Fluoride glasses and crystals with good transparency

low phonon energy and large rare earth ion solubility are promising hosts for optically active ions

which have attracted great attention because of the possibilities of realizing blue or green solid state lasers.However

they are difficult to fiberize due to low chemical and mechanical stability.Most oxide glasses are chemically and mechanically stable although they have higher phonon energy comparing with those of the fluoride host.Recently

oxyfluoride glass-ceramics were developed by growing the fluoride micro-crystals containing rare earth ions into oxide host.As a result

oxyfluoride glass-ceramics have low phonon energy just like fluoride and its good chemical and mechanical stability just like oxide glass. The relation between upconversion intensity and pumped power is quadratic (or cubic) in the process of up-conversion luminescence corresponding to double-photon(or three photon)process.But in our experiment

green up-conversion fluorescent intensity of Er

3+

in Er

3+

-Yb

3+

codoped SiO

2

-Al

2

O

3

-PbF

2

-CdF

2

transparent glass-ceramics does not show a quadratic dependence versus the pumped laser intensity although green up-conversion luminescence is corresponding to a double-photon process.And the green up-conversion fluorescent intensity saturated gradually with the pumped laser power. Relation between Er

3+

up-converted luminescent intensity and pump power in Er

3+

-Yb

3+

-codoped material are studied by transfer function theory.Er

3+

up-converted luminescent process in oxyfluoride glass-ceramics is discussed and it’s found that the non-quadratic relation between green up-conversion intensity and pump power is caused by strong cross-relaxation process of rare earth ions.Methods of increasing Er

3+

up-converted luminescent intensity in oxyfluoride glass-ceramics are suggested.