Zhengping Wang

Shandong University, Chi-nan-shih, Shandong Sheng, China

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Publications (156)381.59 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Nonlinear refractive index n2 is an important parameter for the nonlinear optical properties of the medium. This paper is primarily targeted to measure the third-order nonlinear optical properties of potassium dihydrogen phosphate (KDP) and deuterated potassium dihydrogen phosphate (DKDP) with 70% deuteration content at λ=532 nm using Z-scan technique. The relationship between nonlinear refraction and directions has been studied in detail. Nonlinear refractive index n2, γ and third-order nonlinear susceptibilities were calculated through normalized transmittance curve and theoretical formulas. The results indicate that nonlinear refractive indexes of KDP and DKDP are positive and possess obvious self-focusing effect in high-power laser system.
    No preview · Article · Jan 2016 · RSC Advances
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    ABSTRACT: The band structure of graphene can be adjusted by incorporating other elements or functional groups, correspondingly, the response to an external light field will also be changed. In this study, we investigated the nonlinear optical (NLO) responses of N-doped graphene nanosheets (N-Gns) with an open aperture Z-scan method, under the excitation of picosecond laser pulses. To the best of our knowledge, this is the first time that two-photon absorption (2PA) of N-Gns has been reported. The normalized nonlinear transmission demonstrates that with the increasing excitation energy, the saturable absorption (SA) and the 2PA appear successively. Compared to the 532 nm excitation, the 1064 nm excitation exhibits smaller saturable intensity Is and larger 2PA coefficient β. At the same time, the N-Gns present superior NLO property compared to pure graphene. Consequently, N-Gns will be a promising candidate for SA or optical limiting (OL) applications.
    No preview · Article · Jan 2016 · RSC Advances
  • Shaohua Ji · Bing Teng · Weijin Kong · Degao Zhong · Xun Sun · Zhengping Wang

    No preview · Article · Jan 2016 · CrystEngComm
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    Dongsheng Yuan · Yang Li · Jun Shu · Zeliang Gao · Zhitai Jia · Zhengping Wang · Xutang Tao
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    ABSTRACT: Towards the spatial optimum phase matching (PM) crystal device through a novel way, the micro-pulling-down (μ-PD) technique was used for crystal growth along second-order harmonic generation (SHG) direction for the first time to the best of our knowledge. In this paper, the spatial distribution of |deff| for a potential nonlinear optical (NLO) crystal TbCa4O(BO3)3 (TbCOB) at 1064 nm was calculated and analyzed firstly, and the PM angle (113°, 46°) was found to possess the largest deff value (type-I) being on the order of 1.39 pm/V. Along the optimum SHG direction, a rod-shape TbCOB crystal with 3 mm in diameter was successfully grown by using the μ-PD method. After simple cutting and polishing of the ends for μ-PD grown crystal, a high SHG efficiency (single-pass light reached up to 57%) was realized through a Nd:YAG pico-second laser at 1064 nm, which was comparable to that of crystal samples from Czochralski (Cz) growth. TbCOB crystals also exhibit a high laser damage threshold of >15 GW/cm2.
    Full-text · Article · Dec 2015 · Journal of Crystal Growth
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    ABSTRACT: The self-frequency-doubling (SFD) lasers in visible region are of importance for optical applications. In this work, SFD green laser was realized on newly designed nonlinear optical crystal Nd doped Ca3TaGa3Si2O14 (Nd:CTGS). By optimizing the configurations, measuring the refractive indexes and coating the surfaces of Nd:CTGS crystal samples, the SFD green laser output at 533 nm was observed, and the maximum output power for type I (38.7°, 30.0°) crystal cut was obtained and found to be on the order of 71.58 mW. Meanwhile, the Nd:CTGS type I (38.7°, 30.0°) crystal cut was found to show low output threshold, being on the order of 0.52 W. The output power stability within 30 mins was observed to be better than 1%.
    No preview · Article · Dec 2015 · Journal of Alloys and Compounds
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    Gang Zhao · Fang Zhang · Yongzhong Wu · Xiaopeng Hao · Zhengping Wang · Xinguang Xu
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    ABSTRACT: Hexagonal boron nitride (h-BN) nanosheets are attracting increased attention because of their excellent optical properties. Inspired by the natural exfoliation of seaside rocks, we propose a “chemical weathering” concept for fabricating h-BN nanosheets from their bulk counterparts. We experimentally demonstrate that chemical weathering-assisted exfoliation is a simple and efficient method for preparing h-BN nanosheets. These nanolayers have a high solubility in water because of the hydroxylation of h-BN (OH-BNNS). Interestingly, the as-prepared OH-BNNSs exhibit excellent optical limiting properties with fascinating two-photon absorption. It is a new and advanced optical material in the application of sensitive optical components, and shield human eyes from laser-induced damage.
    Full-text · Article · Oct 2015 · Advanced Optical Materials
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    ABSTRACT: We report subnanosecond passively Q-switched Nd:GdxY1−xVO4 (x = 0, 0.18, 0.42, 0.51, 0.64, 1) microchip lasers. To the best of our knowledge, this is the first demonstration of subnanosecond mixed-vanadate-crystal microchip lasers. Compared with Nd:GdVO4 and Nd:YVO4 lasers, we obtain enhanced peak power by the microchip lasers proposed and elaborated. Using a Cr4+:YAG crystal with initial transmission of 77%, we achieve the shortest pulse duration of 588 ps, highest pulse energy of 30 μJ, and peak power of 48 kW.
    No preview · Article · Sep 2015 · Journal of Russian Laser Research
  • Lisong Zhang · Fang Zhang · Mingxia Xu · Zhengping Wang · Xun Sun
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    ABSTRACT: Noncritical phase matching (NCPM) fourth-harmonic-generation (FHG) experiments were conducted on different deuterium content DKDP crystals by adjusting crystal temperature to generate 266 nm deep UV laser. Specially, near room temperature NCPM is realized in extremely high deuterium content DKDP crystal at 38.6 °C, which is the lowest temperature to the best of our knowledge. NCPM temperature of DKDP crystals in 60-100% deuterium content range and 1050-1070 nm wavelength range are determined by a linear relationship according to the experimental and calculated results. Angular tuning properties are independent with deuterium content in medium and higher deuterium content DKDP crystals. All of these results will provide good references for future FHG applications of 1 μm laser with DKDP crystals.
    No preview · Article · Sep 2015 · Optics Express
  • Lisong Zhang · Fang Zhang · Mingxia Xu · Zhengping Wang · Xun Sun
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    ABSTRACT: Noncritical phase matching (NCPM) fourth-harmonic-generation (FHG) experiments were conducted on different deuterium content DKDP crystals by adjusting crystal temperature to generate 266 nm deep UV laser. Specially, near room temperature NCPM is realized in extremely high deuterium content DKDP crystal at 38.6 degrees C, which is the lowest temperature to the best of our knowledge. NCPM temperature of DKDP crystals in 60-100% deuterium content range and 1050-1070 nm wavelength range are determined by a linear relationship according to the experimental and calculated results. Angular tuning properties are independent with deuterium content in medium and higher deuterium content DKDP crystals. All of these results will provide good references for future FHG applications of 1 mu m laser with DKDP crystals. (C) 2015 Optical Society of America
    No preview · Article · Sep 2015 · Optics Express
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    Full-text · Dataset · Sep 2015
  • Lisong Zhang · Fang Zhang · Mingxia Xu · Zhengping Wang · Xun Sun
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    ABSTRACT: A high quality, large size (100 × 105 × 96 mm3) deuterated potassium dihydrogen phosphate (DKDP) crystal with high deuterium content was successfully grown by the rapid growth method. A noncritical phase matching (NCPM) fourth-harmonic-generation (FHG) of Nd:YAG laser (1064 nm) was realized at 39.7°C or so. The smallest full width at half maximum (FWHM) of angular acceptance for the longest crystal sample (20 mm) is 33.5 mrad, which is 10 times larger than the value of critically PM of a KDP crystal. The FHG conversion efficiency increases with the crystal length and reaches 64% for the 20 mm long crystal. As we have known, this is the highest FHG conversion efficiency of a 1064 nm laser with a repetition rate of 10 Hz in low drive conditions.
    No preview · Article · Aug 2015 · RSC Advances
  • Yanqing Liu · Fang Zhang · Zhengping Wang · Fapeng Yu · lei wei · Xinguang Xu · Xian Zhao
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    ABSTRACT: A borate crystal, Ca3(BO3)2, is reported for stimulated Raman scattering (SRS) from deep ultraviolet to near infrared. This crystal was found to possess a strong Raman response, and an outstanding anti-optical damage threshold as well as being easy to grow and having a low production cost. The short ultraviolet cut-off wavelength of 180 nm makes it available for deep ultraviolet or even vacuum ultraviolet SRS. This journal is
    No preview · Article · Aug 2015 · Journal of Materials Chemistry C
  • Baoan Liu · Shaotao Sun · Bo Wang · Xun Sun · Zhengping Wang · Xinguang Xu
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    ABSTRACT: A series of deuterated potassium dihydrogen phosphate (DKDP) crystals with different degrees of deuteration are grown from aqueous solution by the point-seed technique. The microhardness of (100), (001) and so-called ‘tripler’ faces for these DKDP crystals were measured. Initially the hardness number of (001) face for each crystal increases with the increase of the applied load until it reaches 25 g. With further increase in load, the hardness number decreases gradually. The hardness numbers decline with the increase in deuterium content. These composition dependences are expected since the bond strength is weakened by the substitution of deuterium for hydrogen. The hydrogen bond is considered to play the key role in effecting the crystal’s hardness. The visible hardness anisotropy of the different faces is attributed to the inhomogeneous distribution of the oxygen–hydrogen bond on these faces.
    No preview · Article · Aug 2015 · Bulletin of Materials Science
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    ABSTRACT: For the first time, graphene saturable absorber (SA) is used as the Q-switcher for a 946 nm Nd:YAG laser. Using a 5-7 layer graphene SA with initial transmission of 78% and an output coupler with transmission of 5%, efficient Q-switching operation is realized. When the absorbed pump power is raised to 9.5 W, a maximum output power of 0.9 W is obtained, corresponding to an optical conversion efficiency of 9.5%. The pulse repetition frequency and the pulse width are 225 kHz, 162 ns, respectively, resulting a pulse energy of 4 μJ and a peak power of 24.7 W. With a BiB3O6 (BIBO) crystal as the frequency doubler, 473 nm blue laser is generated. The present research manifests graphene has great potential for short wavelength laser modulation.
    No preview · Article · Jul 2015 · Optik - International Journal for Light and Electron Optics
  • Yanqing Liu · Fapeng Yu · Zhengping Wang · Xinguang Xu · Xian Zhao
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    ABSTRACT: High optical quality La0.09Gd0.91Ca4O(BO3)3 and Nd0.03La0.08Gd0.89Ca4O(BO3)3 crystals, grown by Czochralski (Cz) pulling method, were investigated for their nonlinear optical (NLO) and laser properties. These crystals were found to possess moderate birefringence (0.0320 at 1064 nm), wide transparency (320 ∼ 2300 nm) and large effective nonlinear effects (deff ∼1.2 pm/V), which were suitable for green laser generation. The second-harmonic-generation (SHG) phase matching (PM) properties, including PM curve, deff, angular acceptance and walk-off angle were investigated. Both of the calculations and experiments have indicated that the 1064 nm optimum PM direction which has maximum deff (∼1.2 pm/V) and SHG conversion efficiency (57.1%) locate in the second octant, i.e. (113.5o, 48.6o). Pumped by the 0.8 μm AlGaAs laser diodes (LD), the self-frequency-doubling (SFD) performance of Nd0.03La0.08Gd0.89Ca4O(BO3)3 crystal was evaluated, where as much as 115 mW green light at 546 nm was obtained with a (113o, 48.9o)-cut, 6 mm long and uncoated Nd0.03La0.08Gd0.89Ca4O(BO3)3 sample.
    No preview · Article · Jun 2015 · Journal of Alloys and Compounds
  • Fang Zhang · Shuo Han · Yanqing Liu · Zhengping Wang · Xinguang Xu
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    ABSTRACT: Using an optical parametric oscillation laser as the excitation source, the dependence of the saturable absorption of multiple-layer graphene upon photon energy is investigated and, in all cases, the saturation intensity is lower for lower excitation photon energy. This result experimentally proves the hourglass shape of the energy band of graphene, which is a well-known theoretical deduction from first principles. The modulation depth increases from 1.5% to 5.1% when the layer number increases from a monolayer to 5–7 layers and, at the same time, the saturation intensity decreases with increasing number of layers. The results demonstrate that, as a saturable absorber of a pulsed laser, graphene can more easily achieve optical modulation in the low energy region, i.e., the infrared waveband.
    No preview · Article · Mar 2015 · Applied Physics Letters
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    ABSTRACT: As excellent nonlinear optical (NLO) crystals, YCa4O(BO3)3 (YCOB) and GdCa4O(BO3)3 (GdCOB) have been paid much attention since their first appearance in 1990’s. From that time to now, almost all of related researches and applications have focused on their type-I phase-matching (PM) configurations which possess large effective NLO coefficient (deff). In this paper, type-II second-harmonic-generation (SHG) properties of these two crystals are reported, including PM curve, deff, angular acceptance and walk-off angle. Both of the type-II SHG experiments for 1064 and 1320 nm have indicated that the optimum directions which have maximum deff locate in the second octant, i.e. (90° < θ< 180°, 0° < ϕ < 90°). For a (112°, 81.3°)-cut, 24 mm long YCOB crystal, the largest type-II SHG conversion efficiency of a 1064 nm Nd:YAG pico-second laser is 55%, which reaches the same level of the optimum type-I sample. To our knowledge this is the first time that type-II SHG performance of YCOB and GdCOB crystals is investigated intensively. Our research has shown that the smaller deff of type-II PM can be compensated by its larger angular acceptance and less beam walk-off. The same level SHG conversion efficiency implies for such type crystals the type-II components have the potential to replace type-I ones and obtain important NLO applications in the future.
    Preview · Article · Feb 2015 · Optics Express
  • Shuo Han · Yanqing Liu · Fang Zhang · Ying Zhou · Zhengping Wang · Xinguang Xu
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    ABSTRACT: In this paper, a new method is used to direct generate Ince-Gaussian (IG) modes from a pulsed solid-state microchip laser. By moving a circular aperture horizontally, the gain size in the laser medium is adjusted, and different IG laser modes are obtained successively. The output laser possesses a stable pulse duration of 500-600 ps; at the same time, the repetition frequency varies between 7 and 16 kHz. To our knowledge, this is the first time that IG modes are obtained in the subnanosecond laser domain, which will be helpful for making large-energy high-peak-power devices.
    No preview · Article · Feb 2015 · IEEE Photonics Journal
  • Shuo Han · Yanqing Liu · Fang Zhang · Haohai Yu · Zhengping Wang · Qingtian Gu · Xinguang Xu
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    ABSTRACT: Sub-nanosecond passively Q-switched microchip lasers based on Nd:YVO4 and Cr4+:YAG were reported. On the whole, 2 at.% doped Nd:YVO4 crystals exhibited better performance than 3 at.% doped crystals. The shortest pulse duration of 693 ps was obtained from a-cut, 2 at.% doped Nd:YVO4, and the highest peak power of 32 kW, largest pulse energy of 29 μJ were produced by c-cut, 2 at.% doped sample. These experiment results illustrate that Nd:YVO4 and Cr4+:YAG are good combination for producing sub-nanosecond, high peak power microchip lasers.
    No preview · Article · Dec 2014 · Infrared Physics & Technology
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    ABSTRACT: The linear and nonlinear optical properties of TbCa4O(BO3)3 (abbreviated as TbCOB) single crystals were investigated for the first time. The refractive indices of TbCOB at several wavelengths were measured by using the minimum deviation method and the parameters of Sellmeier’s dispersion equation were determined from the experimental data. The complete set of six second-order nonlinear optical (NLO) coefficients of TbCOB single crystals were obtained using the Maker fringe (FM) technique, with the largest d32 being on the order of 1.65 pm/V. Moreover, the phase-matching (PM) configurations of second-order harmonic generation (SHG) in the principal planes were calculated, and the largest effective NLO coefficient is deff = 0.86 pm/V along (22.56°, 180°) PM direction. The SHG conversion efficiency from 1064 nm to 532 nm of 8 mm long crystal samples without AR coating along this direction was achieved 57.1% at 28.2 mW input power, and it has a small walk-off angle of 13.8 mrad. In addition, the comparison and discussion with GdCOB and YCOB were carried out.
    Full-text · Article · Nov 2014 · Optics Express