| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical modulator which has a high-performance optical modulation characteristic and has improved stability. SOLUTION: The optical modulator includes: a z-cut LN substrate 1; an optical waveguide 3 formed on the substrate; an SiO<SB>2</SB>buffer layer 2 formed on the upper side of the substrate; a conductive layer 5 laminated on the SiO<SB>2</SB>buffer layer; and a traveling wave electrode 4 which is disposed on the upper side of the conductive layer and includes a center conductive body 4a and earth conductive bodies 4b, 4c; wherein the traveling wave electrode is composed of a modulation part 17 of modulating a phase of light that is guided through the optical waveguide, an input part 18 and an output part 19, and ridge parts 45, 46 are formed with recessed parts 31, 32, 33 which are disposed by digging down at least a part of the area where electric field strength of a high-frequency electric signal propagated through the modulation part is strong on the substrate. Therein, the substrate has recessed parts 34, 35 formed by digging down at least a part between the center conductive body and the earth conductive bodies on the input part and the output part. COPYRIGHT: (C)2009,JPO&INPIT
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