When a medium was excited by a laser

the thermal effect always existed.Especially for a laser whose pulse width was beyond ns.or the sample had large absorption

the effect could not be neglected.So the investigation of the thermally induced optical properties of a compound was very important.The thermally-induced nonlinear refraction index changes of a sample always covered the change of quick electron effect when the refraction index was measured by some techniques.The thermally-induced third-order optical nonlinerity property of the coordinated compound of three kinds of transition metals Ni

Cu and Pd was studied by Z-scan technique for the first time.Both 488 nm and 632.8 nm CW laser were used for excitation.The result showed that the optical nonlinear refractions of the three compounds under CW laser resulted from the thermal effect

and they had no nonlinear absorption.By combining experimental curves and the thermal effect theory

we calculated the thermoptical coefficient d

n

/d

T

and the thermal-induced refractive index

n

2

of the compounds.By comparison

it could be discovered that the thermoptical coefficient d

n

/d

T

and the thermal-induced refractive index

n

2

of the three compounds were different from each other under different excitation conditions.In general

the values of d

n

/d

T

and

n

2

under 488 nm laser excitation were bigger than those under the excitation of 632.8 nm laser

this was in according with other paper's results.Moreover

the values of d

n

/d

T

and n

2

of the compounds also depended on the linear absorption under certain condition.The stronger the absorption

the bigger the values.Finally

the atomic number of the central metal atom of the coordinated compounds influenced on the values too.If the central metal atomic number was bigger

then the thermoptical coefficient and the thermally-induced nonlinear refractive index of the compound were bigger.