CHEN Bao-jiu, WANG Hai-yu, QIN Wei-ping, XU Wu, HUANG Shi-hua. Optical Transitions and the Upconversion from IR to Visible of Yb<sup>3+</sup> and Er<sup>3+</sup> Co-doped Fluoroborate Glass[J]. Chinese Journal of Luminescence, 2000,21(1): 38-42
CHEN Bao-jiu, WANG Hai-yu, QIN Wei-ping, XU Wu, HUANG Shi-hua. Optical Transitions and the Upconversion from IR to Visible of Yb<sup>3+</sup> and Er<sup>3+</sup> Co-doped Fluoroborate Glass[J]. Chinese Journal of Luminescence, 2000,21(1): 38-42DOI:
Fluoroborate glasses have been the subject of several spectroscopic investigations due to their potential as laser host matrix. In recent letters infrared conversion to visible and ultraviolet by Yb
3+
-Er
3+
and Yb
3+
-Ho
3+
ions in some glasses host has been reported. In this paper
the aim is to find suitable host for upconversion luminescence
and a fluoroborate glass co doped with Yb
3+
and Er
3+
was designed. The optical transition properties and upconversion under 970nm LD excitation were discussed for this glass sample. The fluoroborate glass with component 30H
3
BO
3
-15AlF
3
-19.5PbF
2
-10BaF
2
-10ZnF
2
-10NaF
5
Yb
2
O
3
-0.5Er
2
O
3
was prepared. The absorption spectrum was measured in visible range from 350nm to 700nm. The J-O theory was used to calculate the optical properties of Er
3+
and Yb
3+
codoped in fluoroborate glass. The J-O parameters were obtained
Ω=1.2E-20(cm
2
)
Ω=3.6E-20(cm
2
)
Ω=7.7E-21(cm
2
). The transition probabilities
the oscillator strengths
branching ratios and the radioactive lifetimes were obtained. The red (
4
F
9/2
→
4
I
15/2
) and green (
2
H
11/2
4
S
3/2
→
4
I
15/2
) upconversion luminescence under 970nm LD excitation was observed
the upconversion mechanism was discussed. In this system the upconversion luminescence by energy transfer from Yb
3+
to Er
3+
and from Er
3+
to Er
3+
and excited state absorption of Er
3+
was proposed. The relationship between LD working current and intensity of upconversion luminescence was discussed. The results confirmed that the upconversion process is consisted by two photons.