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- 저자 : Chaoyi Qian (검색결과 3 건)
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A novel scheme to acquire enhanced up-conversion emissions of Ho3+ and Yb3+ co-doped Sc2O3
Chaoyi Zhang,Qian Jiang,Xinyu Wang,Jing Liu,Yantao Xiao,Chun Li,Hai Lin,Fanming Zeng,Zhongmin Su 한국물리학회 2020 Current Applied Physics Vol.20 No.1
A detailed investigation about the effect of Sc2O3: 1 mol%Ho3+/5 mol%Yb3+ co-doped with Ce4+ ions prepared by sol-gel methods was performed systematically. Under the excitation of 980 nm laser diode, both green emission (553 nm, 5F4/5S2→5I8) and red emission (672 nm, 5F5→5I8) were both observed in the emission spectra of the samples, which were found to be two-photon process and sensitized by Yb3+ ions. With the increasing of Ce4+ ions, the up-conversion green emission intensity are increased by 6.52, 8.69, 10.85, 13.92 and 16.66 fold, corresponding to the Ce4+ ions concentrations from 5 mol% to 13 mol%, respectively. The number of photons are necessary to populate the upper emitting state decreases to 2 and the infrared absorption coefficient is reduced, when the Ce4+ ions concentration increase to 13 mol%. Ce4+ ions play an important role in tailoring the local crystal field around Ho3+ ions, lowering the highest phonon cut-off energy of matrix and reducing the infrared absorption coefficient, thus hindering the non-radiative processes, which contribute to the increased emission intensity. The excellent enhancement makes it a promising multifunctional optical luminescence material.
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Response of Water Tetramer to Intense Femtosecond Laser Pulses
Zhiping Wang,Xuefen Xu,Chaoyi Qian,Yanbiao Wang,Xu Wang 한국광학회 2017 Current Optics and Photonics Vol.1 No.4
We theoretically study the dynamics of water tetramer in intense femtosecond laser pulses with differentfrequencies. The simulations are carried out by incorporating the molecular dynamics method non-adiabaticallyinto the time-dependent local-density approximation (TDLDA-MD). Three typical scenarios of watertetramer including the normal vibration with enlarged OH bonds, free OH bonds breaking and the pureCoulomb explosion are presented by investigating the electronic and ionic dynamics. The result indicatesthat the ionization is enhanced and the corresponding fragmentation effect as well as the damping of thedipole moment are found more notably when increasing the laser frequency especially when the frequencyfalls in the resonant region of the absorption spectra. The study of the level depletion reveals that theratio of the emission amount from different levels can be controlled by changing the laser frequencyreferring to the Keldysh parameter.
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Uniform Side Illumination Generated from LEDs Arranged by an Annealing Algorithm
Xu Wang,Panling Lei,Chaoyi Qian,Zhiping Wang,Xuefen Xu,Zhouping Su 한국광학회 2022 Current Optics and Photonics Vol.6 No.3
Given a cubic space, it is easy to uniformly illuminate the floor with light sources placed on top. However, little has been reported about uniform illumination on walls with the same configuration of light sources. Here we present a luminaire consisting of nine light-emitting diodes (LEDs) with perfect Lambertian distribution, placed on the top as a 3 × 3 rectangular LED array. The distances between LEDs and tilt angles of each individual LED are adjustable and optimized by an annealing algorithm. After optimization, the array produces a rectangular illumination pattern on one wall with a uniformity of about 89%. Analysis shows that the tilt angles of individual LEDs are key parameters for uniform side illumination. In a scenario that is more practical, the tilt angles of all the LEDs are set to be the same, only decreasing the uniformity to 83%.
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