| 摘要 |
PROBLEM TO BE SOLVED: To simplify the constitution of a device which utilizes different wavelength bands and to reduce a manufacturing cost by modulating the single mode light of at least two wavelength bands in the same element. SOLUTION: The main surface of a substrate 1 is provided with a silica insulating film 4 in order to prevent the absorption of light by control electrodes 3 which are metallic electrodes for impressing electric fields on the optical waveguide forming parts of the substrate 1. The control electrodes 3 are formed by electroplating etc., in the position facing the optical waveguides 2 on this insulating film 4. In such a case, the optical waveguides 2 are approximately composed of titanium diffused regions 2b including high-refractive index regions 2a and the high-refractive index regions 2a and the titanium diffused regions 2b are so adequately set that the light propagating in the plural wavelength bands to be used attains the single mode. As a result, the manufacture of the optical waveguides 2 in such a manner that the single mode is attained for the respective wavelength bands to be used is made possible. The integration of the single mode optical modulators which are heretofore separately designed and manufactured to one is made possible. |
