METHOD OF MEASURING HALF-WAVE VOLTAGE OF LIGHT MODULATOR

摘要

PROBLEM TO BE SOLVED: To provide a method of measuring a half-wave voltage in a high-frequency domain without using a 0-th order component of output light of a light modulator.;SOLUTION: The light modulator includes a substrate 1 having electrooptic effect, an optical waveguide 2 formed on the substrate and having Mach-Zehnder optical waveguide parts 21, 22 formed at least partially, and modulation electrodes 31-34 for modulating lightwave propagating in the optical waveguide including the Mach-Zehnder optical waveguide parts. In the measurement method of the half-wave voltage of the light modulator, a power spectrum of a light output C from the light modulator with a modulation signal of a predetermined frequency f applied on the Mach-Zehnder optical waveguide parts is measured, at least two sideband waves of different orders are extracted from a sideband wave, an operation value is calculated based on a light intensity value, a variable value of a Bessel function which satisfies the operation value as a solution of an operation expression similar to the sideband wave is developed on the Bessel function of the same degree as the extracted sideband wave, and the half-wave voltage is determined based on the variable value and an amplitude value of a modulation signal.;COPYRIGHT: (C)2010,JPO&INPIT