High confinement waveguide on an electro-optic substrate

Abstract

The invention relates to an optical device including a passive high confinement waveguide, such as of silicon-rich silicon nitride, on an electro-optic substrate, like lithium niobate, optically coupled to a waveguide in the electro-optic substrate. A wide range of electro-optic devices are enabled by this high confinement waveguide structure, including: directional couplers, compact tap couplers, folded electro-optic devices, electro-optic modulators including ring resonators, electro-optic gratings. Further applications enabled by the present invention include hybrid passive planar lightwave circuits (PLC) integrated with electro-optically active waveguides, using the high confinement waveguide as an intermediary waveguide to transfer optical power between the passive and active components.

Description

TECHNICAL FIELD[0001]The present invention relates to an optical device including a passive high confinement waveguide, such as of silicon-rich silicon nitride, on an electro-optic substrate, like lithium niobate, optically coupled to a waveguide in the electro-optic substrate. A wide range of electro-optic devices are enabled by this high confinement waveguide structure, including: directional couplers, compact tap couplers, folded electro-optic devices, electro-optic modulators including ring resonators, electro-optic gratings. Further applications enabled by the present invention include hybrid passive planar lightwave circuits (PLC) integrated with electro-optically active waveguides, using the high confinement waveguide as an intermediary waveguide to transfer optical power between the passive and active components.BACKGROUND OF THE INVENTION[0002]A high confinement waveguide for use on electro-optic substrates is highly desirable for its ability to increase the bend radius of ...

AI Technical Summary

Benefits of technology

[0017]The present invention has found that significant advantage can be obtained by creating high confinement waveguides directly on the electro-optic substrate, such as with SiN:Si on lithium niobate coupled to diffused waveguides such as Ti, or other waveguides within the electro-optic substrate, such as annealed proton exchange (APE) waveguides, in order to reduce the mode size for portions of the waveguide circuit. Generally, the high confinement waveguide will not be the only waveguide in the electro-optic device, because only the tail of the optical mode is transmitted through the electro-optic material in a high confinement waveguide. Consequently, the electro-optic effect is limited. This is acceptable for certain applications. It is preferred to combine the high confinement waveguide for small bend radius areas with Ti diffused waveguides for straight sections and for better mode size matching to optical fiber. Alternatively, a hybrid waveguide in which a high confinement core is coincident with a diffused waveguide of similar refractive indices can be created to provide optical transmission in the electro-optic substrate with a smaller mode size.

Problems solved by technology

Consequently, the electro-optic effect is limited.

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