Yb

3+

is a good active ion.It has the simplest level structure

consisting of only two multiplets

2

F

7/2

and

2

F

7/2

which results in several advantages

such as no excited state absorption

no more up-conversion

and low quantum defect able to reduce the thermal loading.In addition

the longer fluorescence lifetime(about 1 ms) is propitious to store energy and the broad emission band allows the generation of high power laser pulse.But Yb

3+

can only operate in a quasi-three level scheme.The terminal state of laser emission is very close to ground state

which results in high thermal population of the laser terminal state and strong re-absorption at the emission wavelengths

and high laser pumping threshold.In order to limit thermal population of the terminal level

a relatively strong crystal field increasing the Stark-splitting of the Yb

3+

ground manifold as large as possible is expected.In our experiment

we discover that Yb

3+

has bigger stronger Stark-splitting in the crystalline field of LuScO

3

.We take ammonia as precipitator

Yb

2

O

3

Sc

2

O

3

and Lu

2

O

3

as starting mate-rials to prepare Yb:LuScO

3

precursor by co-precipitation method.We obtained Yb:LuScO

3

nano-polycrystalline powders by sintering the precursor at 1500℃.X-ray powder diffraction indicated that the polycrystalline Yb:LuScO

3

belongs to the cubic phase

space group Ia3.Its lattice parameter a is 1.0126 nm

calculated by the least square method

and its size is about 50 nm.When excited at 937 nm

the strongest emission peaks of Yb:LuScO

3

are at 976 nm and 1037 nm

the weaker peak at 1085 nm.According to its emission and absorption spectra

the energy structure of Yb

3+

is determined.The overall splitting value of

2

F

7/2

is 1029 cm

-1

which is larger than 785 cm

-1

of Yb:YAG.By comparison to emission spectrum with Yb:YAG

the emission peaks move to longer wavelength and the emission spectrum band is very wide

which advantages to decrease laser threshold and improves laser efficiency.In addition

the broader emission band of Yb:LuScO

3

is propitious to ultra-short pulses output.