| 摘要 |
PURPOSE:To allow an operation on a low voltage and to enhance the coupling efficiency to an optical fiber by forming an optical waveguide into a specific structure. CONSTITUTION:Light propagates mainly in the optical waveguide layer constituted of a low impurity concn. compd. semiconductor layer 35a of a 1st conduction type, a high impurity concn. compd. semiconductor layer 35b of the 1st conduction type, an intrinsic compd. semiconductor layer 35c, a high impurity concn. compd. semiconductor layer 35d of a 2nd conduction type, and a low impurity concn. compd. semiconductor layer 35e of the 2nd conduction type. Further, a depletion layer spreads mainly to the laminate part constituted of the compd. semiconductor layers 35b, 35c and 35d and electric fields can be concentrated to this laminate part when, for example, a 2nd electrode 41b and a common electrode 43 and grounded and a voltage is impressed to the 1st electrode 41a. The film thickness of both of either of the compd. semiconductor layers 35a and 35e is merely necessitated to increase the coupling to the optical fiber in this way and since the electric field intensity for the purpose of switching of the optical switch is assured, the operating voltage is lowered. |
