Optical waveguide modulator
First Claim
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1. A waveguide modulator, comprising:
- a substrate comprising electro-optical material that is responsive to a vertical electrical field normal to the substrate;
an optical splitting arrangement (OSA) formed in the substrate for splitting input light into four light portions;
an optical combining arrangement (OCA) formed in the substrate for combining a first two of the four light portions into first combined light and a second two of the four light portions into second combined light, wherein the OSA is spaced apart from the OCA for defining therebetween a first modulation section;
four optical waveguides formed in the substrate and extending optically in parallel between the OSA and the OCA traversing the modulation section for separately guiding the four light portions from the OSA to the OCA;
wherein two of the four optical waveguides comprise at least one domain inverted waveguide portion each and the other two of the four optical waveguides comprise at least one non-inverted waveguide portion each, wherein said domain inverted waveguide portions have an electro-optic domain structure that is inverted relative to an electro-optic domain structure of the non-inverted waveguide portions in the absence of external electrical field; and
,an RF signal electrode and two ground electrodes disposed upon the substrate in the first modulation section in the absence of other signal electrodes therein, wherein the RF signal electrode and the two ground electrodes are disposed for inducing an RF electrical field in the domain inverted portions of the two of the four optical waveguides and for inducing an RF electrical field in the non-inverted portions of the other two of the four optical waveguides so as to effect counter-phase modulation of the first and second combined light, whereby third-order modulation distortions in the first and second combined light have opposite signs for at least partially compensating each other, when the RF signal electrode is connected to a source of RF electrical signal.
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Abstract
The invention relates to waveguide optical modulators wherein two or more waveguides are modulated with specific modulation strengths using a single straight signal electrode or a single multi-segment signal electrode. Modulation strengths for each of a plurality of waveguides modulated by a single multi-segment electrode are matched over a wide modulation frequency range. Linearized output characteristics with respect to second and third order distortions arc achieved in one aspect of the invention.
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Citations
14 Claims
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1. A waveguide modulator, comprising:
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a substrate comprising electro-optical material that is responsive to a vertical electrical field normal to the substrate; an optical splitting arrangement (OSA) formed in the substrate for splitting input light into four light portions; an optical combining arrangement (OCA) formed in the substrate for combining a first two of the four light portions into first combined light and a second two of the four light portions into second combined light, wherein the OSA is spaced apart from the OCA for defining therebetween a first modulation section; four optical waveguides formed in the substrate and extending optically in parallel between the OSA and the OCA traversing the modulation section for separately guiding the four light portions from the OSA to the OCA; wherein two of the four optical waveguides comprise at least one domain inverted waveguide portion each and the other two of the four optical waveguides comprise at least one non-inverted waveguide portion each, wherein said domain inverted waveguide portions have an electro-optic domain structure that is inverted relative to an electro-optic domain structure of the non-inverted waveguide portions in the absence of external electrical field; and
,an RF signal electrode and two ground electrodes disposed upon the substrate in the first modulation section in the absence of other signal electrodes therein, wherein the RF signal electrode and the two ground electrodes are disposed for inducing an RF electrical field in the domain inverted portions of the two of the four optical waveguides and for inducing an RF electrical field in the non-inverted portions of the other two of the four optical waveguides so as to effect counter-phase modulation of the first and second combined light, whereby third-order modulation distortions in the first and second combined light have opposite signs for at least partially compensating each other, when the RF signal electrode is connected to a source of RF electrical signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification