| 摘要 |
PURPOSE:To reduce the size of the element by specifying the element length about lengths to a Te mode and a TM mode which are required for the complete movement of waveguide light power from one of two close three- dimensional optical waveguides to the other optical waveguide. CONSTITUTION:On a (100) azimuth semiconductor substrate, a 1st semiconductor clad layer, a semiconductor waveguide layer, and a 2nd semiconductor clad layer are laminated, a directional coupler is composed of the two nearby three- dimensional optical waveguides which are formed on the semiconductor substrate, and a means which applies electric fields to them independently is provided. Denoting the lengths to the TE and TM modes which are required for the complete movement of the waveguide light power from one of the two nearby three-dimensional optical waveguides to the other optical waveguide as LTE and LTM, the element length L of the directional coupler is nearly equal to LTE and LTM is much longer than the element length L and LTE. Consequently, element size of <=1mm is obtained. |
