Third-order nonlinear optical properties of the small-molecular organic semiconductor tris (8-Hydroxyquinoline) aluminum by CW Z-scan technique

The linear optical and electroluminescence properties of small molecular organic material tris-(8-hydroxyquinoline) aluminum (Alq(3)) are known and extensively investigated by many studies. However, the studies on the nonlinear optical (NLO) properties of this material are still scarce. Herein, the third-order NLO (TONLO) properties of Alq(3) chloroform solutions with different concentrations have been examined using the Z-scan technique. At different laser powers and different laser wavelengths, the Z-scan signals were recorded using a continuous-wave (CW) laser beam. The open-aperture (OA) and closed- aperture (CA) Z-scan signals revealed strong TONLO properties. Both nonlinear refractive index (n(2)) and nonlinear absorption coefficient (beta) showed negative values, and their smallest values were in the fold of 10(-8) cm(2)/W and 10(-2) cm/W, respectively. The negative values of n(2) and beta suggest thermal nonlinearity and saturable absorption (SA), respectively. The TONLO susceptibility (chi((3))) was calculated and found to be in the order of 10(-6) esu. Besides, they increased with increasing the concentrations of Alq(3) and laser powers. Therefore, the results indicate that Alq(3) could be one of the potential materials as a saturable absorber for starting a passive mode-locking operation.

Automated summary

The third-order nonlinear optical properties of Alq(3) chloroform solutions were examined in this study using the Z-scan technique. The results showed strong third-order nonlinear optical properties, suggesting that Alq(3) could be a potential material as a saturable absorber for passive mode-locking operation.