Chinese Journal of Liquid Crystals and Displays, Volume. 36, Issue 3, 379(2021)
Characteristics of twisted nematic liquid crystal terahertz phase modulator
A terahertz phase modulator based on twisted nematic liquid crystal is designed, and the influences of twist angles of 30°, 45°, and 90° on the phase modulation characteristics are analyzed using Jones matrix simulation. The results show that a smaller twist angle leads to the higher phase retardation and larger light utilization efficiency. In addition, with the increase of the voltage at the same frequency, the transmittance increases and the phase retardation decreases. When LC1825 liquid crystal with a twist angle of 30° is injected into a liquid crystal cell with a thickness of 250 μm, the transmission-based terahertz phase modulator is built. The phase retardation of 126° is obtained at a frequency of 1.2 THz. In order to maximize the phase modulation, a reflection-based terahertz phase modulator is also structured, which has similar structural parameters as the transmission-based terahertz phase modulator. As a result, the phase retardation reaches 270° at 1.2 THz, which is much larger than the transmission-based one due to the double effective optical length.
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GAO Rui, WU Ri-na, SONG Yun-he, LU Jia-qi, DAI Qin. Characteristics of twisted nematic liquid crystal terahertz phase modulator[J]. Chinese Journal of Liquid Crystals and Displays, 2021, 36(3): 379
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Received: Sep. 29, 2020
Accepted: --
Published Online: Sep. 3, 2021
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