Optical waveguides – Temporal optical modulation within an optical waveguide – Electro-optic
Reexamination Certificate
2000-12-15
2003-03-25
Font, Frank G. (Department: 2877)
Optical waveguides
Temporal optical modulation within an optical waveguide
Electro-optic
C385S003000, C385S004000, C385S005000, C385S008000, C385S009000, C385S014000, C385S015000
Reexamination Certificate
active
06539130
ABSTRACT:
BACKGROUND OF THE INVENTION
1 Field of the Invention
The present invention relates to traveling wave optical modulators.
2 Related Art Statement
NGK Insulators, Ltd. reported in JP-A 10-133,159 that a traveling wave optical modulator was successfully operated at not less than 10 GHz by providing a thinner portion in a substrate of the modulator under an optical waveguide and setting the thickness of this thinner portion to not more than 10 &mgr;m, while providing no buffer layer made of silicon oxide or the like. In this manner, the optical waveguide substrate advantageously comprises such thick and thinner portions, because optical modulation is possible at high speeds without the formation of the buffer layer, a DC drift originating from the buffer layer can be avoided, and a product (V&pgr;·L) between a driving voltage V&pgr; and the length L of an electrode can be reduced.
However, NGK more specifically examined traveling wave optical modulators of this type, and then found that light absorption loss sometimes occurred in the optical waveguide. Particularly when the optical waveguides of the Mach-Zehnder type is formed, it is necessary that the optical waveguide is branched into two lines, and that lights, which come out from the branched optical waveguides are coupled together again, so that the absorption loss in each of the branched optical waveguide needs to be the same. However, the absorbing loss of one branched optical waveguide actually differed from that of the other, which might result in reduction in the extinction ratio.
SUMMARY OF THE INVENTION
It is an object of the present invention to suppress the absorption loss of the light in the optical waveguide in the traveling wave optical modulator, which can effect optical modulation at a high speed, and reduce a DC drift and a product (V&pgr;·L) between a driving voltage V&pgr; and the length L of an electrode.
The present inventors succeeded in suppressing the absorption loss in a traveling wave optical modulator, by constructing the modulator from (a) an optical waveguide substrate made of an electro-optic and ferrodielectric single crystal in the form of an X- or Y-orientation plate_and comprising a thicker portion having a larger thickness and a thinner portion having a smaller thickness; (b) first and second branched optical waveguide portions formed at least on the thinner portion of the optical waveguide substrate; (c) a set of electrodes provided on at least the thinner portion of the substrate and adapted for applying voltage to the first and second optical waveguide portions to modulate a light propagating the optical waveguide portions; and (d) a buffer layer provided to cover a part of the optical waveguide portions at the thinner portion of the substrate, the electrodes crossing on the buffer layer.
REFERENCES:
patent: 6069729 (2000-05-01), Gill et al.
patent: 6167169 (2000-12-01), Brinkman et al.
patent: 6198855 (2001-03-01), Hallemeier et al.
patent: 6219469 (2001-04-01), Minakata et al.
patent: 6226423 (2001-05-01), Minakata et al.
patent: 6341031 (2002-01-01), McBrien et al.
patent: 0 485 993 (1992-05-01), None
patent: 0 828 175 (1998-03-01), None
patent: 10-133159 (1998-05-01), None
U. S. Patent application Ser. No. 09/636,568, Kondo et al., filed Aug. 27, 2000.
U.S. Patent application Ser. No. 09/738,176, Kondo et al., filed Dec. 15, 2000.
Patent Abstracts of Japan, vol. 11, No. 026 (P-539), Jan. 24, 1987 & JP 61 198133 A (Fujitsu Ltd), Sep. 2, 1986 *abstract*.
Patent Abstracts of Japan, vol. 016, No. 540 (P-1450), Nov. 10, 1992 & JP 04 204815 A (Matsushita Electric Ind. Co. Ltd.), Jul. 27, 1992 *abstract*.
Bulmer, C.H. et al.; “Phase Tuning of LiNbO3Interferometric Modulators by Laser Ablation,” Integrated Photonics Research, Technical Digest Series, U.S. Washington, DC, vol. 8, p. 63.
Aoki Kenji
Kondo Atsuo
Kondo Jungo
Burr & Brown
Font Frank G.
Mooney Michael P.
NGK Insulators Ltd.
LandOfFree
Traveling wave optical modulators does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Traveling wave optical modulators, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Traveling wave optical modulators will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3062496