Highly efficient and polarization-independent Fresnel lens based on dye-doped liquid crystal

Lin, L. Y.; Jau, Hung‐Chang; Lin, Tung‐Ching; Fuh, Andy Ying–Guey

doi:10.1364/oe.15.002900

Cited by 82 publications

(47 citation statements)

References 12 publications

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“…The combination of bulk-mediated hybrid photoalignment and homeotropic alignment in a single pixel supports the fabrication of LCDs with a controllable viewing-angle, [52] on which simultaneously displays two images that can be seen from different viewing angles. Other applications in photonic devices, such as optical gratings [53][54][55] and Fresnel lenses have also been investigated [56][57][58][59][60]. Photoalignment is a unique tool for achieving LC alignment in mechanically inaccessible volumes.…”

Section: Bulk-mediated Photo-isomerization and Adsorption Effectsmentioning

confidence: 99%

Photo-Alignment Technology

Lin

2014

Topics in Applied Physics

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LCDs are used in many everyday devices, including mobile phones, notebook computers and wide screen televisions. A typical LCD is composed of two glass substrates between which is a gap that is filled with LC. The arrangement of the LC is controlled by the boundary condition of an alignment film. A long-range orientational interaction causes the preferable alignment of a LC by the surface boundary to extend into the LC bulk. The alignment layer is typically rubbed with a special cloth to induce a unidirectional alignment of the LC. In the first devices based on twisted LCs, these LCs were aligned only by rubbing transparent electrodes. The rubbing technique became much more reliable when the glass substrate was covered with a rubbed polymer layer. The rubbing of polymers is a very simple technique and it is now extensively utilized in both small scientific laboratories and large LCD factories.Despite the extensive use of rubbing in LCD manufacturing, it has some serious shortcomings that arise from the contact involved in rubbing. These critically affect the production of the most recent generation of LCDs and miniature LC photonic devices. First, rotational rubbing for the polymer surface causes the accumulation of static charges and the formation of fine dust particles. The accumulation of static electricity may destroy the transistors or diodes in the LCD. The second shortcoming is the effect of decreasing in manufacturing yield. Rubbing for large and high-resolution active matrix LCDs (AMLCDs) involve additional difficulties that are associated with the precise control of the rubbing characteristics. Other problems are the difficulty of producing local structures with the required LC director alignment in the selected areas of the device. Finally, this method cannot be used to align LCs in closed volumes.For all of the above reasons, new alignment solutions and approaches are sought. There are some alternative methods of rubbing include laser writing, micro-rubbing, ion beam irradiation and photoalignment. Of these methods, the

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Section: Bulk-mediated Photo-isomerization and Adsorption Effectsmentioning

confidence: 99%

Photo-Alignment Technology

Lin

2014

Topics in Applied Physics

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“…When excited by light in the absorption spectrum, the azo dye in the LC sample would undergo trans-cis isomerization, followed by molecular reorientation, diffusion, and adsorption on the ITO glass surface. The adsorbed dyes then align liquid crystals by forcing the LC molecules to reorient along the direction of the azo dye's long axis [13,14].…”

Section: Experiments and Simulationmentioning

confidence: 99%

“…Azo-dye-doped nematic LC is a good candidate for fabricating polarization-related optical devices, such as polarization Fresnel lenses [13,14], polarization gratings [15][16][17], vertical photonic crystals [18], polarization rotators [19], and photonic crystal fiber devices [20].…”

Section: Introductionmentioning

confidence: 99%

Polarization-dependent circular Dammann grating made of azo-dye-doped liquid crystals

et al. 2011

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A polarization-dependent circular Dammann grating (CDG) was generated from an azo-dye-doped liquid crystal (LC) cell. A simple multiexposure photo-alignment process was used to fabricate a binary phase LC CDG zone plane, which was composed of an odd zone with a twisted nematic LC structure and an even zone with a homogenous LC structure. A two-order CDG with equal-intensity rings was produced through a Fourier transform. The maximum zeroth and first diffraction orders of obtained CDG can be separately achieved by rotating the analyzer's polarization direction. The CDG using an azodye-doped LC cell can be used to generate diffractions by lasers in a broad wavelength range, hence expanding possible device applications.

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“…Effective control of the direction of the alignment, pretilt angle, and anchoring energy by polarized light irradiation and the possibility of alignment on curved and flexible substrates and in confined volumes made the photoalignment technology an indispensable tool. Applications of this approach in modern LC-based photonic devices include electrically controlled Fresnel lenses [4,5], polarization convertors [6,7], optical gratings [8,9], and waveguides [10].…”

Section: Introductionmentioning

confidence: 99%

Photoinduced anchoring on a chalcogenide surface

et al. 2012

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We present basic characteristics and a model of photoinduced anchoring of liquid crystals (LCs) on a chalcogenide surface. It was found that characteristics of the alignment strongly depend on the LC material for the same chalcogenide glass. The photoalignment is partially reversible and can be controlled by changing the light polarization direction. We propose a model in which the existence of dichroic units on the chalcogenide surface and competition between two mechanisms of the photoalignment is suggested. The first mechanism is related to the light-induced anisotropy on the chalcogenide surface and results in an easy orientation axes of a LC parallel to the polarization of the incident light. The second mechanism is attributed to an energy transfer from the dichroic units after the light absorption to the LC molecules adsorbed on the chalcogenide surface. The transferred energy causes polarization-sensitive desorption of the LC molecules from the chalcogenide surface and the light-induced easy orientation axis of a LC perpendicular to the incident light polarization. The competition between these mechanisms leads to the observed change of the direction of the easy axis with the exposure.

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Highly efficient and polarization-independent Fresnel lens based on dye-doped liquid crystal

Cited by 82 publications

References 12 publications

Photo-Alignment Technology

Photo-Alignment Technology

Polarization-dependent circular Dammann grating made of azo-dye-doped liquid crystals

Photoinduced anchoring on a chalcogenide surface

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