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Author

Yuquan Shen

Bio: Yuquan Shen is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Azobenzene & Laser. The author has an hindex of 16, co-authored 52 publications receiving 773 citations. Previous affiliations of Yuquan Shen include Washington State University & Academia Sinica.
Topics: Azobenzene, Laser, Femtosecond, Poling, Chromophore


Papers
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Journal ArticleDOI
TL;DR: In this paper, permanent holographic gratings were fabricated in bulk azodye-doped polymethylmethacrylate by the coherent field of a femtosecond laser.
Abstract: Permanent holographic gratings were fabricated in bulk azodye-doped polymethylmethacrylate by the coherent field of a femtosecond laser. Optical microscopy and atomic force microscopy observations revealed that the gratings consist of two parts, surface relief gratings on both surfaces and refractive index modulated volume gratings in the interior of the polymers. The diffraction efficiency of the first-order Bragg for the gratings was estimated to be 90%.

71 citations

Journal ArticleDOI
TL;DR: Experimental results show that conjugation modulation of the bridge in donor/acceptor molecules simultaneously optimizes the transition moments and the energy-level spacing in the context of quantum limits.
Abstract: A new strategy for optimizing the first hyperpolarizability based on the concept of a modulated conjugated path in linear molecules is investigated. A series of seven novel chromophores with different types of conjugated paths were synthesized and characterized. Hyper-Rayleigh scattering experiments confirmed that modulated conjugation paths that include benzene, thiophene, and/or thiazole rings in combination with azo and/or ethenyl linkages between dihydroxyethylamino donor groups and various acceptor groups result in enhanced intrinsic hyperpolarizabilities that exceed the long-standing apparent limit for two of the chromophores. The experimental results are analyzed and interpreted in the context of quantum limits, which show that conjugation modulation of the bridge in donor/acceptor molecules simultaneously optimizes the transition moments and the energy-level spacing.

71 citations

Journal ArticleDOI
TL;DR: In this article, NLO azo-based chromophores containing strong electron-withdrawing groups and benzene or thiazole moiety as conjugated bridges were synthesized and characterized.
Abstract: Novel NLO azo-based chromophores containing strong electron-withdrawing groups and benzene or thiazole moiety as conjugated bridges were synthesized and characterized. β values were measured by HRS method, they are in the range of 238–1459 × 10−30 esu at the fundamental wavelength of 800 nm. For chromopheres 3 and 4, β values at the fundamental wavelength of 1064 nm were also measured, they are 1575 × 10−30 esu and 935 × 10−30 esu, respectively. Thermal stabilities for these chromophores are reported. We also discuss the effects of different acceptors and conjugating moieties on β.

60 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the stress-induced martensitic transformation behaviors and the associated elastocaloric effect for non-textured polycrystalline all-d-metal Heusler alloys of Ni50Mn32Ti18 and Ni35Co15Mn35Ti15 by a combination of Digital Image Correlation (DIC) and Infrared (IR) thermography techniques.
Abstract: We have studied the stress-induced martensitic transformation behaviors and the associated elastocaloric effect (eCE) for non-textured polycrystalline all-d-metal Heusler alloys of Ni50Mn32Ti18 and Ni35Co15Mn35Ti15 by a combination of Digital Image Correlation (DIC) and Infrared (IR) thermography techniques. A large but irreversible adiabatic temperature change (ΔTad) of 10.7 K at a strain level of 3.9% is observed for Ni50Mn32Ti18, whereas Ni35Co15Mn35Ti15 exhibits a reversible eCE with ΔTad = 9.0 K at a strain level of 4.6%. At lower strain levels ( 3.2%), Ni50Mn32Ti18 is plastically deformed with small strain variation in space from the DIC map. In contrast, Ni35Co15Mn35Ti15 can be deformed superelastically accompanied by large strain variation in space, which can be ascribed predominately to the crystalline orientation dependence of both the transformation strain and the Young's modulus from different orientated grains under mechanical loading. The improved reversibility of eCE for Ni35Co15Mn35Ti15 is supposed to be associated with the enhancement of d-d hybridization by the introduction of the element Co.

60 citations

Journal ArticleDOI
TL;DR: In this paper, a new class of nonlinear optical (NLO) chromophores, 2-dicyanomethylen-3-cyano-4-{2]-2-(4-( N, N, N -di(2-hydroxyethyl)-amino)phenylazo)-thien-5]-E -vinyl}-5,5-dimethyl-2,5dihydrofuran (2a ) is synthesized based on the azothiophene conjugated spacer and TCF electron-

31 citations


Cited by
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Proceedings Article
14 Jul 1996
TL;DR: The striking signature of Bose condensation was the sudden appearance of a bimodal velocity distribution below the critical temperature of ~2µK.
Abstract: Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

3,530 citations

Journal ArticleDOI
TL;DR: In this article, the design and synthesis of several classes of suitable azobenzene functionalized polymers for the surface relief grating (SRG) formation process is discussed and experimental studies are carried out to understand the chemical and physical intricacies involved in the SRG formation process.
Abstract: All optical fabrication of Surface Relief Grating (SRG) on azobenzene functionalized polymer films is reviewed in this article. The uniqueness of the single step erasable photofabrication of large amplitude surface relief structures on azo polymer films is mainly due to the photoisomerization and photoanisotropic behavior of the azobenzene group. The design and synthesis of several classes of suitable azobenzene functionalized polymers for the SRG formation is presented. Experimental studies are carried out in a systematic manner to understand the chemical and physical intricacies involved in the SRG formation process. Structural requirements and their limitations for the efficient fabrication of SRGs on azo functionalized polymer films are also discussed. Understanding the fundamental mechanism of SRG formation on the azo functionalized polymer films enables us to make use of these structures in a variety of applications.

699 citations

Journal ArticleDOI
TL;DR: In this paper, the design and main properties of phthalocyanines for second-and third-order nonlinear optical (NLO) and optical limiting applications are discussed, both at the microscopic and macroscopic level.
Abstract: Phthalocyanines (Pcs) and related compounds with their extended two-dimensional pi;-electronic delocalization are important targets to study nonlinear optical responses. The tailorability of these macrocycles allows the fine-tuning of the chemical structure and nonlinear optical response. In this article, the design and main properties of phthalocyanines for second- and third-order nonlinear optical (NLO) and optical limiting applications are discussed, both at the microscopic and macroscopic level. The points of view of synthetic organic chemists and physicists are accorded, the main aim of the review being to highlight the key problems of the field and place them within the general context of NLO materials.

538 citations