H. L. Fan et al. / Natural Science 1 (2009) 136-141

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140

MeAu and MeNi show larger third-order nonlinear opti-

cal properties because of the delocalized electronic states

formed by the overlapping between p-p and d orbits [10].

But the nonlinear absorption coefficient of MeNi is rap-

idly larger than that of MeAu. The resonant wavelength

of 1064 nm of MeNi gives to the stronger saturable ab-

sorption comparing with the weaker nonlinear absorp-

tion of MeAu at 1064 nm which locates on the

off-resonant field of linear absorption [27]. The figures

of merit of MeAu were calculated to be W=22.84 and

T≈0, which finely satisfy the requirement of suitability

for all-optical switching devices W>>1 and T<<1. So the

material can be considered to be an excellent candidate

to be applied in integrated optics field as all-optical

switching devices. While for MeNi, W=0.013 and

T=1.94, the values of two figures of merit don’t satisfy

the requirement of all-optical devices but may be applied

in laser mode-locking, laser Q-switching and optical

bistability fields because of its saturable absorption

properties.

4. CONCLUSIONS

The third-order nonlinear properties of two metal-dmit

complexes MeAu and MeNi were investigated using a

Z-scan technique at 1064 nm with 20 ps pulse width and

10 Hz repetition rate. Z-scan curves indicated that both

MeAu and MeNi show negative nonlinear refraction

which are regarded as self-defocusing effects. Mean-

while, tiny nonlinear absorption and stronger saturable

absorption was found in MeAu and MeNi, respectively.

The figures of merit W and T of two materials were cal-

culated to judge the suitability as all-optical switching

devices. The values of MeAu W=22.84 and T≈0 were

considered to be appropriate for applications in

all-optical integrated field. While for MeNi, the stronger

saturable absorption comparing with nonlinear refraction

makes it a fine material to be applied in laser

mode-locking, laser Q-switching, optical bistability field

and so on.

5. ACKNOWLEDGEMENTS

This research work is supported by the grants (Nos.

50772059, 60778037, 60608010 and 50872067) of the

National Natural Science Foundation of China (NNSFC)

and the Foundation for the Author of National Excellent

Doctoral Dissertation of P. R. China (No. 200539).

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