2003, 1(12) Column
Chinese Optics Letters 第1卷 第12期
It is reported that the wave-front aberration produced by atmosphere disturbance can be compensated with nonlinear optics phase conjugate technology. The distance of laser propagating in atmosphere is up to 1.27 km away. The result shows that SBS phase conjugating beam energy can be focus in a little area on target. And the biggest energy of phase conjugating beam on target is up to 142 mJ.
010.1300 atmospheric propagation 290.5900 scattering stimulated Brillouin A scheme for the generation of two-mode atomic laserDownload:635次
The quantum dynamic behavior of the system composed of V-type three-level atomic Bose-Einstein condensate (BEC) interacting with two-mode coherent light field has been studied. The results show that the atoms of V-type three-level atomic BEC, which are excited to higher-level states under the action of light field, still keep their properties of coherent states. It demonstrates theoretically that two-mode atomic laser may be prepared by V-type three-level atomic BEC.
140.1340 atomic gas lasers 270.3430 laser theory 020.5580 quantum electrodynamics A novel morphological filtering algorithm is proposed for suppressing speckle noise in images. The algorithm employs directional morphological close-open and open-close operations, then computing the membership of the filtered versions’ every pixel according to the designed fuzzy rule. The final filtered image is composed of all the pixels with corresponding maximal membership. The validity of the algorithm is demonstrated.
100.2980 image enhancement A new direction recognizing and subdividing method for moire (interference) fringes is presented. By setting two certain thresholds, counting errors caused by direct voltage excursion are avoided. Counting and direction recognizing are discussed in detail. Experimental results are given. The better adaptability and large subdivision number are the good quality of this method.
120.4120 moire' techniques 120.2650 fringe analysis 120.0120 instrumentation measurement and metrology Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor saturable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.
140.5680 rare earth and transition metal solid-state lasers 140.4050 mode-locked lasers 140.7090 ultrafast lasers 230.5590 quantum-well devices A passively Q-switched diode pumped Yb:YAG microchip laser with Cr^(4+):YAG saturable absorber mirror is reported. The TEM00 laser pulses are obtained with 1.7-μJ pulse energy, 15-ns pulse width, 0.11-kW peak power, and a repetition rate of 2.2 kHz at 1049 nm. The doped concentration and dimension of Yb:YAG microchip crystal are 10 at.-% and Ф5 × 0.6 mm^(2), respectively.
140.3540 lasers Q-switched 140.3480 lasers diode-pumped 140.3580 lasers solid-state New chemically stable Er^(3+)-Yb^(3+) co-doped phosphate glass for optical waveguide lasers and amplifiersDownload:537次
A set of phosphate glasses with different amounts of Al_(2)O_(3), Na_(2)O, La_(2)O_(3) and AlF_(3) contents were prepared to search for a phosphate glass which is suitable for ion-exchange process. Based on chemical durability test results and spectroscopic properties, a glass with excellent chemical durability and good spectroscopic properties is developed for ion-exchange process. The emission cross section of Er^(3+) in this glass is calculated to be 0.72×10^(-20) cm^(2) by McCumber theory. The planar waveguide with three modes at 632.8 nm and one mode at 1540 nm can be realized by 335 ℃ 3 hours ion-exchange in 5%AgNO_(3)+95%KNO_(3) molten salt.
160.5690 rare earth doped materials 300.6170 spectra 140.3500 lasers erbium Influence of OH groups on 1.5-μm emission of Yb^(3+)/Er^(3+) co-doped tungsten-tellurite glassesDownload:584次
The Yb^(3+)/Er^(3+) co-doped TeO_(2)-WO_(3)-ZnO glasses bubbling with different times were prepared. The infrared (IR) transmission spectra, emission spectra and fluorescence lifetime of Er^(3+) at 1.5μm were measured. The quench effects of OH groups on emission intensity of Er^(3+) at 1.5 μm as well as the relationships between fluorescence decay rate and OH group content were investigated. The constant k_(OH-Er), which represents the strength of the interactions between Er^(3+) ions and OH groups, is approximately 17.0×10^(-20) cm^(4)/s, and is comparable to that for Er^(3+) in Yb^(3+)/Er^(3+) co-doped phosphate glasses.
160.2750 glass and other amorphous materials 160.5690 rare earth doped materials 300.2140 emission 300.6250 spectroscopy condensed matter 160.4670 optical materials Coupling theory is employed to analyze coupling gain and a new optical system is proposed for image edge enhancement, in which the ordinarily discarded background light is recycled as a pump source to amplify the signal light. We demonstrate the principle of optical correlation and compare the discrimination capability of two kinds of correlators by computer simulation. The results show that edge enhancement preprocessing can improve discrimination capability effectively.
070.1170 analog optical signal processing 070.4340 nonlinear optical signal processing 070.4550 optical correlators The conversion efficiency of THG on the flattened Gaussian and Gaussian beams is obtained in detail numerical stimulation for CsLiB_(6)O_(10). The conversion efficiencies of 86.7% and 96% of the flattened Gaussian are larger than those of Gaussian beams of 72.6% and 88% under type I and type II(1) phase matching. The efficiencies affected by the pump intensity, polarization rate, crystal lengths and orders of the flattened Gaussian beams were presented.
190.2620 frequency conversion An optical parametric oscillator (OPO) based on periodically-poled lithium niobate (PPLN) and pumped by 1064.2-nm laser is demonstrated, which can be conveniently tuned by the means of changing its operating temperature. The parameters of the set-up and experimental results are introduced in this paper. We adjusted the operating temperature from 80 to 250 ℃, the output wavelength shifted from 1485.4 to 1540.7 nm. The average of the shifts is 0.33 nm/℃.
190.2620 frequency conversion 190.4970 parametric oscillators and amplifiers A reliable target-triggering plasma shutter was applied to second harmonic generation (SHG) of AgGaSe_(2) crystal with a TEA CO_(2) laser. Under normal air pressure, argon charged plasma shutter was triggered by focusing beam companying with a pair of adjustable metal targets. Conversion efficiency was enhanced by 3.3 times and the maximal efficiency 9.3%, with 1.4-mJ second harmonic energy was obtained. Finally, crystal damage was discussed together with previous work.
190.4400 nonlinear optics materials 190.7220 upconversion 320.5540 pulse shaping Thermal phase change and activation energy of crystallization of Ge-Sb-Te-Sn thin filmsDownload:512次
To improve the optical storage performance, Sn was doped into Ge_(2)Sb_(2)Te_(5) phase change thin films. The optical and thermal properties of Sn-doped Ge_(2)Sb_(2)Te_(5) film were investigated. The crystal structures of the as-sputtered and the annealed films were identified by the X-ray diffraction (XRD) method. The differential scanning calorimeter (DSC) method is used to get the crystallization temperature and crystallization energy (Ea). It was found that proper Sn-doping could highly improve storage performance of the Ge_(2)Sb_(2)Te_(5) media.
210.0210 optical data storage 210.4810 optical storage-recording materials Two-dimensional (2D) triangular void channel photonic crystals with different lattice constants stacked in two different directions were fabricated by using femtosecond laser micro-explosion in solid polymer material. Fundamental and higher-order stop gaps were observed both in the infrared transmission and reflection spectra. There is an approximately linear relationship between the gap position and the lattice constant. The suppression of the fundamental gap is as high as 70% for 24-layer structures stacked in the Γ-M direction.
230.4000 microstructure fabrication 160.5470 polymers 300.6340 spectroscopy infrared The line of sight (LOS) wind velocity can be determined from the incoherent Doppler lidar backscattering signals. Noise and interference in the measurement greatly degrade the inversion accuracy. In this paper, we apply the discrete wavelet denoising method by using biorthogonal wavelets and adopt a distancedependent thresholds algorithm to improve the accuracy of wind velocity measurement by incoherent Doppler lidar. The noisy simulation data are processed and compared with the true LOS wind velocity. The results are compared by the evaluation of both the standard deviation and correlation coefficient.The results suggest that wavelet denoising with distance-dependent thresholds can considerably reduce the noise and interfering turbulence for wind lidar measurement.
280.3640 lidar 280.3340 laser Doppler velocimetry 100.7410 wavelets 动态信息
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