Ultrafast third-order optical nonlinearities of vertically-aligned ZnO nanorods

• Published in: Chemical physics letters Vol. 447; no. 1; pp. 86 - 90
• Main Authors: Lee, H.W., Lee, K.M., Lee, S., Koh, K.H., Park, J.-Y., Kim, K., Rotermund, F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2007
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2007.08.086

Third-order optical nonlinearities of vertically-aligned ZnO nanorods are investigated at 815 nm by femtosecond z-scan measurements with closed and open-apertures. Vertically-aligned ZnO nanorods with different rod diameters of 50 nm, 110 nm and 240 nm were synthesized by a low-temperature wet-chemical method. Morphologies and structures of ZnO nanorods were examined by scanning electron microscopy and X-ray diffraction. Third-order optical nonlinearities such as nonlinear refraction and absorption were determined by closed- and open-aperture z-scan measurements at 815 nm using femtosecond laser pulses. Enhanced optical nonlinearities were observed with increasing rod diameters and aligned degrees of ZnO nanorods along the c-axis. Nonlinear response time, measured by using a time-resolved optical Kerr-gate technique, was less than 95 fs.