| 摘要 |
PURPOSE:To control a spot size in the horizontal direction, by providing multiple quantum well structures on two sides in the lateral direction of a waveguide layer of a three-dimensional optical waveguide and controlling the refractive index of the waveguide layer by means of electrodes facing each other in the direction vertical to the base body. CONSTITUTION:Multiple quantum well structures 2 are provided on both sides of a homogeneous waveguide layer 4 in the lateral direction and electrodes 7 and 8 are provided on both sides of the layer 4 in the vertical direction. When an electric field is impressed in the direction normal to the well structures, the refractive index of the waveguide layer 4 decreases in accordance with the intensity of the impressed electric field, but the quantity of the variation becomes by far the larger as compared with a homogeneous semiconductor layer whose composition corresponds to the mean value of the refractive index. Therefore, the distribution of refractive index in the horizontal direction over the waveguide layer 4 and multiple quantum well structures 2, which controls a spot side in the horizontal direction, can be controlled effectively by the voltage impressed across the electrodes 7 and 8. |
