Direct measurement of chirp parameters of high-speed Mach-Zehnder-type optical modulators

A method is described for measuring the chirp parameters and optical respon ses of Mach-Zehnder-type optical modulators by using an optical spectrum an alyzer. The chirp parameter and the optical response for small-signal opera tion are expressed by the magnitude of the phase induced in each optical pa th of the Mach-Zehnder waveguides. The induced phase can be obtained from t he ratio of the high-order optical harmonic intensities generated by large- signal operation in the millimeter-wave region. This method permits the chi rp parameter to be evaluated at a specific frequency, while it is assumed t o be independent of the frequency of the applied electric rf signal in the conventional method. (C) 2001 Elsevier Science B.V. All rights reserved.