The acousto-optic modulator (AOMs) have great applications in the fields of laser technology, information processing and micro-processing, which is mainly applied to control and modulate the intensity of light at high frequency. The diffraction efficiency (DE) is the important parameter of AOMs. Researchers have studied many influencing factors of diffraction efficiency. However, few research on internal transducer parameter design in AOMs. In this paper, we propose an electrode optimization scheme to obtain AOMs with high diffraction efficiency. Combining the divergence angle ratio, we experimentally demonstrated the optimal size of the electrode. Furthermore, we model the sound pressure field in COMSOL Multiphysics® software, and analyze the DE of the optimized apodized transducer and the conventional transducer AOMs. The results show that comparing with rectangular transducer, optimized apodized shaped transducer can increase the DE of AOMs by 8.33% on average.
The luminescence decay curve from transitions of 4I 13/2->4I15/2 in the Er3+/Yb3+-codoped PLZT transparent ceramic was measured. A model for the dynamics of frequency upconversion in Er3+/Yb3+-codoped PLZT transparent ceramic based on the rate equations was proposed. The dynamics of the upconverted emissions were studied to evaluate energy transfer rates between Er3+ and Yb3+ ions, and the forward energy transfer rate for Yb3+ to Er3+ and the backward transfer rate for Er3+ to Yb3+ were 7.19x10-17 cm3s-1 and 3.73×10-17 cm3s-1, respectively.
Sm(DBM)3phen-doped polymer optical fibers were prepared by thermal polymerization. The cross relaxation model of
clustering Sm3+ ions was described, and the cluster in this kind of fibers was studied based on the above model. The
percentages of clustering ions in different fibers were obtained by the rate equation combining with fiber transmission
experiment. While rare-earth-doped concentrations in these fibers are 1000 ppm, 2000 ppm, 3000 ppm, 4000 ppm, 5000
ppm and 10000 ppm, the percentages of clustering ions are 0.05, 0.05, 0.05, 0.05, 0.06, and 0.07, respectively. The result
shows that this kind of fibers has low percentage of clustering ions. With the increasing of Sm3+ concentration, the
percentage of clustering ions hardly increases, the clustering of Sm3+ ions is not obvious.
The upconversion fluorescence spectrum and the luminescence decay curves from transitions of 4I13/2→4I15/2 and 4I11/2→4I15/2 in the Er3+-doped PLZT transparent ceramic were measured experimentally. A model for the dynamics of frequency upconversion in Er3+-doped PLZT transparent ceramic based on the rate equations was proposed. The dynamics of the upconverted emissions were studied to evaluate energy transfer (ET) rates by solving the rate equations of the model and fitting the experimental curves. The upconversion coefficient C22 for the cross relaxation 4I13/2+4I13/2→4I9/2+4I15/2 and the upconversion coefficient C33 for the cross relaxation 4I11/2+4I11/2→4I15/2+4F7/2 were 0.91×10-18 cm3/s and 18.23×10-18 cm3/s, respectively. The model provides a good basis for explaining the experiment data because it shows a high sensitivity to the input fitting parameters. The analysis reveals that Er3+-doped PLZT transparent ceramic have a great prospect to be applied for monolithic multifunction compact devices and upconversion devices.
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