A new method is proposed for the measurement of imaginary part of refractive index n i of aerosol by using an optical particle counter (OPC) and a visibility meter (VM). The number density distribution of aerosol particle is measured by an OPC with nominal radii, and visibility is measured simultaneously with a VM. According to the Mie scattering theory, the different distributions can be obtained with different n i for the same set of data measured by OPC. Then, a curve of extinction coefficient can be calculated with n i from these distributions. Actual value of n i can be decided with the real extinction coefficient provided by visibility measurement. Finally, the actual number density distribution of aerosol particles is obtained from the OPC data and the decided ni.

Two novel schemes are proposed to form double well magnetic surface microtraps for cold atoms using double U shaped or double Z shaped current carrying wires. By changing the direction of current in a straight wire, a double U shaped wire trap will be changed into a double Z shaped wire trap. This study shows that the two double well magnetic microtraps can be continuously changed into a single well one by reducing the current in the straight wire from a suitable value into zero, and vice versa. The spatial distributions of magnetic fields from double U shaped and double Z shaped current-carrying wires layouts and their gradients and curvatures are calculated and analyzed. It is found that the maximum magnetic field gradient greater than 0.2 T/cm and the maximum field curvature (at each trap center) greater than 10 T/cm2 can be generated in our double well magnetic surface microtraps as I 1=I 2=0.2 A. Since there is a point of zero magnetic field at each trap center in the double U-shaped wire trap is only used to realize two-species MOT and to study cold collisions from two atomic samples and so on. The double Z-shaped wire trap cannot only be used to study the collisions of cold atoms, but also to realize and study two-species BEC or experimentally study the properties of double-well BEC and so on.

The mode symmetry can be obtained according to the symmetry of photonic crystal fiber. Optical field can be developed by using fundamental function with the same symmetry, the calculation will be simplified by using suitable spread function with same symmetry. The dispersion of hexagonal photonic crystal fiber is studied, and the fit polynomial functions are derived by which the parameter of structure can meet and the dispersion can be zero at 1.55 μm wavelength.

The characteristic of arrayed waveguide gratings is analyzed with the linear systems theory and the optical grating equation is educed. A new method for calculating the number of arrayed waveguide is proposed in consideration of reducing the crosstalk and gathering the radiating beam of light. This method is accurate and simple compared with the method given in Ref.[1]. The reason of causing the diffraction loss is analyzed, and the method to reduce the diffraction loss is introduced. As an example, 8×0.8 nm AWG multiplexer is designed with a center wavelength 1550 nm. The accuracy of this methods is proved by numeric model calculation.

Using Cole Hopf transformation, eigenvalue equations for guided modes in inhomogentous optical waveguides are transformed to Riccati equation, and rigorous analytic solutions for propagation constants and modal field distributions are deduced in a simple and convenient way. Formulas for square law index profile, symmetric Epstein profile, Epstein layer model of planar guides and for parabolic profile circular optical fibers are deduced.

An Er 3+ ,Yb 3+ codoped phosphate glass waveguide amplifier is reported, which is fabricated by Ag +,K + Na + ion exchange and the process is demonstrated. This 1.8 cm length channel glass waveguide amplifier produces a net gain of ～2.1 dB/cm at signal wavelength of 1.55 μm with input power of 110 mW at 980 nm.

A novel method is developed to design the gain flat multiwave pumped fiber Raman amplifier. This method uses reasonable simple algorithm to reduce computing time but no effect on system performance. It can give the result of optimal pump wavelength and power scheme at the condition of given parameters of signal bandwidth and pump number.

Based on the rate equations applicable to the erbium-doped fiber laser, a continuous erbium-doped fiber laser of ring cavity has been studied, and analytical expressions on threshold pump power, laser output power and slope efficiency under stationary condition have been derived. Variations of these basic parameters with the length of erbium-doped fiber have been analyzed by the analytic expressions and demonstrated by simulation, which will be help full to the optimization of designing a practical erbium-doped fiber ring laser. The experimental study on erbium-doped fiber laser pumped by 980 nm source has shown that the output characteristics were in good agreement with the theoretical calculations.

Intensity/phase transfer matrices are derived to characterize both cross phase modulation (XPM) and stimulated Raman Scattering (SRS) in IM DD optical fiber systems. Based on the calculation of intensity noise spectrum, comparative study of XPM and SRS induced crosstalk is performed analytically and numerically. Analysis reveals that SRS and XPM leads mainly to low frequency and high frequency noise, respectively; crosstalk from adjacent channels is mainly attributed to XPM while that from channels afar mainly attributed to SRS; and in single span transmission system, crosstalk noise power from XPM will in general exceeds that from SRS.

When applying phase-stepping interferometry to measure a surface, distortion will be caused as a result of various error factors especially the phase stepping error from the phase shifter. Even seriously flexuosity can be produced. Aiming at the main error sources to the phase stepping interferometry——the phase stepping error from the phase shifter, theoretical analyses was made for phase stepping algorithm by applying Fourier method. Based on the theory of characteristic polynomial, a new phase stepping algorithm, which is insensitive to disturbance and error, was put forward and improved. Experimental results show that the algorithm has effectively improved the measuring accuracy of the phase stepping interferometry, and made the measured results more approach the actual numerical value.

Through the analysis of the results obtained from inspecting actual surface of optical plane glass, the system theoretical error and methods to classify the type of surface shape in analysis of plane error with Zernike polynomials are studied in depth. A new theory and method are proposed by using error theory to appraise the precision of the laser digital system for inspecting surface of optical plane glass.

A resolution has been derived for time domain broadening of submarine pulse Laser for different range,water clarity or system parameters, which is validated by the new range gated means instead of the traditional ways.The experimental result is consistent with the theoretical calculation curve, which is useful for application research of submarine pulse laser.

The fluorescent emission spectra and radiative lifetime of Cr∶Nd∶GSGG crystal between -70 ℃ and +80 ℃ are measured and the peak stimulated emission cross sections at 1.061 μm for different temperature are calculated. A linear temperature dependence between -70 ℃ and +80 ℃ is given for the peak stimulated emission cross section of Nd 3+ ions and Cr 3+ ions co doped GSGG.

The order of magnitude of the cross relaxation propability between active ions and sensitive ions in Tb,Tm∶YVO 4 crystal and the cross relaxation among active ions in Tm∶YVO 4 are close with that of the non radiating transition probability and the radiant transition probability of higher level to lower level. The formula to estimate the laser threshold in the crystal including two sort codoped ions must take into account the cross relaxation among the ions. The estimated formula of the laser threshold including the probability of the cross relaxation among the ions is deduced from the transition rate equations and transmission equations of lasing and pumping light for end-pumped laser. The lasing performance of Tm∶YVO 4 and Tb,Tm∶YVO 4 at 1.5 μm and 1.9 μm wavelengths is discussed with these threshold equations, the action of Tb 3+ ions is also expounded. The results show that doping Tb 3+ ions in Tm∶YVO 4 increases intensity of lasing light and minifies the laser threshold at 1.9 μm wavelength.

Absorption spectra, emission spectra and fluorescence time of 2F 5/2 energy level of Yb 3+ with different Yb 3+ ions concentration Er 3+ /Yb 3+ codoped SiO 2 Al 2O 3-La 2O 3 glasses have been measured. The effect of Yb 3+ ions concentrations on the absorption characteristics of Yb 3+ , stimulated emission spectra characteristics of Er 3+ , and the energy transfer efficiency from Yb 3+ to Er 3+ have been discussed. The result show that the optimal range of Yb 3+ ions concentration in this glass are from 3.94 to 5.92×10 20 cm -3 . In the optimal range of Yb 3+ ions concentrations, the maxim absorption coefficient of Yb 3+ is 9.8 cm -1 , the highest stimulated cross section of Er 3+ and the energy transfer coefficient η from Yb 3+ to Er 3+ are 0.64 pm 2 and 92% respectively.

A numerical method for photon migration in heterogeneous bio tissue is derived and verified. The effects of heterogeneous diffusion coefficient on the fluence rate (reflectance and transmittance ) are investigated. The result shows that this effect cannot be neglected.

The principle of designing an electric field controlled 2×2 bypass exchange switch in the photorefractive LiNbO 3 crystal is discussed. By controlling the magnitude of the applied electric field, the readout beam can satisfy or deviate the Bragg condition, which makes the diffraction efficiency be 1 or 0, and thus realize the exchange or bypass operation of the switch. Fully regarded the piezoelectric effect, the electrooptic effect caused by the applied electric field and based on the equation of diffraction efficiency and Bragg condition, the of between the applied electric field, the writing beam ratio with respect to the writing angles are analyzed.

The electric field poling was used to achieve the periodic poling Z cut 1 mm KTiOPO 4 crystal (PPKTP). The grating period inverted was 9.0 μm and the interaction length was 3 mm in the crystal. By using a CW Nd∶YAG laser as a fundamental wave at 1.064 μm, input power in PPKTP of 900 mW, 22 μW green SHG at 0.532 μm was obtained at 32 ℃. The conversion efficiency of SHG was 0.0024%.

According to the theory of quasi-phase-matching (QPM), the periodical domain structure in gadolinium molybdate crystal for QPM second harmonic generation is designed. The designed domain period is 5.54 μm if the fundamental wavelength is 1.064 μm. The periodical domain structure is fabricated via poling the crystal with applied external pulse field. The switching time t c of the crystal is 500～600 μs when the external field is 2.5 kV/mm. The periodical domain structure has been obtained under the conditions that the voltage is 2.5 kV/mm and the duration of the applied pulse is 0.6～0.8t c. Using the periodically poled sample, harmonic wave of 0.532 μm has been achieved when the power of the fundamental Nd∶YAG laser is 7～10 W.

The diffraction aberration of focusing atom beam of metastable helium in laser standing wave is studied by using quantum mechanics. A quasi classical model accordance with the existing model under the particular condition is built. The time dependent evolution operator method with fast computational speed and convergence is put forward to perform the calculations. Under given parameters of laser power and diameter etc, the simulation resnlts show that atom beam of metastable helium has been focused with a FWHM of 54 nm and contrast of 16∶1, the focal length and focal depth related to velocity and energy of atom beam. The diffraction effect contribute to the limited width of focus mostly.

Expressions are derived for the correlation function and the spectral density of an atom laser driven by a colored noise and a white noise, with a correlation of the exponential form. The spectral density displays one, two or three peaks, depending on the correlation strength between noises. A possible way of measuring the spacing of interference pattern is suggested to demonstrate this multi peak feature in the experiment. Effects of the correlation time of noises on the spectral density also are discussed.

A new three dimensional electronic speckle pattern interferometry (ESPI) system is constructed by three ESPIs through a large shearing device and a PZT phase shifter used as reference. Independent dispelacement fields (i.e. field u, v and w) can be obtained through the system with phase shifting technique and image processing. This new technique includes three lasers as light source, a PZT phase shifter which can push reference plane to change optical path of reference light. A large shearing Wollaston prism is placed in front of CCD camera to make interference between object wave and reference wave. This system is used in measuring parts of diesel engine. Three dimensional displacement fields around the hole of the main axle are obtained.

Phase unwrapping is widely applied in a variety of fields including optical and microwave interferometry, adaptive optics, synthetic aperture radar and image processing. A phase unwrapping method is developed based on simulated annealing. The local behavior of the unwrapped phase is approximated by a plane. The parameters of the plane are optimized by simulated annealing. Computer simulation and experimental results make it clear that this method can effectively remove noise in phase map, unwrap the wrapped phase, and reconstruct the surface of the detected object.

A new type of electrooptic modulator using annealed proton exchanged (APE) planar lithium niobate waveguide is proposed. Two prism coupling method is used to implement the electrooptic modulation is proposed by changing the angle of the m lines before and after the voltage applied on the electrodes. This type of the modulator is easily fabricated and can be operated at more than 40 GHz bandwidth.

A variable optical attenuator (VOA) based on the internal reflection effect is proposed. This simple configuration makes use of an enlongated prism with SiO 2 thin film on both underside of it to realize polarization insensitivity and large range of dynamic attenuation. As a result, a sample VOA was obtained with an attenuation range above 20 dB and polarization dependent loss below 0.5 dB experimentally.