Song Z

An initial experimental comparative investigation of direct and indirect up-conversion sensitization of the level of Tm,Yb co-doped material

This paper reports the study of both direct and indirect up-conversion sensitization luminescence phenomenon of the Tm3+ ions (1)G(4) level in ZBLAN glass, oxyfluoride grass and pentaphosphate non-crystallite. We found, in the case of indirect up-conversion sensitization, the up-conversion luminescence of Tm0.03Yb0.18La0.79P5O14 non-crystallite is enhanced up to a level comparable to that of Tm(0.1)Yb(3):ZBLAN glass. And especially the up-conversion luminescence of Tm(0.1)Yb(10.9):oxyfluoride glass is also enhanced greatly, and its intensity even exceeds slightly that of Tm(0.1)Yb(3):ZBLAN glass. This result is contradicting to a generally accepted concept, i.e. that the up-conversion luminescence of the high cut-off phonon energys materials is only about ten thousand times smaller than that of fluoride. Therefore, it is possible to find some materials having both high up-conversion efficiency under indirect up-conversion sensitization and advanced material properties for Various up-conversion application. To our knowledge, a similar result has not been reported before

Initital research of three-dimensional volumetric display based on di-frequency upconversion

3D display may be one of the most wonderful techniques attracting scientists to research on. But most of current approaches are fictitious ones. On the CLEO94, E. A. Downing and L. Hesselink et al. reported a virtual 3D volumetric display using Pr doped fluoride glass upconversion luminescence which is evaluated as a new excellent physics achievement in 1996. The ZBLAN:Pr glass is proved by L. Hesselink to be a interesting material for 3D volumetric display based on upconversion. In the processes of upconverting near-infrared radiation to visible, the 1G4 level of Pr3+ locates at an important position. But the transition probability of 3H4- 1G4 proved to be one or two order of magnitude smaller than other strong transitions. So to improve the population on 1G4 has an practical significance. In this paper, we report a simple 3D volumetric display experiment which has used the upconversion sensitization method. A bulk ZBLAN:Pr,Yb and ZBLAN:pr glasses were selected as display medium. Just as the sensitized action of Yb3+ ion, the di-frequency upconversion luminescence intensity of Pr3+ ion is enhanced more than thirty times. So, the brightness of 3D display is better than the work of E. A. Downing and L. Hesselink. Some technique consideration is discussed. In addition a conception of multilayer 3D display device is also presented, which are thought having several advantages.

Dynamic up-conversion population processes of erbium-doped pentaphosphate crystal

Rate equations describing the dynamic processes in erbium (Er3+)-doped pentaphosphate crystals were developed to obtain the population processes of all levels of Er3+ ions in pentaphosphate ErP5O14 crystals under 650 nm laser excitation. The effects of pump power on the population (rho) dynamic process were analyzed. The spontaneous radiative processes, multiphonon nonradiative processes, absorption of the pump photons, corresponding stimulated radiation processes, and all other possible energy transfer processes between Er3+ ions were included in the rate equations. The pump power was assumed to be constant with time (t). Considering that the equation rho(t(0)+Deltat)=rho(t(0))+(drho/dt)Deltat would be held if Deltat was small enough and using the initial condition rho(1)=1.0, rho(i)=0(inot equal1), the time-dependent populations of all states could be obtained from the rate equations, from which the steady-state solution of the rate equation was deduced. The comprehensive study of the population dynamic process of all energy-level Er3+ ions in ErP5O14 crystal when excited by 100 mW-10(7) W has resulted in the conclusion that the strong upconversion luminescence would behave excellently when 650 nm pump laser power reaches the level of 1000-10(5) W. The representative population dynamic process when excited by 10(5) W laser power indicates I-4(15/2) and F-4(9/2) levels have a kind of great takeover co-contribution in up-converting population to higher states. The steady-state population probability of I-4(15/2) is as small as 0.0617. The population of the F-4(9/2) state increases rapidly to about a 0.362 high level and sequentially decreases smoothly to a stable value of about a 0.0374 low level, which implies a population already having been upconverted to higher level. Excellent results clearly exhibit that the main up-conversion luminescent level S-4(3/2) has a great population probability of about 0.212, which results in a strong up-conversion luminescence of 543 nm, and it is so exciting that a very strong 379 nm blue up-conversion luminescence could be achieved when 650 nm pump laser power is enhanced to the level of 1000-10(5) W. The results of this article are significant both to science and applications