最新刊期
卷 28 ， 期 4 ， 2007
- 摘要：In this paper we briefly review our research progress in the past twenty more years on the theory of rare-earth luminescence and spectroscopy,which can be enumerated as follows:1.On one-photon transition intensities:A.Extending the Judd-Ofelt 3-parameter formula to contain the effect of J-mixing caused by even-parity component of crystal field Hamiltonian.The extended formula still uses 3 parameters while introduces J-mixing coefficients which can be obtained from crystal-field splitting data of a few terms.B.Conforming the relative sign between the "dynamic term" and the "static term" contained in the Judd-Ofelt all-parameter formula is still negative by finding another sign error in the original paper.2.On two-photon processes intensities:Presenting a direct calculation scheme of intensities of this sort of processes by simulating energy-wavefunction structure of the intermediate configuration(4f)N-15d based on the(4f)N-1 energy-wavefunction deta of the left labour RE3+and the 5d deta of Ce3+.This scheme was used to Tm3+ compared to the Judd-Ofelt approximation with some discussion.3.On theory of phonon-assistant process of energy transfer(ET) between RE ions in solids:It is found that the coherent cancellations occurring in the HLO theory of one-phonon-assisted ET process only holds for diagonal process in which one phonon emits or absorbs from a definite electronic state of the donor or acceptor.For nondiagonal processes in which one phonon emits or absorbs accompanying the electronic electric-dipole transition at the donor or acceptor site,the coherence is enhanced that the most important is one-phonon but two-phonon assisted process.In addition,instead of Debye model used in HLO theory,the running lattice wave is introduced for the first time into the ET theory to describe the phonon involved in the above diagonal and nondiagonal processes.The formulae calculating transition rates etc of both the above processes based on the lattice wave model are given.And it is noticed that contrary to and out of the HLO theory,the contributions to the one-phonon nondiagonal process from optical phonons with wave-vector q=0 and corresponding to flat parts of dispersion curves are important.4.On theory of 4f-5d transition spectra:A simple model to calculate approximate term energies of the configuration(4f)N-15d and the 4f-5d transition intensities based on 3 energy parameters and the quantum numbers of the initial and the final states was presented and developed in the past few years.Therefore,the 4f-5d transition spectra can be analyzed and assigned by executing at the same time energy and intensity fitting.There has been successful examples of RE ions from(4f)3 to(4f)13 doped in a few hosts.5.On interaction between RE ions:The fine structure of zero phonon lines in the low temperature electronic absorption spectra of the elpasolite crystals(like Cs2NaLnCl6 etc.where Ln=Er,Yb) is interpreted by an effective spin hamiltonian model describing superexchange interaction between RE ions.关键词：luminescence of RE;spectra of RE;theory of luminescence190|305|5更新时间：2020-08-11
- 摘要：The first excitation energy and the mean number of phonon of the strong-coupling magetopolarons in the polyatomic semi-infinite polar crystals were studied through a linear-combination operator and unitary transformation.When the electron is approaching infinitely to the surface of crystals,the results show that when the magnetic field is strong,the first excitation energy of the magnetopolaron is only twice the Landau ground state energy,and the mean number of phonon is equal to the number of LO phonons and that of SO phonons that each one has coupling with the electron;and when the magnetic field is weak,the first excitation energy of the magnetopolaron is other four sections nothing the Landau ground state energy,and the mean number of phonon is equal to the contributions of LO phonons and that of different LO phonons that each one has coupling with the electron and magnetic field.When the electron is situated in the depth of crystals,the results show that when the magnetic field is strong,the first excitation energy of the magnetopolaron is equal to the twice Landau ground state energy and the double add energy of LO phonons that each one has coupling with the electron and magnetic field,and the mean number of phonon is only the contributions of LO phonons with its frequency and the magnetic field that each one has coupling with the electron;and when the magnetic field is weak,the first excitation energy of the magnetopolaron is other six sections nothing the Landau ground state energy,and the mean number of phonon is the double contributions of LO phonons and that of different LO phonons that each one has coupling with the electron.关键词：polyatomic polar crystals;magnetopolaron;strong-coupling;excitation energy;mean number of phonon100|112|0更新时间：2020-08-11
- 摘要：A great deal of work on study of polaron properties in semiconductor surface and interface was performed,since Ibach carried out low-energy electron diffraction experiments on ZnO and other semiconductor surface.Huybrechts proposed a linear combination operator method,by which the dependence of internal excited state properties of polaron on coupling strength was discussed.Kandmir et al.studied the properties of two-dimension magnetopolaron by using bound Landau state method.MuKhopadhyay et al.calculated polar correction of the first excited state of electron in parabolic quantum dot for different values of the electron-phonon coupling by using LLP method.Others also investigated the many relations between the properties of polaron and coupling strength.We discussed the dependence of the properties of optical polaron on coupling strength and magnetic field in this paper.The varied relation of ground state energy,and the first excited energy of optical polaron with coupling strength and magnetic field was derived by using the linear combination operator and unitary transformation methods.The numerical calculation indicates that the vibration frequency increase with increasing coupling parametert and magnetic field strength,because interaction between electron and crystal vibration falls and vibration increases with increasing coupling parameter and interaction between electron and magnetic field increases with increasing magnetic field strength.The numerical calculation also shows that the ground state energy and the first excited energy both increase with increasing coupling parameter and magnetic field strength,since interaction energy between electron and crystal vibration increase with increasing coupling parameter and interaction energy between electron and magnetic field increase with increasing magnetic field strength.关键词：optical polaron;magnetic field strength;coupling parameter99|159|0更新时间：2020-08-11
- 摘要：Based on quantum waveguide theory,the effect of impurities on the transmission probability and the persistent currents in mesoscopic structure is studied.It is found that the persistent currents not only depend on the sizes of the rings but also are influenced by the impurities.Moreover,the impurity potential may help the enhancement of current magnification and also can suppress the amplitude of persistent current.The persistent currents can be controlled by adjusting the impurity potential.关键词：quantum waveguide theory;mesoscopic structure;the function impurity;persistent currents88|119|2更新时间：2020-08-11
- 摘要：With the development of molecular beam expitaxy(MBE) technology and metal organic chemical vapor deposition(MOCVD) technology,there has been great interest in investigating quantum dot in both material science and condensed state physics field.Due to size of quantum dot was small,they had a series of new and serious character,for example,quantum size effect,quantum coherent effect,quantum tunnel effect,Coulomb resistance effect and surface effect,etc.,these had brought infinite chance and hope on development and use of new materials.The properties of the polaron in a quantum dot have been studied by many investigators theoretically and experimentally.In recent years,with the study of the properties of bound polaron in a quantum dot,people have paid more attention to them.The vibrational frequency,the average number of optical phonons and the interaction energy of bound polaron in a parabolic quantum dot have been discussed using the linear combination operator method by the present authors.However,the properties of excited state of bound polaron in a quantum dot have not been investigated by a linear combination operator method so far.The purpose of the present paper is to explore the effect of Coulomb bound potential on the properties of the bound polaron in a quantum dot.With the strong-coupling between the electron and bulk LO phonon included,we obtain an expression for the vibrational frequency,the first internal excited state energy,the excitation energy and the resonance frequency of the strong-coupling bound polaron in a quantum dot by using the linear combination operator method.The relation of these quantities with the effective confinement length of the quantum dot,the Coulomb bound potential and the electron-phonon coupling strength were discussed.Numerical calculations show that the vibrational frequency,the first internal excited state energy,the excitation energy and the resonance frequency of the strong-coupling bound polaron in a quantum dot will strongly increase with decreasing the effective confinement length of the quantum dot,and will increase with increasing the Coulomb bound potential and the electron-phonon coupling strength.关键词：quantum dot;strong-coupling bound polaron;linear combination operator;excited state92|115|0更新时间：2020-08-11
- 摘要：1,8-Naphthalimide derivatives are luminophore compounds that are widely used in various fields of science and technology and exhibit all the necessary optical characteristics for polymer materials.And they are readily available from a synthetic point of view.They have been used as fluorescent brightening agents and fluorescent dyes.Furthermore,in recent years many organic luminophores with highly p-conjugated systems on phenylacetylene-based moieties have been developed quickly.The elongated electronic pathways along p-extended conjugations in these molecules often present a bathochromic shift in the absorption and fluorescence spectra.Because of their intriguing electro-conductive,magnetic and optical properties,these compounds can be used as electrical conductors in LED displays,fluorescence sensors,lasers etc.Here,two new 4-phenylethynyl-1,8-Naphthalimide fluorescent compounds which phenylethynyl moietie is conjugated at the 4-position of the naphthalene ring are prepared through Pd(PPh3)2Cl2-catalyzed Sonogashira reaction from 4-bromo-1,8-naphthalimide in ethanol with CuI as co-catalyzer and Ph3P as ligand,and their UV/vis absorption and fluorescence emission spectral properties were studied using prepared solutions in DMF.The respective quantum yields were determined using quinine sulphate as the emission standard.Their electroluminescent characteristics were also determined as a dopped device.Reactions were carried out using 5% bis-[triphenylphosphine]palladium dichloride as catalyst and 5% CuI as co-catalyst in ethanol at reflux temperature with triethylamine as base.N-alkyl-4-bromo-1,8-naphthalimides were conveniently prepared by the condensation of 4-bromo-1,8-naphthalimides and primary alkyla-mine in ethanol with good yields.Their structures are characterized using IR,NMR and EA.The absorption-emission spectra and fluorescence quantum yields are determined and the relationships between molecular structure and fluorescence properties are studied.It is shown from the absorption and fluorescent spectra that the compounds present excellent fluorescence properties.The UV/vis absorption and fluorescence spectra of target product in DMF solution are presented.For compound N-butyl-4-phenylethynyl-1,8-naphthalimide,which were unsubstituted at the p-position on the phenylacetylene,the maximum absorption(λmax,FL) was in 374,but with a methyl at the p-position on the phenylacetylene,the λmax,UV was shift to 380 nm,which caused an obviously hypsochromic shift.For compound N-butyl-4-phenylethynyl-1,8-naphthalimide the maximum emission(λmax,FL) was in 446 nm,but with a methyl at the p-position on the phenylacetylene,the λmax,FL was shift to 462 nm,presented an obviously red shift.In addition,extending the conjugated chain caused a greater bathochromic effect on the absorption and emission maximum.4-Arylalkynyl-1,8-naphthalimides showed high fluorescence quantum yields.The fluorescence quantum yield ΦF was determined using absorption and fluorescence spectra of compounds in DMF at a concentration of 1×10-6 mol/L.Quinine sulphate,which has a quantum yield of 0.55,was used as the standard.From the result of the test,it can be seen that these compounds have quantum yields between 0.71~0.75.The electroluminescent properties of 4-phenylethynyl-1,8-naphthalimide compounds were also measured through the doped electroluminescent devices which contains 1% 1,8-naphthali-mides and 99% CBP(4,4′-N,N′-dicarbazole-biphenyl),and their maximum brightness is 2250 cd/m2 at 22.5 V and 1600 cd/m2 at 25 V,respectively.From the tested electroluminescent characteristics,it can be expected that 4-arylalkynyl-1,8-naphthalimides have potential applications as electroluminescent devices.关键词：1;8-naphthalimide;phenylethynyl;electroluminescence100|123|0更新时间：2020-08-11
- 摘要：Work function is an important information for understanding carrier injection in organic electroluminescence.We have made a novel instrument for the measurement of work function using contact potential difference method.The reference tip and sample are used to form a vibrating capacitor.By counting the current between the sample and a reference tip,we found the work function by fixing the zero point of the current.It is mainly composed of signal generator,power amplifier,and oscillator.Signal generator was the signal source of system,it generate sine signal.After magnified by power amplifier,signal was sent to oscillator which can make the reference oscillating.Current between the sample and a reference tip was sent to oscillograph for real-time monitor.At the same time,we apply complement voltage to the surface of sample.By adjusting the complement voltage,we can found the zero point of the current.The instrument can be used to measure the work function of metal,semiconductor and metal-oxide in ambient conditions.This instrument with high practicability and definition is handy to operate,and it can work in ambience.We have measured the work function of p-type silicon(Si) and the thin film of ITO which is used as the anode of organic light emitting devices(OLEDs).We have set up a relation between work function and time,which shows the change of work function with time.For confirm the practicability of the instrument,we have fabricated two white organic light emitting device with configuration:ITO/CuPc/NPB/TBAND:TPBe:DCJTB/Alq3/Al.We used UV-ITO(ITO treated by UV-Ozone) and ITO without UV for anode of devices.We obtain the current density(J)-voltage(V) character of the devices.It is clear that the performance of devices with UV-ITO is better as the result of the increased work function of ITO.It is useful for the optimization of the devices.关键词：work function;contact potential difference;ITO;organic eletroluminescence105|195|0更新时间：2020-08-11
- 摘要：To study the emission dynamics for the Ru(Ⅱ) complexes bond to DNA,and show the effects of the molecular structure of complexes on bonding to DNA,three kinds of Ru(Ⅱ) complexes [Ru(bpy)2(7-CH3-dppz)]2+,[Ru(bpy)2(7-F-dppz)]2+ and [Ru(phen)2(7-F-dppz)]2+,[bpy=2,2′-bipyridine,dppz=dipyrido[3,2-a:2′,3′-c]phenazine,phen=1,10-phenanthroline],have been synthesized.Their electronic absorption spectras and steady-state fluorescence spectra have been investigated.The electronic absorption spectra show that the wavelength of metal-to-ligand charge transfer(MLCT) peaks of the three kinds of Ru complexes are all at about 400 nm.Under the same power of photoexcitation at the wavelength of the MLCT peaks,the binding of [Ru(bpy)2(7-CH3-dppz)]2+ to calf thymus DNA has the strongest fluorescence,and [Ru(bpy)2(7-F-dppz)]2+ to calf thymus DNA has the feeblest one.On the base of the study for the absorption spectra and steady-state fluorescence spectra,the transient luminescence in three kinds of Ru(Ⅱ) complexes bond to DNA have been studied by using picosecond time resolved spectroscopy.The results show that the fluorescence decay for the Ru(Ⅱ) complexes bond to DNA exhibits as a biexponential form.Among the three kinds of Ru(Ⅱ) complexes,[Ru(bpy)2(7-CH3-dppz)]2+ bonds to DNA has the longest luminescence lifetime(about 382 ns and 108 ns),[Ru(bpy)2(7-F-dppz)]2+ bonds to DNA has the shortest lifetime(about 65 ns and 16 ns),and [Ru(phen)2(7-F-dppz)]2+ bonds to DNA has the lifetime(about 326 ns and 37 ns) shorter then [Ru(bpy)2(7-CH3-dppz)]2+ and longer then [Ru(bpy)2(7-F-dppz)]2+.The possible origin of the luminescence dynamics has been discussed.The luminescence is attribute to radiative decay from the MLCT excited state to the ground state.Through the interaction with the DNA,the radiativeless rate of the photoexcited Ru(Ⅱ) complex molecules is decreased,which results in the increase of luminescence lifetime and efficiency.The more stronger for the interaction,the more longer for the luminescence lifetime and higher for luminescence efficiency.The molecular structure of the Ru(Ⅱ) complex has an important impact on the interaction with DNA.关键词：Ru complex;DNA;transient luminescence;ultrafast spectroscopic technology110|115|3更新时间：2020-08-11
- 摘要：Since electroluminescence(EL) for an organic semiconductor was reported,Poly(phenylenevinylene)(PPV) derivates are the most promising materials for organic light-emitting diodes(OLEDs).To realize more brightness and luminescence efficiency,the strong electron-withdrawing CN groups were introduced to conjugated side chains because cyano group posses strong electron-deficiency and electron-transporting charac-teristics.Moreover,bigger side chains structures could reduce aggregation state in solid film,which is suitable to OLEDs.A new alternating copolymer DiCN-PPV containing bis(2-phenylacrylonitrile)-2,5-dibromo-1,4-phenylene) and 1-(heptyloxy)-4-(octyloxy)-2,5-divinylbenzene was successfully synthesized via Heck polymerization with moderate yields.Since Poly(phenylenevinylene)(PPV) posses strong electron-rich and hole-transporting characteristics and cyano group is obviously a electron-deficiency material,the donor-acceptor conjugated structures could change the energy band gap and light-emitting color.The polymer was cha-ractered by 1H-NMR,MS,element analysis and GPC.It possesses good thermal stability(Td=247℃) and is adequate for the fabrication processes of optical-electric devices.In the optimized polymerization reaction conditions,the polymer of DiCN-PPV(Mn=1.76×104,Pd=1.9,production rate 50%) was soluble in common organic solvents.The absorption spectrum of DiCN-PPV solution shows two absorption peak and that of film shows one absorption peak,which means a new energy level was formed after energy transfer between donor and acceptor units.Moreover,the onset of absorption edge is located at 623 nm in solid film,which is red shift by 80 nm than that in solution because more aggregation conformation were formed in solid state.Photoluminescence(PL) spectra coincide with above conclusion and the fluorescence peaks of DiCN-PPV in solution and solid film,were at 573 nm and 645 nm,respectively.Because of λmax FL=645 nm in solid film,it can be a potential red light-emitting material for fabrication of organic light-emitting diodes(OELD).关键词：PPV;cyano;synthesis;light-emitting diode113|98|1更新时间：2020-08-11
- 摘要：Luminescent conjugated polymers have been extensively studied due to their use as active materials in cheap and efficient light-emitting diodes(LED).However,despite the fact that many exciting progresses have been achieved,a lot of work is still needed to develop new polymers(or modified version of existing ones) that can emit red,green and blue light.Doping of the emission layers in LEDs with luminescent dyes can control the colour of emission as well as improve device efficiency.Porphyrins have potential applications in LED because of their pure red-light emission and optimized efficiency over all other fluorescent materials.However,there have been few reports about them used in LEDs.This is due to their propensity to π-π stack,which causes the material non-luminescent in the solid state.These problems can be overcome by incorporating porphyrin chromophores as the side-chain groups to control the porphyrin-porphyrin interactions in solid states.In this paper,the transient fluorescence dynamics of two porphyrin side-chain polyers,P[(por)A-S] and P[(por)FeA-S],were measured by using femtosecond time-resolved luminescence spectroscopy.Using nanosecond spectroscopic technology,we also measured the transient fluorescence dynamics of the monomer porphyrin molecules(TPP).The results show that all the transient luminescence decays are composed of two components:an initial fast decay(58 ps for P[(por)FeA-S],and 200 ps for P[(por)A-S]),and a following slowing relaxation processes(217 ps for P[(por)FeA-S],and 2.1 ns for P[(por)A-S]).The interchain and intrachain nonradiative exciton relaxation processes may play an important role in the luminescence dynamics in the porphyrin side-chain polymer films.The intermolecular interactions result in the faster fluorescence decay than that of TPP.The intramolecular charge transfer and the intermolecular interactions result in the ultrafast fluorescence decay in P[(por)FeA-S] compared with that of P[(por)A-S].关键词：porphyrin side-chain polymer;transient fluorescence dynamics;femtosecond laser technique113|117|0更新时间：2020-08-11
- 摘要：The possibility to obtain two blue photons under excitation of one VUV photon in NaGdF4:Tm3+,Dy3+ has been investigated by means of spectroscopic techniques,based on quantum cutting principle.In this compound visible quantum cutting is achieved through downconversion,i.e.,by making use of energy transfer between different lanthanide ions.Upon VUV excitation in the 4f105d levels of Tm3+,part of the energy is transferred directly from the Tm3+ 4f105d states to Gd3+.The cross-relaxation between Gd3+-Tm3+ is followed,and then the left energy is transferred from Gd3+ to Dy3+.Two visible photons are yielded:one from Tm3+ due to 1G4→3H6 transition,and one from Dy3+ due to 4F9/2→6H15/2 transition.In this paper,the possibility to obtain a new quantum cutting phosphor with higher efficiency,higher stability and higher VUV absorption based on NaGdF4:Tm3+,Dy3+ has been investigated.The spectroscopic techniques,including luminescent emission,excitation,decay,etc.were performed to characterize the donor Gd3+ ion-acceptor Dy3+ ion energy transfer preceded by energy migration among Gd3+ lattices in NaGdF4 doped with different concentrations of Dy3+ ions.It is shown by the results that the Gd3+-Dy3+ transfer preceded by energy migration among the Gd3+ ions is mainly governed by the exchange interaction.By the theory on excited state relaxation processes,which was developed by Burshtein et al.,the donor-acceptor energy transfer parameter kDA can be calculated from the 6P7/2 emission decay of Gd3+.The quantum efficiency of Gd3+-Dy3+ energy transfer was derived as well.Powders of NaGdF4:Tm3+(1.5%) and NaGdF4:Tm3+(1.5%),Dy3+(0.3%) were prepared by the hydrothermal technique,and NaGdF4:Dy3+(0.3%,0.6%,1%,3% and 5 %) by the method described in Ref.[4].The emission and excitation spectra were measured by home-made VUV spectrometer and F4500 monochromator.The decay curves were obtained under excitation of OPO laser.The quantum efficiencies for the Gd3+-Dy3+ energy transfer have an optimal value for acceptor concentrations at about NA=0.6% and concentration quenching can be observed obviously.关键词：NaGdF4：Tm3+;Dy3+;energy migration and transfer;cross relaxation;quantum efficiency121|52|0更新时间：2020-08-11
- 摘要：Tm3+-doped and Tm3+,Dy3+-codoped YP1-xVxO4 phosphors were synthesized by co-precipitation reaction.The X-ray powder diffraction,photoluminescence,photoluminescence excitation spectra and luminescence decay were measured.With increasing the amount of vanadate group,the excitation band shifts to the lower energy that satisfies the application demand for the LED phosphors.Tm3+and Dy3+ co-doped samples exhibited full color emission with various red-green-blue intensity rates.The chromaticity coordinates of YP1-xVxO4:Tm3+,Dy3+ phosphors were calculated.It was found that the chromaticity coordinates are dependent on both the ratios of P/V and Tm/Dy.This phosphor system with proper composition and dopants may be a promising phosphor candidate for white light emitting LED applications.关键词：luminescent materials;energy transfer;phosphor;chromaticity coordinates93|89|3更新时间：2020-08-11
- 摘要：Tetragonal tungsten-bronze-type strontium barium niobate(SBN) material is an attractive materials for many applications such as ferroelectric,pyroelectric,electro-optic,and photorefractive devices.A number of techniques for fabricating SBN ferroelectric films have been developed in the past years.Among these techniques,the pulsed laser deposition(PLD) technique is ideally suited to the epitaxial growth of SBN.The epitaxial Sr0.61Ba0.39Nb2O6 SBN61 thin films deposited on MgO(100) substrate have been prepared by pulsed laser deposition(PLD).The structural properties of the thin films were studied by X-ray diffraction.The θ~2θ scan pattern indicates single crystalline layers with the(001) orientation perpendicular to the substrate plane.The diffraction of SBN61(001),MgO(002) and SBN61(002) are identified,and no trace of other diffraction is observed.The films are thus with single phase with c-axis perpendicular to the substrate.The lattice constant of c=0.3923 nm was calculated,which is in good agreement with c=0.3935 nm for bulk SBN61.Optical studies by spectroscopic ellipsometry(SE) measurements were carried out,and their optical constants were determined.It is found that the refractive index of the SBN61 films is almost the same as that of SBN61 single bulk crystal.The birenfrigence shift as a function of applied voltage of SBN61 thin films on MgO(001) were measured.The SBN61 samples showed a quadratic response and quadratic electro-optic coefficient R has been derived to be 0.21×10-16(m/V)2 at 632.8 nm.关键词：SBN;electro-optic effect;optical constants116|80|0更新时间：2020-08-11
- 摘要：The achievement of Si-based white light emission is one of the challenging goals in the field of display and lighting technologies.Generally,there are two methods to produce white light from light-emitting diodes(LEDs):combining three LED chips(red,green,and blue) in one discrete package or as a cluster LED chips,and coating blue indium-gallium-nitride(In-GaN) LED chips with phosphors.In addition,fabricating multilayer devices using different materials that emit lights with different colors,based on the principle of tricolor(red,green,and blue) overlay,white light can also be obtained.ZnS films were deposited on porous silicon(PS) substrate by pulsed laser deposition(PLD),and the room-temperature photoluminescence spectra of ZnS films,PS and ZnS/PS composite system were measured.The results show that,after ZnS films were deposited,a blueshift of the red emission from PS layer occurs.Then the ZnS/PS sample was cut into three pieces,and annealed in vacuum at 400℃ for 10,20 and 30 min respectively.In the PL spectra of the three annealed samples,there appeared a new green emission band located at about 550 nm compared with the PL spectra of ZnS/PS composite system before annealing,which is ascribed to the defect-center emission of ZnS.With the increase of annealing time,the intensity of the red emission from PS layer decreases,and a redshift of the peak occurs,which is attributed to the optical band gap shrinking of a-Si:H as a function of hydrogen loss during annealing.Combining the blue,green emission from ZnS films with the red emission from PS layers,a broad PL band from 450 nm to 700 nm in the visible region is obtained,exhibiting intensively white light emission.This work offers a cheap route for fabricating a white LED,which is significant for display and lighting technology.关键词：photoluminescence;white light;annealing;ZnS films;porous silicon104|88|1更新时间：2020-08-11
- 摘要：There has been sustained interesting in the area of band-gap III-V compound semiconductors for 3~5 μm infrared device applications.InSb is an attractive material because of its potential use for large area detector arrays,high frequency devices and magnetoresistive sonsors for position sensing.Unfortunately,InSb itself cannot be used as a substrate due to its very large parallel conduction.Semi-insulating GaAs has been widely employed as the substrate for InSb growth,because of its electrical isolation,low-cost and mechanical strength.The main obstacle to acquiring high quality InSb comes from the large lattice mismatch of 14.6%,between InSb and GaAs,which is particularly detrimental to thin films.In the experiments,obtaining high quality InSb by two-step growth process had been reported in the high mismatch systems.In this study,all the InSb epitaxial thin films were grown on SI-GaAs by VG solid source MBE.Reflection high-energy electron diffraction(RHEED) was used for in-situ monitoring InSb surface morphology,the effect of the buffer on quality of heteroepitaxial InSb films was systematically studied.Including a serious of samples,a GaAs buffer was not required,as it shows no apparent improvement for the quality of InSb.Optimized of the low-temperature(LT) layer was performed at maintaining binary growth,which in the cases was 350℃,and the folllowing high-temperature(HT) growth at 450℃.The epitaxial thin films characterization was presented and analyzed,including surface morphology,interface inspection and crystalline quality by atomic force microscopy(AFM),transmission electron microscopy(TEM) and X-ray diffraction(XRD) etc.We also described the problem between the different thickness InSb epilayer and Hall-mobility.In conclusion,high quality InSb epilayers strongly depends on LT InSb buffer layer.The InSb films were grown directly onto semi-insulating GaAs substrate,for our typical InSb samples with optimized buffer layer,room temperature DCXRD FWHM of 172″ and mobility of 64300 cm2·V-1·s-1 at 77 K,were obtained.关键词：MBE;antimonide;surface morphology;TEM122|216|3更新时间：2020-08-11
- 摘要：The forward current-voltage characteristic and forward capacitance-voltage characteristic measurements are the most important methods to study the forward electrical characteristic of light-emitting diodes.These methods can be used to characterize the properties of light-emitting diodes.To further understand p-n junction characteristics of light-emitting diodes,a novel method for measuring p-n junction was proposed.A direct current electrical source was used to charge the junction capacitance of light-emitting diodes,and the voltage-time characteristics of light-emitting diode was measured when the direct current electrical source was switched off.If the changed voltage is lower than the threshold voltage of light-emitting diodes,the voltage-time characteristics of light-emitting diodes is like the general diodes.If the charged voltage of is higher than the carrier recombination and emitting light threshold voltage of light-emitting diode,firstly,there is a fast voltage drop down process on the moment of discharge.The end voltage of drop down process is lower than the threshold voltage of light-emitting diodes.If the charged voltage of light-emitting diode is higher,then the end voltage of drop down process is lower.Some new conclusions can be obtained by analysing the discharge phenomena of light-emitting diodes.In fact,the non-equilibrium carriers which infused into the diffusion layer will be recombined and result in the formation of current when the direct changed voltage was switched off.The voltage-time characteristics of light-emitting diodes that we measured and observed reflect the recombination and attenuation process of the non-equilibrium carriers.By the theoretical analysis,we conclude that the non-equilibrium carriers will be less when the direct charged voltage is higher than the threshold voltage.The reason of this phenomenon needs further research.关键词：light-emitting diode;fast drop course;voltage-time characteristic;junction capacitance106|122|0更新时间：2020-08-11
- 摘要：Ga1-xMnxAs thin films with a thickness of 200 nm and with various Mn mole concentrations(x=0,2.6%,4.2% and 6.3%) were grown on epi-ready semi-insulating GaAs(001) substrates by low temperature molecular beam epitaxy.The Curie temperature of samples,in the range of 30~50 K,was determined using a superconducting quantum interference device.For photo-modulated reflectance(PR) spectra measurements at room temperature,a halogen lamp dispersed by a monochromator was used as the light source.The He-Ne laser(632.8 nm) with a power of 1 mW was used as the modulation light and the chopper frequency was at 184 Hz.A Si detector was employed to collect the modulated signal.Franz-Keldysh oscillations(FKO) from epitaxial layers of the diluted magnetic semiconductor(Ga,Mn)As have been studied by PR at room temperature.The PR line shape is broadened with increasing Mn concentration but the critical points of E0 and E0+Δ0 are not shifted obviously.Based on FKO oscillation data,the calculated electric field of Ga1-xMnxAs is 21,45,77 and 160 kV/cm for x=0,2.6%,4.2% and 6.3%,respectively.It suggests that the surface electric field increases with the increase of Mn concentration up to 6.3%.In addition,Mn-related impurity state is observed,which is about 100 meV above the top of the valence band of the host GaAs.Based on depletion layer approximation,we solve the equations of semiconductor statistics together with Poisson’s equation for the relationship between the potential and charge concentration.The calculated hole concentration is about 1017 cm-3,which is two orders of magnitude less than the reported value due to the PR signal coming from the(Ga,Mn)As layer with a part of depletion of the delocalized holes,or a lower Curie temperature.Further work is needed to deplete all holes within the(Ga,Mn)As layer by applied external electric field.关键词：diluted magnetic semiconductor;PR spectra;Mn-related impurity energy109|101|0更新时间：2020-08-11
- 摘要：ZnO has attracted great attentions due to its stimulated emission and optically pumped laser behavior.Recent studies proved that the emission properties of ZnO films are dependent on the growth conditions and certain doping of other elements can improve the luminescence properties greatly.Therefore,suitable dopants and proper growth conditions are of great benefit to current research.In this report,V-doped ZnO thin films were investigated including their microstructures,photoluminescence properties and the effects of post-annealing.The undoped ZnO and 1%V-doped ZnO thin films were prepared on single crystalline Si(100) substrates by sol-gel spin coating method.The spin-coating process was repeated 8 times to increase the thickness of the films,with two-step rapid-annealing(300℃ for 300 s and 550℃ for 300 s) in air.A further annealing at 800℃(post-annealing) was performed after the 8th rapid-annealing.The structures,morphologies,and luminescence properties of the films were investigated by X-ray diffraction(XRD),scanning electronic microscopy patterns(SEM),and photoluminescence(PL).According to XRD pattern,no V-related phases were detected in the prepared samples.The crystalline quality of V-doped ZnO thin films was worse than that of undoped sample before post-annealing,in that the doping of V destroyed the structure of ZnO.Whereas,after post-annealing,the crystallinity of V-doped films became better and there appeared diffraction peaks of zinc silicate in the XRD pattern of V-doped films.We attribute the formation of high crystalline of zinc silicate to the catalytic effect of V.Scanning electronic microscopy patterns indicated all samples were compact and homogeneous thin films composed of uniform nano-particulates.The thickness of the films is about 300 nm.As to photoluminescence spectra,measurements of the V-doped samples without post-annealing showed that the intensities of the UV peak and green peak decreased greatly compared with those of pure ZnO films.Nonradiative recombination due to implantation induced damage is obviously dominating.After additional annealing at 800℃ for an hour,the optical quality can be well restored.Both the UV peak and green peak of the V-doped ZnO thin film increased while the former increased more.Moreover,the intensity of UV emission due to exciton recombination for V-doped ZnO films was obviously stronger than that of undoped ZnO thin films,while the intensity of the green peak was on the contrary.During post-annealing,doped V could fill part of defects of ZnO.The origin for the green emission could be attributed to the decrease of defects in the films.At the same time,the post-annealing decreased the quenching centers induced by V-dopant.As a result,the intensity of UV emission for the V-doped ZnO thin film was increased compared with undoped ZnO sample at the same conditions.95|105|1更新时间：2020-08-11
- 摘要：Morin is a bioactive plant flavonoid of immense importance as a potentially useful therapeutic drug.The interaction between morin and bovine hemoglobin(BHb) was investigated by UV/Vis absorption spectrum and fluorescence quenching spectroscopic methods.The experimental results showed that the fluorescence quenching of BHb by morin is a result of the formation of morin-BHb complex;static quenching was confirmed to result in the fluorescence quenching.The binding site number n(293 K:1.11;308 K:1.08),apparent binding constant KA(293 K:4.96 L·mol-1;308 K:4.64 L·mol-1) and corresponding thermodynamic parameters(ΔHΘ=-3.34 kJ·mol-1;ΔGΘ=-26.34 kJ·mol-1/-27.51 kJ·mol-1;ΔSΘ=78.50 J·mol-1·K-1) were measured at two temperatures.The process of binding morin molecule on BHb was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased.The binding distance r(r=4.13 nm) and energy-transfer efficiency E(E=0.10) between morin and BHb were obtained according to fluorescence resonance energy transfer.The hydrophobic and electrostatic interactions play a major role in stabilizing the complex.The interaction of morin with BHb does not obviously affect the conformation of tryptophan and tyrosine micro-region of BHb.Thus,the results provided a quantitative understanding of the binding of morin to BHb,which is important in understanding its effect as therapeutic agent in therapy.关键词：morin;BHb;fluorescence spectrum;thermodynamic parameters116|232|2更新时间：2020-08-11
- 摘要：Bilirubin is one of important endogenous fluorophores in human serums.Bilirubin,excited by some wavelengths of light,can emit fluorescence in the range of 500 to 600 nm.There are four forms of bilirubin in human serum;different bilirubin fractions have different physiological meaning and different fluorescent spectra.Investigation of bilirubin fluorescence in human serum will provide some theoretic basis and references for diagnosing some diseases by the autofluorescence of human serum.The fluorescence and absorption spectra of bilirubin solutions and mixed solutions of bilirubin and bovine serum albumin under normal physiological conditions,and the fluorescence spectra of normal human serum samples were measured and analyzed.The experimental results showed that different bilirubin solutions had different fluorescence and absorption spectra;serum albumin has a fluorescent enhancement effect on the fluorescence of bilirubin.BR+BSA mixed solutions aging for two days have different absorption and fluorescence spectra compared with BR+BSA mixed solutions.Moreover,it was educed that the fluorescent peaks located about 525 nm did not mainly derive from the contribution of bilirubin-albumin complex in human serum samples.In other words,the concentration of Bδ fraction in normal human serum may be very low.Human serum compositions are very complex.There are many endogenous fluorophores that can emit fluorescence in the range of 500 nm to 600 nm.In this experiment,the measured fluorescent peaks of serum samples may come from the contributions of other bilirubin fractions or β-carotene and riboflavin derivatives.The above conclusion was drawn based on some healthy serum samples.But in other cases,such as diseases of jaundice and hepatitis,Bδ fraction may demonstrate stronger fluorescence.As a result,its fluorescence should be observed.关键词：fluorescence spectrum;bilirubin;bovine serum albumin;human serum122|78|1更新时间：2020-08-11
- 摘要：Generally,silicon carbon nitride(SiCN) thin films have attracted much interest for a wide rang of applications due to their excellent thermal properties,large bonding energy and adjustable band gaps varying from UV to visible light range.Hydrogenated amorphous silicon nitride films(a-SiNx:H) were implanted by C+ ions with 30 keV and the doping dose of 2×1017 ions cm-2 at room temperature and then treated by annealing for 2 hours at 800,1000 and 1200℃,respectively.The composition and bonding structure of SiCN were analyzed by X-ray photoelectron spectroscopy(XPS),Raman spectroscopy and X-ray diffraction(XRD).The luminescent properties of SiCN have been studied by synchrotron radiation at RT and 20 K,respectively.XPS results showed that the C—Si,C=N and Si—N bonds existed in the films.When the films were annealed at 800℃ for 2 hours,two structures could be found at different depths.SiC and SiNx were found in the depth range of 50~100 nm,while the SiCxNy still existed at the depth of 250 nm.And the Raman spectrum of the SiCN film shows two peaks at approximately 1350 and 1600 cm-1,which corresponded to D and G bands of sp2-carbon.The presence of this pronounced Raman band indicates SiCxNy structure within the film.Furthermore,XRD indicated that the SiCN films annealed at 1200℃ consisted of the structures of α-Si3N4,β-Si3N4 and β-SiC.After SiCN was annealed at 800℃,four luminescent emission bands of SiCN under the excitation of 197 nm at 20 K were observed,which were located at 2.95,2.58,2.29 and 2.12 eV and were attributed to the emissions of SiNx,SiCxNy,SiC and SiOx respectively.However,after the film was annealed at 1200℃,for the modification of particle state and the improvement of film structures,the inten-sity of luminescence signals at 2.58 and 2.29 eV were different.The PL signature in SiCN films can be used to monitor the physical structure,and to point out their defect content.关键词：SiCN;C+ implantation;high-temperature annealing;X-ray photoelectron spectroscopy(XPS);photoluminescence(PL)98|72|0更新时间：2020-08-11
- 摘要：Some kinds of low-dimensional nanostructures can be formed by irradiation of laser on the SiGe alloy sample.Dots structure and lines structure on the Si1-xGex film were formed under a weaker irradiation of laser.Nano-strap pieces structure after digging up the Si1-xGex layer with a stronger laser.Porous structure on the substrate under anodizing and irradiating for 30 min,when the Si1-xGex layer is almost dug out;oxygen distribution on the porous structure is measured.We have studied the photoluminescence(PL) of the porous structure of SiGe where the PL intensity at 725 nm wavelength increases obviously.The effect of intensity-enhancing in the PL peaks cannot be explained within the quantum confinement alone.A new model of three-level system associated with the crystal-oxide interface state has been proposed for interpreting the PL peak at 725 nm wavelength:An injection photon excites an electron in the top of valence band to jump up into the bottom of the conduction band which is called to an absorption jumping process whose gap width increases because of the quantum confinement effect.It is a fast process for electron to jump from the valence band to the conduction band.Then the electrons are very rapidly caught into the interface state distributing in the region below the conduction band.These trap states have a certain distribution round the center state of 1.7 eV energy level.We think that the states distribution is probably related to the frequency distribution of the PL emission.Electrons in the interface state have long lifetimes,and population inversion between the top of the valence band and the interface state is thus possible from which we can explain the enhancing effect of the PL peak at 725 nm wavelength.关键词：porous SiGe;low-dimensional nanostructures;PL enhancement;interface states106|83|1更新时间：2020-08-11
- 摘要：Nanocrystals doped with optically active luminescence centers create new opportunities for luminescent study and application of nanoscale materials.ZnS is the most typical and important crystalline phosphor in both applications and basic science,and doping might change its properties,especially,the transition metallic ions co-activated ZnS nanoparticles form a new class of luminescent materials.The arrested chemical precipitation method is the most popular technique that is used in industrial applications because of its cheap raw materials,easy handing and large-scale production,many doped ZnS nano-particles were prepared by this method.In order to volume-produce homodisperse free-standing,with good surface,and high luminescent doped ZnS nanoparticles,polymer PVP was used as surfactant.Preparation produce was as follows:6.0 g PVP was dissolved in 70~80 mL ultrapure water(R≈18 MΩ),while the solution was stirred,10 mL of 1 mol·L-1 Zn(CH3COO)2·2H2O,and 1~7 mL of 0.1 mol·L-1 Mn(CH3COO)2·4H2O,0.1~2 mL of 0.1 mol·L-1 Pb(CH3COO)2·3H2O were then added.After stirring for 15 min,10 mL of 1 mol·L-1 Na2S·9H2O was injected,a suspension occurred immediately.After centrifuging and washing the particles twice with distilled water and once with ethanol.The nano-particles were dried in vacuum.All agents used are analytical pure and without further treatment.Nanocrystalline ZnS:Mn2+,Pb2+ have been prepared via the precipitation method at room temperature and under ambient conditions.X-ray diffraction analysis shows that the average crystalline particles size of samples is about 2~4 nm.TEM image shows the nanoparticles are homodisperse.By measurement of the fluorescence spectra,the excitation(λexc≈410 nm) and emission(λem≈510~560 nm) wavelength are both in visible-light range.A novel luminescent property has been observed in the photoluminescence(PL) spectra of the ZnS:Mn2+,Pb2+ nanocrystals.These nanocrystals can be doped with Mn2+ and Pb2+ during the synthesis without altering the X-ray diffraction pattern,however,the PL intensities of the co-doped samples vary with changing of the impurity mole ratios in the Mn2+ and Pb2+ co-doped samples,but the emission wavelength is not changed with the changing of the impurity mole ratios.The PL properties of the co-doped samples are dramatically different from those of Mn2+ and Pb2+ single doped ZnS nanorystals,and a probable explanation is presented also.All the results strongly reveal that co-doped ZnS nanocrystals form a new class of luminescent materials.关键词：photoluminescence;ZnS;nanocrystals;co-doped;semiconductor98|129|5更新时间：2020-08-11
- 摘要：Using the speciality of porous silicon,organic dye was impregnated into porous silicon in order to improve the luminescence of porous silicon and realize high luminescence efficiency on silicon basis.This problem had been researched,but the problem of energy transfer between porous silicon and organic dye was still under discussed.In this article,porous silicon was annealed diversely in vacuum and in atmosphere,then,C102 dyes were embedded into both PS samples.In this way,two different kinds of composite system of porous silicon embedded by C102 were obtained.By comparing the optical characteristic of these two kinds of composite system,it was found that the luminescence intensity of C102 embedded in PS was enhanced when porous silicon was annealed in atmosphere.By contrasting the FT-IR spectra of the two kinds of annealed porous silicon,it was found that the Si—H bonding was reduced and hanging-bonding was appeared in surface-state of porous silicon when porous silicon were annealed in vacuum.On the other hand,it was found that the surface-state of porous silicon was oxidized when porous silicon was annealed in atmosphere.The experimental results showed that the oxidized porous silicon could improve the luminescence efficiency of embedded films and improve the transparence of PS underlay.In terms of energy transfer between porous silicon and organic dyes,the oxidation of porous silicon’s surface-state could decrease nonradiation channels and hinder the energy transfer.Therefore,the optics characteristic of organic dyes embedded in porous silicon can be absolutely exposed.In this paper,it was realized luminescence of solid-state C102 and found that luminescence efficiency of these embedded films could be improved by changing surface-state of porous silicon.The results suggested that the porous silicon embedded C102 should be a better approach for realizing the blue-green photoluminescence on silicon basis.关键词：PS;PL;energy transfer;FT-IR spectrum;coumarin 102112|63|0更新时间：2020-08-11
- 摘要：The sp1-hybridized nano-crystalline white carbon films were fabricated by using microwave plasma chemical vapor deposition system filling mixture gas of H2/CH4.The titanium coated glass was used to be substrate.The structure characteristics of deposited films were analyzed by X-ray diffraction,Auger electron en-ergy spectroscopy,and scanning electron microscope.The XRD spectrum exhibits the typical signature of white carbon material.The presence of the peak at 2θ=21.68°(d=0.4107 nm),which corresponds to the(110) diffraction line of β modifications,is taken as one evidence for the existence of white carbon film.The lattice of white carbon material has a layered structure.Each layer is formed by short carbon chains,which result from the interconnecting sp-hybridized carbon atoms.More dangling bonds will exist in the material because of its such special crystal structure,and will lead to form new valence states,which was confirmed by using Auger electron spectroscopy.The characteristics of field electron emission of the film with area of 0.8 cm2 were measured in a base pressure of 10-5 Pa by using diode structure method.The deposited nano-crystalline white carbon films were used to be cathode,and ITO coated glass to be anode.The turn-on field of 2.5 V/μm and the current density of 200 μA/cm2 at electric field of 5 V/μm were obtained.The field electron emission from the white carbon film was so easy to be detected and had low turn-on field,probably due to the existence of the dangling bond states of the films.The growth mechanism of the white carbon films are also discussed.关键词：white carbon;nano-crystalline white carbon film;microwave plasma chemical vapor deposition(MPCVD);field electron emission110|110|0更新时间：2020-08-11
- 摘要：Microscopic imaging spectrum technology is very efficacious in nonuniform matter study.It integrates spectrum technology and imaging technology,identify and analyze the subject investigated through spectra and space.In this paper we apply the technology to petroleum logging.To the oily core,fluorescence analysis is universal.But current research methods have some shortages.Generally,synchronized fluorescence spectrum and three-dimensional fluorescence spectrum are able to quantitative measure the sample,by destroying its original structure feature.General fluorescence analysis and fluorescence microscopic imaging are observational measurements.The two methods identify the sample by eyes,so they have uncertainty and with low spectral resolution.Use the image spectrometer,we get the sample’s fluorescence spectral cube.Through further analysis,we also get the informations about fluorescence wavelength,intensity,position etc.Thus,we can study the hydrocarbon distribution and content by different aspect.In the same time,the rock core’s structure doesn’t be destroyed.As shown by the experiment results,it’s easy to identify fluorescence wavelength,intensity and distribution.This technology is objective comparing with fluorescence microscopic imaging.So it is sure that,facilitated sample treatment,perspicuous experiment procedure and abundant data are its ascendancies.关键词：imaging spectrum;fluorescence;oily core;spectral cube;logging97|95|2更新时间：2020-08-11
- 摘要：The so-called imaging spectrum,spectral intensity information obtained from a specimen is stored in a cube whose appellation signifies the two spatial dimensions of a flat sample(x and y) and the third dimension,the spectrum,representing the light intensity for every wavelength.By mathematical analysis of the spectral cube,it is possible to perform the function of spectral similarity mapping(SSM) which enables the demarcation of areas occupied by the same type material.Spectral similarity mapping constructs new images of the specimen,revealing areas with similar characteristics and enhancing minute features.In this paper,we use spectral similarity mapping to process the reflective spectral cube of true and false leaves.From the image after processing,we can discriminate the true leaves and the false leaves.So,spectral similarity mapping for optical camouflage screening has some advantages.We can analyze spectral information obtained from a specimen at the entire band although the spectra of the material we want to distinguish is unknown.And,we use spectral similarity mapping to process the transmitted spectral cube of Microcystis aeruginosa and Chlorella pyrenoidosa under the microscope.After spectral similarity mapping processing,we define the result which calculate with the absorption spectrum of Chlorella pyrenoidosa as the gray scale of Red,and define the result which calculate with the absorption spectrum of Microcystis aeruginosa as the gray scale of Green.From the image after processing above,we can differentiate between closely related colors even when the total intensity is similar and is thus more sensitive and specific.In summary,spectral similarity mapping expands the application of imaging spectrum,by using this method,imaging spectrum can be used in optical camouflage screening,species identification and counting,medical imaging recognition,remote sensing,etc.关键词：spectral similarity mapping(SSM);imaging spectrum;image processing96|61|0更新时间：2020-08-11
- 摘要：Diamond is one of the most important wide-band-gap semiconductor materials,and the study on the migration transport process of carriers in diamond can help to find out the potential application of diamond in different kinds of electronic devices and to know the material characteristics of diamond more clearly.The flight time of carriers in diamond under low electric field and low energy region is studied through Monte Carlo simulation method.The Monte Carlo simulation method is based on parabolic band model(i.e. nearly free electron approximation band model)and acoustic phonon scattering mechanism.The light absorption in diamond and Bragg reflection at the first Brillouin Zone boundary are considered in the simulation.The flight time distributions of holes in diamond under low electric field and low energy region are obtained through the Monte Carlo simulation,and compared with the reported experimental results.The simulation results are in agreement with the reported experimental results,which verifies the accuracy of the Monte Carlo simulation model.The simulation results shows that the acoustic phonon scattering mechanism is the dominant scattering mechanism in diamond under low electric field and low energy region.The simulation results also show that the relative simple parabolic band model can be considered when the migration transport process of carriers in diamond is studied,but the influence of light absorption in materials on the initial distributions of carriers should be considered when the migration transport process in thin sample is studied,moreover,the Bragg reflection of carriers at the first Brillouin Zone boundary should be considered when the intensity of electric field is relatively strong and the thickness of the sample is relatively large.关键词：Monte Carlo simulation;diamond;carrier;acoustic phonon scattering;light absorption;Bragg reflection97|65|0更新时间：2020-08-11
- 摘要：Polymeric optical waveguide has become the hotspot in recent years,it provide an alternative approach for realizing the next generation of optoelectronic integrated circuits because of a series of merits:(1)In comparison with the traditional material,polymer waveguides are easy to fabricate on almost any substrate of interest which reduces manufacturing costs and opens the possibility of single-chip integration with active components,such as lasers,modulators,and detectors;(2)The refractive indexes of polymer waveguide materials can be adjusted widely to address the compromise between coupling losses and bending losses;(3)Additionally,the thermo-optical coefficient of polymer materials can be greater than that of SiO2 and far more than an order of magnitude,while polymers’ thermal conductivities are a fraction of SiO2 and silicon’s.Polymeric Y-junction waveguide is the key component in fabricating polymeric electro-optic devices,such as intensity modulators,optical switches and so on.Single mode propagation is an important requirement for optical waveguide devices for use with single-mode fiber,it can reduce the coupling loss.In this paper,a technique is used for calculating the field distribution of the polymeric Y-junction rib waveguide.The technique is based on the combination of the effective index method(EIM) and the variational method(VM),it is mixed between the advantages of each method and avoided their disadvantages,where EIM can make the calculations procedures simple but it has some difficult to find the field distribution,other wise,VM can be used with very good accuracy to find the field distribution.An algorithm is implemented to study the effect of the structure parameters on the field distribution of the polymeric Y-junction rib waveguide.The obtained single mode rid waveguide structure parameters are:the core thickness is 1.5 μm,the rib height is 0.2 μm,and the rib width is 5 μm.关键词：polymer;Y-junction rib waveguide;variational method;effective index method113|200|1更新时间：2020-08-11
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