| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small and highly sensitive electric field sensor head which has a dipole antenna formed on the surface of a substrate while the tip of the antenna is made flush with the side end of the surface of the substrate. SOLUTION: A substrate 1 comprises a Z plate of a lithium niobate crystal exhibiting an electrooptical effect and is approx. 100mm long, 10mm wide and 0.5∥mm thick. A branch interference type lightwave guide about 8μm wide, namely, an incoming lightwave guide 2, a 2-phase shift lightwave guide 3 and an oytgoing lightwave guide 4 are formed on the surface of the substrate 1. Moreover, a modulation electrode 5 is formed on the lightwave guide 3. A diapole antenna 6 is formed on the surface of the substrate 1 integral with the electrode 5 and is extended vertically to the lightwave guide 3 to make the tip thereof positioned at the side end of the substrate 1 in substance. Thus, the antenna 6 is exposed to the intensity of an electric field close to a space electric field maintaining the feature in a small size thereby obtaining a highly sensitive electric field sensor head.
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