Switching between transparent and translucent states of a two-dimensional liquid crystal phase grating device with crossed interdigitated electrodes

Choi, Tae‐Hoon; Huh, Jae Won; Woo, Jiyong; Kim, Jin-Hun; Jo, Young-Seo; Yoon, Tae–Hoon

doi:10.1364/oe.25.011275

Cited by 35 publications

(18 citation statements)

References 24 publications

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“…To switch an SmA-LC cell by dielectric switching, we formed interdigitated electrodes. By applying in-plane and vertical electric fields, we can control the diffracted light intensity of an SmA-LC cell [10][11][12]. In the initial state, most of the incident light passes through the cell without diffraction because SmA-LCs are aligned uniformly perpendicular to the substrates because of the natural ability of the SmA-LC material [16].…”

Section: Operational Principlementioning

confidence: 99%

“…1(b). Therefore, when white light is incident to the LC cell, it is diffracted so that the LC cell can be switched to a good translucent state thanks to a large spatial phase difference regardless of the azimuth angle [11].…”

Section: Operational Principlementioning

confidence: 99%

“…Recently, LC phase-grating devices capable of controlling the haze value have been reported [10][11][12]. An LC phase grating driven with interdigitated electrodes is actively studied for its outstanding merits, such as the strong diffraction, large diffraction angle, no diffraction at the initial state, and simple fabrication process [10][11][12][13][14][15]. When an electric field is applied to these devices, they induce diffraction of the incident light.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

P‐166: Bistable Operation of a Smectic‐A Liquid Crystal Grating for Low‐power Window Display Application

Seo

Huh

Choi

et al. 2019

Symp Digest of Tech Papers

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We report a bistable smectic-A (SmA) liquid crystal (LC) cell with crossed interdigitated electrodes. An SmA-LC cell with crossed interdigitated electrodes is switchable between haze-free transparent and high-haze translucent states. It can be operated with very little power because it consumes power only while the state is being switched. Owing to the high diffraction efficiency, it can provide a high haze value of 92.2% in the translucent state. It has shown a clear transparent state with little haze and excellent optical characteristics in the translucent state. We expect that the device will be used for a window display application.

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Section: Operational Principlementioning

confidence: 99%

Section: Operational Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

P‐166: Bistable Operation of a Smectic‐A Liquid Crystal Grating for Low‐power Window Display Application

Seo

Huh

Choi

et al. 2019

Symp Digest of Tech Papers

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“…The nematogel exhibits ultra-fast electric switching of transparency, which is of interest for a broad range of technological uses, including such applications as optical shutters, electro-optic modulators, privacy windows and transflective flexible displays (32). The microsecond-range response time is two order of magnitudes faster than that of conventional LCs and related composite systems, such as the conventional polymer-dispersed LCs.…”

Section: Sub-millisecond Electric Switchingmentioning

confidence: 99%

Liquid crystalline cellulose-based nematogels

Liu

Smalyukh

2017

Sci. Adv.

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“…In these 2D-confined cells, the LC response time is dependent on the distance between the virtual walls in the lateral direction as well as the cell gap between the two substrates in the longitudinal direction, as a result of anchoring provided by the virtual walls. The 2D-confined LC cells exhibited a very short response time, which can be an outstanding feature for such applications as augmented/virtual reality, phase grating, and window display devices 17–26 . In addition, the deformation of 2D-confined LCs generates interesting physical and optical phenomena in the LC cell.…”

Section: Introductionmentioning

confidence: 99%

Formation of Polymer Walls through the Phase Separation of a Liquid Crystal Mixture Induced by a Spatial Elastic Energy Difference

Choi

Jeon

et al. 2019

Sci Rep

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We propose a method to form polymer walls without the use of a photomask in a liquid crystal (LC) cell by phase separation of an LC mixture induced by a spatial elastic energy difference. When an in-plane electric field is applied to a vertically aligned cell filled with a mixture of LC and a reactive monomer (RM), a high spatial elastic energy is induced along the direction perpendicular to the interdigitated electrodes. RMs move to the boundaries where the elastic energy is very high and an in-plane component of the applied electric field exists, which results in the phase separation of the LC/RM mixture. We have shown that we can form polymer walls by applying ultraviolet light irradiation to the LC cell. These polymer walls can function as alignment layers. We observed morphological patterns of the polymer structure through polarized optical microscopy, scanning electron microscopy, and atomic force microscopy. The polymer walls formed in an LC cell can affect the orientation of LCs in the lateral direction. Bistable switching of a polymer-walled cell could be achieved by using three-terminal electrodes where both vertical and in-plane electric fields can be applied. Vertical anchoring with the alignment layer on each substrate allows LC molecules to remain vertically aligned after removal of the applied vertical electric field. Furthermore, in-plane anchoring with the formed polymer walls allows the LC molecules to remain homogeneously aligned after removal of the applied in-plane electric field. The proposed method for the formation of polymer structures could be a useful tool to fabricate LC cells for various applications. As a bistable phase-grating device, the diffraction efficiency of a polymer-walled cell was comparable to that of a pure-LC cell. Its operating voltage was 44% lower than that of a pure-LC cell owing to in-plane anchoring provided by the polymer walls. Moreover, it can be operated with very low power because it does not require power to maintain the state. In addition, the total response time of a polymer-walled cell was approximately 68% shorter than that of a pure-LC cell because all switching was forcibly controlled by applying an electric field.

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Switching between transparent and translucent states of a two-dimensional liquid crystal phase grating device with crossed interdigitated electrodes

Cited by 35 publications

References 24 publications

P‐166: Bistable Operation of a Smectic‐A Liquid Crystal Grating for Low‐power Window Display Application

P‐166: Bistable Operation of a Smectic‐A Liquid Crystal Grating for Low‐power Window Display Application

Liquid crystalline cellulose-based nematogels

Formation of Polymer Walls through the Phase Separation of a Liquid Crystal Mixture Induced by a Spatial Elastic Energy Difference

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