Cr

4+

-doped YAG (Y

3

Al

5

O

12

) crystal is an ideal material used for passive-Q-switch

especially used in high power and high repetition rate lasers. Nd

3+

-doped YAG crystal is the best gain medium at present. Since 1995 Ikesue et al. firstly demonstrated the possibility of fabricating transparent Nd:YAG ceramics of sufficient quality for solid-state lasers

polycrystalline ceramic laser materials have attracted much attention because the optical quality has been improved greatly and highly efficient laser output could be obtained whose efficiencies are comparable or superior to those of single crystal. The purpose of the work is to combine the advantages of the gain medium Nd

3+

and the saturable absorber Cr

4+

using ceramic technology.The transparent Cr

4+

Nd

3+

:YAG ceramics were fabricated by a solid-state reaction and vacuum sintering with CaO as a charge compensator

tetraethyl orthosilicate (TEOS) as a sintering aid and high-purity -Al

2

O

3

Y

2

O

3

Nd

2

O

3

and Cr

2

O

3

powders as starting materials. The absorption spectra

fluorescence spectra and fluorescence of the 0.1%Cr

1.0%Nd:YAG transparent ceramics were measured at room temperature. For the Cr

4+

Nd

3+

:YAG transparent ceramic sintered at 1800℃ for 30h

the absorption cross section

is 4.2710

-20

cm

2

at 808 nm

emission cross section and fluorescence lifetime are 1.5210

-20

cm

2

and 206 s at 1 064 nm

respectively. The laser performance parameters of the gained Cr

4+

Nd

3+

:YAG transparent ceramic were evaluated by

I

sat

min

and

I

min

based on the spectroscopic parameters. The pump saturation intensity parameter

I

sat

the

min

parameter which is defined as the minimum inversion fraction of Nd

3+

ions that must be exited to balance the ions exactly with the ground-state absorption at the extraction wavelength

and the minimum absorption pump intensity

I

min

to reach the threshold at the extraction wavelength are 28.0kW/cm

2

52.2% and 14.6 kW/cm

2

respectively. High-quality Cr

4+

Nd

3+

:YAG transparent ceramics

which combine the gain media and the saturable absorber together

may be a potential self-Q-switched laser material.