Jianda Shao

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (309)474.46 Total impact

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    ABSTRACT: Titanium dioxide (TiO2) nanostructured thin film (TNF), as an important semiconductor exhibiting large surface-to-volume ratio and unique property, has attracted more and more researches. As an important versatile nanofabrication technique, the glancing angle deposition technique (GLAD) is used to fabricate the TNF, frequently. However, little is known about the influence of GLAD on microstructure, crystalline structure, Ti/O chemical state and photoluminescence (PL) properties of TiO2 thin films. In this paper, pure anatase TNF and traditional TiO2 thin film (TTF) were deposited by combining GLAD system with the annealing treatment. All of the prepared TNFs keep discrete nanoscale columnar structures characterized by SEM. The evolution of morphology, crystallization structure, Ti/O chemical state and PL properties of TNFs and TTFs under annealing treatment have been investigated in detail. Simultaneously, comparing with TTFs, the influence of GLAD on TNFs material properties has been analyzed further. With the optimum annealing temperature (400 °C), one can obtain fine nanostructures and pure anatase precipitation of TNFs. The GLAD technique can adjust the preferred crystal orientation of TiO2 thin films, which can be used as a method of material structural design. Both TNFs and TTFs exhibit broad band (380-700 nm) photoluminescence. Nevertheless, the TNFs exhibit much weaker and smoother PL spectra than that of TTFs, due to the large surface-to-volume ratio. The results indicate the potential good catalytic applications of TNFs deposited by GLAD.
    No preview · Article · Feb 2016 · Superlattices and Microstructures
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    ABSTRACT: Y3Al5O12: Ce (YAG:Ce) nanoparticles need annealing treatment at high temperature to transformthe amorphous precursors to crystalline YAG phase.However, little is known about Ce chemical stateanalysis and photoluminescence (PL) properties of YAG:Ce nanoparticles with the different annealing temperatures and atmospheres.In this paper,amorphous nanoparticle-based YAG:Ce films, prepared by electron beam deposition technique on fused silica substrates, have been annealed at different conditions. Ce3+, Ce4+ states and Ce3+/Ce4+ atomic ratio have been distinctly separated and calculated by X-ray photoelectron spectroscopy (XPS). Combined Ce3+/Ce4+ atomic ratio with the microstructures, the Ce chemical state modification and PL properties of YAG:Ce films with different annealing treatments have been investigated throughout. Low temperature annealing in air can cause oxidationof Ce3+, higher temperature (≥750°C) annealing in air can cause partial reduction of Ce4+ due to thehigh-temperature pyrolysis. In this paper, value of Ce3+/Ce4+ is the maximum after 850°C annealing in H2, and YAG:Ce film annealed in H2 has the maximum luminous intensity, which could be proposed to the increased Ce3+ content. According to the systematical research and analysis, one can find that the Ce3+ content controls the luminescence efficiency. This paper provides a feasible approach to produce YAG:Ce nanoparticle-based films for the practical applications, and provides the understanding about YAG:Ce luminescent properties.
    No preview · Article · Jan 2016 · Optical Materials Express
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    Zhou Fang · Yuan’an Zhao · Jianda Shao

    Full-text · Article · Nov 2015 · Optik - International Journal for Light and Electron Optics
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    ABSTRACT: The plasma scald damage is the most typical laser damage morphology presented on the laser conditioned HfO2/SiO2 mirrors. In order to provide guidance for defining the acceptance quantitative specification for the plasma scald on these laser conditioned mirrors, the simulations about the downstream beam modulations of the plasma scald are investigated based on its damage characteristics and the diffraction theory. The single plasma scald with the typical size, induced by the laser conditioning, can hardly cause damage to the downstream optics and its influence on the beam contrast can be reduced easily with the increment of the propagation distance. Those with small size and large depth, or those with big size and shallow depth can also hardly induce downstream damage, but the beam contrasts become worse with the increment of the size of the concave part as well as its depth. For a maximum plasma scald observed on the laser conditioned mirror, the intensity modulation peak is close to 1.3 and the beam contrast reaches to 25% even at 2 m downstream from the mirror. For multi plasma scalds, more diffraction rings show up in the downstream beam and further decrease the overall uniformity of the beam. The uniformity of the beam gets worse as the number of the plasma scald is increased. When the density of the plasma scald with the typical size in these 1ωHfO2/SiO2 mirrors reaches 20 per 1 cm2, the beam contrast is less than 6%.
    Full-text · Article · Oct 2015 · Optics Communications
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    ABSTRACT: The laser damage resistance of the coatings for high-power laser systems depends greatly on the surface quality of the substrate. In our work, experimental approaches were employed to understand the interface coupling effect of the substrate surface and coatings on the laser resistance of the coatings. A 1064 nm anti-reflection (AR) coating was deposited by an e-beam coater onto fused silica with and without micro-scale pits (structural defects). The micro-scale pits were precisely fabricated by femtosecond laser processing to prevent the emergence of subsurface cracks. Different deposition temperatures were characterized in order to verify the intensity of the interface coupling effect of the substrate and coating layers. Our experimental results indicate that impurities that are introduced in the finishing process, shifted to the substrate surface, and aggregated during the heating process, play a much more crucial role than structural defects (length: ∼7 μm; width: ∼3 μm; depth: ∼0.8 μm) in the laser-induced damage process. By effectively reducing the intensity of the interface coupling effect, the e-beam AR coatings, whose laser-induced damage resistance was closed to the bare substrate, was prepared.
    Full-text · Article · Aug 2015 · Optics Letters
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    ABSTRACT: The variation of scattering and absorption in DKDP crystals by laser conditioning was investigated by combining light scattering technique and on-site transmittance measurement technique. Laser-induced disappearance of scattering defects was observed, and variation of transmittance was achieved. Using Mie theory, a kind of absorbing defects, aside from scattering defect, was discovered. Moreover, the experimental results demonstrated that the absorption of crystal could be mitigated by laser conditioning.
    Full-text · Article · Jun 2015 · Optics Express
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    Hu Wang · Hongji Qi · Meng Guo · Yingjie Chai · Bin Wang · Kui Yi · Jianda Shao
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    ABSTRACT: The near-field phase modulation (NFPM) caused by the plasma scalds is investigated with a newly proposed mixed overcoat layer model. Based on the NFPM, the far-field intensity modulation (FFIM) is calculated and discussed with the scalar diffraction theory. The results indicate that both the NFPM and FFIM are sensitive to the scalding depth. A feature curve is developed to analyze the NFPM for arbitrary scalding depth. The modulation can be ignored when the scalding depth is less than the first feature point in the feature curve. Even though the diffraction intensity in the Fresnel region can be enhanced dozens of times, the FFIM in the Fraunhofer region can recover gradually if the scalding depth is below a critical value. The preliminary experimental results are consistent with the theoretical prediction.
    Full-text · Article · Jun 2015 · Optics Letters
  • Bin Wang · Hongji Qi · Hu Wang · Yanyan Cui · Jialu Guo · Yun Cui · Youchen Liu · Kui Yi · Jianda Shao
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    ABSTRACT: Amorphous TiO2 nanostructured thin films (TNFs) were deposited by the glancing angle deposition technique (GLAD) with an electron gun. All of the prepared TNFs were composed of discrete nanoscale columns, characterized by scanning electron microscope. With the annealing treatment, the pure anatase phase was transformed from amorphous TNFs. The morphological, structural and optical properties of TNFs under the annealing treatment were measured, and the evolvement mechanism was further analyzed. The optimum annealing temperature for the pure anatase precipitation of TNFs is about 400°C. The variation of morphology, chemical state and crystallization of TNFs also resulted in the shift of the transmittance spectra. The results show that appropriate postannealing treatment can build fine nanostructures and pure anatase precipitation, which can support the applications and researches about the anatase phase TNFs powerfully.
    No preview · Article · Jun 2015 · Optical Materials Express
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    Zehan Li · Juan Du · Yuanan Zhao · Yueliang Wang · Yuxin Leng · Jianda Shao
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    ABSTRACT: The effect of nanosecond laser conditioning on the femtosecond laser-induced damage behaviors of Al<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub>, SiO<sub>2</sub> single layers and Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> high reflectors (HR) are explored. During femtosecond laser damage test, negative effects on enhancing the femtosecond laser-induced damage threshold (LIDT) of optical films after the nanosecond laser conditioning is found, which is opposite to the LIDT improvement in the nanosecond range. To explain the mechanism after nanosecond laser conditioning, a theoretical model including multiphoton ionization (MPI), avalanche ionization (AI) and decays of electrons with one defect state is built to simulate the evolution of electron density in the conduction band. A permanent mid-gap defect state resulting from the process of laser conditioning is introduced in our model, which is found to contribute seed electrons to conduction band and hence accelerate the final breakdown. Both the experimental result and theoretical calculation agree very well with each other.
    Full-text · Article · Jun 2015 · Optics Express
  • Jianguo Wang · Weili Zhang · Meiping Zhu · Kui Yi · Jianda Shao
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    ABSTRACT: A broadband metamaterial absorber (MA) based on the titanium nitride (TiN) nano-disk array is studied using finite difference time domain simulations. The semiconducting indium tin oxide (ITO) thin film is introduced as the space layer in this sandwiched structure. Utilizing the symmetrical geometry of the MA structure, polarization insensitivity of the broadband absorption was gained. The absorber with TiN nano-disk array shows a peak absorbance of 99 % and larger than 98 % from 560 to 675 nm by numerical simulation. This compact design may have potential applications in the plasmonic sensing and photovoltaic devices.
    No preview · Article · May 2015 · Plasmonics
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    ABSTRACT: A rigorous electromagnetic method is developed to analyze the resonance effect of near field caused by nanoscale subsurface defects, which play a key role in describing absorption enhancement during laser-matter interaction for transparent dielectric materials. The total electric field calculated with this new method is consistent with the result of finite-difference time-domain simulation. The concept of mode amplitude density spectrum is developed to analyze the specific modes of the total field. A new mode parameter is proposed to demarcate the contribution of the resonance. The frequency space is divided into four parts and the resonance effect is analyzed as well as the contributions of different modes to the total field. The influence of the structure parameters on the near-field modulation and energy transference is also discussed. It is found that the enhancement mechanism of the near-field and local absorption is the resonance effect caused by the total internal reflection on the sidewall of the nanostructure. In addition, the surrounding energy is mainly guided into the structure by the root of the structure via the energy flow analysis.
    No preview · Article · May 2015 · Applied Optics
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    ABSTRACT: The laser damage resistance of coatings in high-power laser systems depends significantly on the surface quality of the substrate. In our experiment, pits were precisely fabricated on the surface of fused silica substrate using a femtosecond laser processing bench. The HfO2/SiO2 high-reflective coatings at 1064 nm were deposited by conventional e-beam evaporation onto fused silica substrates with and without pits, respectively. The internal crack that was induced by the substrate geometrical structure was first observed in our experiment. The laser-induced damage threshold test showed negative effects of the substrate pits on the laser resistance of high-reflective coatings. Simulations by the finite element method were carried out, and results demonstrated that the modulation of a high reflector multilayer geometry could lead to electrical-field amplification and reduce laser damage resistance. Combined with its poor mechanical properties, the pits on substrate could contribute to the occurrence of damages.
    No preview · Article · Apr 2015 · Optics Letters
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    Full-text · Dataset · Mar 2015
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    ABSTRACT: A real-time monitoring system is set up based on a computer, dynamic interferometer, beam expanding system, and a beam reflecting system. The stability and repeatability of the monitoring system is verified. A workpiece and a glass monitoring plate are placed in the same ring. The surface figure of the workpiece, monitored by the monitoring plate, synchronizes with the surface of the glass monitoring plate in terms of peak-valley and power. The influence of the reflection and transmission surface are discussed in theory and a numeral deviation in online and offline testing data is quantitatively analyzed. The new method provides a quick and easy real-time method to characterize changes to the optical surface during polishing.
    No preview · Article · Mar 2015 · Chinese Optics Letters
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    ABSTRACT: By considering the rapid change of standing-wave electric-field and assuming the interface defect distribution, an improved model is developed to analyze the defect density distribution and assess the damage performance of high-reflective coatings. Two kinds of high-reflective coatings deposited by e-beam evaporation (EBE) and ion beam sputtering (IBS) techniques are analyzed with this method. The lower overall damage threshold is the major feature for the coatings deposited by IBS method according to the defect parameters extracted from the model. Typical damage morphologies of coatings are also measured and analyzed. The assumption of interface defects is supported by the damage behavior. The damage mechanisms of two high-reflective coatings are attributed to the formation of molten pool and mechanical ejection. The influence of the incident angle on the damage probability is also considered and numerically calculated. The defect analysis model improved here is suitable for high-reflective coatings.
    Preview · Article · Feb 2015 · Optics Express
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    ABSTRACT: Rapid growth processing of KDP crystals was improved by employing continuous filtration to eliminate bulk defects. The performances of the KDP crystals, including scattering defects, laser damage resistance and transmittance, were measured and analyzed. Compared with rapid-grown KDP without continuous filtration, the transmittance in the near-infrared was increased by at least 2%, almost all of ‘micron size’ defects were eliminated and ‘sub-micron size’ defects were decreased by approximately 90%. Laser damage testing revealed that the laser-induced damage thresholds (LIDTs), as well as the consistency of the LIDTs from sample to sample, were improved greatly. Moreover, it identified that ‘micron size’ defects were the precursors which initiated laser damage at relative lower laser fluence (4-6 J cm−2), and there was a lower correlation between smaller size scattering defects and laser damage initiation. The improved consistency in the LIDTs, attributed to elimination of ‘micron size’ defects, and LIDT enhancement originated from the decreased absorption of the KDP crystals.
    Full-text · Article · Jan 2015
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    Xiulan Ling · Gao Wang · Yuanan Zhao · Jianda Shao · Zhengxiu Fan
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    ABSTRACT: The laser-induced damage characteristics and adsorption effects of organic contamination molecules of two high reflectors (HR) prepared by electron beam evaporation (EB) and ion beam sputtering (IBS) method at 1064 nm is investigated in vacuum. It is found that EB films show the performance degradation of laser induced damages in vacuum while for IBS film, seems to have no this effect, in comparison with air environment. In addition, EB coatings also have the strong affinity with organic contamination molecules, in contrast of IBS films. The results reveal that ion beam sputtering (IBS) method seem to be one of the favorite film deposition techniques of the optical films used in vacuum and space environments.
    Full-text · Article · Nov 2014 · Optik - International Journal for Light and Electron Optics
  • Jun Yang · Kui Yi · Minghong Yang · Guohang Hu · Jianda Shao
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    ABSTRACT: Experiments showed that high density point and linear bulges emerged on the surface of fused silica after thermal annealing in an oven. To analyze the source of annealing bulges, the surface morphology was studied by atomic force microscopy, and the depth profile of impurities were analyzed by secondary ion mass spectroscopy. The results showed that impurities in redeposition layer migrated from subsurface to surface during annealing. The potential of using thermal annealing to reveal surface structure was developed.
    No preview · Conference Paper · Sep 2014
  • Jun Cao · Aihuan Dun · Chaoyang Wei · Jianxun Gu · Jianda Shao
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    ABSTRACT: In the inertial confinement fusion (ICF) system, the mid-frequency errors of optical components will cause high-frequency modulation and nonlinear gain of laser beams. In this paper, theoretical simulations and experiments have been designed and operated, aiming at studying the effects of slotting methods on mid-frequency errors in Nd-doped glass continuous polishing. Based on Preston formula, theoretical simulations focus on the effects of slotting methods on the mid-frequency errors. The simulation results show that different slotting methods will cause different mid-frequency errors, and square and logarithmic shape grooves are easier to obtain smaller mid-frequency errors. On the basis of simulation results, two groups of experiments are carried out to do the Nd-doped glass continuous polishing. The results show that the mid-frequency error gradually decreases with the decrease of the spacing between grooves. The results also show that square shape groove is easier to get a smaller mid-frequency error than circular shape groove, which verifies the theoretical simulation results.
    No preview · Conference Paper · Aug 2014
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    ABSTRACT: The low surface laser damage threshold of fused silica components in high power laser systems such as NIF restricts the improvement of the output fluence of those systems. Once damage is initiated and grows under subsequent laser shots, the components will go unusable. Subsurface damage (SSD) introduced during manufacturing has been identified as a main damage initiator. A good knowledge of SSD and how manufacturing influences it is essential to optimize manufacturing processes for damage free optics. Using the magneto-rheological finishing (MRF) wedge technique of better accuracy attributed to a tip, we have characterized the subsurface damage on fused silica optical surfaces ground with loose Al2O3 abrasives of different sizes. Larger abrasives generates longer cracks and the number density of cracks decreases sharply with the depth for each size. Rogue particles account for the occurrence of trailing indent scratches. Addition of rogue abrasives into relatively small base abrasive extends SSD more deeply than that induced by rogue abrasives alone. The linear model, with the proportional coefficient 3.511, fits the relationship between SSD depth and surface roughness (SR) better than the quadratic polynomial one. We believe SSD depth relates to SR more statistically than following some specified physical law. The linear relationship between SSD depth and the abrasive size was also established. The abrasive size turned out not to be as a good indictor of SSD depth as SR.
    No preview · Conference Paper · Aug 2014

Publication Stats

2k Citations
474.46 Total Impact Points

Institutions

  • 2000-2016
    • Chinese Academy of Sciences
      • • Anhui Institute of Optics and Fine Mechanics
      • • Shanghai Institute of Optics and Fine Mechanic
      Peping, Beijing, China
  • 2003-2015
    • Shanghai Institute of Optics and Fine Mechanics, CAS
      • Key Laboratory of Materials for High Power Laser, CAS
      Shanghai, Shanghai Shi, China
  • 2009
    • San Diego Zoo
      San Diego, California, United States
    • North University of China
      Yangkü, Shanxi Sheng, China
  • 2008
    • Shanghai Second Polytechnic University
      Shanghai, Shanghai Shi, China