Patent ID: 8693005

Claim:
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, wherein the method comprises a step of applying driving signal, a step of sweeping bias voltage, a step of measuring output intensity, and a step of evaluating characteristics, wherein the step of applying driving signal is a step of applying driving signal to the MZ interferometer, wherein the step of sweeping bias voltage is a step of sweeping bias voltage to be applied to the MZ interferometer, wherein the step of measuring output intensity is a step of measuring intensity of a first order sideband, a second order sideband, a third order sideband and a fourth order sideband included in a signal output from the MZ interferometer while the bias voltage is being swept at the step of sweeping bias voltage, wherein the step of evaluating characteristics is a step of evaluating characteristics of the MZ interferometer using R 21 , R 31 and R 41 , wherein R xy is S y /S x and S x and S y are intensity of x th order sideband and y th order sideband, respectively, in output from the MZ interferometer measured at the step of measuring output intensity.