The three kinds of fiber amplifiers, which can be used to realize fiber amplification of L-band, were introduced, including their principles, properties and development.
In terms of SU(1,1) algebra, the relationship between energy and wave function of two-dimensional harmonic oscillator and two-dimensional hydrogen atom are discovered.
Reflecting beam expander has been used widely because of its special advantages. But the existing central shade makes an energy loss about 40% of the total energy during the process of expanding. A new method of beam expander, which using two different cone reflecting mirrors, is pointed out in this paper. And this method can be used to remove the energy loss introduced by the central shade. Other methods, based on the principles of this one have been analyzed too.
Based on previous stimulated Brillouin scattering (SBS) experiments, the effects oflength of sample cell, focal length and focusing location on SBS are researched. And the results are in agreement with the theoretical analysis.
This paper introduces a new power supply of preignition for pulse xenon lamp. A single IC TOPSwitch-Ⅱ is used for the main circuit. As compared with traditional power supply, it possesses advantages such as simplified circuit, few elements, stable output and small size.
The phase diagram of YVO4 system, including the binary diagram, the ternary diagram and the schematic phase diagram, etc, are investigated in this pape. From the contrasting result, it can be seen that the phase diagrams affect the crystal growth greatly. Analysis of the black phases which occurred in the procession of the crystal growth, indicates that the black phases are caused by V3+ volatilization, which is identical to the literatures.
A set of microscopic transmission and reflection spectrum system was set up, which can be use to measure the transmittance of individual cell precisely. With this system, we measured the transmittance of alga cell and leukemic leukocytes with and without medication. The results show that: 1) the absorbing peak of alga cell is consistent with that of chloroplast, from which it can be seen that chloroplast is the major organelle for absorbing energy of light;2) there is great difference between two kinds of leukocytes in their transmittance, which suggests that the cell was changed with medication. This is instructive on improvement of photosynthesis efficiency, cell identification and drug screening.
The steady-state expression of local diffuse reflectance from surface of biological tissue is deduced from diffusion theory. Computation result with two set of optical properties of typical colonic tissue is given and compared with the results of Monte Carlo simulation. It is shown that diffusion theory is a conditional approximation. By using a modified expression originated from diffusion theory, the diffuse reflectance is successfully fit with sound enough accuracy, which makes it applicable in deducing optical properties of biological tissues from diffuse reflectance measurements.
In this paper, dynamic properties of two atoms interacting with single-mode light field via intensity-dependent coupling are investigated, and the effects of the initial states and the coupling intensity between atom and atom on the dynamic properties are dicussed.
A mesoscopic coupled circuit will evolve to a squeezed state under the effect of external pulse source. We find that squeezing amplitude parameter is only dependent on the capacitance ratio. The magnetic-flux-leakage has some effect upon quantum fluctuation of charge and magnetic-flux for coupled circuit.
A numerical study of annealed proton exchanged (APE) waveguide in LiNbO3 crystal is presented using finite element methods (FEM) in this paper. Also given are the accurate numerical results of LiNbO3 waveguide corresponding to different annealling time.
The characteristics of propagation and polarization are given for high-birefringence fibers with single crystal as inner cladding in this article. According to the theory of optical waveguide, the dispersion equations and the cutoff characteristics are derived for ordinary light (o light) and extraordinary light (e light) under the condition of weakly guiding fibers. Simulating on computer, we can divide the characteristics plots into four areas: cutoff area, monomode single-polarization area, monomode double-polarization area and multimode area. In the monomode double-polarization area, the polarization mode dispersion characteristics are analyzed for the two polarization modes. The existent condition of monomode single-polarization area and monomode double-polarization area is also analysed. It is found that the geometrical and optical parameters (S and Rx, Ry) and the outer cladding index n3 have great influence on the divided four areas and their polarization properties. These results provide a theory foundation for the design of fiber-optifc polarizers ,and suggests a new type of optical fiber design using high-birefringence monomode fibers
Reflection spectrum and transmission experimental results of chirped fiber Bragg gratings fabricated with 142 mm-long phase masks and beam expansion technology are presented. One bandwidth in reflection spectrum is 0.56 nm and the other is 0.84 nm. From the results of eye diagram transmission we find the chirped fiber Bragg grating dispersion compensation up to 125 km of standard telecommunications fibers has been achieved.
In this paper experimental results on the pulse amplification using Yb doped fiber amplifier were given, gain over 26 dB was obtained on 18 m Yb-doped fiber, and the single mode LD laser at 1.053 μm was used as the injected signal modifying with repeat rate at 1 kHz and the pulses vary with 1 μs, 2 μs. 5 μs, 10 μs. The results of the relationship between the gain and the pump power and other relative relationship, show that the gain is sensitive about the pump power, the length of fiber, and also about the signal's power, and with small signal amplification, the output pulses have not been distorted this show the equipment can be used as the front end of the huge pulse energy laser.
The SNR caused by modulation instability (MI) in transmitter fibers is given. As input signal power P reaches a larger value, MI may degrade SNR. Corresponding to the maximum SNR, there are a suitable P and a transmitter length /. The modulation sidebands △λc is also studied. △λc increases fastly with P. To limit the MI effect to P, channel spacing AA must be bigger than △λc, but bigger P(>20 dBm) will caused the MI effect and make SNR worse.
Alkali-earth metal doped C60 thin film is produced by evaporating C60 powder together with Sn powder. We analyze the influence of doping on component, structure and conductivity of C60 thin film by measuring the SEM, UV optical absorption and resistivity change with temperature of the film. The results show that after doping the tiny drops forming the film stick out of the surface, and the size of the drops increases slightly. So the electron emission threshold value of the film will lower. The Sn atom doped form the impurity level in the forbidden band. So the electron absorption transition changed from directly to indirectly, and the electrical conductivity changed too from insulator to n-type semiconductor.
In this paper we discuss the methods of collecting a pulsed laser beam and describe a special system that we used in our experiments. The system includes CCD camera, image card, synchronous control circuit and PC. Using this system, we have obtained good experimental result
The DC drived electro-luminescent device has a multilayer structure of ITO/ MEMO-PPV: R6G/Alq3/Al. Where MEMO-PPV [poly (2-methyoxy-5-ethyloxy)-4-di- (2- methyoxy-5-octaoxy) -phenylone vinylene] is the emitting layer as well as hole-transport layer, which achieved by means of rotation coating method. Rhodamine (R6G) is doped organic thin film. Alq3(8-hydroxy quinoline aluminium) is electron-transport layer. The wavelength of the device is 550 nm, where emission color is yellow-green. We find that the concentration of R6G has highly effects on the emission color, and show that dye doped device ITO/MEMO-PPV: R6G/Alq3/Al is more durable than undoped device ITO/MEMO-PPV/Alq3/Al. Its maximum luminance is 3600 cd/m2 at 18 V, with external quantum efficiency is 3.2%.
It is presented in this paper a scanning and imaging system which consist of 1024-element MCT line short wavelength IRFPA with reading electrocircuit made in china. It is presented the composing of the imaging system and some key question of the imaging system during picture disposing: 1) nonuniformity correction;2) Correction of lines and rows. With same axial transmission optics and a 1-D equality angle scanner and 1024×1600 pixels per frame, the scan efficiency of the sensor is over 88% and the half periods of scanner is 5 seconds. A better IRFPA picture has been obtained by use of this imaging system.
The architecture of simulation testing platform for software development of CASCOM-1 was introduced in this paper. The study is focused on key implementation technology in simulation testing system, such as global synchronization and real-time network communication. The practical results show that the Platform technology is reliable and useful for modern micro-satellite software development and testing.
The fMRI study on the imaginary cold stimuli and real cold stimuli are reported. The similarity and difference of the brain's functional activities for the two situations have been found. Both imaginary cold stimuli and real cold stimuli are found to have excited the area SI, SII, left middle frontal gyrus and motor area of cerebrum. In addition, the imaginary cold stimuli can also excite the left interior frontal gyrus and cingulat gyrus which are not excited by real cold stimuli. However the real stimuli can also excite the right middle frontal gyrus.