Holographic Photopolymer Linear Variable Filter with Enhanced Blue Reflection

Abstract

A single beam one-step holographic interferometry method was developed to fabricate porous polymer structures with controllable pore size and location to produce compact graded photonic bandgap structures for linear variable optical filters. This technology is based on holographic polymer dispersed liquid crystal materials. By introducing a forced internal reflection, the optical reflection throughout the visible spectral region, from blue to red, is high and uniform. In addition, the control of the bandwidth of the reflection resonance, related to the light intensity and spatial porosity distributions, was investigated to optimize the optical performance. The development of portable and inexpensive personal health-care and environmental multispectral sensing/imaging devices will be possible using these filters.

Laser interference fabrication of large-area functional periodic structure surface

“…Laser interference is a simple and widely used method for the fabrication of large-area and non-defect structures, which paves the way for the wide application of these periodic structures [66][67][68][69].…”

Liquid Crystals for Responsible Photonic Crystals

“…For example, Cartwright et al reported a graded reflection grating based on the H-PDLC material system [43,44]. An obvious rainbow-colored reflection was observed from the same viewing angle by a modification to this standard configuration where the triangular prism is replaced with a cylindrical lens.…”

Frozen “Tofu” Effect: Engineered Pores of Hydrophilic Nanoporous Materials

“…15−17 Our previously reported spatially graded polymeric PhC structure is an example. 18−20 For a given porous material, however, pore size distributions cannot be easily tailored or intentionally modified, especially postpreparation. This is due to low Young’s moduli and thermal expansion coefficients of the materials.…”

“…Porous materials are also established as optical elements for colorimetric humidity and/or chemical sensors. − For instance, micro-/nanoporous photonic crystals (PhCs) have been developed using self-assembly − and holographic lithography − methods to spatially tune the distribution of polymer-rich (P-rich) and void-rich (V-rich) regions within subwavelength dimensions. Therefore, the created photonic bandgaps can result in controlled reflection at selected wavelengths. − Our previously reported spatially graded polymeric PhC structure is an example. − For a given porous material, however, pore size distributions cannot be easily tailored or intentionally modified, especially postpreparation. This is due to low Young’s moduli and thermal expansion coefficients of the materials.…”

“…This process is graphically illustrated by the cross-sectional images in Figure b. To demonstrate its feasibility, in this work, we select nanoporous polymer PhC gratings ,− as a test bed. Specifically, we will fill these hydrophilic porous polymeric materials with water and control its adjacent environment temperature to change the volume of ice in the nano-/micropores of the material.…”