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Rabi oscillations express a phenomenon of periodic conversion between two wave states in a coupled system. The finding of Rabi oscillation has led to important applications in many different disciplines. Despite great progress, it is still unknown whether the Rabi oscillating state can be excited in the framework of the higherorder vector vortex regime. Here, we demonstrate in theory that the higher-order vector vortex light beams can be Rabi oscillating during evolution in an optical coupling system. This new classical oscillating state of light is characterized by a topologically shaped wavefront and coupled with spatially varying polarization. The vector vortex state exhibits a harmonic oscillatory property in the resonant and nonresonant conditions but differs greatly in Rabi oscillating frequencies. During Rabi oscillation, the complex state maintains its topology and intensity profile, while its intrinsic polarization pattern varies adiabatically in a periodic manner. We present an interpretation of the Rabi oscillation of the higher-order wave states in terms of the coupled-mode theory. Furthermore, we reveal a symmetry-protected transition between two Rabi oscillating modes, driven by a slowly varying phase mismatch. This Rabi transition has not been reported in either quantum mechanics or any other physical setting. This work advances the research of Rabi oscillation into the higher-order regime, and it may lead to novel applications in classical and quantum optics. [ABSTRACT FROM AUTHOR]

The rapid and accurate classification of bee pollen grains is still a challenge. The purpose of this paper is to develop a method which could directly classify bee pollen grains based on fluorescence spectra. Bee pollen grain samples of six species were excited by a 409-nm laser diode source, and their fluorescence images were acquired by a hyperspectral microscopy imaging (HMI) system. One hundred pixels in the region of interest were randomly selected from each single bee pollen species. The fluorescence spectral information in all the selected pixels was stored in an n-dimensional hyperspectral data set, where n = 37 for a total of 37 hyperspectral bands (465 to 645 nm). The hyperspectral data set was classified using a Fisher linear classifier. The performance of the Fisher linear classifier was measured by the leave-one-out cross-validation method, which yielded an overall accuracy of 89.2%. Finally, additional blinded samples were used to evaluate the established classification model, which demonstrated that bee pollen mixtures could be classified efficiently with the HMI system. [ABSTRACT FROM AUTHOR]

A diode-side-pumped actively Q-switched first-Stokes eye-safe laser with a Nd:YAP/YVO4 crystal is reported. Under the pump power of 250 W, a stable Raman laser at 1525 nm with an average output power of 4.5Wand pulse width of 60 ns at the pulse repetition frequency of 4.5 kHz is achieved. Another laser crystal Nd: YAG is used to carry out the contrast experiment. The output performances of these two lasers are measured and compared. The result reveals that the first-stokes Raman laser generated by the Nd:YAP/YVO4 crystal has a lower power threshold and higher Raman conversion efficiency because of the large value of the stimulated emission cross section and the fluorescence lifetime at 1342 nm of the Nd: YAP crystal. [ABSTRACT FROM AUTHOR]

The negative and positive thermal focal lengths for 1047 nm and 1053 nm were respectively demonstrated through analyzing different thermal lensing effects along the π- and σ-polarizations in a plane-parallel resonator. A compact and efficient diode-end-pumped 1053 nm Nd:YLF polarized laser is presented. As high as 11.2 W output power of the polarized 1053 nm laser has been obtained at an absorbed pump power of 22.3 W with an optical-optical efficiency of 50% and a slope efficiency of 53%. With the aid of a ray propagation matrix and a &lgr;=4 wave plate, different thermal lensing effects for the π- and σ-polarizations have been theoretically analyzed and experimentally verified. [ABSTRACT FROM AUTHOR]

In this paper, a diode-side-pumped acoustooptic Q-switched 1319-nm Nd:YAG laser is described. The output characteristics under the different repetition rates and output couplers have been studied. With a pumping power of 555 W, the average output power decreases from 94 W at 50 kHz to 71 W (slope efficiency 25.2%, optical conversion efficiency 12.8%) at 5 kHz. The highest peak power is up to 95 kW with the pulse duration of 150 as at the repetition rate of 5 kHz. [ABSTRACT FROM AUTHOR]

Abstract  We report a completely solid-state continuous-wave (CW) blue laser operating at 447 nm utilizing intracavity frequency tripling of an LD-side-pumped Nd:YAlO3 (Nd:YAP) laser operating at 1341.4 nm. An LBO crystal with type-I critical phase matching and a KTP crystal with type-II critical phase matching (CTM) were used for the second harmonic generation (SHG) and the third harmonic generation (THG), respectively. In view of the analysis of the cavity stability, a four-mirror folded cavity was designed and the output characteristics were theoretically analyzed. Experimental characteristics obtained were shown to be in agreement with the theoretical analysis. The maximum output power of the 447 nm CW blue laser reached 114 mW, which corresponds to a red-to-blue conversion efficiency of 9%. [ABSTRACT FROM AUTHOR]