LC Physics

Session 7A: LC Physics
Wednesday, Feb. 15, 2017  10:40-12:05
Chair: Jia-De Lin, National Cheng Kung University, Taiwan
Che-Ju Hsu, National Changhu University of Education, Taiwan
Room: Lecture Hall III
11:05 - 11:20 Paper No.  2017-WED-S0107-O001
Jiun-Yan Lai
Optically Controllable Orbital Motion of Liquid Crystal Microspheres by Optical Vortex Tweezers System

Optical tweezers are achieved by using a highly focused laser beam and can be used to grab micrometer-scale particles. When the particle is transparent and its refractive index is larger than the surroundings, a single focused laser beam can attract it to the focused point through momentum transfer. Due to the non-contact and non-destructive properties, optical tweezers are widely applied in biomedical and materials sciences. The interaction between the microspheres (MSs) and the incident light field of optical tweezers can make the manipulation of microspheres in more diverse ways. This study aims to investigate orbital motions of azo-dye doped nematic liquid crystal (NLC) MSs under the manipulation of optical vortex tweezers (OVTs) and UV irradiation. Home-made q-plates (QPs) are integrated into the optical tweezers system for modulating the phase of laser and generating the optical vortex beam. The laser beam of the OVTs possesses spin and orbital angular momentum simultaneously. Two types of azo-dye-doped NLC MSs, bipolar and radial NLC MSs, are investigated. With the illumination of UV light, the internal orientations of NLC molecules in the azo-dye doped NLC MSs and thus the rotation behaviors of the azo-dye-doped NLC MSs change.

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11:20 - 11:35 Paper No.  2017-WED-S0107-O002
Masahito Oh-e
Anisotropic molecular orientations of cross-shaped bulky molecules observed in the bulk of a thin film

Although the material used in this study does not show any LC phases, it is one of the typical soft-matter materials with unique shape. Here we demonstrate how such soft-matter molecules form an orientational structure in a confined thin film, and how such structures can be analyzed, which can be applicable to LC phases as well. We have observed anisotropy with respect to the polar angle in vacuum-deposited amorphous films using cross-shaped molecules with an accompanying effect on carrier mobility by means of variable angle spectroscopic ellipsometry (VASE), sum-frequency generation spectroscopy (SFG) and impedance spectroscopy (IS). We study molecular orientations of the uniquely shaped molecule, keeping it in mind whether or not anisotropy can be observed with relatively bulky molecules. We make a difference in a more quantitative analysis over how the molecules sit in a thin film on average, introducing the advanced technique beyond linear optics; SFG has been used to deduce more detailed molecular orientations. We also make clear how anisotropy accompanies an effect on carrier mobility at the end.

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11:35 - 11:50 Paper No.  2017-WED-S0107-O003
Mateen Fahad
Liquid crystal based smart window with integrated luminescent solar concentrator

Polymer dispersed Liquid crystal (PDLC) based smart windows have been studied widely for the use as curtain-free windows. Their integration with luminescent solar concentrator (LSC) device is a promising approach towards development of self-sustainable smart windows. The electricity produced by the LSC could potentially be employed for switching operation of smart window. In this study, we have presented a novel configuration of LSC-PDLC smart window. The presented system comprises of two parts, LSC and PDLC as outer and inner part respectively, partitioned by the small air gap. LSC-PDLC smart window was evaluated on the base of spectral contents of power emitted by the edges. PDLC in OFF mode acts as a backside scatterer. Firstly, it reflects the untrapped light back into LSC part, enhancing the edge emissions. Second, it redirects light that is not absorbed towards the edges, and thus to the attached solar cell. Further, the effect of applied voltage on LSC-PDLC smart window has been discussed. Our results are of great interest in view of a possible use of LSC as an onboard power generator for smart window.

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11:50 - 12:05 Paper No.  2017-WED-S0107-O004
Duan-Yi Guo
Special beam shape by virtue of meta-q-plate

In this research, we successfully design a novel microlithography system to conduct photo-alignment, and the concept of meta-q-plate featured by arbitrarily space-variant optical axes is proposed. Furthermore, correspondingly special fields including elliptical, asymmetrical, multi-ringed and hurricane transverse profiles are demonstrated.

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