limited. Next, detailed study of recent publications about holographic sensors, especially made of photopolymers [ 32 , 33 ], helped authors to define that this field faces the problem of irreversibility even after short treatment by relative humidity 70%.…”

Amino Acid Cross-Linked Graphene Oxide Membranes for Metal Ions Permeation, Insertion and Antibacterial Properties

“…From the X-ray scattering data ( Figure 2 b), the average d-spacing value of GO is derived from Bragg’s law (5) [ 26 ]: where d is the layer spacing, λ is the X-ray wavelength of 1.54 nm, and θ is the diffraction angle. The interlayer distances can be obtained from the peak diffraction angle.…”

“…The O-H and N-H stretching vibration peaks red-shifted at~3420 cm −1 , probably indicating the covalent functionalization of GO by amino acid molecules. From the X-ray scattering data (Figure 2b), the average d-spacing value of GO is derived from Bragg's law (5) [26]:…”

Effect of Glycerol on an N-Vinylpyrrolidone-Based Photopolymer for Transmission Holography

“…A photopolymer for holography is a form of light-responsive material based on polymerization reaction, which has the advantages of high diffraction efficiency, high spatial resolution and a simple preparation process. It has broad application prospects in the fields of sensors [ 1 , 2 , 3 , 4 ], diffractive optical elements [ 5 , 6 , 7 , 8 , 9 ], holographic interferometry [ 10 , 11 ], displays [ 12 , 13 ] and holographic recording materials [ 14 , 15 ]. The photopolymer mainly contains film formers, photosensitizers, photoinitiators and polymerizable monomers.…”