Energy transfers and upconversion fluorescence spectroscopy in both Er3+ si
ngly doped and Tm3+-Yb3+ co-doped AlF3-based flouride glass,excited at 970
nm,are investigated experimentally. In Er3+ :AYF glass,the optium Er3+ cont
ent for 550 nm emission is about at 6 mol%,which is 12 mol% in AZF glass. W
ith the increase of E3+ content,the intensity ratio of the red emission to
the green emission ( I-red/I-green) is increased in AYF and AZF glass,and t
he red emission intensity in these gass depends on (p(ex))(1.6). They are m
ainly due to a cross-relaxation process between two erbium ions,one in the
S-4(3/2) and the other in the I-4(9/2) In Tm3+-Yb3+ co-doped AlF3-based flo
uride glass,the concentration quenching of Tm3+ in blue at 476 nm is strong
er than that in infrared light at 793 nm,and the optimum content of Tm3+ fo
r 476 nm emission is about 0.1 mol%,while it is (0.3-5)mol% for 793 nm emis
sion. The concentration quenching of Yb3+ to upconvertion fluorescence is a
lso observed. It may be due to the back-energy transfer from the F-3(4) lev
el of Tm3+ to the F-2(5/2) level of Yb3+.