Response of liquid crystals in the pre-transitional state

Katayama, Kenji; Kato, Daiki; Nagasaka, Kin-Ichiro; Miyagawa, Minako; Sohn, Woon Yong

doi:10.1080/15421406.2017.1403236

Cited by 3 publications

(3 citation statements)

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“…A phase imaging method was developed based on the transient grating (TG) method. The principle of the TG method was described in our previous paper 22 , and the additional difference is explained here. The optical configuration of the TG imaging is shown in Fig.…”

Section: Theory and Methodsmentioning

confidence: 99%

“…Recently, we found that the molecular disordering during the phase transition propagates in a ballistic manner, with a speed of ~100 m/s 21 . In our previous work, the nonlinear refractive index change was observed when the temperature or the pump intensity were adjusted so that the phase was very close to the isotropic condition, and a drastic change in the dynamics was observed, which involved a long-lasting diffraction intensity on the order of 100 ms 22 .…”

Section: Introductionmentioning

confidence: 94%

See 1 more Smart Citation

Origin of optical nonlinearity of photo-responsive liquid crystals revealed by transient grating imaging

Katayama

Kato

Nagasaka

et al. 2019

Sci Rep

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A large optical nonlinearity has been observed for the photo-responsive liquid crystals under the condition that the nematic phase is close to the isotropic condition. The direct observation of the photo-response of a liquid crystal by the time-resolved transient grating phase imaging technique revealed that the optical nonlinearity was caused by the transiently generated phase formed inside the photo-induced isotropic region. A shock-like flow was observed for the formation of the transiently generated phase. Based on the theoretical calculation, we propose that a flow generated at the disordered/ordered interface induced the reorientation of the liquid crystal molecules, thereby generating a larger polarization and ultimately causing the optical nonlinearity.

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Section: Theory and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Origin of optical nonlinearity of photo-responsive liquid crystals revealed by transient grating imaging

Katayama

Kato

Nagasaka

et al. 2019

Sci Rep

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“…The phase transition and photo-induced orientation change were distinguished and the anisotropic phase transition/recovery was clarified by the observation of the extraordinary and ordinary refractive index change [ 35 ], and also revealed that the front surface of phase transition moved at ~100 m/s [ 36 ]. In recent years, we have studied the origin of the optical nonlinearity from the dynamics of the LCs by using time-resolved methods and found that the enhancement occurred on the millisecond time scale [ 37 ]. Furthermore, a new time-resolved imaging technique was developed, and the origin was clarified by visualizing the images of the optically induced flow of the LCs [ 38 ].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Molecular Disordering Processes in the Phase Transition of Liquid Crystals Observed by Patterned-Illumination Time-Resolved Phase Microscopy

Sato

Katayama

2021

Materials

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The initial processes of the phase transition dynamics of liquid crystals (LCs) subject to UV pulse irradiation were clarified using a nanosecond time-resolved imaging technique called pattern-illumination time-resolved phase microscopy (PI-PM). Two types of LCs were studied: a photo-responsive LC and dye-doped LCs. We found two steps of molecular disordering processes in the phase transition, namely local disordering proceeding anisotropically, followed by the spreading of the isotropic phase. These two processes were separated for a photo-responsive LC while being simultaneously observed for the dye-doped LCs. It was found that the photomechanical dyes induced the phase transition process faster than the photothermal dyes.

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