ANALYSIS OF THE EZ SCAN MEASUREMENT TECHNIQUE

The Z scan experiment has been found to be a useful and simple technique for the measurement of both the real and imaginary parts of the third order (and higher orders) of the optical nonlinearity of a wide variety of materials. The sensitivity of the technique, typically lambda/300, may be enhanced by over an order of magnitude in the EZ scan method by the substitution of field stop and collecting lens in place of the usual aperture. In this paper such a detection scheme is analysed numerically and a compact empirical expression for the nonlinearity in terms of the stop transmittance and the change in transmittance during the scan is derived.