Two-dimensional switchable blue phase gratings manufactured by nanosphere lithography

Wahle, Markus; Ebel, Justus; Bürger, Julius; Lindner, J.K.N.; Kitzerow, Heinz‐S.

doi:10.1364/oe.25.022608

Cited by 13 publications

(13 citation statements)

References 35 publications

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“…In a recent work, a 2D switchable polymer stabilized BP grating was fabricated by nanosphere lithography. [296] Besides interdigitated electrodes, regular ITO coated electrodes have been used to drive a polymer stabilized BP LC grating. [297] To Figure 24.…”

Section: Wwwadvmatde Wwwadvancedsciencenewscommentioning

confidence: 99%

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

et al. 2018

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the duality consolidation, the idea of controlling light and how it interacts with matter has always been an exciting topic. Visible light, as we perceive it, is a small portion of the electromagnetic spectrum composed of mutually perpendicular oscillating electric and magnetic fields that propagate through space and presents wave-like and particle-like behavior. Since the elements comprising matter possess dynamic electron clouds, the electromagnetic nature of light prompts different responses when it interacts with different materials, depending on its intensity, frequency, the arrangement of molecules, and so on. Whenever light interacts with matter, it might be absorbed, re-emitted, scattered, or transmitted. Although these effects are well known, the combination of them with new, innovative materials pushes optics forward. In fact, advances in optics have often occurred through the development of materials with improved optical properties, thus creating remarkable applications that tremendously influence our daily lives. These exciting applications include image processing and recording, lasing, data storage, display devices, detector systems, propulsion systems, and optical tweezers, which have enabled remote micromanipulation of colloidal particles and promising applications in various biomedical and biological applications. [1][2][3] There is, however, one component that stands out: the diffraction grating. It is generally regarded as one of the most important devices in the development of several fields of science. [4] Such importance comes from the fact that a diffraction grating is a device with a periodic structure capable of changing the propagation and splitting the spectrum The ability to control light direction with tailored precision via facile means is long-desired in science and industry. With the advances in optics, a periodic structure called diffraction grating gains prominence and renders a more flexible control over light propagation when compared to prisms. Today, diffraction gratings are common components in wavelength division multiplexing devices, monochromators, lasers, spectrometers, media storage, beam steering, and many other applications. Next-generation optical devices, however, demand nonmechanical, full and remote control, besides generating higher than 1D diffraction patterns with as few optical elements as possible. Liquid crystals (LCs) are great candidates for light control since they can form various patterns under different stimuli, including periodic structures capable of behaving as diffraction gratings. The characteristics of such gratings depend on several physical properties of the LCs such as film thickness, periodicity, and molecular orientation, all resulting from the internal constraints of the sample, and all of these are easily controllable. In this review, the authors summarize the research and development on stimuli-controllable diffraction gratings and beam steering using LCs as the active optical materials. Dynamic gratings fabricated by applying external f...

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Section: Wwwadvmatde Wwwadvancedsciencenewscommentioning

confidence: 99%

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

et al. 2018

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“…[18] The presence of a 3D photonic bandgap (for UV or visible light) makes BPLC an excellent candidate for a wide range of applications in photonic and display devices. [30][31][32][33][34][35][36][37][38][39][40] Therefore, it is significant to explore how the BP crystal structure and alignment can be accurately controlled. Due to the non-uniformity and the short period, it is a challenge to obtain full control of the BP alignment.…”

Section: Introductionmentioning

confidence: 99%

Two‐Step Photoalignment with High Resolution for the Alignment of Blue Phase Liquid Crystal

Liu

Nys

Neyts

2022

Advanced Optical Materials

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The self‐assembling properties of liquid crystal (LC) are ideal for realizing switchable optical components. The director organization is strongly determined by the alignment at the substrate interfaces and photoalignment is a versatile method based on linearly polarized UV light. In this work, a two‐step photoalignment procedure is proposed to pattern the alignment at the surface. Illumination with uniform polarization or with an interference pattern is combined to obtain stripe patterns or square patterns of photoalignment. It can indeed be confirmed that the nematic director follows the varying azimuthal orientation. By increasing the angle between the two interfering beams, photoalignment with sub‐micrometer resolution is obtained, compatible with the dimensions of blue phase (BP) LC unit cell. Homogeneous domains of BP II with (100) or (110) crystal orientation are obtained and their Kossel patterns are recorded. The two‐step photoalignment technique allows to create patterns with high resolution and to control the orientation of BP LC, which is promising for photonic applications that require single domains.

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“…Among these pre-existing nanopatterning methods, colloidal nanosphere lithography (NSL) has appeared as a potentially inexpensive and environmentally friendly approach in producing highly periodic arrays of nanoparticles with a distinct size, combining the advantages of both topdown and bottom-up approaches. The NSL process is simply initiated by masking the substrate with a polystyrene nanobead template to pattern the underlying substrate with desired materials [23][24][25]. In our previous works, we successfully integrated NSL by drop casting polystyrene nanobeads (with sizes from 500 nm down to 100 nm) onto a solid substrate with a cm 2 scale area in a monolayer hexagonal close-packed arrangement.…”

Section: Introductionmentioning

confidence: 99%

Gold Nanoframe Array Electrode for Straightforward Detection of Hydrogen Peroxide

et al. 2021

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The nanostructuring of a sensing membrane is performed through colloidal nanosphere lithography (NSL) techniques with a tiny polystyrene nanobead template 100 nm in size. The solvent ratio adjustment has been proven to be effective in assisting the monolayer deposition of small templating particles with minimal defects. Two distinct structures, namely, a billowy gold nanostructure (BGN) where the nanobead template is left unetched and a gold nanoframe array (GNA) with a regular ring-like structure after template removal, are used for the extended-gate field-effect transistor (EGFET) electrodes. The GNA structure generates an electroactive surface area significantly (~20%) larger than its geometrical area as well as a greater surface roughness than the BGN. When integrated with the portable constant voltage–constant current (CVCC) FET circuitry for pH screening to determine the optimized measurement conditions for H2O2 sensing, the GNA sensing membrane also shows more improved Nernstian sensitivity at ~50 mV/pH than the BGN electrode. The more optimized sensitivity is then proven using the GNA in the detection of H2O2, the most common representative reactive oxygen species (ROS) involved in the environment, food, and neurodegenerative diseases, such as Parkinson´s and Alzheimer´s diseases. The GNA electrode has a sensitivity of 70.42 mV/log µM [H2O2] and a limit of detection (LoD) of 1.183 µM H2O2. The integrated ion sensing system employing unique, highly ordered gold array gate electrodes and a portable CVCC circuit system has shown a stable real-time output voltage signal, representing an alternative to bulky conventional FET devices for potential on-site H2O2 detection.

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Two-dimensional switchable blue phase gratings manufactured by nanosphere lithography

Cited by 13 publications

References 35 publications

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

Two‐Step Photoalignment with High Resolution for the Alignment of Blue Phase Liquid Crystal

Gold Nanoframe Array Electrode for Straightforward Detection of Hydrogen Peroxide

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