| 摘要 |
PROBLEM TO BE SOLVED: To modulate the unabsorbed part of optical signals before electric signals come out of a waveguide layer by successively depositing multiple layers upon another including the waveguide layers. SOLUTION: Epitaxial layers 32-41 are successively deposited upon another on a semi-insulating InP substrate 31. The first layer 32 is composed of an n<-> -doped InP layer and works as an electrical contact layer for its overlying layer 33. The layer 33 is made of such a material that the band end of the material shifts as the function of an impressed electric field and, when no electric field is impressed, the layer 33 is selected so that the layer 33 hardly absorb 1.55-μm optical signals propagated through the layer 33 in the X-direction. When a Y-direction electric field of a specific value is impressed upon part of the layer 33, the layer 33 absorbs most of 1.55-μm optical signals horizontally propagated through the layer 33. In this case, the optical signals introduced to the Y-Z plane at one end of the layer 33 are not discharged practically from the other end of the layer 33. Thus electric signals can be used for modulating the optical signals propagated through the layer 33. The material of the layer 33 can be, for example, an n<-> -doped In0.65 Ga0.35 As0.7 P0.3 . |
