最新刊期
卷 11 ， 期 2 ， 1990
- 摘要：The index of refraction of Eu3+ activated phosphor Sample can be evaluated from the emission spectrum of the phosphor by the following procedures.Let Ij be the integral intensity of the spectral line corresponding to the transition 5D0-7Fj-(j=0,1......6),vj-its wave number,Aj-the transitionprobability.109|58|2更新时间：2020-08-11
- 摘要：The channel waveguides with parabolic coupling horns(length of 1 cm and width of 4μm)were fabricated on semiconductor-doped glasses to get aperture match between the laser beam and the channel waveguide to decrease scattering loss of guided wave.The input photoresist grating couplers(period of 0.34μm)were made near the wider ends of parabolic-shaped horns.A top view of the device is shown in Fig.1.The fabrication processes of the sample used in this report weie as follows.1)Sputtering Al on the surface of semiconductor-doped glass;2)Spincoating Shipley AZ 1350 B photoresist on the Al thin film;3)4um width photoresist streak pattern mask with parabolic horns was produced on the Al thin film by means of standard photolithography;4)Except photoresist mask area,Al thin film was oxidized to become γ-Al2O3;5)Moving photoresist streak mask,Al surface of the Streak and both parabolic horns were exposed;6)The sample was immersed in phosphoric acid,then Al streak pattern with parabolic hoins was etched.As a result the streak pattern with parabolic horns was reproduced on the plane of semiconductor-doped glass,on the other hand,γ-Al2O3 was remained on the surface of glass as a thin film mask;7)Channel waveguide with parabolic coupling hoins of semicoductor-doped glass was fabricated with the aid of K+ ion exchange.8)Photoresist grating couplers were formed by writing holographic gratings in photoiesist.YAG laser pulses(with duration of 100 ps and frequency of 10 Hz)were coupled into the channel waveguide by grating coupler.The experimental Set-up is shown in Fig.2.The relation between output and input energy is shown in Fig.3.When YAG laser beam leached to channel waveguide through the coupling horn,the energy was obviously lost due to lower efficiency of grating nonlinear coupler and absorbing and scattering loss of the coupling horn.But the power density of guided wave entered the channel waveguide substantially grewn up to the two-dimension limitation of channel waveguide geometry.Power limit effect of device was mainly caused by both the dis-match of phase of input grating nonlinear coupling and the self-defocusing(n2<0)of channel waveguide.So the turning point of energy curve shown in Fig.2.might be shifted to lower threshold compared with planner waveguide.91|74|0更新时间：2020-08-11
- 摘要：There is considerable interest in luminescence of ZnSxSe1-x bluk crystals and epilayeis.P.K.Chatter jee et al.and M.Yamaguchi et al.observed a broad band(4700-4800Å)in photoluminescence(PL)spectra in Aland Na-doped ZnSe at 4.2K and in Li-or Na-doped ZnSe at 90K,respectively,They attributed this band to D-A pair recombination and free to bound recombination,respectively.In this paper we leport that a broad band A was observed in PL spectra in vacuum heated VPE ZnSxSe1-x epilayers at LNT.The origin of the band A is discussed.VPE ZnSxSe1-x.epilayers used in this work were grown on(100)GaAs substrate with VPE method.Specimen was excited by 500W Hg arc lamp,PL spectra were measured using a grating spectromator of Model 44W with C31034 cooled photomultiplier.105|43|0更新时间：2020-08-11
- 摘要：Fluorescence feature of Ce3+ and Tb3+ in LnBO3 and the energy transfer mechanism from Ce3+ to Tb3+ in borate have been systematically investigated.The quenching concentration of Ce3+ in borate can be very heavy,for example at 0.1 mol and above in LaBO3.The green emission intensity of Tb3+ is best when the concentration of Ce3+ and Tb3+ reaches 0.1 mol in LaBO3.The sensitization process of Tb3+ ions by Ce3+ ions in LnBO3 is mainly energy transfer from Ce3+ ions to Tb3+ ions(5D3 and 5D4)with nonradiative resonance process.Electrons at 5D3 level transit into 5D4 level of Tb3+ ion by cross relaxation.Thus the green emission(5D4-7F7,544nm)intensity of Tb3+ reaches the maximum when the concentration of Tb3+ is at 0.1mol.In the case of heavy doping the blue emission(5D3-7F7)can not be seen.With surveying the fluorescence decay of Ce3+ in borate doped with different concentration of Tb3+,it is found that the experimental results accord well with theoretical values.The mechanism of nonradiative resonance energy transfer is found to be dipole-dipole interaction.The critical transfer distance R0 is approximately 7.7Åand 6.5Åin LaBO3 and GdBO3 respectively.The probability and efficiency of the energy transfer have also been calculated.The efficiency of the energy transfer from Ce3+ to Tb3+ might leach 90% and above in LaBO3 when the concentration of Ce3+ and Tb3+ is at 0.1 mol.Further research has indicated that energy diffuse within the sensitizer(Ce3+)affects the energy transfer process from Ce3+ ions to Tb3+ ions.98|62|1更新时间：2020-08-11
- 摘要：The absorption spectrum,fluorescence spectrum and fluorescence lifetime measurements at room temperature were reported.The energy levels,crystal field strength parameter Dq,and Racah parameters were calculated approximately and finally,some SpectroScopic data which are important for laser performances were estimated.It is shown that the crystal of Cr3+:YAB is a potential tunable laser material.129|23|0更新时间：2020-08-11
- 摘要：Green-function formalism for anisotropic surface optics is developed by translating and reversing Maxwell equations.The approach is to formulate the field directly in terms of s-and p-polarized waves,so that the effects of interfaces can be calculated by introducing the Fresnell reflection and transmission coefficients naturally.As an application the field generated by a source in presence of interfaces and thin films is calculated.118|63|0更新时间：2020-08-11
- 摘要：The fluorescence spectra and absoiption spectra of Cr3+ in GGG(Ca,Mg,Zr)were analysed.The 4T2g-2Eg seperation ΔE≈70cm-1 and the crystal field strength of Dq/B=2.50 were obtained.Finally,the energy level structure of Cr3+ in GGG(Ca,Mg,Zr)has been explained theoretically.108|32|0更新时间：2020-08-11
- 摘要：Sr9Ca(PO4)6Cl2:Eu2+ is a lamp phosphor with high efficiency.Its single crystals have been grown by programed cooling of flux.From the crystal structure determination and spectioscopic study,it has been found that there exist two luminescent centers in this crystal,namely Eu(Ⅰ)and Eu(Ⅱ).111|48|4更新时间：2020-08-11
- 摘要：In seeking for semiconductor lasers with simple fabrication process and good performance,plenty of lager structures has been developed to realize the current confinement in lateral direction.As an effective way for this purpose,it was considered to form a current blocking layer inside the heterostructure and then allow the current to flow within a narrow path,as in the case of VSIS laser.In VSIS laser,two-Step epitaxial growth and photolithography and V-groovc etching on the epitaxial wafer are inevitable.Recently,we designed a laser with new structure,the terraced substrate inner stripe laser(TSIS).The TSIS laser has a simple fabrication process.It is fabricated by one-step liquid phase epitaxy without mask deposition and Zn diffusion.However,this TSIS laser needs a precise control of melt saturation and growth time of the current confinement layer.To make the laser fabrication process even simpler,a new structure laser with a narrow mesa substrate is developed(Fig.1).This new narrow mesa substrate inner stripe laser(NMSIS)is fabricated by simillar techniques to TSIS laser,using one-step liquid phase epitaxy without mask deposition and Zn diffusion.After a narrow trapezoidal mesa is etched on the substrate,making use of the properties of liquid phase epitaxy over a non-planar substrate,the growth of all layers including GaAlAs current confinement layer is accomplished by one-step liquid phase epitaxy.In growing the current confinement layer(first one),because the growth melt is effectively undersatu-rated for convex areas and the lateral diffusion is induced by local Solute concentration gradient between convex areas and concave ones,the shoulder of the mesa is melt-etched,the region on the mesa is just saturated,and at the same time the epitaxy layer is formed on the areas beyond the mesa part.By using this technique of crystal growth,the inner stripe for current channel is as narrow as 3 to 5um on the meSa.The confinement layer could be contiolled as thick as desirable.It's over 1μm in our experiment,which is enough to prevent the current leakage outside current channel.Apart from the very simple fabrication process of this structure,there are some other advantages.The spontaneous absorption in confinement layer instead of GaAs is reduced.Primarily,the lasers stimulate with threshold current of 80~120mA and the wavelength of 7800-8100Å.Since the NMSIS laser is narrow gain guide,the laser has linear power veisus current characteristics and fundamental mode operation with up to 3-4 times threshold current and over 25mW maxium power output.The relation of field distribution to the current path width has been studied.The far field patterns in single,double and triple peaks in fundamental lateral mode are found in different cunent channel width.111|46|0更新时间：2020-08-11
- 摘要：Fabrication technology and performances of 1.55um InGaAsP-InP LED's are reported in this paper.The coupled power of LED into a multimode fiber and a single mode fiber is 20-30μW and 2-4μW,respectively.The way to obtain the accurate p-n junction position is discussed.136|66|1更新时间：2020-08-11
- 摘要：The fluorescence decay time of rare earth materials is a very important parameter which characterizes the transition probability between energy levels,the interaction between host lattics and dopant and the energy transfer dynamics in co-doped phosphors,etc.To date many investigations have dealt with the excitation and emission of these solid materials;however,the decay time data are scare and discrepancies exist among published values.The purpose of the present work was to establish an easily available technique for measuring decay times ranging from tens of nanosecond to several milliseconds and to study the energy transfer phenomenon in some luminescent Systems.According to the excitation and emission characteristics of the particular tare eaith ion studied,samples were excited either by the 337 nm radiation of a nitrogen laser or the 532 nm output of a Nd:YAG laser;and the signals were received either by a photomultiplier for the visible fluorescence or a germanium diode for the near infrared emission.Attention was payed to using weak excitation and eliminating random scattering to avoid the interference in measurements.Our photomultiplier was specially wired for high gain,clean transient response by mounting the tube dhectly on a printed circuit board and a low impedance termination of 50 was used.Thus we have obtained the decay time of 68ns for Ce3+ in Ce:YAG and 42ns in Ce,Nd:YAG,in excellent agreement with the values measured on a SP-70 nanosecond spectrofluorimeter based on time-correlated single-photon counting technique.Shortening of the decay time of Ce3+ in double-doping system compared to that in single doping one cleaily indicates the energy transfer from Ce3+ to Nd3+ in Ce,Nd:YAG.Eu2+-doped phosphors studied are of high luminescent efficiency in the blue-green region.The broadness of the emission band indicates the interaction between host and activator which can be attributed to the presence of an excited electron in an outer shell of the Eu2+ ion.The transitions correspond to 4f-5d.The oscillation strength of these transition are orders-of magnitude higher than those for the normally weak and shielded 4f-4f transitions of Eu3+,Since the radiative probability of 4f level is low(103s-1)compared to that of 5d level(106s-1).The decay time Eu2+-doped(Sr,Ca)5(PO4)Cl:Eu2+,(Eu,Ba)Mg2 Al16O and SrAl2O4:Eu2+ is nearly 1 microsecond,and that of EuP6O14 is 4.3 milliseconds.Nd3+ doped in different tost lattices is one of the most powerful and widely used laser active materials.In the present study the decay times were measured for Nd:YAG,Nd,Ce:YAG,Nd,Cr:YAG and NdP5O14.We found that the 4F3/2 lifetime of Nd3+ in Ce and Cl co-doped Systems was not noticeably changed as compared to that in single doping system.Nd3+ has a shorter lifetime in NdP5O14 probably as a lesull of concentration quenching.212|90|3更新时间：2020-08-11
- 摘要：The luminescence of covalently linked "triad" compounds X-P-Y have been studied in DMF and benzene solutions.It is found that the attachment of sub-stituent X=CI,CH3O-as well as Y=phenyl(B)and nitrophenyl group(NB)has no detectable effect on both absorption and luminescencs spectra of the central porphyrin P,although a little solvent-dependent shift in their maximum frequency is observed.The substitutions,however,lead to a change in the luminescence intensity,particularly that of vibronic band.In these cases,the luminescence of Cl-attached P-B compounds is always more intense as compared with the rompounds with CH3O substituent as the X moiety.The replacement of phenyl substituent by nitrophenyl in Y moiety of compounds CH3O-P-Y leads to an enhancement of their luminescence,but the opposite trend is observed in the Cl-substitued compounds Cl-P-Y upon the same structural change in Y substituent.In both cases,the substitution of-NO2 at ortho position of phenyl ring of substituent Y shows again so-called "Ortho effeect" at we reported previously in compounds of nitroporphyrins.These pictures are the same in both polar and apolar solvents and seem to be understandable by a tentative assumption that the luminescence intensity of these compounds is regularly coorelated to the substitution-induced shift of eletron density in the electronic system of porphyrin macrocycle.Thus,it is believed that these findings reported here will offer some hint leading to improve our scientific knowledge for an ingenious design of artificial molecular system for utilization of solar energy with high efficiency.109|37|0更新时间：2020-08-11
- 摘要：The absorption and luminescence spectia of Chl C in solusion have been analyzed.The energy levels of molecular orbital,charge density and heteroplar bond of π-electrons have been calculated quantitatively for Chl C by approximate method of Huckel molecular orbital(HMO).The sensitized fluorescence between Chl C and O2 has been analyzed qualitatively.Since the absorption of biomolecules arises from electronic transition of co-jugated π-election,only π-electrons at the porphyrin frame are considered in the calculation of the energies of molecular orbits.130|137|0更新时间：2020-08-11
- 摘要：Emission at 445nm was generated by continuous-wave frequency-doubling in a annealed proton-exchanged Mg:LiNbO3 channel waveguide using a channeled twin-ridge substrate,three-segmented large optical cavity structure GaAlAs/GaAs laser(λ=890nm)as pumping source.The conversion efficiency is ~4×10-4.100|45|0更新时间：2020-08-11
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