Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Effect of P5+/Al3+ molar ratio on structure and spectroscopic properties of Nd3+/Al3+/P5+ co-doped silica glass
No full textNational Natural Science Foundation of China [61505232]Glasses with compositions of (95.8-x) SiO2-4Al(2)O(3)-xP(2)O(5)-0.2Nd(2)O(3) (in mol%, x = 0-10) were prepared. Structural variation caused by P5+ was investigated by Judd-Ofelt parameters and Raman spectra. Results reveal that Nd3+ preferentially coordinates to P=O sites at molar ratio of P5+/Al3+ > 1 and thus it leads to a sudden change in fluorescence effective linewidth, stimulated emission cross section, fluorescence lifetime and non-radiative transition rate of Nd3+ ions. The fluorescence lifetime changes in the range of 315-379 mu s. The emission cross section changes in the range of 139-1.79 x 10(-20) cm(2). With the increase of P5+/Al3+ ratio, the fluorescence effective linewidth varies from 45.77 to 37.03 nm. The shortest fluorescence lifetime was observed at molar ratio of P5+/Al3+ = 1. The maximum non-radiative transition rate of 1694/s occurred at molar ratio of P5+/Al3+ = 1.25. The highest emission cross section of 1.79 x 10(-20) cm(2) was obtained at the highest P5+/Al3+ molar ratio. Furthermore, structure-property relationship in these glasses was discussed through Judd-Ofelt parameters and luminescent behaviors. (C) 2015 Elsevier B.V. All rights reserved
Optical properties of Ce3+ doped fluorophosphates scintillation glasses
No full textNational Natural Science Foundation of China (NSFC) [51472162, 51272262]Fluorophosphates (P2O5-BaO-BaF2-Al2O3-Gd2O3-Ce2O3) glasses with different Gd2O3 and BaF2 concentrations have been prepared by a melt quenching method. The effect of Gd2O3 and BaF2 on the glass performance including the density, absorption as well as luminescence properties under both ultraviolet (UV) and X-ray excitation was studied systematically. Energy transfer from Gd3+ to Ce3+ plays an important role in the scintillation mechanism of these glasses and the optimum concentration of Gd2O3 is found to be approximately 3 mol%. The highest integrated light emission intensity of these glass samples excited by X-ray is 25% of BGO and the decay time constants are in the range of 25-35 ns, much shorter than the 300 ns decay time of BGO. Meanwhile, replacing lighter compound BaO with the BaF2 can increase the density of the glasses and also improve the light yield. (C) 2015 Elsevier B.V. All rights reserved
百微米芯径掺镱光子晶体光纤实现皮秒级脉冲放大输出
No full text有源光子晶体光纤的芯径较大,主要用于实现高峰值功率(高能量)的脉冲放大输出。目前只有NKT Photonics公司可提供商品化的掺镱(Yb3+)有源光子晶体光纤,其最大芯径约为85μm。光子晶体光纤的制作主要受光纤预制棒中纤芯尺寸的限制。为实现百微米芯径的光子晶体光纤,预制棒中纤芯材料的直径须达到5mm,目前较难实现。中国科学院上海光学精密机械研究所立足于自身在
A 15 W 1152 nm Raman fiber laser with 6 nm spectral width for Ho3+ -doped crystal's pumping source
No full textProject of Shenyang Normal University [L201522]A 11.5 W 1152 nm Raman fiber laser with 6 nm spectral width was demonstrated based on the resonator constructed with one fiber loop mirror and one fiber Bragg grating. By mans of experimental measurement and theoretical calculation, the reflectivity of the fiber loop mirror was confirmed as 0.93. The Yb3+-doped 1090 nm fiber length was about 5 m. When the maximum pumping power of 976 nm laser was 54.8 W, 32.2 W 1090 nm laser was obtained and the optical to optical conversion efficiency from 1090 nm to 1152 nm light was 48%. Finally, the 1152 nm Raman fiber laser was used for pumping Ho3+:LLF crystal, and the 1194 nm fluorescence emission peak was detected for the first time. (C) 2016 Elsevier B.V. All rights reserved
Brillouin Optical Time Domain Reflectometry with Sub-Meter Spatial Resolution Based on Double-Pulse Detection
No full text在传统的布里渊光时域反射(BOTDR)技术中,空间分辨率和自发布里渊散射谱宽相互制约。针对这一问题,将探测光改进为超短双脉冲,并利用检测频谱包络的方法得到BOTDR系统的空间分辨率。该方法提高了 BOTDR系统的空间分辨率,同时可避免压窄脉冲引起的布里渊增益谱展宽对测量精度的影响。实验表明,该方案能实现0.5 m空间分辨率的温度测量,避免自发布里渊散射谱发生较大展宽。国家自然科学基金; 国家863计划; 上海市优秀技术带头人计划In conventional Brillouin optical time domain reflectometry (BOTDR),mutual restraint between the spatial resolution and the width of spontaneous Brillouin scattering spectrum can not be avoided. To solve this problem, we ameliorated the approach using double ultra-short pulses as probe light. By detecting spectral envelope, the spatial resolution of BOTDR can be extracted. This method improves the spatial resolution of the BOTDR system and meanwhile avoids the influence of Brillouin gain spectrum broadening caused by narrowing pulse on measurement accuracy. The experimental results show that with this novel BOTDR system, the temperature measurement can be realized at a 0.5 m spatial resolution, and the large broadening of the spontaneous Brillouin scattering spectrum can be avoided
High-sensitivity intravascular photoacoustic imaging of lipid-laden plaque with a collinear catheter design
No full textCenter of Excellence in Cardiovascular Research Grant; AHA Postdoctoral Fellowship; IUPUI Graduate Imaging Research Fellowship; [R01HL125385]A highly sensitive catheter probe is critical to catheter-based intravascular photoacoustic imaging. Here, we present a photoacoustic catheter probe design on the basis of collinear alignment of the incident optical wave and the photoacoustically generated sound wave within a miniature catheter housing for the first time. Such collinear catheter design with an outer diameter of 1.6 mm provided highly efficient overlap between optical and acoustic waves over an imaging depth of >6 mm in D2O medium. Intravascular photoacoustic imaging of lipid-laden atherosclerotic plaque and perivascular fat was demonstrated, where a lab-built 500 Hz optical parametric oscillator outputting nanosecond optical pulses at a wavelength of 1.7 mu m was used for overtone excitation of C-H bonds. In addition to intravascular imaging, the presented catheter design will benefit other photoacoustic applications such as needle-based intramuscular imaging
Performance of multi-hop parallel free-space optical communication over gamma-gamma fading channel with pointing errors
No full textNational Natural Science Foundation of China (NSFC) [61475049]; National Basic Research Program of China [2013CB29204]Multi-hop parallel relaying is considered in a free-space optical (FSO) communication system deploying binary phase-shift keying (BPSK) modulation under the combined effects of a gamma-gamma (GG) distribution and misalignment fading. Based on the best path selection criterion, the cumulative distribution function (CDF) of this cooperative random variable is derived. Then the performance of this optical mesh network is analyzed in detail. A Monte Carlo simulation is also conducted to demonstrate the effectiveness of the results for the average bit error rate (ABER) and outage probability. The numerical result proves that it needs a smaller average transmitted optical power to achieve the same ABER and outage probability when using the multi-hop parallel network in FSO links. Furthermore, the system use of more number of hops and cooperative paths can improve the quality of the communication. (C) 2016 Optical Society of Americ
Research on laser induced damage in PLZT electro-optical transparent ceramic
No full textNational Natural Science Foundation of China [61137004, 61405218, 61535014]; Shanghai Natural Science Foundation [14ZR1445100]; Key Basic Project of Science and Technology Commission of Shanghai Municipality [11JC1413500]Nanosecond single and multiple pulses laser damage studies on electro-optic transparent ceramic PLZT ceramic are performed. The evolution of damage morphology and damage probability threshold under multiple irradiations reveals that fatigue effects are affected by both laser fluence and shot numbers. The bulk damage is caused by themal explosion and self-focusing. Femtosecond single and multiple pulses are also employed to irradiate on the sample. Nonlinear absorption property of sample is studied to analyze different damage mechanism. Investigations on laser-induced damage in PLZT are of high practical importance for high-power laser applications. (C) 2016 Optical Society of Americ
Study on the key technology of spectral reflectivity reconstruction based on sparse prior by a single-pixel detector
No full textNational Natural Science Foundation of China [61405115]; Natural Science Foundation of Shanghai [14ZR1428400]; Innovation Project of Shanghai Municipal Education Commission [14YZ099]; National Basic Research Program of China (973 Program) [2015CB352004]By studying the traditional spectral reflectance reconstruction method, spectral reflectance and the relative spectral power distribution of a lighting source are sparsely decomposed, and the orthogonal property of the principal component orthogonal basis is used to eliminate basis; then spectral reflectance data are obtained by solving a sparse coefficient. After theoretical analysis, the spectral reflectance reconstruction based on sparse prior knowledge of the principal component orthogonal basis by a single-pixel detector is carried out by software simulation and experiment. It can reduce the complexity and cost of the system, and has certain significance for the improvement of multispectral image acquisition technology. (C) 2016 Chinese Laser Pres
V-groove-based compact FBG package for thermal tuning and mechanical stability
No full textNational Natural Science Foundation of China [61405218, 61535014]; Shanghai Natural Science Foundation [14ZR1445100]We demonstrated a V-groove-based fiber Bragg grating (FBG) package that has been glue-filled and cured to make it a bulky component with much improved mechanical stability. The V-groove can be executed with many types of materials including plastics, ceramics, semiconductors, and metals, providing an easy method for redesigning the thermal tuning performance of FBGs by selecting among a wide variety of materials and processes. We achieved more than 10-nm thermal wavelength tuning and thermal sensitivity ranging from 15 to 160 pm/K. The original FBG spectrum can be maintained without any degradation because the fiber is buried in the V-groove. The compact package does not increase the original grating length and turns the FBG into a planar waveguide grating, improving FBG applications in telecommunications, external cavity lasers, and sensing areas