Abstract: Herein disclosed is an optical modulator, having: a substrate (1); and a center and ground electrodes (4a to 4c), in which the substrate has ridge portions (8a to 8c), the center and ground electrodes are respectively formed above the ridge portions, the ridge portions below the center and ground electrodes respectively have top parts (10a, 10b) having a respective first and second end points (18, 19) separated with a distance of “WR”, the substrate has a bottom surface (21b) between the ridge portions having center and midway points (23, 24) positioned with a respective distance of WR/2 and WR/N (3?N?25) from the first end point, the ridge portion below the center electrode has a normal line (13), and the center point and the midway point define a straight line (25) crossed with the normal line at an angle larger or equal to 90.1°.

Abstract: In an optical modulator comprising substrate 1 having electro-optical effect, two optical waveguides 3a, 3b formed in the substrate, buffer layer 2 formed on the substrate, traveling-wave electrode 4 having center conductor 4a and ground conductors 4b, 4c above the buffer layer, and ridge sections formed with recessed sections 9a to 9c by carving at least a part of the substrate where an electrical field strength of high-frequency electrical signal propagating the traveling-wave electrode is strong, in which the ridge sections include center conductor ridge section 8a having the center conductor formed above and ground conductor ridge section 8b having the ground conductor formed above, and the center conductor ridge section has one of the two optical waveguides formed therein, the recessed sections are practically symmetrical to the center line between the two optical waveguides and the traveling-wave electrode is practically symmetrical to the center line of the center conductor.

Abstract: An optical modulator, including: a substrate; an optical waveguide embedded in the substrate; a traveling wave electrode mounted on the substrate and having a traveling wave applied thereon so that a light wave is modulated by the traveling wave with an electro-optic effect. The traveling wave electrode includes a center electrode and ground electrodes; in which the optical waveguide has a plurality of interaction optical waveguides that form a Mach-Zehnder optical waveguide that modulates the light wave in a phase modulation manner when the traveling wave is applied to the traveling wave electrode, the interaction optical waveguides form a region where respective widths of the interaction optical waveguides are different from each other, and the center electrode and the ground electrodes are positioned such that interaction efficiencies between the high frequency electric signal and the light wave guided in the respective interaction optical waveguides are substantially equal to each other.

Abstract: A technical problem related to a traveling wave electrode type of optical modulator comprising a substrate having the electro-optical effect, optical waveguides formed in the substrate, and a traveling wave electrode formed above the substrate includes improvement of the characteristics such as optical modulation bandwidth, driving voltage, and characteristic impedance of the traveling wave electrode type of optical modulator. To solve the problem, the structure of ridge portions is optimized which is formed in such a manner that a part of the substrate at regions where electric field generated by a high frequency electric signal traveling through the traveling wave electrode is strong is reduced in thickness by digging. Further, a buffer layer is formed over the substrate where the ridge portions are formed and a conducting layer is formed over the buffer layer.

Abstract: In an optical modulator comprising substrate 1 having electro-optical effect, two optical waveguides 3a, 3b formed in the substrate, buffer layer 2 formed on the substrate, traveling-wave electrode 4 having center conductor 4a and ground conductors 4b, 4c above the buffer layer, and ridge sections formed with recessed sections 9a to 9c by carving at least a part of the substrate where an electrical field strength of high-frequency electrical signal propagating the traveling-wave electrode is strong, in which the ridge sections include center conductor ridge section 8a having the center conductor formed above and ground conductor ridge section 8b having the ground conductor formed above, and the center conductor ridge section has one of the two optical waveguides formed therein, the recessed sections are practically symmetrical to the center line between the two optical waveguides and the traveling-wave electrode is practically symmetrical to the center line of the center conductor.

Abstract: Herein disclosed is an optical modulator, comprising: an optical waveguide (3); and a traveling wave electrode (4) including an interaction portion (9) for modulating a phase of incident light and an input feed-through portion (7), in which the optical modulator further comprises at least one impedance transformation portion for reducing an impedance mismatching between a characteristic impedance of the interaction portion and at least one of characteristic impedances of the input feed-through portion, a connector electrically connected to the input feed-through portion, and an external circuit, at least one of the impedance transformation portions has a characteristic impedance which is different from a geometric mean of the characteristic impedances of said interaction portion and said input feed-through portion, a geometric mean of the characteristic impedances of the interaction portion and the connector, or a geometric mean of the characteristic impedances of the interaction portion and the external circ

Abstract: Herein disclosed is an optical modulator, comprising: a substrate (1) having an electro-optic effect; an optical waveguide (3) formed in the substrate; a traveling wave electrode (4) including a center electrode (4a) and ground electrodes (4b, 4c) to have a high frequency electric signal applied thereto, the traveling wave electrode and the optical waveguide collectively forming a high frequency interaction portion (20) to have the incident light phase modulated under the condition that the high frequency electric signal is applied to the traveling wave electrode; and bias electrodes each including a center electrode (22a, 23a) and ground electrodes (22b, 22c, 23b, 23c) to have a bias voltage applied thereto, each of the bias electrodes and the optical waveguide collectively forming a bias voltage interaction portion (19, 21) to have the incident light phase modulated under the condition that the bias voltage is applied to the bias electrode, in which the traveling wave electrode and the bias electrodes are e

Abstract: Herein disclosed is an optical modulator, having: a substrate (1); and a center and ground electrodes (4a to 4c), in which the substrate has ridge portions (8a to 8c), the center and ground electrodes are respectively formed above the ridge portions, the ridge portions below the center and ground electrodes respectively have top parts (10a, 10b) having a respective first and second end points (18, 19) separated with a distance of “WR”, the substrate has a bottom surface (21b) between the ridge portions having center and midway points (23, 24) positioned with a respective distance of WR/2 and WR/N ( 3 ?N?25 ) from the first end point, the ridge portion below the center electrode has a normal line (13), and the center point and the midway point define a straight line (25) crossed with the normal line at an angle larger or equal to 90.1°.

Abstract: Herein disclosed is an optical modulator, comprising: a substrate (1) having an electro-optic effect; an optical waveguide (3) formed in the substrate; a traveling wave electrode (4) including a center electrode (4a) and ground electrodes (4b, 4c) to have a high frequency electric signal applied thereto, the traveling wave electrode and the optical waveguide collectively forming a high frequency interaction portion (20) to have the incident light phase modulated under the condition that the high frequency electric signal is applied to the traveling wave electrode; and bias electrodes each including a center electrode (22a, 23a) and ground electrodes (22b, 22c, 23b, 23c) to have a bias voltage applied thereto, each of the bias electrodes and the optical waveguide collectively forming a bias voltage interaction portion (19, 21) to have the incident light phase modulated under the condition that the bias voltage is applied to the bias electrode, in which the traveling wave electrode and the bias electrodes are e

Abstract: Herein disclosed is an optical modulator, comprising: a substrate 1 having an electro-optic effect; an optical waveguide 12 embedded in the substrate 1 to have a light wave guided therein; a traveling wave electrode 4 mounted on the substrate 1 to have a traveling wave applied thereon so that the light wave is modulated by the traveling wave with the electro-optic effect, the traveling wave electrode being constituted by a center electrode 4a and ground electrodes 4b, 4c; in which the optical waveguide has a plurality of interaction optical waveguides 12a, 12b to collectively form a Mach-Zehnder optical waveguide operative to modulate the light wave in a phase modulation manner under the condition that the traveling wave is applied to the traveling wave electrode, the interaction optical waveguides 12a, 12b collectively form a region where respective widths of said interaction optical waveguides are different from each other, and the center electrode 4a and the ground electrodes 4b, 4c are positioned such tha