最新刊期

    34 2 2013

      paper

    • XIE Dong-hua, CHEN Xiang-ying, CHEN Chong
      Vol. 34, Issue 2, Pages: 123-132(2013) DOI: 10.3788/fgxb20133402.0123
      摘要:A simple and efficacious hydrothermal and post-annealing method has been developed to prepare Sr5(PO4)3Cl∶Ce3+ phosphors. The experimental results reveal that modulating the solvent species as well as the solvent composition (i.e. solvent effect) can give rise to Sr5(PO4)3Cl∶Ce3+ phosphors with granular/rugby-like shapes and various sizes under hydrothermal conditions. The driving force for rugby-like Sr5(PO4)3Cl∶Ce3+ phosphor growing along [001] direction originates from its intrinsic symmetry of P63/m. More importantly, post-annealing method was further carried out to investigate the luminescent properties of Sr5(PO4)3Cl∶Ce3+ phosphors. Ce3+ doping content, calcination temperature, volume ratio in H2O-triethyleneamine and two different synthetic methods play important roles in determining the emission intensity. The PL, PLE spectra and CIE chromaticity coordinates illustrate the excellent blue emission feature of Sr5(PO4)3Cl∶Ce3+ phosphors.  
      关键词:Sr5(PO4)3Cl∶Ce3+;phosphors;hydrothermal;solvent effect   
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    • HE Long-fei, FAN Guang-han, LEI Mu-yun, LOU Zai-liang, ZHENG Shu-wen, SU Chen, XIAO Yao, CH
      Vol. 34, Issue 2, Pages: 133-138(2013) DOI: 10.3788/fgxb20133402.0133
      摘要:High-purity ultrafine MgAl2O4 powder was synthesized by metal-alkoxide method and calcining for 2~4 h.After mixing the YAG∶Ce phosphor with MgAl2O4 powder, MgAl2O4/Ce∶YAG transparent ceramics were obtained by hot-pressed sintering and hot isostatic pressed sintering technique. The transparent ceramics were characterized by X-ray diffraction and UV-Vis spectrometer. The crystal phase of the transparent ceramic was composed of MgAl2O4 and YAG. The excitation spectra had a weak band at 345 nm and a strong band at 475 nm. The broad emission peaks at about 533 nm can be attributed to 5d→4f transition of Ce3+ ions. The luminous efficacy of the white LED which packaged by the transparent ceramic and blue LED chip was 133.47 lm·W-1 at 35 mA, and its color temperature are not varied with the change of driving current. It had better performance in stability and lifetime than that packaged in traditional ways under the same condition. All results show that MgAl2O4/Ce∶YAG transparent ceramic may be a promising fluorescent material for white LEDs.  
      关键词:YAG;MgAl2O4;transparent ceramic;white LED   
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    • Preparation and Characterization of Cu-doped ZnO Nano Materials

      LAN Fei-fei, WANG Jin-zhong, WANG Dun-bo, LI Qian, YAN Yuan, YU Qing-jiang, GAO Shi-yong, J
      Vol. 34, Issue 2, Pages: 139-143(2013) DOI: 10.3788/fgxb20133402.0139
      摘要:Cu-doped ZnO samples were prepared by CVD under different growth temperature, and their growth mechanism was analyzed. The samples were characterized by X-ray diffraction patterns, SEM, and PL spectra. XRD patterns confirm that the samples are polycrystal and show single ZnO hexagonal phase. EDS analysis proved that Cu is doped in ZnO samples. Room temperature PL spectra indicate that the intensity ratio of UV to deep energy level emission increases with Cu content in ZnO, which implies the introduction of Cu causes the decreases in the emission related to defects.  
      关键词:ZnO;Cu doping;photoluminescence   
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    • XIA Zhang-gen, LIANG Yu-jun, HUANG Wen-zhu, LI Yun-li, YANG Fan, LI Xue-jing
      Vol. 34, Issue 2, Pages: 144-148(2013) DOI: 10.3788/fgxb20133402.0144
      摘要:The novel green-emission phosphors (Ce0.67Tb0.33)Mg1-xAl11O19xMn2+ have been prepared at 1 300℃ by solid-state reaction method. The crystal structure and photoluminescence properties were characterized by XRD and fluorescence spectra, respectively. The results show that (Ce0.67Tb0.33)Mg1-xAl11O19xMn2+ has the same crystal structure with the typical commercial green phosphor (Ce0.67Tb0.33)MgAl11O19 (CMAT). The excitation spectrum consists of a broad band range from 237 to 326 nm centered at 291 nm, which can be attributed to the characteristic excitation peaks of Ce3+. While excited under ultraviolet light, the phosphors exhibit not only the characteristic emission peaks of Tb3+ at 490, 541, 590 and 620 nm, but also a new broad emission band around 516 nm, which is assigned to the 4T1g(G)→6A1g(S) electron transition of Mn2+. The integral area of the emission spectrum increases while doped with Mn2+ as a co-activator, and the integral area is about 226% of CMAT as x=15.0%, and the CIE 1931 chromaticity coordinates of Mn2+ doped phosphors (0.194, 0.695) are closer to the NTSC standard values (0.21, 0.71) while compared with CMAT (0.288, 0.572). The results indicate that this new phosphor has a higher luminous efficiency in green area and color purity than that of CMAT, and it has a promising application in display fields.  
      关键词:(Ce0.67Tb0.33)Mg1-xAl11O19xMn2+;phosphors;photoluminescence   
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    • TU Lang-ping, KONG Xiang-gui
      Vol. 34, Issue 2, Pages: 149-153(2013) DOI: 10.3788/fgxb20133402.0149
      摘要:We present a facile method to integrate NaYF4∶Yb,Er upconversion nanoparticles with Au nanoparticles for constructing NaYF4∶Yb,Er@SiO2@Au composite nanostructures, in which a silica layer on NaYF4∶Yb,Er nanoparticles to make them water-stable and acts as an interface for Au decoration. The green and red emissions of the upconversion nanoparticles can be conveniently adjusted by altering the amount of surrounding Au nanoparticles. These results are positive for the widely exploring applications of upconversion nanoparticles in biological imaging, detection, and sensing.  
      关键词:NaYF4 upconversion nanoparticle;Au nanoparticle;resonance energy transfer   
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    • WU Yi-liang, ZHOU Guo-fang, WANG Wen-jian, ZHANG Zi-han, WU Chun-yan
      Vol. 34, Issue 2, Pages: 154-159(2013) DOI: 10.3788/fgxb20133402.0154
      摘要:Tetragonal CuInS2 flower-like microspheres were successfully synthesized through the solvothermal reaction in ethylene glycol (EG) with the assistance of cationic surfactant cetyltrimethylammonium bromide (CTAB). The morphology, structure and composition of the products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoelectron spectroscopy (XPS) and UV-Vis spectroscopy, respectively. XRD spectra showed that the lowest temperature for the synthesis of pure CuInS2 was 200 ℃. CuInS2 microspheres obtained at the temperature 200 ℃ and 220 ℃ were verified to be Cu-rich and In-rich, respectively. UV-Vis spectrum showed that there existed intensity absorption in the visible region for CuInS2 microspheres obtained at 200 ℃. The band gap was estimated to be ~1.62 eV, which is very close to that of bulk CuInS2. Back-gate field effect transistor based on CuInS2 microspheres obtained at 200 ℃ was constructed and their electrical characterizations indicated that as-prepared CuInS2 microspheres were p-type semiconductor with conductivity of ~2 S·cm-1, which is similar to that of p-type CuInS2 films. As-prepared CuInS2 microspheres showed their potential application in the fields of low-cost and high-performance photovoltaic devices.  
      关键词:CuInS2;microspheres;field effect transistor (FET);photovoltaic devices   
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    • ZHANG Jing-ying, HOU Guang-hui, SHI Jian-jun, XIONG Teng-jie, LIU Zhong-xin
      Vol. 34, Issue 2, Pages: 160-164(2013) DOI: 10.3788/fgxb20133402.0160
      摘要:Upconversion nanocrystals have caused much attention, due to their superior optical and chemical properties. In this study, upconversion nanocrystals loaded chitosan microshperes were designed to develop the applications in biomedicine. Polyethyleneimine (PEI) modified NaYF4∶Yb3+,Tm3+ upconversion nanocrystals were prepared by solvothermal method. XRD and TEM indicated that the particles crystallized very well and the size was about 20 nm. The dispersity was enhanced, both in water and in chitosan solution. NaYF4∶Yb3+,Tm3+ loaded chitosan microshperes were fabricated using microemulsion method. SEM pictures showed that the chitosan microspheres' surface was rough and the NaYF4∶Yb3+,Tm3+ particles were embedded in the surface shell. For PEI and chitosan having the same positive charge, during the cross-linking process, PEI modified particles moved to the surface of the chitosan microshperes drived by repulsive force. The luminescence intensity of the NaYF4∶Yb3+,Tm3+ loaded chitosan microshperes increased with the increasing of nanopaticles. Due to the biocompatibility and biodegradability of the chitosan carrier, this material can improve the duration in vivo, avoid process release effect. This kind of nanocrystals loaded chitosan microshperes may have broad application prospects in photodynamic therapy, biological imaging, fluorescent identification, as controlled release materials.  
      关键词:solvothermal synthesis;upconversion fluorescence;chitosan microshpere   
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    • Fano-like Resonances in Symmetric Planar Metamaterials

      CAO Yang
      Vol. 34, Issue 2, Pages: 165-170(2013) DOI: 10.3788/fgxb20133402.0165
      摘要:The Fano-like resonance in symmetric planar metamaterials comprised of complimentary split ring resonators (CSRRs) is investigated by calculations from modal expansion method and transmission measurements. The Fano-like resonance is observed for one polarization with electric field component parallel to the mirror line of the structure, while only the broad dipole response can be found for the cross-polarization. Numerical simulations of field distributions reveal that the sharp response arises from the excitation of subradiant mode with nearly zero net dipole moment and poorly coupled with free space photons. The fast roll-off characteristic of Fano-like resonances is favorable for filtering and sensing applications.  
      关键词:Fano-like resonance;metamaterials;high quality factor   
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    • HE Dong-li, LYU Shu-chen, QU Xiu-rong, MAO Jin-wei, MENG Qing-yu
      Vol. 34, Issue 2, Pages: 171-177(2013) DOI: 10.3788/fgxb20133402.0171
      摘要:Eu3+, Sm3+ doped and co-doped Gd2(WO4)3 nanocrystalline powders were prepared by chemical co-precipitation method, respectively. The structure and luminescent properties of nanocrystalline Gd2(WO4)3∶Eu3+ and Gd2(WO4)3∶Eu3+,Sm3+ were studied by using XRD and fluorescence spectrophotometer. The results show that the crystal phase of the samples as prepared is base centered monoclinic structure. When the mole fraction of Eu3+ is 20%, the luminescent intensity of Eu3+ is the greatest. Sm3+ sensitized Eu3+ in the samples Gd2(WO4)3∶Eu3+,Sm3+. The sensitized effect of Sm3+ on Eu3+ was more obvious when the sample Gd2(WO4)3∶Eu3+,Sm3+ was excited by 464 nm light than by 395 nm light. Sm3+ can realize the energy transfer from Sm3+ to Eu3+, making the emission of 5D07F2 more strength. When the mole fraction of Sm3+ was 5%, the luminescent intensity of the sample Gd2(WO4)3∶20%Eu3+,5%Sm3+ was the greatest. The transition of 5D07F2 was clearly observed under 405 nm or 440 nm excitation. Therefore, Eu3+ and Sm3+ co-doped in the matrix Gd2(WO4)3 greatly expanded the range of the wavelength of the excitation light source.  
      关键词:chemical co-precipitation;energy transfer;photoluminescence   
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    • Preparation and Luminescence Properties of YAl3(BO3)4∶Dy3+ Phosphors

      XIAO Lin-jiu, LIU Jiao-na, XIE Ying, WANG Gang, CHEN Yong-jie, LI Wen-ze, GENG Xiu-juan
      Vol. 34, Issue 2, Pages: 178-183(2013) DOI: 10.3788/fgxb20133402.0178
      摘要:Dy3+ ions doped YAl3(BO3)4 phosphors were prepared by sol-gel method. Their structure and luminescence properties were characterized by X-ray diffraction (XRD) analysis and fluorescence spectrometry (FL). The preparation conditions of the precursor synthesis, including the Dy3+ concentration and crystallization temperature were investigated. The results showed that the luminescence intensity of YAl3(BO3)4∶Dy3+ is the biggest at the calcination temperature of 1 100 ℃.The optimum doping mole fraction of Dy3+ ions was x=0.05. The main emission peak was about 575 nm excited at 774 nm. The YAl3(BO3)4∶Dy3+ phosphors can convert spectra band from 700 to 900 nm and from 290 to 490 nm into visible light around 575 nm which is absorbed strongly by the dye sensitized solar cells.  
      关键词:sol-gel method;near-infrared phosphors;Dy3+ ions doped   
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    • WANG Yun-hua, BO Bao-xue
      Vol. 34, Issue 2, Pages: 184-191(2013) DOI: 10.3788/fgxb20133402.0184
      摘要:The optical analysis of the lossless and lossy distributed Bragg reflector (DBR) structure using the transfer matrix method was reported. For DBR structures with different configurations of HL, HLH, LH and LHL, the optical field distributions were gained from the simulation. The theoretical analysis showed that the level of optical field amplitude within HL and HLH structure was much lower than other structures. For the extinction coefficient of 0.01, the energy absorption in HL and HLH DBR structures was only 10% of the one within LH and LHL structures. Due to the optical absorption, the reflectivity at the central wavelength of HL and HLH DBR structures decreased by 3.6%, comparing with 29.2% for LH and LHL structures. Thus, the reflectivity of DBR could be increased if the high index layer was used as the first layer, and the optical absorption could be decreased by this method. At last, the lossy DBR consisted of Al0.12Ga0.88As/Al0.9Ga0.1As was grown and its reflectivity was measured.  
      关键词:transfer matrix method;distributed Bragg reflector;optical field distribution;reflectivity spectrum   
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    • TIAN Miao-miao, LI Chun-jie, HE Xiao-guang, YU Li-jun, QI Jin-gang, QU Xue-song, SUN Xiao-
      Vol. 34, Issue 2, Pages: 192-196(2013) DOI: 10.3788/fgxb20133402.0192
      摘要:Two heterojunction organic solar cells based different anode (ITO and ILTO) were investigated to compare the power conversion efficiency (PCE) of organic solar cell (OSCs) in two types of devices with different hole-extracting electrodes. Except for a slight decrease in the open circuit voltage (Voc), the OSC with an ILTO anode exhibits an obvious increase in short-circuit current (Jsc) and fill factor (FF) as comparing with that of the ITO-anode OSC (Voc=0.412 V vs. 0.413 V, Jsc=5.64 mA穋m-2 vs. 3.26 mA穋m-2, FF=0.635 vs. 0.611). Sequentially, a power conversion efficiency (PCE) of 1.45% in the ILTO-anode OSC is demonstrated while only 0.91% for the ITO-anode OSC is achieved. The improved PCE in the ILTO-anode OSC is mainly attributed to the energy level alignment between the work function of ILTO and the HOMO level of CuPc, and a higher light transmission in the UV region of the ILTO. Our results indicate that a suitable TCO can effectively improve the performance of organic optoelectronic devices.  
      关键词:transparent conductive anode;organic solar cell;work function   
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    • SHANG Ming-wei, LIU Chun-ting, SUN Qiong, ZHANG Qian, DONG Hong-zhou, DONG Li-feng
      Vol. 34, Issue 2, Pages: 197-201(2013) DOI: 10.3788/fgxb20133402.0197
      摘要:Single-crystal n-type zinc oxide (ZnO) nanorod arrays, p-type cuprous oxide (Cu2O) film, and Cu2O/ZnO heterostructures were fabricated by electrochemical deposition. The diameter of ZnO nanorods can be controlled by changing the ZnCl2 concentration as it increases with the concentration of ZnCl2. Electrical measurements demonstrate a p-n junction forms between Cu2O film and ZnO nanorod arrays. External quantum efficiency of the p-n junction is higher than that of ZnO nanorod arrays and Cu2O film, which indicates that the formation of a p-n junction between Cu2O film and ZnO nanorod arrays can efficiently facilitate the separation and transport of charge carriers for applications in solar cells.  
      关键词:ZnO;Cu2O;heterojunction;photovoltaic;external quantum efficiency   
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    • YANG Mei-jia, ZHU Li-ping
      Vol. 34, Issue 2, Pages: 202-207(2013) DOI: 10.3788/fgxb20133402.0202
      摘要:Cu2O-ZnO heterojunction has shown great potential for photovoltaic application due to the low-cost, nontoxicity, abundance and variety of preparation methods. However, the resistivity of the Cu2O film in present ZnO-Cu2O heterojunction solar cell is relatively high, which seems to be the major problem for the low photoelectric conversion efficiency. Cu2O films were prepared using reactive direct current magnetron sputtering. The microstructures and properties were characterized using X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Hall-effect measurements. The influences of qV(Ar)∶qV(O2) on the structures and properties of deposited films were investigated. Single-phase Cu2O film with a resistivity of 88.5 Ω·cm, a Hall mobility of 16.9 cm2·V-1·s-1 and a carrier concentration of 4.19×1015 cm-3 were obtained at qV(Ar)∶qV(O2)=90∶0.3. The as-deposited Cu2O films have a great improvement in electrical performance and have more advantage in photovoltaic application compared with that prepared by electrochemical deposition or thermal oxidation. On that basis, the Cu2O-ZnO heterojunctions were fabricated in reversed growth sequence and the band alignments of the heterojunctions were given to investigate their potential application in solar cells. Possible areas for future work in this field were outlined and some suggestions were made based on our investigation of the Cu2O-ZnO heterojunctions fabricated by magnetron sputtering.  
      关键词:compound semiconductor;Cu2O-ZnO heterojunction;solar cell;resistivity;band alignment   
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    • XIN En-long, LI Xi-feng, ZHANG Jian-hua
      Vol. 34, Issue 2, Pages: 208-212(2013) DOI: 10.3788/fgxb20133402.0208
      摘要:The amorphous InZnO (a-IZO) thin films were prepared by sol-gel technology, and thin film transistors (TFTs) were further fabricated by employing the IZO films as the active channel layer after low temperature (300 ℃) annealing treatment. The influence of indium concentration on the electrical properties of IZO thin films and the IZO-TFTs was investigated in this paper. The results revealed that the IZO film was amorphous, surface was uniform and smooth, grain about 20 nm, and the visible average optical transmittance was more than 85%. IZO-TFT with a threshold voltage of 1.3 V, a mobility of 0.24 cm2·V-1·s-1, and a Ion∶Ioff current ratio of 105 was obtained when n(In)∶n(Zn)=3∶2.  
      关键词:sol-gel technology;indium zinc oxide;thin film transistor;low temperature   
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    • Rapid Reliability Evaluation Method of LED Based on Pseudo-failure Lifetime

      GUO Wei-ling, FAN Xing, CUI De-sheng, WU Guo-qing, YU Xin
      Vol. 34, Issue 2, Pages: 213-217(2013) DOI: 10.3788/fgxb20133402.0213
      摘要:An efficient and rapid reliability evaluation method of LED has been proposed. The pseudo-failure lifetime is tested and the lifetime data is analyzed by Minitab. The results show that the pseudo-failure lifetime of all samples are Weibull distribution. The reliability evaluation of LED products are made by comparing the scale parameters of Weibull distribution. This method has a certain reference value to reliability evaluation and life prediction of LED.  
      关键词:LED;fixed time test;pseud-failure lifetime;Weibull distribution   
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    • SUN Fang-fang, HE Yun-qiu, LI Yi-ming, LI Le, CHU Xiao-fei, HUANG He-zhou
      Vol. 34, Issue 2, Pages: 218-224(2013) DOI: 10.3788/fgxb20133402.0218
      摘要:By using the constant-current electrochemical method, nanostructure ZnO was deposited on the modified ITO substrate. the relationship between Zn(NO3)2·6H2O concentration and the morphology, the crystalline phases, morphology and thickness, sheet resistances, transmittance, the oxidation and reduction potential were researched by XRD, FE-SEM, RTS-8, UV-Vis, Cyclic Voltammetry. The results indicated that one-dimensional(1D) nanopillars were prepared by low concentration of electrolyte, whereas two-dimensional(2D) nanodisks with compact hexagonal were obtainted by high concention of electrolyte. UV-Vis spectroscopy revealed that the transmittance of ZnO nanopillars and nanodisks were more than 85% at the range of 400~900 nm, RTS-8 analysis indicated that sheet resistances of ZnO thin films are about 14.5 Ω/□, Cyclic Voltammetry analysis indicated significant differences of the potentials of oxidation and reduction between two kinds of morphology, whose ZnO nanopillars were -0.54 V(vs.SCE)and ZnO nanodisks were-0.72 V(vs.SCE), respectively. The results revealed that ZnO thin films with nanodisks had better chemical stability.  
      关键词:ZnO films;constant-current;modification;transparency electrode   
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    • Fabrication of High-performance 400 nm Violet Light Emitting Diode

      WANG Dong-sheng, GUO Wen-ping, ZHANG Ke-xiong, LIANG Hong-wei, SONG Shi-wei, YANG De-chao
      Vol. 34, Issue 2, Pages: 225-229(2013) DOI: 10.3788/fgxb20133402.0225
      摘要:High-performance 400 nm violet InGaN multi-quantum-wells light-emitting diodes (LED) with p-AlGaN electron blocking layer were fabricated on sapphire substrate by metal organic chemical vapor deposition technique. Different kinds of p-AlGaN electron blocking layers were grown in three violet LEDs: bulk p-AlGaN with Al mole fraction of 9%, bulk p-AlGaN with Al mole fraction of 11% and super lattice p-AlGaN/GaN with Al mole fraction of 20%. The output power of violet LED with bulk p-AlGaN(11%) is higher than the LED with bulk p-AlGaN(9%). Typically, the output power of the LED with 10 pairs of p-AlGaN/GaN super lattice electron blocking layer has been greatly improved. A LED with an output power of 21 mW at an injection current of 20 mA is achieved. In additional, the LED also shows an almost linear I-L characteristics at high injection current and uniform intensity mapping on LED chip surface.  
      关键词:metal organic chemical vapor deposition;violet light emitting diodes;GaN light emitting diodes;electron blocking layer;super lattice   
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    • ZHENG Ling, ZHAO Yan-ping
      Vol. 34, Issue 2, Pages: 230-234(2013) DOI: 10.3788/fgxb20133402.0230
      摘要:We demonstrate a fast, simple and scientific method to identify the Pu'er teas with different fermentation time by using surface-enhanced Raman scattering (SERS) technology at range of 600~1 800 cm-1.The results indicate that there exist many peaks at 655, 732, 959, 1 238 cm-1. The realationship between fermentation time and the content of tea polyphenol, nitrogenous compounds, organic acid and sugar material in Pu'er teas are discussed. This way can provide a fast, simple and scientific optical method to identify the Pu'er teas with different fermentation time.  
      关键词:Pu'er tea;surface enhanced Raman scattering;fermentation years;identification   
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    • Spectral Calibration of The Hyperspectral Optical Remote Sensor

      JIN Hui, JIANG Hui-lin, ZHENG Yu-quan, MA Hong-tao
      Vol. 34, Issue 2, Pages: 235-239(2013) DOI: 10.3788/fgxb20133402.0235
      摘要:Accurate calibration of hyperspectral optical remote sensing spectral performance parameters is the basic premise of the quantitative application of hyperspectral optical remote sensing data. Based a monochromatic collimated cursor titration hyperspectral optical remote sensor calibration of the spectral performance parameters, spectral performance parameters of high-spectral optical remote sensor calibration data were analyzed by the data acquisition software and data processing software. The analysis results show that the calibration test repeatability is less than 0.2 nm within 1 h, and less than 0.35 nm within 20 h. The spectral scaling results show that the average spectral resolution of hyperspectral optical remote sensor is 4.94 nm, and the spatial dimension of the high-spectral optical remote sensor spectral resolution is less than 5 nm, the average of the typical spectral bandwidth is about 6 nm.  
      关键词:hyperspectral;spectral performance parameters;spectral calibration   
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    • YANG Zhen-ling, FANG Wei, YANG Yan-qiang
      Vol. 34, Issue 2, Pages: 240-244(2013) DOI: 10.3788/fgxb20133402.0240
      摘要:Two-photon-excited fluorescence (TPEF) enhancement effect in CdSe quantum dot modified Au nanoparticle was theoretically investigated. TPEF enhancement factor was obtained in dipole approximation by taking surface plasmon resonance enhancement effect and nonradiative energy transfer to Au NP into account. An available method to achieve sufficient TPEF enhancement factor with noble metal nanoparticles was concluded from the analysis of numerical simulation. Greater TPEF enhancement effect will be obtained by adjusting the surface plasmon resonant peak of noble metal nanoparticles to the excitation wavelength. This theoretical analysis result was proved to be appropriate to the reported experimental results.  
      关键词:noble metal nanoparticles;surface plasmon;two-photon-excited fluorescence;energy transfer   
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    • ZHOU Jian-wei, LIANG Jing-qiu, LIANG Zhong-zhu, WANG Wei-biao
      Vol. 34, Issue 2, Pages: 245-250(2013) DOI: 10.3788/fgxb20133402.0245
      摘要:A novel variable optical attenuator (VOA) based on the photonic crystal (PC) cavity with liquid crystals is demonstrated. Two photonic crystal waveguides are connected by photonic crystal cavity. The point defect of photonic crystal cavity is filled with phenylacetylene liquid cyrstals. The output of optical attenuator is controlled by adjusting rotation angle of the liquid cyrstals orientation vector. The VOA properties are numerically investigated by using the finite difference time domain (FDTD) method and plane wave expansion method. Numerical simulation shows that the attenuator based the PC cavity can be changed by adjusting the applied field. Furthermore, the attenuator performs output of 3.40%~99.58% at the wavelength of 1.55 μm.  
      关键词:two-dimensional photonic crystals cavity;waveguide;finite difference time domain (FDTD) method;liquid cyrstals   
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