Abstract:High-density CdS hollow nanospheres are successfully synthesized by a simple chemical vapor deposition technology.The crystal structure,compositional information,and morphological structure are characterized by X-ray diffraction(XRD),scanning electronic microscopy(SEM),transmission electronic microscopy(TEM),and energy-dispersive X-ray spectrometer(EDX).The results show that the as-prepared CdS hollow nanospheres have uniform size about 1-3 μm in diameter.The Kirkendall phenomenon is proposed fo...

Abstract:In this paper,theoretical analysis of two-dimensional photonic crystal ring resonator(2D PCRR) based add-drop filter(ADF) is presented for coarse wavelength division multiplexing(CWDM) system to drop a channel at 1511 nm using hexagonal rods that are positioned in the square lattice.The 2D finite difference time domain(2D FDTD) method and plane wave expansion(PWE) method are used for obtaining the filter response and band structure of the filter respectively.Close to 100 dropping and coupling ef.

Abstract:In order to improve the test accuracy of CCD,a new type of CCD device is proposed.Several columns(rows) of photoelectric diodes(PDs) are combined together,and staggered with the distance of H1=H/N,where H is the space between two adjacent PDs,and N is the number of columns(rows).The photoelectric signals are collected simultaneously by multi-channel A/D,and the accurate measurement result is obtained through appropriate signal processing.Without changing the size or space of PDs,more photographi...

Abstract:In this paper,we present a novel oil level monitoring sensor based on string tilted fiber Bragg grating(TFBG).The measurement range and sensitivity of oil level monitoring can be modulated via changing the length and number of string tilted fiber gratings.The transmission spectrum of string TFBGs immersed in oil changes obviously with the oil level variation.Experiments are conducted on three 2 cm-length serial TFBGs with the same tilted angle of 10o.A sensitivity of 3.28 dB/cm in the string TFB..

Abstract:The band structure of the confined states is calculated for Si/SiGe multi-quantum well infrared photodetector(M-QWIP).The influence of the Ge component in pseudosubstrate on the energy band structure of Si/Si0.54Ge0.46 multi-quantum wells(MQWs) is investigated.It is found that the high energy levels in the MQWs move up while the low energy levels move down as the Ge component in pseudosubstrate increases.The influence of the barrier width on the energy band structure of MQWs is also studied base...

Abstract:A new scheme for fabricating a kind of flexible semiconductor micro-laser is put forward.And the optical properties of this kind of flexible semiconductor laser are investigated by the finite difference time domain(FDTD) method.The results show that the light should be localized by photonic crystals(PCs),and the interaction between light and gain medium should be enhanced,while the mode of laser should be modulated.These results indicate that the PCs could control the spontaneous emission,and le...

Abstract:Based on digital signal processing theory,a novel method of designing optical notch filter is proposed for Mach-Zehnder interferometer with cascaded optical fiber rings coupled structure.The method is simple and effective,and it can be used to implement the designing of the optical notch filter which has arbitrary number of notch points in one free spectrum range(FSR).A design example of notch filter based on cascaded single-fiber-rings is given.On this basis,an improved cascaded double-fiber-ri...

Abstract:This paper presents a closed-form analysis of the synchronization phenomenon of the quantum cascade laser(QCL).The analysis has been made with considering higher order nonlinearity of the modal gain of the QCL.The frequency response characteristics of the synchronized QCL along with the stability of the locked state,the effect of nonlinearity on the lockband of the QCL and the amplitude limiting action of the locked QCL have been calculated.The analysis demonstrates the effect of higher order no...

Abstract:An accurate frequency response characterization method for photoreceivers with optical heterodyne technique is presented in this paper.The characterization is implemented with two single-mode tunable lasers operating near the wavelength of 1.55 μm.The errors introduced by extra fixtures as well as laser output fluctuations are considered and calibrated simultaneously.Compared with previous works,the proposed calibration procedures are more complete.Experimental results indicate that the signific...

Abstract:A hexagonal solid-core bismuth-oxide micro-structure fiber is developed to balance its dispersion and nonlinearity.This simulation and calculation results show that the bismuth-oxide photonic crystal fiber(Bi-PCF) has near zero dispersion around 1550 nm.Its dispersion slop in the communication wavelength range is also relatively flat.Moreover,both nonlinear coefficient and model field distribution are obtained.Compared with the experimental results by SiO2-PCF,it can be seen that the Bi-PCF show...

Abstract:We present a numerical gas phase reaction model for hydrogenated microcrystalline silicon(μc-Si:H) films from SiH4 and H2 gas mixtures with plasma enhanced chemical vapor deposition(PECVD).Under the typical μc-Si:H deposition conditions,the concentrations of the species in the plasma are calculated and the effects of silane fraction(SF=[SiH4]/[H2+SiH4]) are investigated.The results show that SiH3 is the key precursor for μc-Si:H films growth,and other neutral radicals,such as Si2H5,Si2H4 and SiH...

Abstract:The quasi-phase-matched(QPM) condition of broadband second harmonic generation(SHG) in Ti-diffused MgO:LiNbO3 waveguide is theoretically simulated.The results show that the center wavelength of broadband SHG dependent on the waveguide width is around 1550 nm and the bandwidth is 50 nm. 更多还原

Abstract:Using an adaptive split-step Fourier method,the coupled nonlinear Schrdinger equations have been numerically solved in this paper.The nonlinear propagation of an ultrashort optical pulse in the birefringent photonic crystal fibers is investigated numerically.It is found that the phenomenon of pulse trapping occurs when the incident pulse is deviating from the principal axis of the fiber with some angle.Owing to the birefringence effect,the incident pulse can be regarded as two orthogonal polari...

Abstract:After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerical analysis.The performance factors,such as net gain(NG),amplified spontaneous emissions(ASE) noise,double Rayleigh backscattering(DRB) noise,noise figure(NF) and optical signal noise ratio(OSNR),are discussed in depth.It can be found that the NGs of the three DRAs are almost equal.T...

Abstract:Channel estimation is a key technology in indoor wireless visible light communications(VLCs).Using the training sequence(TS),this paper investigates the channel estimation in indoor wireless visible light communications.Based on the propagation and signal modulation characteristics of visible light,a link model for the indoor wireless visible light communications is established.Using the model,three channel estimation methods,i.e.,the correlation method,the least square(LS) method and the minimu...

Abstract:Considering that the noises resulting from low modulation frequency are serious and cannot be totally eliminated by the classic filters,a novel infrared(IR) gas concentration detection system based on the least square fast transverse filtering(LS-FTF) self-adaptive modern filter structure is proposed.The principle,procedure and simulation on the LS-FTF algorithm are described.The system schematic diagram and key techniques are discussed.The procedures for the ARM7 processor,including LS-FTF and ..

Abstract:The characteristics of optical fiber are quite important for improving the performance of optical fiber communication and sensor systems.Based on the Mach-Zehnder interferometer,a new measuring method is proposed and the digital holograms between the single mode fibers(SMFs) and specialty double-cladding(DC) fibers are analyzed.The experimental results show that the fringe density can be changed under the conditions of coaxial and off-axial interferences.Therefore it can be used to analyze the o...

Abstract:The time-dependent formation of one-dimensional two-photon screening-photovoltaic(PV) grey spatial solitons under low-amplitude conditions is presented theoretically.The time-dependent propagation equation of two-photon screeningphotovoltaic solitons is obtained by the numerical method.The results indicate that as the time evolves,the intensity width of grey screening-photovoltaic spatial solitons decreases monotonously to a minimum value towards the steady state.The higher the ratio of soliton ...

Abstract:Under the circumstance of optical axis being in the incident plane,the evanescent wave of total reflection is studied when an extraordinary beam is incident from an isotropic medium upon a uniaxial crystal by using the general characteristics of uniaxial crystal and electromagnetic field.This paper presents the propagation directions of equiphase plane and the images of evanescent wave,and reveals that the equiamplitude plane and the equiphase plane are not in quadrature any more,and the phase d..

Abstract:In this letter a Monte Carlo(MC) algorithm is used to simulate the propagation of polarized light in double-layer turbid media and the 2-dimentional backscattered Stokes vectors and Mueller matrices are obtained.Relationships between backscattered Mueller matrix and optical properties,such as scattering,absorption and layered structure,are discussed in detail.Integrating the 2-dimentional Mueller matrix elements along radial and azimuthal directions,we obtain a reverse trend with respect to the ...

Abstract:Aiming at the problem in infrared image enhancement,a new method is given based on histogram.Using the gray characteristics of target,the upper-bound threshold is selected adaptively and the histogram is processed by the threshold.After choosing the gray transform function based on the gray level distribution of image,the gray transformation is done during histogram equalization.Finally,the enhanced image is obtained.Compared with histogram equalization(HE),histogram double equalization(HDE) and...

Abstract:The goal of Optoelectronics Letters is to rapidly report original, new and important results in the fields of photonics and optoelectronics in English,to advance the international academic exchanges. 更多还原