Real-time manipulation of light in a diffractive optical
element
made with an azomaterial, through the light-induced reconfiguration
of its surface based on mass transport, is an ambitious goal that
may enable new applications and technologies. The speed and the control
over photopatterning/reconfiguration of such devices are critically
dependent on the photoresponsiveness of the material to the structuring
light pattern and on the required extent of mass transport. In this
regard, the higher the refractive index (RI) of the optical medium,
the lower the total thickness and inscription time can be. In this
work, we explore a flexible design of photopatternable azomaterials
based on hierarchically ordered supramolecular interactions, used
to construct dendrimer-like structures by mixing specially designed
sulfur-rich, high-refractive-index photoactive and photopassive components
in solution. We demonstrate that thioglycolic-type carboxylic acid
groups can be selectively used as part of a supramolecular synthon
based on hydrogen bonding or readily converted to carboxylate and
participate in a Zn(II)–carboxylate interaction to modify the
structure of the material and fine-tune the quality and efficiency
of photoinduced mass transport. Compared with a conventional azopolymer,
we demonstrate that it is possible to fabricate high-quality, thinner
flat diffractive optical elements to reach the desired diffraction
efficiency by increasing the RI of the material, achieved by maximizing
the content of high molar refraction groups in the chemical structure
of the monomers.