Guangdong Provincial Key Laboratory of Optomechatronics

Shenzhen, China

Guangdong Provincial Key Laboratory of Optomechatronics

Shenzhen, China
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Shi X.,Tsinghua University | Shi X.,Guangdong Provincial Key Laboratory of Optomechatronics | Zou C.,Tsinghua University | Zou C.,Guangdong Provincial Key Laboratory of Optomechatronics | And 8 more authors.
Tribology International | Year: 2017

In this paper, a significant improvement of chemical-mechanical polishing on gallium nitride with S2O8 2 −-Fe2+ based slurry is presented in detail. The results indicate that the S2O8 2 −-Fe2+ additives possessed obvious effect to enhance the polishing efficiency of GaN, and successfully achieved good surface quality after polishing. The addition of complexing agent obviously improves the stability of catalytic system. Besides, we also studied the special change rule of atomic step-terrace topography from the surface of GaN to describe the material removal mechanism during CMP process. The results show that the removal of materials by CMP follows rigid rules, which may help to improve the material removal mechanism of CMP. © 2016 Elsevier Ltd


Qiu B.,Tsinghua University | Qiu B.,Guangdong Provincial Key Laboratory of Optomechatronics | Wang W.,Raybow Optoelectronics Ltd. Inc. | Liu W.,Raybow Optoelectronics Ltd. Inc. | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

We report on our design and fabrication of 1470 nm high power InGaAlAs quantum well lasers. It is found that the 2-mm-long-cavity devices with aperture size of 96 μm can reach maximum power of around 4.2 W. The threshold is around 500 mA, and slope efficiency is about 0.42 W/A. Apart from the excellent external quantum efficiency and thermal performance, devices also show reduced beam divergence which is about 30°. Accelerated life-time test has also been performed to determine the reliability performance. Thus far more than 9000 life-test-hour has been accumulated, and there is no detectable sign of the power degradation, indicating our devices are extremely reliable. © 2016 SPIE.


Hu H.M.,Tsinghua University | Hu H.M.,Guangdong Provincial Key Laboratory of Optomechatronics | Qiu B.,Tsinghua University | Qiu B.,Guangdong Provincial Key Laboratory of Optomechatronics | And 6 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

We report on our design and fabrication of very high power semiconductor lasers based on a core-aluminum-free (CAF) active structure. The optical power of as high as 45 W, limited by the thermal roll-over, has been obtained when the single emitter devices are tested under quasi-continuous wave (QCW) conditions, and more than 10 W has been acquired at the operation current of 10 A under continuous wave (CW) conditions. For 10 mm long bar chips, emitting power of up to 200 W is attainable for the operation current of 200 A. The lasers also exhibit excellent slope efficiency of about 1.3 W/A and beam divergence of only 25 °. © 2016 SPIE.


Qiu B.,Tsinghua University | Qiu B.,Guangdong Provincial Key Laboratory of Optomechatronics | Hu H.M.,Tsinghua University | Hu H.M.,Guangdong Provincial Key Laboratory of Optomechatronics | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

We report on our design and fabrication of 830 nm high power semiconductor lasers with extremely low beam divergence. Here we propose a novel approach in which by combining asymmetric waveguide and a feature called "pins" together, we were able to design an optimized epi structure which not only produces a beam divergence of less than 16°, but also has very good growth tolerance as well. Tested devices show the beam divergence is as small as 13°, yet they still retain very high slope efficiency of around 1.15 W/A and low threshold current of 400 mA for the devices with cavity length being 2 mm long, and ridge width being 40 μm wide. © 2016 SPIE.


Zhou Y.,Tsinghua University | Zhou Y.,Guangdong Provincial Key Laboratory of Optomechatronics | Pan G.-S.,Tsinghua University | Pan G.-S.,Guangdong Provincial Key Laboratory of Optomechatronics | And 7 more authors.
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2017

Surface quality of LED sapphire substrate influences epitaxy quality greatly, and further influences the performance of LED devices. After the chemical mechanical polishing (CMP) of slurry including Al2O3 abrasive and SiO2 abrasive of sapphire grinding wafer, finally ultra smooth surface of sub-nanometric roughness was achieved with surface roughness reaching 0.101 nm measured by atomic force microscope (AFM) and atomic step morphology was presented. Using Zygo profiler and AFM to observe the variations of surface of sapphire grinding wafer from being polished by Al2O3 abrasive slurry to SiO2 abrasive slurry, the generation reason of atomic step morphology of sapphire surface was elaborated, and the CMP removal mechanism of the sapphire atomically ultra-smooth surface was proposed. Through controlling the process conditions of sapphire polishing, a-a type and a-b type atomic step periodic morphologies were obtained respectively. The experimental result shows the chemical reaction speed of double-atom layer 6H1, 6H2 of different adsorptive energy between layers is slightly different. When the revolving speed is relatively slower and mechanical effect Rm is slightly weaker than chemical effect, the difference of chemical reaction speed Rc of different double-atom layer is also presented, and mechanical removal only acts on softening double-atom layer with sapphire polishing surface presenting step morphology of different width of a-b type; while when the revolving speed is relatively faster and mechanical effect Rm is slightly stronger than chemical effect, the mechanical removal speed of each double-atom layer is the same with sapphire polishing surface presenting step morphology of the same width of a-a type. © 2017, Science Press. All right reserved.


Lin H.,Guangdong University of Technology | Lin H.,Shaoguan University | Gao J.,Guangdong University of Technology | Zhang G.,Guangdong University of Technology | And 3 more authors.
Journal of Sensors | Year: 2017

In the last decade, a significant number of techniques for three-dimensional (3D) shape measurement have been proposed. There are a large number of measurement demands for metallic workpieces with shiny surfaces in industrial applications; however, such shiny surfaces cannot be directly measured using the conventional structured light method. Therefore, various techniques have been investigated to solve this problem over the last few years. Some reviews summarize the different 3D imaging techniques; however, no comprehensive review exists that provides an insight into high-dynamic range (HDR) 3D shape measurement techniques used for shiny surfaces. We present a survey of recent HDR techniques for the digitization of shiny surfaces and classify and discuss the advantages and drawbacks of different techniques with respect to each other. © 2017 Hui Lin et al.


QIAN X.,Tsinghua University | ZHANG Q.,Tsinghua University | LU X.-Q.,Tsinghua University | YU Q.,Tsinghua University | And 3 more authors.
Chinese Journal of Analytical Chemistry | Year: 2017

An electrospray/ultraviolet lamp dual-source ion trap mass spectrometer was developed for the rapid detection of gas and liquid samples. A discontinuous atmospheric pressure sampling system was used in the instrument, in which both the electrospray ions and gaseous analytes were sampled and transferred by a pinch valve device. The two ionization sources used here were generally suitable for different kinds of analytes and provide complementary applications. Electrospray was used for the ionization of polar compounds in solution, while the UV ionization source was mainly applied to the analysis of gaseous organic compounds. A variety of samples such as anisole, toluene, 2,4-dimethylaniline, arginine, reserpine and aspartame were employed to test the performance in different working mode of the instrument. The result showed that the two sources was suitable for ionization of different samples, and different types of molecular ions were generated when analyzing 2,4-dimethylaniline. Two ionization sources could be used alternately or simultaneously without interference with the other and the working mode could also be switched to fit the application requirements. Dual-source configuration was an effective way to extend the applications for miniature mass spectrometers. It did not significantly increase the size of the instrument, but provided more versatile analysis to meet the need for the measurement of different types of samples. © 2017 Changchun Institute of Applied Chemistry, Chinese Academy of Sciences


Cao X.,Tsinghua University | Pan G.,Tsinghua University | Pan G.,Guangdong Provincial Key Laboratory of Optomechatronics | Huang P.,Tsinghua University | And 2 more authors.
Langmuir | Year: 2017

The core-shell structured PS/SiO2 composite nanospheres were synthesized on the basis of a modified Stöber method. The mechanical properties of monodisperse nanospheres were characterized with nanoindentation on the basis of the atomic force microscopy (AFM). The surface morphologies of PS/SiO2 composite nanospheres was scanned with the tapping mode of AFM, and the force-distance curves were measured with the contact mode of AFM. Different contact models were compared for the analyses of experimental data. The elastic moduli of PS/SiO2 composite nanosphere (4-40 GPa) and PS nanosphere (∼3.4 GPa) were obtained with the Hertz and Johnson-Kendall-Roberts (JKR) models, respectively, and the JKR model was proven to be more appropriate for calculating the elastic modulus of PS/SiO2 nanospheres. The elastic modulus of SiO2 shell gradually approached a constant value (∼46 GPa) with the increase of SiO2 shell thickness. A core-shell model was proposed for describing the relationship between PS/SiO2 composite nanosphere's elastic modulus and shell thickness. The mechanical properties of the composite nanospheres were reasonably explained on the basis of the growth mechanism of PS/SiO2 composite nanospheres, in particular the SiO2 shell's formation process. Available research data of PS/SiO2 composite nanospheres in this work can provide valuable guidance for their effective application in surface engineering, micro/nanomanufacturing, lubrication, and so on. © 2017 American Chemical Society.


Zhou Y.,Tsinghua University | Zhou Y.,Guangdong Provincial Key Laboratory of Optomechatronics | Pan G.,Tsinghua University | Pan G.,Guangdong Provincial Key Laboratory of Optomechatronics | And 8 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2015

The material removal mechanism of sapphire wafer during chemical mechanical polishing has been studied through X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements. XPS results indicate that alumina silicate (Al2Si2O7·2H2O) is generated on the polished sapphire surface by SiO2 slurry, otherwise alumina hydrate (AlO(OH)) on the polished surface by H2O solution. Meanwhile, ultra-smooth polished surface with extremely low Ra of below 0.1 nm and atomic step structure morphology via AFM is realized using SiO2 slurry. Through investigating the variations of the surface characteristics polished by different ingredients via the morphology and force curve measurements, it’s reveals that the product-aluminum silicate with stronger adhesion and lower hardness is more readily to generate and be removed than the product-alumina hydrate induced by H2O. Thus, except for atomic scale mechanical abrading, the abrasive SiO2 nanoparticle is used for anticipating in the chemical reaction, resulting in superior surface finish of sapphire wafer with high efficiency. © 2015 Springer Science+Business Media New York

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