| 摘要 |
PROBLEM TO BE SOLVED: To provide a small and low power consuming light modulator that easily generates intensity modulation by push-pull operation using a single modulation power source.SOLUTION: A light modulator of the present invention is a Mach-Zehnder light modulator including a first waveguide on a semiconductor substrate, a second waveguide, a p-type clad layer and an n-type clad layer. The first waveguide includes a first modulation region and the second waveguide includes a second modulation region. The first modulation region and the second modulation region each has, as a core, a modulation layer which is an n-doped impurity layer. A modulation operation is performed by applying a first bias voltage to the first modulation region and a second bias voltage to the second modulation region and by further applying a modulation voltage to the first modulation region and the second modulation region. The first bias voltage and the second bias voltage are set in such a manner that refractive indices of the first waveguide and the second waveguide change in a direction opposite with respect to the application direction of the modulation voltage. |
