Si-based optoelectronics is becoming a very active research area due to its potential applications for optical communications. One of the major goals of this study is to realize all-Si optoelectronic integrated circuit. We mainly reviewed the current developments of this exciting field in the recent years. The involved contents indude the design of direct bandgap Si-based low dimensional materials, fabrication of ordered Si-based nanocrystalline films and approach of stable and high-efficient Si-based light-emitting devices. Finally, we predicate the developed tendency of all-Si optoelectronic integrated technology in the near future.
Emerald is an excellent tunable laser crystal. The characteristics of emerald single crystal grown by the hydrothermal method and flux method as well as present situation of laser optics research had been summed up. By researching on the domatic hydrothermal emerald optical spectra and laser properties, the author concluded that the development direction of emerald laser is the lager size and the better quality crystal growth.
ISI2000NV is a system for both semispherical spectral reflectance and color difference measurement. It can gives color difference of objects based on semispherical spectral reflectance in visible and near infrared wave bands measured by its internal spectrometer. The principle and method of color difference computation were investigated in detail.
Optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy(OH-MR-VMS) is an absorption spectroscopic technique for selective detection of the molecular ions. The advantages of this technique with high sensitivity and high signal-to-noise ratio were discussed. The factors that affect the experimental results were analyzed and the process of signal optimization was also proposed.
By the reaction of water vapor with He+ and He* which were generated by hollow cathode discharge of helium, H3O+(H2O)n(n= 0-4) was produced. We studied the reactions of H3O+(H2O)n(n= 0-4) with methanol and ethanol in a flowing afterglow mass spectrometer. Various ionic products were identified. They were formed by proton-transfer, ligand switching . association and condensation reactions.
Laser-induced fluorencence excitation spectrum of B←X(l-0) transition of C2 anions producing from discharging with the CH4/Ar mixture under the supersonic jet was reported. The rotational spectrum was assigned, furthermore rotational constants of X and B states were determined. In addition, the lifetime measurement for the B(v = 1) state was carried out and the lifetime obtained is 80±1 ns.
The relaxation oscillation in solid-state laser with relaxation oscillation pumping was studied theoretically. The undulation of the laser photon density contains relaxation oscillation frequency itself and that of pumping. When those two frequencies are close, the oscillation will be resonated. Especially, when the decay rates of the two frequency oscillations are same, the resonation will be strengthened greatly. PD feedback can restrain the relaxation oscillation effectively.
The relation of the solid-state Nd:GdVO2 output power and pulse width with pump power variety, using different perrneation-ratio Q-switched crystal was studied. We obtained the optical-optical transform efficiency of 53%, and the smallest pulse width of 27.29 ns.
A simple model of temperature field was presented for the Ne-H2-CuBr laser discharge tube, and discharge tube with diaphragms. An analytical expression of the radial temperature distribution in the tube was given. The relation between radial temperature distribution and input power and thermal conductivity of the buffer gas has been described.
Based on analyzing the interaction of pumping photons and a nonlinear crystal with no center of symmetry, an explanation about the generation mechanism of spontaneous parametric down-conversion (SPDC) light field was put forward. Then state function of SPDC biphoton light field was derived and a probability explanation was given.
The simulation of quantum cryptography on classical computer was discussed. Methods to express the preparation and measurement of quantum states on current computer and the basic algorithms for simulating the quantum key distribution protocols were given. All the corresponding results of each protocol were presented and compared with the theoretic results. It was shown that the simulation results are completely tallied with theoretic ones.
The dipole squeezing of a A-type three-level atom interacting with a strong coherent field in a high-Q Kerr cavity is investigated. The effects of the Kerr medium, the field-atom coupling coefficient and the detuning on the atomic dipole squeezing are discussed by numerical calculation.
The influence of the coupling strength between two atoms on bunching and anti-bunching effects of photons in the system that two atoms with two levels are interacted with a single-mode light field was studied. Numerical simulation results show that the influence of atomics coupling on bunching and anti-buriching effects is non-linear. But we can get anti-bunching light field for proper atomic coupling strength. And the explanation for the mechanism of the influence was given.
The time evolution of linear entropy of atom-field coupling system, atom and field in the system of two two-level atoms inside a single-mode cavity with amplitude-damping under the condition of large detuning were investigated. The effects of the initial preparation of two atoms, the decay rate of cavity field and the mean photon number of field on all kinds of linear entropy were discussed. The results show that if both the two atoms are in their excited states or ground states, all the linear entropies equal to zero. But when the two atoms are in their coherent superposition state of excited state and ground state, the cavity dissipation will lead to the system to evolve into a mixed state, the linear entropy of atom and field exhibits periodic oscillations with damped amplitude.
Chua's circuit and its characteristics, as well as the circuit of realizing non-linearity resistance, are presented. Using Chua's circuit, a drive-response chaotic synchronization system is constructed, by means of imitation, it can be concluded that this synchronization system possesses a certainly stability, resisting-disturbance and so on. Based on its system and using imitation, the characteristic of chaos synchronization self-maintenance is put forward, and imitation results are presented, this discovery provides the foundation of putting chaos into practice application to secret communication.
The accustomed simulating method-shooting of Er-doped fiber source is improved on and optimized, moreover, the evaluation module of initial value is added on the basis of shooting. The improved arithmetic enhances astringency and astringent rate of the simulation with saturated accuracy, reduces the iteration time obviously. We also simulate the output characteristics of sources with different configurations versus the fiber length by using the improved shooting. The correlational conclusions accord with the experimental results.
Properties of some GaN and GaN:Mg films with different blue luminescence relative intensity were investigated by Rutherford backscattermg/channeling measurement, double crystal X-ray diffraction measurement, photoluminescence technique, respectively. The blue luminescence in unintentional doped GaN layers obvious relates with the crystalline quality of those films. The RBS/channeling Xmin and the FWHM of double crystal X-ray diffraction increase with the increase of the intensity ratio of the blue luminescence to the band edge emission. The blue luminescence is due to some defects in unintentional doped GaN films. The peak position of blue luminescence in unintentional doped GaN films do not shift and its intensity superlinear increases with the growth of excitation density. These results indicate that it is the transition from the free electron to acceptor levels. The peak energy of blue luminescence about 2.88 eV in GaN:Mg films increases about 25meV and its intensity linearly increases with the growth of excitation density.These results indicate that it is the transition of donor-acceptor pair in GaN:Mg films.The mechanism of the blue luminescence in unintentional doped GaN films is different from the blue luminescence about 2.9eV in GaN:Mg films.
Using the parabolic potential as confinement potential in quantum dot and using a finite difference method to discrete the Schrodinger-Poisson equations, an numerical self-consistent solution of three-dimension cube GaAs quantum dot is carried out based on spin-density-functional theory (SDFT). The electronic properties such as total ground state electronic energy, electron density are obtained, and a comparison with the electron density of the two-dimension square GaAs QD with same condition (electron number, spin, length) is hold.
Optical properties of YOCl:Eu3+ powders and EuCl3 solution embedded in nanoporous glass were investigated. In comparison with those in the normal micro-powder phosphor, emission spectra of Eu3+ in nano-YOCl:Eu3+ became much broader. Blueshift (7 nm) was observed in the lines due to 5D0→7F2 transition and Eu-O charge transfer excitation band. The ratio intensities of the 5D0→7F1 transition to the 5D0→7F2 transition of Eu3+ became larger and changed at different excitation wavelengths (254 nm and 393 nm). In comparison with those in the bulk EuCl3 solution, nano-EuCl3 solution had neither small size effects nor quantum confinement effects. Luminescence due to upper levels of Eu3+ in the nano-solution was enhanced. This approach also combines the advantages of nanoporous glass in offering good chemical shielding and mechanical support. The results obtained indicate that this approach likely may make a new kind of luminescent material.
Understanding of electrical performance for Si/Si bonding structure is of great importance for both study of interface and fabrication of micro-electronic elements. We firstly analyzed I-V performance for different Si/Si bonding structures, and then using SOS model made capacitance curve-fitting for n-Si/n-Si structure. Comparing theoretical curve with experimental data, we got shifting voltage VFB and interfacial states density Din. These results availed to study the interface of silicon bonding structure.
ano-scale α-phase nickel hydroxide electrode materials were fabricated by multi-ion substitution. XRD test indicates that the crystal is α-style and TEM shows that the particles are between 20 and 30 nanometers in size with an irregular shape. Optimum technological parameters are obtained through orthogonal test of the substitution quantities of A13+ ions , Zn2+ ions, categories of anions , surfactants and reaction temperature. By using the optimized technological parameters, electrode materials with electrochemical capacity of 316 mA·h/g are prepared.
A kind of module design method for software telemetry of micro-satellite is introduced in this paper. Compared with traditional hardware telemetry method, software telemetry can not only get correct parameters of satellite, but also reduce the power consumption, weight and size of satellite, shorten time to launch. It is very useful to the reliability of satellite.
The polarization change during transmission course was analyzed when the partially polarized light beam from an object passed CCD's optical system. A kind of specific case was calculated, and change ranges of polarization are given. Calculations show that polarization degree of partial polarized light beam presents certain distribution on the cross section of transmitted output beam from interface. Changes of polarization degree have not only relation to angle of incidence, but also location of point light source.