| In this thesis, a single beam system called Z-scan is developed which is a method for measuring the nonlinear refractive index of optical media. The sample is moved along with the z direction of a focused Gaussian beam and a detector measure the intensity through a finite aperture at a far distance. Due to the self-focusing or self-defocusing effect it is easy to get the sign and the magnitude of the nonlinear refractive index n2 from the resultant transmittance trace.; The basic concept of quantum dots is introduced and other kind measurements in detecting n2 are briefly compared. The detecting sample is Cadmium Sulfide (CdS). Steps of Z-scan construction are described and the result is shown and analyzed. |
