2, National University of Singapore, Singapore, , Singapore
To study the nonlinear optical property of MNbO3, we performed single beam open aperture Z-scan measurement on the MNbO3 thin films deposited on LSAT (100) substrates by pulsed laser deposition. The wavelength of excitation laser which is generated by femtosecond laser system is 800 nm. The CaNbO3 and SrNbO3 thin films grown on LSAT show a metallic behavior in the curve of resistivity as a function of temperature, while the BaNbO3 thin film show a metal to insulator transition behavior which may be due to the large lattice mismatch with substrate. All the alkaline earth niobates thin films show a significant saturable absorption nonlinear optical property. The saturable absorption intensity of CaNbO3, SrNbO3 and BaNbO3 are 9×1017, 7.5×1017 and 2.8×1017 GW/cm2 for 800 nm excitation laser, respectively. Since the plasmon resonance exists because of the extremely large carrier densities of all MNbO3 (1022 cm-3), the saturable absorption property can be attributed to the bleaching of the absorption of the ground state absorption. Therefore, MNbO3 thin films may have potential application as saturable absorber in the field of ultrashort pulsed laser technique.