Stimulated Raman adiabatic passage (STIRAP) has been successfully extended to multilevel system. During the STIRAP process, the intermediate levels have notable population which is detrimental if these levels could decay to other levels through spontaneous emission. This paper proposes a novel method to reduce the intermediate level population during the STIRAP process. A complete population transfer can be achieved in this modified STIRAP even if the intermediate level decays to other levels.

We report experimentally the measured rate coefficients for the energy pooling (EP) collisions process Cs(5D)+Cs(5D)->Cs(6S)+Cs(nL=9D,11S,7F) in cesium densities of 10^(16)-10^(17) cm^(-3). The 5D state was populated via 8S->7P->5D spontaneous emission following two-step pumping 6S->6P_(3/2)->8S. Since the 5D->6P (3.0-3.6 microns) fluorescence could not be detected in this experiment, we carried out a relative measurement for the process 6P+5D->6S+7D. The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode laser beam, tuned to 6P_(3/2)->9S_(1/2) transition, which could be translated parallelly to the pump beam. The excited atom densities have been combined with the measured fluorescence ratios to yield EP rate coefficients. The average values for nL=9D,11S and 7F are 8.0+-4.0, 7.0+-3.5, and 9.3+-4.6 (in units of 10^(-10) cm3/s), respectively. Influence of the energy transfer process 11S+6S->7F+6S on the rate coefficients k_(11S) and k_(7F) is also discussed.

Intensity distribution of the partially coherent Bessel vortex beams focused by an aperture lens is investigated. It is found that the intensity distribution in the neighborhood of the geometrical focus is not only dependent on the topological charge and the radial frequency of the incident partially coherent Bessel vortex beam, but also on its coherence length. Based on this, the desired partially coherent vortex bottle beams can be obtained by choosing appropriate values of parameters. Because such bottle beams possess characteristics of low coherence and vortex, it may be used in microscopic particles guiding, trapping, and inducing rotation.

The comparatively large mode field single-mode photonic crystal fibers (PCFs) were fabricated, the lightwave from 600- to 1600-nm wavelength along this PCF could be transmitted in single mode. The manufacturing process technologies of the PCFs were exploited, and the drawing parameters of PCFs were also presented. The structure parameters on the single-mode performance of PCFs were theoretically studied, and in practice the design was proved. The measurements of cut-off wavelength and light intensity distribution showed that the PCF had comparatively wide single-mode operating wavelength range.

All-optical wavelength conversion of 10-Gb/s signal based on four-wave mixing is experimentally demonstrated in a 30-m-long dispersion-flattened microstructure fiber with small positive dispersion. For an average pump power of 26 dBm, the conversion efficiency was around -19.5 dB with the fluctuation less than +-1.4 dB, covering a conversion bandwidth of 20 nm. The eye diagram of the converted signal shows good eye opening.

A new approach to the simultaneous registration of multiple medical images is proposed using shared chain mutual information (SCMI) as the matching measure. The presented method applies SCMI to measure the shared information between the multiple images. Registration is achieved by adjusting the relative position of the floating image until the SCMI between all the images is maximized. Using this measure, we registered three and four simulated magnetic resonance imaging (MRI) images using downhill simplex optimization to search for the optimal transformation parameters. Accuracy and validity of the proposed method for multiple-image registration are testified by comparing the results with that of two-image registration. Furthermore, the performance of the proposed method is validated by registering the real ultrasonic image sequence.

A three-dimensional (3D) wavelet coder based on 3D significance tree splitting is proposed for hyperspectral image compression. 3D discrete wavelet transform (DWT) is applied to explore the spatial and spectral correlations. Then the 3D significance tree structure is constructed in 3D wavelet domain, and wavelet coefficients are encoded via 3D significance tree splitting. This proposed algorithm does not need to use ordered lists, moreover it has less complexity and requires lower fixed memory than 3D set partitioning in hierarchical trees (SPIHT) algorithm and 3D set partitioned embedded block (SPECK) algorithm. The numerical experiments on AVIRIS images show that the proposed algorithm outperforms 3D SPECK, and has a minor loss of performance compared with 3D SPIHT. This algorithm is suitable for simple hardware implementation and can be applied to progressive transmission.

Baseline algorithm, as a tool in wavefront sensing (WFS), incorporates the phase-diverse phase retrieval (PDPR) method with hybrid-unwrapping approach to ensure a unique pupil phase estimate with high WFS accuracy even in the case of high dynamic range aberration, as long as the pupil shape is of a convex set. However, for a complicated pupil, such as that in obstructed pupil optics, the said unwrapping approach would fail owing to the fake values at points located in obstructed areas of the pupil. Thus a modified unwrapping approach that can minimize the negative effects of the obstructed areas is proposed. Simulations have shown the validity of this unwrapping approach when it is embedded in Baseline algorithm.

Multisensor image fusion could improve system performances such as detection, tracking, and identification greatly. In this paper, a long distance target detection approach is presented based on multisensor image features fusion. This method extracts two different features from visual and infrared (IR) image sequences respectively to detect regions of motion information content. Temporal change feature is extracted from the visual image sequence using temporal decomposition based on wavelet, which reflects the dynamical content variation at a pixel at any time. And correlation features between local regions are extracted from IR image sequence to distinguish regions with potential moving targets. All these features are merged into a multi-dimensional space and the support vector machine is trained to select regions that have the potential target at each pixel location. The method is robust and feasible to detect long distance targets in clutter background scene.

An improved method of angle measurement is proposed based on a parallel plate interferometer. A position detection system is incorporated into a parallel plate interferometer in order to realize large deflection angle measurement. A reflecting mirror is introduced for increasing the measurement resolution. In experiments, a deflection angle of a measured target was measured within about 3 deg. with high accuracy. And as a phase modulating interferometer, it was used to measure a small angular displacement with a repeatability of 5.5*10^(-8) rad.

Efficient continuous-wave (CW) intracavity frequency doubling of a diode-end-pumped Nd:GdVO4 laser operating on 4F_(3/2)-4I_(9/2) transitions at 912 nm has been demonstrated. A symmetrical cavity with two laser rods is designed, which divides the pump power between the two laser rods, allowing for greater power scalability. An 18-mm-long BiBO crystal, cut for critical type I phase matching, is used for the intracavity frequency-doubled laser. A maximum output power of 6.2 W in the blue spectral range at 456 nm has been achieved with the pump power of 36 W. The beam quality M2 value is 2.5 in both horizontal and vertical directions. The ellipticity of the deep blue laser is 0.98, and the power stability is better than 3.2% at the maximum output power.

In order to explore a 56-J high energy, high frequency lamp-pumped pulsed Nd:YAG solid-state laser, the main factors influencing the higher laser output energy are analyzed, the relation between output power and input power and reflectivity is simulated theoretically, and the effective measures to improve the efficiencies of the laser are brought forward. As a result, pulse width is tunable between 0.1 and 10 ms, frequency between 1 and 1000 Hz. When the input electrical power is 12 kW, the laser can output maximum single pulse energy of 56 J and average power of 500 W with the beam quality of 16.5 mm.mrad, total electro-optic efficiency of 4.2%, and the in stability of +-2% output power. It is indicated that the parameters corresponds with the results of theoretical analysis and simulation.

Phase locking for two ytterbium-doped large-core fiber lasers has been demonstrated by using a self-imaging confocal resonator with a spatial filter. Steady high-contrast interference stripes are observed. The visibilities of coherent and incoherent stripes are 59% and 6%, respectively. The measured width of the central strip is in good agreement with the calculated result. For in-phase mode, the output power of the phase-locked fiber laser array is up to 113 W and corresponding slope efficiency is 38.5%.

A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 microns is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 microjoule and 2.36 kW, respectively.

Transitions of laser diode (LD) pumped Er^(3+)-Yb^(3+) co-doped glass laser are rather complicated. Considering energy transfer between Er^(3+) and Yb^(3+) ions, cross-relaxation, upconversion luminescence, and other transition processes, rate equations of quasi-three energy-level-system of the Er^(3+)-Yb^(3+) co-doped laser are presented. The output characteristics are also calculated and analyzed in detail. The results show that Er^(3+)-Yb^(3+) co-doped phosphate waveguide lasers with high slope efficiency and low threshold can be achieved.

Using two-step method InP epilayers were grown on GaAs(100) substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). X-ray diffraction (XRD) and room-temperature (RT) photoluminescence (PL) were employed to characterize the quality of InP epilayer. The best scheme of growing InP/GaAs(100) heterostructures was obtained by optimizing the initial low-temperature (LT) InP growth conditions, investigating the effects of thermal cycle annealing (TCA) and strained layer superlattice (SLS) on InP epilayers. Compared with annealing, 10-period Ga0.1In0.9P/InP SLS inserted into InP epilayers can improve the quality of epilayers dramatically, by this means, for 2.6-micron-thick heteroepitaxial InP, the full-widths at half-maximum (FWHMs) of XRD 'omega' and 'omega'-2'theta' scans are 219 and 203 arcsec, respectively, the RT PL spectrum shows the band edge transition of InP, the FWHM is 42 meV. In addition, the successful growth of InP/In0.53Ga0.47As MQWs on GaAs(100) substrates indicates the quality of device demand of InP/GaAs heterostructures.

A periodically poled magnesium oxide-doped lithium niobate (5 mol% MgO:PPLN) intracavity optical parametric oscillator (OPO) pumped by a diode-pumped Q-switched Nd:YLF laser operating at 1.047 microns is reported. A broad continuous tunable middle-infrared (mid-IR) spectrum of 2.69-4.07 microns is obtained by changing the crystal grating periods from 28.5 to 31.5 microns. When the diode pump power is 8 W, the intracavity OPO operating at a repetition rate of 10 kHz produces average output power of 0.42 W, corresponding to conversion efficiency of 5.2% from the laser diode pump to OPO idler output.

A self-organized thin film of a cyanine dye is fabricated by the spin-coating technique and is characterized by ultraviolet-visible spectroscopy, infrared (IR) spectroscopy, small-angle X-ray diffraction, ellipsometer, and atomic force microscopy (AFM). The nonlinear optical properties of the thin films are investigated by degenerate four wave mixing (DFWM) technique. The cyanine dye thin film sample exhibits high optical nonlinearities ('chi(3)=2.55*10^(-12) esu), and the mechanism is analyzed by the exciton coupling theory.

Many attempts have been made to standardize the calculation of whiteness. Whiteness formulas currently in use satisfactorily characterize the appearance of commercial whiteness. However, they have poor correlations with the observers' evaluations, and are often unsuccessful in assessing tinted white samples. A whiteness formula in the CIELAB uniform color space is developed in this paper. Several whiteness formulas are analyzed and compared. The experimental results show that the whiteness formula in the CIELAB uniform color space agrees well with the visual ranking, and it is superior to the CIE whiteness formula and the others in visual correlativity, uniformity and applicability.