摘要:This paper reviews on the history and the development status for semiconductor lasers, meanwhile focuses on the high power semiconductor laser achievements acquired by Changchun Institute of Optics, Fine Mechanics and Physics(CIOMP) in recent years, especially at the aspects of high power semiconductor laser sources, vertical cavity surface emitting lasers(VCSEL) and novel laser chips.
摘要:A series of Yb3+-Tm3+ and Yb3+-Er3+ codoped NaYGdF4 upconversion luminescent nanoparticles were prepared via a facile modified solvothermal method. The phase (cubic or hexagonal), size and upconversion luminescence properties of the final products can be well controlled by adjusting Gd3+ content. The introduction of Gd3+ can effectively promote the hexagonal to cubic phase transformation and size reduction of NaYGdF4 nanocrystals. The upconversion emission intensity of NaYGdF4:Yb3+,Er3+/Tm3+can be improved by optimizing Gd3+ content. Meanwhile, the upconversion mechanism was discussed by studying the excitation power dependent visible emission intensity of Tm3+ and Er3+ in different wavelength regions.
摘要:Bi3+, Yb3+ co-doped Y2O3 down-conversion film has been prepared by the pulse laser deposition technique on Si(100) substrate with the way of metal-assisted wet etching. The average reflectance of the film has a minimum value of 5.28% in the visible region from 300 to 800 nm. Under 311 nm excitation, the film can emit 980 nm light which is in the best response range to crystalline silicon solar cells. Compared to the film without anti-reflection structure that we have done before, the film with anti-reflection structure has the higher PL intensity. With the increasing of the etching time, the emission intensities of Bi3+ and Yb3+ increase monotonically. The enhancing light conversion performance by using anti-reflection structure will provide a simple method to the light conversion films which can be used in enhancement of energy efficiency for crystalline Si solar cells.
关键词:solar cells;anti-reflection light trapping;down-conversion;Y2O3:Bi;Yb film;etching time
摘要:CdS/bentonite composites were prepared by using CdCl2 and thioacetamide as reactants. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR) and ultraviolet-visible spectra (UV-Vis). The effect of CdS/bentonite composites on photocatalysis degradation of organic dyes (such as rhodamine B and methylene blue) was investigated in detail. Under irradiation for 3 h, it was found that 80.6% (for rhodamine B) and 88.3% (for methylene blue) of degradation rates were achieved when the dye initial concentration was 20 mg/L. The performance of CdS/bentonite composites catalyst is superior to pure CdS or bentonite.
摘要:N-hexyl-4-[2-(3-phenyl-thiourea)-ethylamino]-naphthalimide (HTN), a naphthalimide derivative, was synthesized and its structure was determined by NMR and MS. The recognition of HTN for picric acid (PA) was investigated by fluorescence spectrum. The results show that the fluorescence intensity of HTN significantly reduces with the increasing of PA concentration in C2H5OH/H2O (2:1). For PA concentration from 1×10-6 mol·L-1 to 5×10-4 mol·L-1, the quenching rate, (I0-I)/I0, correlates linearly with [PA]0.5, and R2=0.995 5. Meanwhile, no obvious interference is observed in the presence of the benzene series such as aniline, benzaldehyd, trinitrotoluene, phenol, styrene, pyridine, p-toluenesulfonic acid, toluene, nitrobenzene and chlorobenzene, indicating HTN's excellent selectivity and high sensitivity for the detection of PA.
摘要:Hexagonal NaYF4:Yb/Er microcrystals were prepared by a facile trisodium citrate-assisted hydrothermal method. The microparticles were characterized by TEM, X-ray diffraction (XRD), and luminescent spectra. Intense green upconversion luminescence was observed under 980 nm excitation. By introducing Ca2+ dopants into the grain lattices, the upconversion luminescence intensity of NaYF4:Yb/Er microcrystal was improved significantly. The enhancement is proposed to originate from a modification of the crystal structure and an improvement in the crystallinity of NaYF4:Yb/Er microcrystals.
摘要:A terbium complex [Tb(3,5-pdc)(3,5-Hpdc)(H2O)(phen)]n (3,5-H2pdc=3,5-pyridinedicarboxylic acid, phen=1,10-phenanthroline) was synthesized by reacting terbium nitrate with 3,5-H2pdc and phen at hydrothermal condition. X-ray diffraction analysis of single crystal shows that the complex is crystallized in monoclinic system, C2/c space group. The cell parameters are as follows: a= 2.734 9(3) nm, b=1.099 48(12) nm, c=2.200 0(3) nm, β=132.147 3(12)°, α=γ= 90°, Z=8, V=4.904 8(10) nm3. One-dimensional chain structure is constructed by alternated connection between Tb3+ ions and 3,5-pyridinedicarboxylates for the complex. A three-dimensional coordination polymer is formed by the π…π stacking interaction between the phen ligands. The complex exhibits intense characteristic luminescence of Tb3+ ion under 352 nm excitation.
摘要:Graphene-like nanoflakes were synthesized on silicon substrates deposited with carbon dots and gold film by hot filament chemical vapor deposition. The structure, composition and photoluminescence (PL) properties of graphene-like nanoflakes were studied using scanning electron microscope, transmission electron microscope, micro-Raman spectroscope, Fourier transform infrared spectroscope, X-ray photoelectron spectroscope and Ramalog system, respectively. The results indicate that the introduction of carbon dots and gold changes the thickness and defects of graphene-like nanoflakes. Furthermore, they lead to the shift of PL bands and the change of PL intensity. According to the characterization results, the reason of PL shift in graphene-like nanoflakes was analyzed.
摘要:Hydroxyapatite particles doped with Tb3+ (Tb-HAP) were prepared via chemical deposition method. The crystalline phase, structural and fluorescent properties of the samples were investigated by X-ray diffraction (XRD), Fourier transform infarred (FT-IR) spectroscopy, and photoluminescence (PL) measurements, respectively. XRD and FT-IR results show that Tb3+ doping has no significant influence on the structure of HAP. PL spectra of Tb-HAP samples show that the best excitation light is 378 nm when the wavelength of the monitoring light is 545 nm. The luminescent intensity of Tb-HAP sample reaches the maximum when the doping mole fraction of Tb3+ is 8%. Furthermore, the fluorescent life of Tb-HAP samples present a decreasing trend along with the increasing of Tb3+ concentration.
摘要:Theoretical analyses of growing processes were made in the case of superluminesecnt diode with crescent structure by liquid phase epitaxy (LPE), which could perfectly explain some phenomena in experiments of LPE on curved InP surfaces. The results of numerical calculation were consistent with the experimental results. The epitaxy structure was optimized to enhance the output power and reduce the polarization of the SLD. As a result, polarization dependence as low as 2% and 3.6 mW output power were obtained at 100 mA and 25 ℃ heat-sink temperature, corresponding to 39 nm spectral width with spectral modulation of less than 0.17 dB.
摘要:The near-infrared detector of In0.82Ga0.18As with PIN structure was designed and simulated by APSYS. The long-wave cutoff wavelength was extended to 2.6 μm. Three doped layers were deposited on the absorption layer, which contained P type N type, N type and by growth order. The thickness and concentration of each doped layer in cap layer were analyzed. The results show that In0.82Ga0.18As, InAs0.6P0.4 and In0.82Al0.18As layers by growth order are determined to obtain the excellent performance. The relative spectral responsivity of the detector keeps almost the same, and dark current decreases by one magnitude compared with the PIN structure. The defect tunneling current predominates when the detector works at 120-250 K, the inter-band tunneling current dominates the dark current when the detector works at 250-300 K, and the G-R current and diffusion current dominates the dark current when the detector works above 300 K.
关键词:infrared detector;APSYS;cap layer;responsivity;dark current
摘要:A fluorescein derivative named fluorescein hydrizido 4-imidophenol (FHP) has been designed to build a molecular logic device. The device is composed of two parts: lock-part and calculate-part. In this derivative, fluorescein is reffered to as calculate-part owing to it was previously adopted to mimic calculator. And the rest portion of this derivative is reffered to as lock-part. The operational principle of this device is that if input combination is optimal, calculate-part fluorescein is released and ready for calculating; if not, calculate-part remains locked. It effectively improves the security of calculator simulated by molecular logic. In addition, lock-part will be totally destroyed like self-distruction under a special input combination, resulting in that calculate-part can not be unlocked at all events. Hence, it is more sufficient to make brute-force attack on this device unrealistic.
摘要:The characteristics of the low pressure direct current arc thermal spray plasma jet were analyzed by using optical emission spectra. The effects of different power levels, flow rates of H2 and detection distance on the electron number density of the thermal spray plasma jet were investigated. The electron number density of the plasma jet was determined using Δλ1/2 of Hβ (486.13 nm) line. At the same time, the degree of ionization was analyzed using Saha equation, and the effects of H2 flow rate and arc electric current on the degree of ionization were discussed. The results show that the electron number density and ionization degree of the plasma increase with the increasing of the input power, and the increasing of H2 flow rate can enhance the energy of the plasma jet, but has a little effect on the degree of ionization.
关键词:thermal spray plasma;emission spectroscopy;degree of ionization;electron number density
摘要:The lasing performances of Tm3+/Ho3+ co-doped tellurite microstructure fibers were reported. The microstructure fibers were fabricated by using a rod-in-tube method. Pumped by an Er3+ doped silica fiber laser operating at 1 560 nm, a continuous wave output power of ~8.34 mW at 2 065 nm was obtained from 22 cm long microstructure fiber. The slope efficiency of the microstructure fiber laser was 2.29% with an absorbed pump power of 507 mW. The results indicate that the Tm3+/Ho3+ doped tellurite microstructure fiber is a promising gain medium for constructing compact 2 μm fiber lasers.
摘要:In order to detect the defect on solar panels and improve the conversion efficiency, two neural network models were established between solar panels electroluminescence (EL) images and defect types, which can detect different types of defects on solar panels adaptively. Firstly, the dimensions of EL images training samples set were reduced by using principal component analysis (PCA). Then, EL images training samples set after dimension reduction was put into the neural networks for training. Finally, the testing samples set was simulated by the trained network through choosing the best parameters. Compared with BPNN, RBFNN has the advantages of global optimization characteristics and simple structure, which leads to the highest accuracy rate of 96.25% and shorter computational time. The experiment results show that RBFNN can meet the requirements of online detection.
摘要:The activated Ag electrode which was treated by electrochemical cyclic voltammetry to obtain surface enhancement Raman scattering (SERS) effect was used to investigate the self-assembled monolayers (SAMs) behavior of 2-mercaptobenzimidazole (MBI). The results show that SAMs of MBI are of ideal SERS effect on roughened Ag electrode and its SERS effect is related to concentration and pH. With the increasing of concentration, the SERS effect is strengthened firstly but weakened latterly because of its steric hindrance when it happens to the high concentration. As a result, the most effective enhancement is at 1×10-6 mol·L-1. On the other hand, the SERS effect of MBI in acid solution is better than in alkaline or neutral solution. It is further illustrated that MBI molecule has two different isomers and three kinds of existing forms, and all of them keep dynamic balance in solution. When the pH is lower than 2, MBI+, the main form of MBI molecule, is absorbed on roughened Ag electrode with coordinate bond between S: and Ag. MBI molecules stand vertically on Ag surface through π bond and produce relatively higher SERS effect. When the pH is higher than 2, thiol absorbed on Ag surface with S—Ag covalent bond and N—Ag coordinate bond is stronger than thione. This results in competitive absorption between thiol and thione of MBI, so SERS effect rapidly decreases from pH=2 to pH=3.7. As a result, thiol form of MBI lays aslant to Ag surface with S—Ag covalent bond and N—Ag coordinate bond, making the weaker SERS effect than thione.
摘要:A novel design of LED mixing color based on improved artificial fish swarm algorithm (AFSA) was proposed. In order to improve convergence rate and accuracy of AFSA, opposition-based reinforcement learning was utilized to optimize solution space of AFSA,Normal and Cauchy distribution function were employed as adaptive weight operators to optimize vision field and step-size. The white, amber and blue LEDs were chosen to design LED lamp samples. LED proportions of 4 000 K color temperature among those LEDs were optimized by AFSA and new AFSA in the Matlab. Simulations indicate that improved AFSA has the higher convergence rate and accuracy. After LED lamps were tested by integrating sphere, the results show that the difference between the actual value and simulation calculation value is tiny, and the improved AFSA is effective. The improved AFSA provides a new efficient method for the calculation of LED proportions. Compared with the traditional method, the new method not only saves a significant amount of time, but also achieves higher luminous efficacy for lamps. All these show that the new method is effective and has high practical value.
关键词:color mixing;artificial fish swarm algorithm;optimization
摘要:The optical fiber's base-mode transmission and energy loss under integrated thermal boundary conditions were analyzed by using a coupling equation set composed of an electromagnetic beam envelope equation and an energy equation. The impact of the temperature on the material's dielectric coefficient as well as the heat generation induced by energy loss during transmission were taken into account. As the fiber core's radius increases, the electric-field intensity and power dissipation density decrease and the propagation constant increases. Lower ambient temperature, higher convective heat transfer coefficient, and higher surface emissivity can lead to lower propagation constant, higher electric-field intensity, and higher power dissipation density. The changes in power dissipation density and electric-field intensity with the cross-section curvature are not linear and also influenced by other factors.