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Photoinduced micropattern in an azobenzene polymer film
Lingzhi Zhang,Jian Wang,Zhaoxi Liang,Zeda Xu,Zhigang Cai,Weilong She,Jianying Zhou
Chinese Science Bulletin , 2003, DOI: 10.1007/BF03183291
Abstract: The micropattern observed in the amorphous azobenzene polymer film by degenerated four-wave mixing has been reported. Patterns with well-defined structures are examined with the scanning electron microscopy and the polarizing optical microscopy. It is demonstrated that the control of photoinduced micropattern in the azobenzene polymer film is possible by using appropriate polarized writing beams with total incident power exceeding a certain threshold.
Photoinduced micropattern in an azobenzene polymer film
ZHANG Lingzhi,WANG Jian,Liang Zhaoxi,XU Zeda,Cai Zhigang,SHE Weilong,Zhou Jianying,

科学通报(英文版) , 2003,
Abstract: The micropattern observed in the amorphous azobenzene polymer film by degenerated four-wave mixing has been reported. Patterns with well-defined structures are examined with the scanning electron microscopy and the polarizing optical microscopy. It is demonstrated that the control of photoinduced micropattern in the azobenzene polymer film is possible by using appropriate polarized writing beams with total incident power exceeding a certain threshold.
Photomechanical Bending of Azobenzene-Based Photochromic Molecular Fibers  [PDF]
Hideyuki Nakano,Ryoji Ichikawa,Riku Matsui
Micromachines , 2013, DOI: 10.3390/mi4020128
Abstract: Microfibers composed of azobenzene-based photochromic amorphous molecular materials, namely low molecular-mass photochromic materials with a glass-forming property, could be fabricated. These fibers were found to exhibit mechanical bending motion upon irradiation with a laser beam. In addition, the bending direction could be controlled by altering the polarization direction of the irradiated light without changing the position of the light source or the wavelength of the light. In-situ fluorescence observation of mass transport induced at the surface of the fiber doped with CdSe quantum dots suggested that the bending motions were related with the photoinduced mass transport taking place near the irradiated surface of the fiber.
Temperature Dependence of Photoinduced Birefringence in an Azobenzene Polymer
XU Hong-Tao,WANG Chang-Shun,PAN Xu,ZHANG Xiao-Qiang,WANG Chuan-Yu,SUN Cun-Ying,

中国物理快报 , 2007,
Abstract: The photoinduced birefringence in an azobenzene polymer is investigated at different temperatures between -20°C to 50°C. It is found that there is a peak value of photoinduced birefringence in the temperature dependence of the photoinduced birefringence under a certain pumping intensity. With the pump light in 90mW/cm2, the peak value of the photoinduced birefringence appeared at about 0°C. The effect of temperature on the photoinduced birefringence is discussed using the competition mechanism between the photoinduced reorientation and the thermal random motion.
Low Driving Voltage and Analysis of Azobenzene Polymer Doped Liquid Crystal Grating
SONG Jing,LIU Yong-Gang,MA Ji,XUAN Li,

中国物理快报 , 2006,
Abstract: We mix azobenzene polymer and liquid crystal in certain ratio. Then the mixture is injected into cells. Nonlinearly photoinduced birefringence takes place when linearly polarized ultraviolet is applied with the pattern photomask covering on the cells, which results in the formation of azobenzene polymer doped liquid crystal grating. The obtained grating is characterized by an optical microscope and a He-Ne laser. The results indicate that the samples have clear grating structure, and the diffraction efficiencies can be modulated by electric field. The sample driving voltage is 0.6 V/μm. It is lower than the driving voltage of holographic polymer dispersed liquid crystal transmission grating and could be matched with the driving integrated circuit.
Photomechanical Energy Conversion of Photoresponsive Fibers Exhibiting Bending Behavior  [PDF]
Kazuya Nakata,Yosuke Ishikawa,Munetoshi Sakai,Baoshun Liu,Tsuyoshi Ochiai,Hideki Sakai,Taketoshi Murakami,Masahiko Abe,Akira Fujishima
International Journal of Photoenergy , 2012, DOI: 10.1155/2012/574124
Abstract: Photoresponsive fibers based on poly(acrylamide) (PAA) with methylene blue (MB) dye were prepared. All semicircular fibers show bending towards the direction of the flat surface of the fiber when illuminated. The fibers recover their initial shape when the illumination stops. The fiber is heated upon illumination and cooled to room temperature once the illumination is stopped. The fiber also is sensitive to humidity, showing bending behavior towards the direction of the flat surface of the fiber upon changing the humidity. The mechanical energy of the PAA/MB fiber is approximately 0.6?mN for the bending direction when it is illuminated. A possible mechanism for the bending behavior is as follow: (1) the fiber is heated upon illumination because of the photothermal effect, (2) the fiber loses water molecules, (3) the fiber shrinks; bending towards the direction of the flat surface of the fiber occurs because of a difference in the shrinkage for the flat surface and the other side of the fiber. Finally, we demonstrated that a PP ball (1.5?mg) can be moved by the mechanical energy produced by the changing shape of the fiber upon illumination. 1. Introduction Utilization of solar energy is a key factor for development of a sustainable society. Among a number of approaches for solar energy conversion, photomechanical energy conversion has significant advantages such as direct energy conversion from photo to mechanical, which may potentially lead to high energy conversion efficiency, no cable for working, and space-saving. Typical photomechanical materials that change shape in response to light are liquid crystalline elastomer films based on azobenzene derivatives [1–14]. These materials show bending behavior upon illumination because the structure of azobenzene derivative molecules in the film changes from trans to cis form, which generates mechanical energy. Although these materials have attracted much attention because they can be applied as photodriven motors [9], actuators [1, 3, 4, 6, 8, 10, 11, 15–17], and new types of solar energy conversion systems [2, 5, 7, 11–14, 16, 18, 19], they need multiple synthetic procedures followed by rubbing to align the azobenzene molecules, which makes them impractical for many applications. Materials exhibiting a volume change in response to light are of interest [20–22]. For example, hydrogels that show a volume change upon the application of light have been reported previously [21–23]. The basic mechanism for the volume change is a solvent absorption/desorption process. Suzuki and Tanaka reported that a polymer gel
An optically activated cantilever using photomechanical effects in dye-doped polymer fibers  [PDF]
Shaoping Bian,Dirk Robinson,Mark G. Kuzyk
Physics , 2005, DOI: 10.1364/JOSAB.23.000697
Abstract: We report on what we believe is the first demonstration of an optically activated cantilever due to photomechanical effects in a dye-doped polymer optical fiber. The fiber is observed to bend when light is launched off-axis. The displacement angle monotonically increases as a function of the distance between the illumination point and the fiber axis, and is consistent with differential light-induced length changes. The photothermal and photo-reorientation mechanisms, each with its own distinct response time, are proposed to explain the observed time dependence. The measured degree of bending is consistent with a model that we have proposed which includes coupling between photoisomerization and heating. Most importantly, we have discovered that at high light intensity, a cooperative release of stress results in cis-to-trans isomerization that yields a large and abrupt length change.


物理学报 , 2000,
Abstract: Pattern formation and transverse effect are reported for azobenzene polymer film.We show,through scanning electron microscopy and polarizing optical microscopy investigation of azobenzene polymer film after being irradiated by degenerate four-wave mixing,that many peak-like islands of azobenzene polymer molecules array in some patterns.Experimental evidence that it is possible to control the photoinduced micro-patterns of the nonlinear organic film via adequately polarized write beams and appropriate power of the write beams,thus making easy growth of nanostructures crystals in azobenzene polymer film.
Modulational instability of incoherently coupled beams in azobenzene-containing polymer with photoisomerization nonlinearity

Zhang Bing-Zhi,Cui Hu,She Wei-Long,

中国物理 B , 2009,
Abstract: The modulational instability of two incoherently coupled beams in azobenzene-containing polymer with photoisomerization nonlinearity is investigated analytically and numerically. Our results show that as a precursor to spatial optical soliton formation, modulational instability can be adjusted and controlled by the wavelength combinations of the signal and background beams. We also discuss the dependences of strength of modulational instability on intensities of two signal beams and background beam. These findings make it possible to predict the formation of incoherently coupled soliton pairs in azobenzene-containing polymer.
Delocalized Photomechanical Effects of UV ns Laser Ablation on Polymer Substrates Captured by Optical Holography Workstation: An Overview on Experimental Result  [PDF]
Vivi Tornari
Advances in Optics , 2014, DOI: 10.1155/2014/105482
Abstract: A brief overview of results from an experimental investigation performed on polymer materials to examine delocalized photomechanical effects generated due to UV laser ablation is provided. Delocalized structural modifications were observed in PMMA, PS by means of optical holographic interferometry. The integrity of samples was examined before and after irradiation in 193 and 248?nm (15?ns) above and below ablation threshold, F = 0.1–1.0?J/cm2. A value of structural continuity was initially determined for each sample by generation of a reference holographic image before irradiation. Microscopic discontinuities were intentionally induced to act as preexistent defects. Sequential holographic recording monitored the growth of morphological alterations according to the number of pulses in the neighbor as well as far from the preexistent discontinuities. The imposed alterations are visually observable at the whole extent of the irradiated sample in distances far off the ablation spot as local cracks and voids. The induced flaws cannot be classified as transient or instantly generated. Fracture follows a long-term emergence and deterioration pattern. Extensively fluctuated long-term effects were also observed in laser-assisted varnish removal of multilayered technical samples simulating Byzantine icons with decrease of effect duration and fluctuation being according to increase in sample homogeneity. 1. Introduction Irradiation of solid organic material with pulsed ultraviolet laser light of intense power density leads to cold etching or ablative photodecomposition (APD) of the substrate. The APD effect located in the limited region of the laser spot is attributed to local photochemical mechanism causing discrete ejection of target material without altering the adjacent bulk which allows for controlled substrate processing conveniently suited for many applications. The mass ejection and the expansion of high-density plasma though induce a mechanical effect characterized by a recoil pressure and a shock wave propagating inside the solid. The photomechanical effects in contrast to the presented study are mainly reported in literature in concern to the physical processes in the ablated region as influence of pressure versus time. Specifically, laser ablation using 193, 248?nm excimer laser radiation is commonly used [1–12] in microelectronic industry for etching of polymer substrates and in medical applications for controlled excision of tissue as well as in ophthalmology and in photorefractive surgery for restoring of myopia and has been proved to be a highly
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