| 摘要 |
PURPOSE:To provide the optical modulator of low loss and low voltage driving by forming a single mode waveguide structure consisting of an org. high-polymer material exhibiting a high primary electrooptical effect. CONSTITUTION:This optical modulator has the structure disposed with a coplanar electrode 11 consisting of metal on the uppermost part (or oxide silicon film of the lower part) and is constituted by using the org. high-polymer material exhibiting the primary electrooptical effect as the material of core layers 8, optimizing the difference in the specific refractive index from the materials of the ambient clad layers 7, 9, 10 to constitute the single mode waveguides and providing the surface of the silicon oxide layer (or upper clad layer) in the lower part with another grounding electrode 6. The confinement of electric fields is thereby increased and the modulation operation with the low voltage is executed. Then, the org. high-polymer material having the high primary electrooptical effect is used as the material of the waveguide layer and the difference in the specific refractive index from the material of the ambient clad layers is optimized to form the single mode waveguide. In addition, the grounding electrode 6 is separately provided in order to increase the confinement of the electric fields of coplanar line type electrodes 11. Further, the spacing between the upper and lower electrodes is narrowed and, therefore, the modulation operation is executed with the extremely low driving voltage. |
