Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Fabrication and near-infrared optical responses of 2D periodical Au/ITO nanocomposite arrays
No full textNational Natural Science Foundation of China (NSFC) [61308087, 61405224, 61522510, 61675217]; Natural Science Foundation of Shanghai [16ZR1440300]; China Scholarship Council (CSC); Science Foundation Ireland (SFI); Chinese Academy of Sciences (CAS) [XDB16030700, QYZDB-SSW-JSC041]; Science and Technology Commission of Shanghai Municipality (STCSM) [17XD1403900]Two-dimensional (2D) periodical Au and indium tin oxide (ITO) nanocomposite arrays have been fabricated based on a self-assembled nanosphere lithography technique. A button-shaped Au nanoparticle was formed on each hollow hemisphere-shaped ITO shell. Importantly, the underlying formation mechanism during the thermal treatment has been thoroughly explored by comparing structures resulting from different deposition conditions in detail. Compared to the Au nanoparticle arrays without ITO shells, the Au/ITO nanocomposite arrays showed a stronger localized surface plasmon resonance effect and higher absorption in the near-infrared (NIR) region, benefiting from the free-electron interaction enhancement between Au and ITO. The nonlinear optical properties were investigated using a modified femtosecond intensity-scan system, and the results demonstrated Au/ITO nanocomposite arrays with a remarkable two-photon absorption saturation effect for femtosecond pulses at 1030 nm. The versatile NIR optical responses indicate the great potential of the elaborately prepared 2D periodical Au/ITO nanocomposite arrays in many applications such as solar cells, photocatalysis, and novel nano optoelectronic devices
Laser-damage characteristics of Nd: glass active mirrors
No full textNational Natural Science Foundation of China (NSFC) [61308021, 6140521]The active-mirror architecture is widely used in high-power laser systems. In this study, the laser-damage characteristics of Nd: glass active mirrors are investigated. They are exposed to nanosecond 1064 nm laser incident from the Nd: glass. The laser-induced damage thresholds (LIDTs) of the coated sides are lower than those of the uncoated sides. The LIDT of the active mirror whose substrate is manually scrubbed is lower than that of one whose substrate is ultrasonically cleaned. Analysis shows that the absorbing surface defects on the manually scrubbed Nd: glass surface are responsible for the lower LIDT of the active mirror prepared via manual scrubbing, while the subsurface defects in the ultrasonically cleaned Nd: glass substrate are the main reason for the damage of the active mirror prepared via ultrasonic cleaning. The strong standing-wave electric field near the interface between the coating and the Nd: glass substrate is another factor affecting the damage of the active mirror. (C) 2017 Optical Society of Americ
Sensitization and deactivation effects of Nd3+ on the Ho3+: 3.9 mu m emission in a PbF2 crystal
No full textNational Natural Science Foundation of China (NSFC) [11404332, 1404332, 51302283, 51472257, 614750671, 61605062]; National Key Research and Development Program of China [2016YFB0701002]; Guangdong Project of Science and Technology Grants [2014B010124002, 2014B010131004, 2014B090903014, 201508010021, 2016B090917002, 2016B090926004]; Guangzhou Union Project of Science and Technology Grants [201604040006, 201604040007]The use of Nd3+ codoping for sensitizing the Ho3+ ion and enhancing the similar to 3.9 mu m emission from Ho3+:I-5(5) -> I-5(6) was investigated in the PbF2 crystal for the first time, to the best of our knowledge. The similar to 3.9??mu m fluorescence emission properties and energy transfer mechanism of the as-grown crystals were investigated. The results show that the Nd3+ ion can act as a sensitizer to the Ho3+ ion, providing an efficient excitation channel, making the Ho3+/Nd3+:PbF2 crystal propitious to be pumped by commercialized InGaAs laser diodes (LDs). Moreover, an enhanced similar to 3.9 mu m emission was obtained in the Ho3+/Nd3+:PbF2 crystal due to the codoping of Nd3+ ions, leading to an efficient energy transfer from a lower laser level of Ho3+:I-5(5) to Nd3+:I-4(15/2), while having little influence on the higher laser level of Ho3+:I-5(5). These advantageous spectroscopic characteristics indicate that the Ho3+/Nd3+:PbF2 crystal might have potential application in similar to 3.9 mu m mid-infrared lasers under a conventional 808 nm LD pump
Effect of Sintering Temperature on Luminescence Properties of Color Conversion Glasses in Borosilicate Glasses
No full text采用共烧结法制备了硼硅基质Ce: YAG荧光玻璃,研究了烧结温度在600℃~900℃范围内, Ce: YAG荧光玻璃的发光强度变化和色坐标漂移规律。结果表明, 随着烧结温度的升高, Ce: YAG荧光玻璃发光强度先增强后减弱, 700℃烧结时, 荧光玻璃获得最大发光强度; 超过850℃烧结时, 荧光玻璃无发光性能; 同时, 色坐标(x, y)发生漂移, 且比相同烧结温度的荧光粉漂移幅度大。通过X射线粉末衍射仪、差示扫描量热分析仪和X射线光电子能谱分析仪测试分析表明: 随着烧结温度升高, 荧光粉中的Ce~(3+)被玻璃基质氧化成Ce~(4+), 玻璃液体腐蚀破坏了荧光粉YAG晶体结构, 降低了荧光玻璃的发光强度, 从而导致色坐标劣化漂移。National Natural Science Foundation of China [51302171]; Science and Technology Commission of Shanghai Municipality [14500503300]; Shanghai Municipal Alliance Program [LM201547]The color conversion glass is a promising material for light emitting diodes encapsulation due to its high thermal conductivity and good thermal stability. In present study, color conversion glasses were prepared by sintering a mixture of borosilicate glass fits and a YAG phosphor at temperature from 600 degrees C to 900 degrees C. The effects of sintering temperature on luminescence properties were examined. Characteristics of color conversion glasses, with respect to luminescence intensity, CIE (Commission International de I'Eclairage) chromaticity and CCT (Correlated Color Temperature) were analyzed based on luminescence excitation and emission spectra. These characteristics are dependent on sintering temperature of the color conversion glasses. The CIE coordinates shift with increase of sintering temperature. The glass, sintered at 700 degrees C, shows the best luminescence properties. But for the glasses sintered above 850 degrees C, their luminescence properties may be destroyed. Test results of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS) reveal that degradation of luminescence properties with increase of sintering temperature is ascribed to the lattice disturbance of YAG and oxidation of Ce3+, which is caused by reactions between glass matrix and YAG phosphors. The present study may promote the application of color conversion glasses in light emitting diodes encapsulation
Near Infrared Quantum Cutting Luminescence of Er3+/Tm3+ Ion Pairs in a Telluride Glass
No full textNational Natural Science Foundation of China [51472028]; Fundamental Research Funds for the Central Universities of China [2017TZ01]The multiphoton near-infrared, quantum cutting luminescence in Er3+/Tm3+ co-doped telluride glass was studied. We found that the near-infrared 1800-nm luminescence intensity of (A) Er3+(8%) Tm3+(0.5%): telluride glass was approximately 4.4 to 19.5 times larger than that of (B) Tm3+(0.5%): telluride glass, and approximately 5.0 times larger than that of (C) Er3+(0.5%): telluride glass. Additionally, the infrared excitation spectra of the 1800 nm luminescence, as well as the visible excitation spectra of the 522 nm and 652 nm luminescence, of (A) Er3+(8%) Tm3+(0.5%): telluride glass are very similar to those of Er3+ ions in (C) Er3+(0.5%): telluride glass, with respect to the shapes of their excitation spectral waveforms and peak wavelengths. Moreover, we found that there is a strong spectral overlap and energy transfer between the infrared luminescence of Er3+ donor ions and the infrared absorption of Tm3+ acceptor ions. The efficiency of this energy transfer {I-4(13/2)(Er3+) -> I-4(15/2)(Er3+), H-3(6)(Tm3+) -> F-3(4)(Tm3+)} between the Er3+ and Tm3+ ions is approximately 69.8%. Therefore, we can conclude that the observed behaviour is an interesting multiphoton, near-infrared, quantum cutting luminescence phenomenon that occurs in novel Er3+-Tm3+ ion pairs. These findings are significant for the development of next-generation environmentally friendly germanium solar cells, and near-to-mid infrared (1.8-2.0 mu m) lasers pumped by GaN light emitting diodes
Hexabromocyclododecane and tetrabromobisphenol A in tree bark from different functional areas of Shanghai, China: levels and spatial distributions
No full textNational Natural Science Foundation of China [41473090, 41430644, 11675098, 41373098, 41573096]; Program for Changjiang Scholars and Innovative Research Team in University [IRT13078]The concentrations and spatial distributions of hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA) were measured in tree bark from different functional areas of Shanghai. Sigma HBCDD (sum of alpha-, beta-, and gamma-HBCDD) concentrations ranged from 1.2 x 10(2) to 6.6 x 10(3) ng g(-1) lw (median 5.7 x 10(2) ng g(-1) lw) and TBBPA concentrations ranged from 48 to 7.2 x 10(4) ng g(-1) lw (median 2.8 x 10(2) ng g(-1) lw). The concentrations of Sigma HBCDD and TBBPA all followed the order of industrial areas > commercial areas > residential areas. The mean percentage of alpha-HBCDD in bark samples (44%) from Shanghai was higher than that in technical HBCDD products, but comparable with that in air. The concentrations of TBBPA and individual HBCDD diastereoisomers between industrial areas and commercial areas were correlated. Based on the concentrations of HBCDD in the bark, the corresponding atmospheric HBCDD concentrations were estimated. Compared with the published data for HBCDD in urban air, the estimated atmospheric HBCDD concentrations in Shanghai had a relatively high level, and more attention should be paid to the pollution status of HBCDD in Shanghai
Injection-seeded single frequency 2.05 mu m output by ring cavity optical parametric oscillator
No full textNational Natural Science Foundation of China [61505230]; National Key Research and Development Program of China [2016YFC1400902]An injection-seeded single-resonant optical parametric oscillator (SROPO) with single frequency nanosecond pulsed 2.05 mu m wavelength output is presented. Based on two potassium titanyl phosphate crystals and pumped by a 1064 nm single frequency laser pulse, injection seeding is performed successfully by using the ramp-hold-fire technique in a ring cavity with a bow-tie configuration. The SROPO provides 2.65 mJ single frequency signal pulse output with a 17.6 ns pulse duration at a 20 Hz repetition rate. A near-diffraction-limited beam is achieved with a beam quality factor M-2 of about 1.2. The spectrum linewidth of the signal pulse is around 26.4 MHz, which is almost the Fourier-transform-limited value
Narrow-spectral-span spectral beam combining with a nonparallel double-grating structure
No full textShanghai Science and Technology Committee [16DZ2290102, 15JC1403500]; Chinese Academy of Sciences [QYZDJ-SSW-JSC014]; National Natural Science Foundation of China [61405216]We propose a nonparallel double-grating structure in a spectral-beam combining technique, where two gratings are placed nonparallel satisfying the Littrow mount in the focal region of the convergent lens. The most attractive advantage of this approach is that it will compress the spectral span into half of its original spectrum, which means the number of combined elements can be doubled in the gain range of diode lasers. Experimental results demonstrate that the CW output power of the combined beam is 30.9 W with a spectral span of 7.0 nm, compared with its original spectrum span of 13.6 nm, and the spectral beam combining efficiency is 70.5%. In consideration that a single grating could have a high efficiency of > 97% in a bandwidth of over ten nanometers, the efficiency loss of the grating pair should be less than 6%, which is acceptable for most applications, so this method of using double gratings should be highly interesting for practical applications when a nearly doubled number of diode lasers could be combined into one single laser compared with the previous single-grating methods
Electron localization of H-2(+) in a dc electric field
No full textNational Natural Science Foundation of China [11127901, 61521093, 11134010, 11227902, 11222439, 11274325]; National Basic Research Program of China [2011CB808103]A dc electric field is utilized to steer the electron motion after the molecular ion H-2(+) is excited by an ultrashort ultraviolet laser pulse. The numerical simulation shows that the electron localization distribution and the dissociation control ratio are dependent on the polarization direction and amplitude of the dc electric field. Most electrons of the dissociation state move opposite to the dc electric field and stabilize at the dressed-up potential well, for the dressed-down well is occupied by the electrons of the 1s sigma(g) state
Hot-electron refluxing enhanced relativistic transparency of overdense plasmas
No full textResearch Foundation of the National Key Laboratory of Shock Wave and Detonation Physics [9140C670902140C67001]A new phenomenon of an enhanced relativistic transparency of overdense plasmas by the influence of hot-electron refluxing has been discovered via particle-in-cell simulations. When a p-polarized laser pulse, with intensity below the self-induced-transparency (SIT) threshold, obliquely irradiates a thin overdense plasma, the initially opaque plasma becomes transparent after a time interval that is linearly dependent on the thickness of the plasma. This phenomenon can be interpreted as a consequence of hot-electron refluxing, which reduces the effective electron density by longitudinal heating. When the laser intensity is higher than the SIT threshold, the penetration velocity of the laser in the plasma is enhanced when the refluxing is present. Published by AIP Publishing