Patent ID: 8351047
Filing Date: 2013-01-08
Classification: G02F

Abstract:
1. A method for evaluating characteristics of an optical modulator including a first Mach-Zehnder, MZ, interferometer, wherein the MZ interferometer includes a branching section, two arms, a coupling section, and electrodes, the two arms are connected to the branching section, the coupling section is connected to the two arms, the electrodes make it possible to apply bias voltages to the two arms, the electrodes make it possible to apply modulation signals to the two arms, the method comprises a step of adjusting bias voltage, a step of eliminating zeroth-order component, a step of measuring output intensity, and a step of evaluating characteristics, the step of adjusting bias voltage is a step for adjusting phase difference between the bias voltages to be applied to the two arms of the MZ interferometer to be π, the step of eliminating zeroth-order component is a step for adjusting an extinction ratio η of the optical modulator, the extinction ratio η relating to imbalance of light amplitude between the two arms, such that the intensity of zeroth-order component of the output light from the MZ interferometer becomes 0, the step of measuring the output intensity is a step for obtaining the intensity of first-order component and the intensity of second-order component included in the output light from the MZ interferometer, the zeroth-order component of the output light having been eliminated at the step of eliminating the zeroth-order component, the step of evaluating the characteristics is a step for evaluating the characteristics of the MZ interferometer by using the intensity of the first-order component and the intensity of the second-order component measured at the output intensity measuring step.