Upconversion luminescence of Tm3+- and Yb3+-codoped pentaphosphate noncrystalline under the pumping of a 798-nm laser diode

摘要

When excited into Tm$+3$VBAR$/ $+3$/F$-4$/ level by a LD at approximately 798 nm, Tm$+3$VBAR$/ and Yb$+3$VBAR$/ codoped pentaphosphate noncrystalline samples emit blue light at 475 nm, which corresponds to transition $+1$/G$-4$/ $YLD $+3$/H$- 6$/. Although laser is directly absorbed by Tm$+3$PLU$/ ions, the upconversion process rely on the codoping of Yb$+3$PLU$/ ions. One Tm$+3$PLU$/ $YLD Yb$+3$PLU$/ transfer process excites Yb$+3$PLU$/ ions, then backward Yb$+3$VBAR$/ $YLD Tm$+3$VBAR$/ energy transfer excites Tm$+3$VBAR$/ ions from $+3$/H$-4$/ to $+1$/G$-4$/ level.