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Z-Scan
Z-scan is a technique used to measure the nonlinear refractive index and nonlinear absorption coefficient of a material [1].
The
sample is translated in the Z-direction along the axis of a focused Gaussian
beam. The self focusing nature of the material effects the laser beam focus position, the Z-scan is obtained by moving the sample along the
well-defined, focused laser beam, and thereby varying the light intensity incident on the detector. By varying the diameter of the aperture in front of the detector, one makes the Z-scan
transmittance more or less sensitive to either the nonlinear refractive index or the nonlinear absorption of the material.
This system is operated and mantained by the Molecular Electronics Group under Professor Werner Blau, contact Dr. Jun Wang by e-mail
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Operational setup
A standard open aperture Z-scan apparatus is used to measure the nonlinear extinction coefficients of materials. All experiments were performed with 6-ns pulses from a Q-switched Nd:YAG laser. The beam is spatially filtered to remove higher-order modes and tightly focused using a 9 cm focal length lens. The laser is operated at the second harmonic, 532 nm, with a pulse repetition rate of 10 Hz.
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Typical Z-scan spectra from Single-walled carbon nanotubes (SWNTs) dispersed in solvent from which the nonlinear extinction coefficient and the optical limiting properties can be investigated [2].
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References
1. Sensitive measurement of optical nonlinearities using a single beam
Sheik-Bahae, Mansoor (Univ of Central Florida, Cent for Research in Electro-Opt & Lasers,Orlando, FL, USA); Said, Ali A.; Wei, Tai-Huei; Hagan, David J.; Van Stryland, E.W. Source: IEEE Journal of Quantum Electronics, v 26, n 4, Apr, 1990, p 760-769
ISSN: 0018-9197 CODEN: IEJQA7
2. Solvent effect on optical limiting properties of single-walled carbon nanotube dispersions
Jun Wang*, Werner J. Blau, The Journal of Physical Chemistry C, 112, 2298-2303 (2008).
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