Browsing by Author "Lin, Shivan-Huei"

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Dynamic characterization of photo-alignment of azo-dye-doped polymer using phase modulated polarimetry
(2013-01-01)
Chuang, Chun-I
;
Lin, Shivan-Huei
;
Chao, Yu-Faye
;
電子物理學系
;
光電工程學系
Using a combination of two-probe-beam phase modulated polarimetry and a waveform extraction technique, we show it is possible to determine all the optical parameters of an anisotropic medium. Particularly, we have measured the dynamic changes of refractive index ellipsoid of the disperse red 19-doped poly(methyl methacrylate) under the irradiation of linear polarized lights. The long axis of the trans molecule can be aligned to the propagation direction of P-polarized light while it is irritated by two crossed polarized lights. The refractive indices and orientation angles can be determined in one cycle of modulation (20 mu s) with sufficient precision of 10(-6) and 0.1 degrees, respectively. This work shows a new way to simultaneously monitor and control the photo-alignment process of azobenzene molecules in a polymer matrix. (c) 2012 Elsevier B.V. All rights reserved.
Environment-Dependent Ultrafast Photoisomerization Dynamics in Azo Dye
(2011-10-27)
Hsu, Chun-Chih
;
Wang, Yu-Ting
;
Yabushita, Atsushi
;
Luo, Chih-Wei
;
Hsiao, Yi-Nan
Azoaromatic dyes have been extensively investigated over the past decade due to their potential use in a variety of optical devices that exploit their ultrafast photoisomerization processes. Among the azoaromatic dyes, Disperse Red 19 is a commercially available azobenzene nonlinear optical chromophore with a relatively high ground-state dipole moment. In the present study, we used ultrafast time-resolved spectroscopy to clarify the dynamics of a push-pull substituted azobenzene dye. Solution and film samples exhibited different ultrafast dynamics, indicating that the molecular environment affects the photoisomerization dynamics of the dye.
Real-time measurement of photo-induced effects in 9,10-phenanthrenequinone-doped poly(methyl methacrylate) photopolymer by phase-modulated ellipsometry
(2010-09-01)
Chuang, Chun-I.
;
Hsiao, Yi-Nan
;
Lin, Shivan-Huei
;
Chao, Yu-Faye
;
電子物理學系
The photo-induced effects in 9,10-phenanthrenequinone-doped (PQ-doped) poly(methyl methacrylate) (PMMA) photopolymer were studied by phase-modulated ellipsometry and polarimetry in real time. The PQ-doped PMMA was exposed to an Ar/Kr tunable laser at the wavelength of 488 nm and measured by a HeNe laser (632.8 nm). We measured the induced birefringence and the variation of the refractive index separately during exposure; there was a difference of three orders of magnitude between these two effects. This suggested that the physical mechanism of holographic recording in PQ-doped PMMA is mainly due to the photo-induced variation in the refractive index. (C) 2010 Elsevier B.V. All rights reserved.
Reduction of phase error on phase-only volume-holographic disc rotation with pre-processing by phase integral
(2020-09-14)
Yu, Yeh-Wei
;
Chen, Yuan-Cheng
;
Huang, Kun-Hao
;
Cheng, Chih-Yuan
;
Yang, Tsung-Hsun
In this paper, we present a study of observation of phase error of a volume holographic storage disc during the reading process when the disc is rotated or displaced in the theoretical calculation and the corresponding experiment. This additional phase error will dramatically decrease the bit error rate of a phase-only signal, even applying double-frequency shearing interferometry to retrieve the stored phase signal. Then we propose a novel approach to solve the problem. The stored signal is pre-processed by phase integral along the shearing direction so that applying the integral process to decode the phase signal is not necessary in the readout process. The proposed approach effectively reduces the error in phase retrieval and will be useful when applying double-frequency shearing interferometry in the readout process for volume holographic storage. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement