High efficiency white luminescence in Tm3+/Er3+/Yb3+ tri-doped oxyfluoride glass ceramic microsphere pumped by 976Â nm laser

In this paper, transparent Tm3+/Er3+/Yb3+ tri-doped oxyfluoride glass ceramic samples containing LaF3 nanocrystals were prepared by a melt quenching method, and were subsequently fabricated into transparent microspheres with handles. A new method to study the luminescent properties of Tm3+/Er3+/Yb3+ tri-doped oxyfluoride glass ceramic was proposed, which was using the biconical tapered fiber-microsphere coupled structure. The structure has characteristics of low excitation optical power, easy preparation and convenient testing. We obtained strong white light including the blue (471 nm), green (523 nm and 544 nm) and red (651 nm) emission under the excitation of a 976 nm laser diode (LD) and the relationship of the luminous flux of white light versus pump power simultaneously. In addition, the up-conversion (UC) luminescence mechanism of rare earth (RE) ions and the reason of high luminescence efficiency in our experiment were also explained. The white light obtained by UC of 976 nm laser has more advantages than that by down-conversion of blue light. It may be applied in many fields such as background light, lighting, etc.