Tunable Optical Diffusers Based on the UV/Ozone-Assisted Self-Wrinkling of Thermal-Cured Polymer Films

Abstract

Tunable optical diffusers have attracted attention because of the rapid development of next generation stretchable optoelectronics and optomechanics applications. Flexible wrinkle structures have the potential to change the light path and tune the diffusion capability, which is beneficial to fabricate optical diffusers. The generation of wrinkles usually depends on an external stimulus, thus resulting in complicated fabricating equipment and processes. In this study, a facile and low-cost method is proposed to fabricate wrinkle structures by the self-wrinkling of thermal-cured polymer for tunable optical diffusers. The uncured polydimethylsiloxane (PDMS) precursors were exposed to UV/ozone to obtain hard silica layers and then crosslinked via heating to induce the wrinkle patterns. The wrinkle structures were demonstrated as strain-dependent tunable optical diffusers and the optical diffusion of transmitted light via the deformable wrinkle structures was studied and adjusted. The incident light isotropically diffused through the sample at the initial state. When the wrinkle structures deformed, it showed a more pronounced isotropic optical diffusion with uniaxial tensile strain. The optical diffusion is anisotropical with a further increase in uniaxial tensile strain. The proposed method of fabricating wrinkles by UV/ozone-assisted self-wrinkling of thermal-cured polymer films is simple and cost-effective, and the obtained structures have potential applications in tunable optical diffusers.

A comprehensive review of optical diffusers: progress and prospects

“…5e and f ); as PDMS precursors are exposed to UV/ozone, hard silica layers are obtained, which make the precursors crosslinked via heating; thus, the obtained wrinkle patterns show straindependent tunability. 52 Yang et al have proposed an approach to fabricate an optical diffuser by interfacial hydrogen-bonding polymer complexation; one polymer has been replaced by the dispersed polymer complex nanoparticles (NPs) for the layer-by-layer (L-B-L) assembly of poly(vinylpyrrolidone) (PVPON) and poly (acrylic acid) (PAA), and light diffusion performance has been enhanced. [53][54][55][56] Stretchable and bendable optical diffusers are indispensable components in wearable display devices by constructing interfacial hydrogen bonding among methylcellulose (MC), poly(ethylene oxide) (PEO), and polymer complex nanoparticles (PCNP), which exhibits 92% transmittance, 93% haze, and 73% elongation.…”

Development of a High‐Performance, Anti‐Fouling Optical Diffuser Inspired by Morpho Butterfly's Nanostructure

“…In addition to the conventional diffusers mentioned above, various types of novel diffusers have been proposed to date. These include fibrous structures of wood/cellulose-based materials, [6][7][8]24,25] specific crystal structures, [26] liquid crystals, [27][28][29] polymer composites, [9,10,30] surface microwrinkles, [31][32][33][34][35][36][37] and laser-ablated surfaces. [38][39][40] It is remarkable that certain of these novel diffusers show tunable light diffusion upon mechanical/thermal/electrical stimuli, acting as smart windows.…”

“…[38][39][40] It is remarkable that certain of these novel diffusers show tunable light diffusion upon mechanical/thermal/electrical stimuli, acting as smart windows. [27][28][29][30][31][32][33][34]36,37,40] However, despite these efforts, the realization of an ideal diffuser with high optical performance and anti-fouling properties remains challenging: as well as the conventional diffusers, volumetric diffusers [6][7][8][9][10][24][25][26][27][28][29][30] result in low transmittance due to multiple scattering, and surfacerelief diffusers [31][32][33][34][35][36][37][38][39][40] can be damaged by spontaneous surface contamination. Furthermore, the novel surface-relief diffusers are characterized by insufficient diffusion and in certain cases by color dispersion, derived from the lack of steepness and randomness in their surface reliefs, respectively.…”

Two-Stage Link Loss Optimization of Divergent Gaussian Beams for Narrow Field-of-View Receivers in Line-of-Sight Indoor Downlink Optical Wireless Communication (Invited)

“…Alternatively, increasing the divergent angle of the optical beam can potentially cover the same area as AWGRs without any additional operations, albeit at the expense of increased link losses. Moreover, employing a ground glass-based diffuser to achieve this angular expansion naturally transforms the Gaussian-shaped beam generated by lasers into a flat-top beam [10]. Therefore, a more divergent beam holds the potential advantage of a homogenized intensity distribution compared to AWGRs.…”