Jianda Shao

Shanghai Institute of Optics and Fine Mechanics, CAS, Shanghai, Shanghai Shi, China

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Publications (298)398.13 Total impact

  • [Show abstract] [Hide abstract]
    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.
    Optics Letters 04/2015; 40(7). DOI:10.1364/OL.40.001330 · 3.39 Impact Factor
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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.
    Optics Express 02/2015; 23(4). DOI:10.1364/OE.23.005213 · 3.53 Impact Factor
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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.
    Optik - International Journal for Light and Electron Optics 11/2014; 125(21):6474–6477. DOI:10.1016/j.ijleo.2014.08.039 · 0.77 Impact Factor
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    ABSTRACT: Continuous ring polishing is the key process in large aperture optical elements. The surface figure of polishing pad is inferred by the offline testing surface figure of workpiece. The defects, low processing efficiency and uncertainty processing time in traditional continuous polishing, the real-time monitoring method of polishing is proposed. The realtime monitoring system is set up based on the computer, the dynamic interferometer, a beam expanding system and a beam reflecting system. There are a workpiece and a glass monitoring plate placing in same ring. The surface figure of workpiece, monitored by the monitoring plate, synchronize with the surface of glass monitoring plate in Peak-Valley (PV) and POWER. The new method with simple structure is fast measuring and judgmental directly to the changes of surface figures. The results of real-time monitoring and surface figure converging on the workpiece are valid for continuous polishing through experimental validation.
    7th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2014); 08/2014
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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.
    7th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2014); 08/2014
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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.
    7th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2014); 08/2014
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    ABSTRACT: Wave propagation of symmetry incidence on the biaxial birefringent film is discussed in this paper based on the characteristic matrix method. Furthermore, based on the refractive index surface, the refractive indices and effective optical admittances of the forward and backward propagating extraordinary waves (p-polarized wave) are analyzed in detail. With regard to the symmetry incidence, optical properties, such as the input optical admittance, transmittance and reflectance, are not identical for an extraordinary wave under common condition, i.e., angular selectivity. Based on an analysis of refractive index surface, the effective optical admittances of the forward and backward propagating extraordinary waves are equal in this particular case; transmittance and reflectance under the symmetry incidence are completely overlapped, similar to findings in the isotropic thin film. We validate our analysis using the developed software package. Based on the novel theory analysis, we can gain a new perspective of symmetry incidence about angular selectivity for the biaxial birefringent film.
    Optics Communications 08/2014; 325:1–4. DOI:10.1016/j.optcom.2014.03.079 · 1.54 Impact Factor
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    ABSTRACT: Commercial fused silica (50 mm diameter × 5 mm thickness) irradiated by single pulse of Nd:YAG laser (1064 nm, 12 ns) is experimentally investigated. The exit surface of fused silica is easier to be damaged than the entrance surface, so in this paper we only study the damage formed on the exit surface. The typical damage morphologies, irradiated at normal and oblique incidence, were observed with scanning electron microscope and atomic force microscope. The concentric ring structures with a central defect precursor are appeared in all damage sites. Furthermore, the whole damage sites are filled with the surface periodic striped structures, which direction is perpendicular to the incident electric field. Further analysis show that the incident energy has great effect on the size of damage sites, the depth of damage sites, and also the depth of the ripples, but has no effect on the period of the ripples. Additional experiments are performed to investigate the dependency between the period of ripples and the incident angle.
    Applied Surface Science 08/2014; 309:79–84. DOI:10.1016/j.apsusc.2014.04.179 · 2.54 Impact Factor
  • Optical Engineering 08/2014; 53(8):084107. DOI:10.1117/1.OE.53.8.084107 · 0.96 Impact Factor
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    ABSTRACT: High performance optical coatings are essential for the laser systems. To increase the performance of the laser coatings, including optical and mechanical properties, as well as the laser induce damage resistance, many efforts have been done. The developments of the coating design, deposition process and post treatment process, as well as the understanding of mechanical and laser damage mechanism have promoted the advance the laser coatings, various coatings with high performance have been developed.
    2014 International Conference Laser Optics; 06/2014
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    ABSTRACT: Laser-induced damage behaviors of the chirped mirrors (CMs) are studied by single 800nm-38fs lasers. The CMs provide group delay dispersion (GDD) of around -60fs2 and average reflectivity of about 99.4% with bandwidth range of 200nm~300nm at a central wavelength of 800nm. Interestingly, a circular blister feature appears in the CMs at a wide range of laser fluence. Optical Microscope, Atomic Force Microscope, Scanning Electron Microscope and Surface Profiler, are applied to describe the blister characteristics. An adiabatic expansion model of ideal gas is adopted to illustrate the formation dynamics of blisters. The evolution of blisters can be explained by partial evaporation of the film and a subsequent gas expansion, driving the bulging of the film stack up to the stress limit, where the blister fractures. According to this model, the energy absorption ratio of blisters increases monotonously with increasing laser fluence before the occurrence of focal spot confinement effect.
    Applied Optics 05/2014; 53(15):3347-3354. DOI:10.1364/AO.53.003347 · 1.69 Impact Factor
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    ABSTRACT: Four mirror coatings were designed for transporting 1064 nm light, and prepared under the same process parameters. The laser induced damage threshold (LIDT), electric field distribution, as well as the damage morphology of the prepared transport mirror coating was investigated. The results indicate that the SiO2 overcoat layer and electric field distribution have a great impact on the LIDT and damage morphology of the transport mirror coating. A thicker SiO2 overcoat layer can suppress the delamination damage morphology, and significantly increase the LIDT. For the designs with similar SiO2 overcoat layer thickness, the nano-absorbing defects can survive at higher laser fluence in the design with lower electric field intensity. In addition, the HfO2 over SiO2 interface has a better interfacial strength and less “invisible” nano-absorbing defects than the SiO2 over HfO2 interface, suggesting that improving the SiO2 over HfO2 interfacial quality will be an effective way to enhance the laser damage performance of the transport mirror coating.
    Optics Communications 05/2014; 319:75–79. DOI:10.1016/j.optcom.2014.01.014 · 1.54 Impact Factor
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    ABSTRACT: A model is developed to improve thickness uniformity of coatings on spherical substrates rapidly and automatically using fixed shadow masks in a planetary rotation system. The coating thickness is accurately represented by a function composed of basic thickness, self-shadow effect, and shadow mask function. A type of mask with parabolic contours is proposed, and the thickness uniformity of coatings on spherical substrates can be improved in a large range of ratios of clear aperture (CA) to radius of curvature (RoC) by optimizing shadow masks using a numerical optimization algorithm. Theoretically, the thickness uniformity improves to more than 97.5% of CA/RoC from -1.9 to 1.9. Experimentally, the thickness uniformities of coatings on a convex spherical substrate (CA/RoC = 1.53) and on a concave spherical substrate (CA/RoC=-1.65) improve to be better than 98.5% after corrected by the shadow masks.
    Chinese Optics Letters 05/2014; 12(5). DOI:10.3788/COL201412.053101 · 1.07 Impact Factor
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    Jian Sun, Xu Li, Weili Zhang, Kui Yi, Jianda Shao
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    ABSTRACT: As important components in deep-ultraviolet (DUV) optics, especially 193 nm lithographic systems, high-reflectivity (HR) mirrors with excellent optical properties and long lifetimes are needed urgently. In this study, we designed and produced three HR coatings for 193 nm on fused quartz substrates: Al2O3/AlF3 coating, LaF3/AlF3 coating and a double stack mirror with combined Al2O3/AlF3 and LaF3/AlF3. The reflectance of the Al2O3/AlF3 coating with 14 layer pairs reached 98.0% at 193 nm. However, the absorption of Al2O3 prevented the reflectance to increase further. The maximum reflectance of the LaF3/AlF3 coating with 15 layer pairs reached 98.1%, with initial micro-cracks formation. The reflectance decreased as the number of layer pairs increased to 16 because of numerous micro-cracks. The mirror with combined Al2O3/AlF3 and LaF3/AlF3 coatings which combined their advantages obtained a reflectance of 98.8% at 193 nm after deposition. This value could still reach 98.5% at 4 months after deposition and remain stable thereafter. Therefore, the combined coating of Al2O3/AlF3 and LaF3/AlF3 is an excellent candidate for practical application.
    Optics & Laser Technology 03/2014; 56:65-70. DOI:10.1016/j.optlastec.2013.07.017 · 1.65 Impact Factor
  • Jian Sun, Jianda Shao, Kui Yi, Weili Zhang
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    ABSTRACT: As a low refractive index material widely used in coatings for deep-ultraviolet optical systems, magnesium fluoride (MgF<sub>2</sub>) films were prepared by electron beam evaporation at different substrate temperatures. The effects of the substrate temperatures on the optical properties in vacuum and in air, microstructures, and composition were investigated, as were the microstructures, their composition, and the relation between them. In vacuum, the substrate temperature directly affected the microstructures which dominated the packing density and inhomogeneity along the film thickness. When the films were exposed to air, the refractive index increased and a nonmonotonic change trend of the refractive index with substrate temperature was observed due to adsorbed water and magnesium oxide (MgO) formed in the film. While a moderate amount of MgO reduced absorption loss by decreasing vacancy defects, excessive MgO increased the absorption loss because of the high extinction coefficient of the oxide.
    Applied Optics 03/2014; 53(7):1298-305. DOI:10.1364/AO.53.001298 · 1.69 Impact Factor
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    ABSTRACT: Metal multi-layer dielectric gratings (MMDG) for pulse compressors in high-energy laser systems should provide broad bandwidth as well as high laser-induced damage thresholds. The non-uniform optical near-field distribution of MMDG is an important factor that limits damage resistant capabilities. MMDG for pulse compressors operating at 800 nm with a corrugated SiO2 layer are designed by using a genetic algorithm and the Fourier mode method. The diffraction efficiency, bandwidth, and near-field distribution of the MMDG are theoretically investigated. For the single dielectric match layer grating, the bandwidth is 140 nm, if the thickness and refractive index of the match layer are changed, the maximum electric field in the grating ridge, match layer, and metal layer of the grating increases with the decrease in grating diffraction efficiency. For the multi-dielectric match layer grating, the bandwidth and the maximum electric field in the metal layer decrease with the increase in high- and low-index material pairs, and the maximum electric field in the grating ridge and match layer initially decreases and then increases. Over a wide wavelength range, the maximum electric field in the grating ridge, match layer, and metal layer is minimal near the central wavelength. Moreover, MMDG should be used at larger incident angles while keeping enough bandwidth to reduce the electric field in the grating.
    Applied Physics B 02/2014; 114(4). DOI:10.1007/s00340-013-5560-9 · 1.63 Impact Factor
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    ABSTRACT: We report the periodic concentric surface structures on SiO<sub>2</sub> layer induced by a single shot nanosecond laser pulse at 1.06 μm. The fringe period of the structures ranges from 7.0 μm to 26.8 μm, depending on the laser fluence and the distance from central defect precursor. The size and depth of the damage sites increase almost linearly with the laser fluence from 19.6 J/cm<sup>2</sup> to 61 J/cm<sup>2</sup>. Plasma flash was clearly observed during the damage process. We attribute the formation mechanism of the structures to the interference between the reflected laser radiations at the air/shock-front and the shock-front/film interfaces.
    Optics Express 02/2014; 22(3):2948-54. DOI:10.1364/OE.22.002948 · 3.53 Impact Factor
  • Yun Cui, Kui Yi, Hu Guohang, Jianda Shao
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    ABSTRACT: Coating stacks of HfO2/SiO2 and Ta2O5/SiO2 were separately prepared by electron beam evaporation and dual ion beam sputtering. Damage characteristics at the interlayer interfaces were analyzed after irradiation of the coatings by a 1064 nm laser. The cross-sectional morphologies of damage spots indicated that peeling-off damages always occurred at the interface where the low refractive index material (SiO2) was deposited on the high refractive index material (HfO2 or Ta2O5). The effects of interface microstructure and components on peeling-off damages were also discussed. The microstructure of the interface was not a major factor that influenced peeling-off damages. Incomplete oxides (SiOx) and Na, K, Li ions accumulated near the interface and caused the formation of micro-defects layers with nano-sized thicknesses. Micro-defects layers maybe reduced adhesion of different interfaces and formed plasmas by absorbing laser energy. Finally stripping damages happened from micro-defects layers during irradiation by a 1064 nm laser.
    Applied Surface Science 01/2014; 290:71–79. DOI:10.1016/j.apsusc.2013.10.191 · 2.54 Impact Factor
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    ABSTRACT: We report on an 800 nm center-wavelength metal/multilayer-dielectric grating (MMDG) with broadband, high diffraction efficiency. The trapezoidal grating ridge consists of an HfO<sub>2</sub> layer sandwiched between two SiO<sub>2</sub> films. Combining the advantages of SiO<sub>2</sub> and HfO<sub>2</sub>, the grating ridge reduces the difficulties of grating ridge attainment. For such a configuration, high-performance MMDG can be successfully fabricated using the existing technology. Experimentally we demonstrated a 163 nm bandwidth MMDG with -1st-order diffraction efficiency greater than 90%. The fabricated MMDG achieved high performance as the design with large fabrication tolerances.
    Optics Letters 01/2014; 39(1):170-3. DOI:10.1364/OL.39.000170 · 3.39 Impact Factor

Publication Stats

2k Citations
398.13 Total Impact Points


  • 2003–2015
    • Shanghai Institute of Optics and Fine Mechanics, CAS
      • Key Laboratory of Materials for High Power Laser, CAS
      Shanghai, Shanghai Shi, China
  • 2003–2012
    • Chinese Academy of Sciences
      • Anhui Institute of Optics and Fine Mechanics
      Peping, Beijing, 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