| 摘要 |
PURPOSE:To obtain a branch type optical switch which can increase a variation of a refractive index and can enlarge a branch angle, by forming a multiple quantum well structure in a branch position of a waveguide, and also, providing a means for applying an electric field to this multiple quantum well structure. CONSTITUTION:A multiple quantum well structure 3Q is formed in a branch position of a waveguide, and also, a means for applying an electric field to the multiple quantum well structure 3Q is provided. In case of a state that an electric field is not applied to the multiple quantum well structure 3Q, a light beam which has reached the branch position transmits through this multiple quantum well structure and transmitted to one branch line, and in case of a state that the electric field has been applied to the multiple quantum well structure, said light beam is brought to a total reflection by an interface of the multiple quantum well structure area concerned, and transmitted to the other branch line. For instance, when an electric field in the vertical direction to the heterodyne junction interface is applied to the multiple quantum well structure consisting of InP/InGaAsP, etc., a refractive index variation of about 100 times of the case the same electric field has been applied to a homogeneous InGaAsP layer which has averaged this composition is obtained by a quantum confinement stark effect, therefore, the variation quantity of a critical angle increases remarkably, and a branch angle can be enlarged. |
