Tetragonal calcium rare-earth aluminates, CaLnAlO4, combine a structural disorder with good thermo-mechanical properties. We report on efficient continuous-wave (CW) and passively Q-switched (PQS) ~2-μm laser operation of a 4 at.% Tm:CaYAlO4 crystal using a compact (6-mm-long) plane-parallel cavity. The pump source was a 791 nm fibercoupled AlGaAs laser diode. The CW output power reached 5.78 W at ~1970 nm with a slope efficiency of 43.6% and a linear laser polarization. Stable PQS operation was achieved using a single-walled carbon nanotube (SWCNT) based transmission-type saturable absorber. The PQS laser generated 2.15 W at ~1945 nm, a record-high average output power for this type of lasers. The best pulse characteristics (energy/duration) were 9.1 μJ/165 ns at a repetition rate of 235 kHz.
The experimental curriculum system is directly related to talent training quality. Based on the careful investigation of the developing request of the optoelectronic information talents in the new century, the experimental teaching goal and the content, the teaching goal was set to cultivate students' innovative consciousness, innovative thinking, creativity and problem solving ability. Through straightening out the correlation among the experimental teaching in the main courses, the whole structure design was phased out, as well as the hierarchical curriculum connotation. According to the ideas of "basic, comprehensive, applied and innovative", the construction of experimental teaching system called "triple-three" was put forward for the optoelectronic information experimental teaching practice.
Since the spectral imaging technology emerged, it has gained a lot of application achievements in the military field,
precision agriculture and biomedical science. When the fluorescence spectrum imaging first applied to the detection of
the feature resource of Chinese herbal medicine, the characteristics of holistic and ambiguity made it a new approach to
the traditional Chinese medicine testing. In this paper, we applied this method to study the Chinese medicine north and
south isatis root granules by comparing their fluorescence spectra. Using cluster analysis, the results showed that the
north and south Banlangen can not be divided by ascription. And these indicate that there is a large difference in the
quality of Banlangen granules on the market, and fluorescence spectrum imaging method can be used in monitoring the
quality of radix isatidis granules.
This paper aims at designing and demonstrating a video and audio signals synchronous wireless transmission of free-space optical communication (FSO) system. Video and audio signals were modulated by the acousto-optical modulator (AOM). With the help of a designed circuit and programmable microcontroller, the system based on time division multiplexing (TDM) achieves the functions of signal de-multiplexing and wireless transmitting. Proved by experiments, the system meets the actual requirements with advantages of flexibility, practicality and low cost. And it provides an efficient scheme of synchronous wireless transmission of video and audio signals for monitoring system and TV access network.
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.
By using Nd:YAG/Cr:YAG/YAG composite crystal as gain media, a passively Q-switched LD side-pumped laser with high average output power, working at 1064 nm, is set up. The 1064 nm laser output power increases linearly with the pumping light power and the maximum average output power of 83.68 W is observed. With the help of a KTP nonlinear crystal, 532 nm laser pulses with the corresponding pulse width of 210 ns and the repetition rate of 21.2 kHz are obtained under the maximum LD pumping light of 187.5 W. The average output power of 532 nm laser is 27.2 W. The singlepulse energy is 1.28 mJ and the peak power is 6.1 kW. The optical-to-optical conversion efficiency of LD pumping light to 532 nm output light is 14.72%.
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 4.5 W and 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.
Real-space transfer (RST) has many excellent characteristics, such as high speed, high frequency and negative differential resistance (NDR). RST has drawn a lot of attention since it was proposed by Z.S.Gribnikov in 1972. However, most of the researches about RST were restricted to the classical regime with the hot electron theory. Quantum real-space transfer (QRST) which relies solely on the wave nature of electrons has not been given sufficient attention. In this work, the quantum real-space transfer was deeply investigated. Al0.48In0.52As/GaAs0.51Sb0.49/Al0.48In0.52As alternative symmetry quantum-well structures was designed, and each thickness of the layer is 10 nm, 12 nm, 10nm. We carried out theoretical calculations on the wave-function module and the electrons confinement probability as the function of the in-plane wave-vector. According to our calculations，a sharp electron transfer occurs in the wave-vector range of 3.42×106-7.6×106 /cm. Therefore, it’s feasible to achieve a quantum real-space transfer. We also compared the results to that of the previous quantum structures. At last we propose the optimization to realize quantum real-space transfer (QRST) and discuss the potential applications of the quantum real-space transfer.