Patent ID: 9568801
Date: 2017-02-14
CPC Classifications: G02F

Claim:
1. An optical modulator comprising: a first coupler that branches an input light into two and outputs a first output light and a second output light; a first Mach-Zehnder interferometer (MZI) that modulates the intensity of the first output light from the first coupler and outputs a third output light; a second MZI that modulates the intensity of the second output light from the first coupler and outputs a fourth output light; a second coupler that combines the third output light from the first MZI and the fourth output light from the second MZI, branches a combined light into two, and outputs a fifth output light and a sixth output light, wherein each of the first coupler and the second coupler has two crossing optical waveguides, and the angle made by the two optical waveguides of the first coupler and the angle made by the two optical waveguides of the second coupler are set based on splitting ratios of the first coupler and the second coupler, intensities of the third output light and the fourth output light, and wavelengths of the fifth output light and the sixth output light, such that the wavelength dependence of the splitting ratio of the first coupler is inversely related to the wavelength dependence of the splitting ratio of the second coupler, wherein the first MZI includes a third MZI formed at parallel portions of optical waveguides of the first MZI, the second MZI includes a fourth MZI formed at parallel portions of optical waveguides of the second MZI, and the input light is subjected to quadrature amplitude modulation (QAM).