• Title/Summary/Keyword: Bistability

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Optical transmission characteristics of a bistable TN LCD (쌍안정 TN LCD의 광투과 특성)

  • 최길재;김양수;강기형;정태혁;윤태훈;김재창;남기곤;이응상
    • Korean Journal of Optics and Photonics
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    • v.8 no.3
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    • pp.218-222
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    • 1997
  • We fabricated a bistable TN LCD with 180$^{\circ}$ twist angle and confirmed that it has a fast switching response time and a high contrast ratio. We also investigated the effects of the amplitude and width of the reset and selection pulses on a bistable TN LC cell and the conditions of the bistability and the memory time. The range of d/p values showing the bistability is determinded for the pretilt angle according to the rubbing depth.

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Phenomenon of the absorptive optical bistabililty in amorphous $As_2S_3$ thin film (비정질 $As_2S_3$ 박막에서의 흡수형 광쌍안정 현상)

  • 안웅득;김석원;한성홍
    • Korean Journal of Optics and Photonics
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    • v.7 no.2
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    • pp.129-135
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    • 1996
  • We observed the absorptive optical bistability in the single layer amorphous $As_2S_3$ thin film which has an isolated electron pairs at roomtemperature, for the frist time, $Ar^+$ laser beam (λ=514.5 nm) was used as a light source and was focused by thin lens. The experiment was performed in cavityless system and the occurrence of optical bistability in this material could be explained by the temperature-dependent absorption coefficient of the sample. Also, this effect was explained by the reversible shift of the absorption edge in this material. The condition of optical bistability is determined by detuning value ($a_0L$) and this value was 0.12 when thikness of that sample was about 0.8 ${\mu}{\textrm}{m}$. The switching was observed clealy when light intensity is 150~180 mW and the swiching time was about $10^{-4}$ s.

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Wide viewing angle of reflective cholesteric liquid crystal display

  • Kwon, Jang-Un;Kang, Dae-Seung
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.608-610
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    • 2003
  • In the paper, we have investigated the reflective cholesteric display based on the polymer stabilization. The bistability in the polymer stabilized cholesteric texture(PSCT) films was observed and wider viewing angle was achieved due to imperfect planar texture.

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A Simple Analytical Model for the Study of Optical Bistability Using Multiple Quantum Well p-i-n Diode Structure

  • Jit, S.;Pal, B.B.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.4 no.1
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    • pp.63-73
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    • 2004
  • A simple analytical model has been presented for the study of the optical bistability using a $GaAs-Al_{0.32}Ga_{0.68}As$ multiple quantum well (MQW) p-i-n diode structure. The calculation of the optical absorption is based on a semi-emperical model which is accurately valid for a range of wells between 5 and 20 nm and the electric field F< 200kV/cm . The electric field dependent analytical expression for the responsivity is presented. An attempt has been made to derive the analytical relationship between the incident optical power ( $(P_{in})$ ) and the voltage V across the device when the diode is reverse biased by a power supply in series with a load resistor. The relationship between $P_{in}$ and $P_{out}$ (i.e. transmitted optical power) is also presented. Numerical results are presented for a typical case of well size $L_Z=10.5nm,\;barrier\;size\;L_B=9.5nm$ optical wave length l = 851.7nm and electric field F? 100kV/cm. It has been shown that for the values of $P_{in}$ within certain range, the device changes its state in such a way that corresponding to every value of $P_{in}$ , two stable states and one unstable state of V as well as of $P_{out}$ are obtained which shows the optically controlled bistable nature of the device.