Optical device having electro-optic silicon modulator on large core fin waveguide and method to make the same

摘要

An optical modulator device made on large core silicon fin waveguide platform and its fabrication methods. The optical device includes two silicon optical coupling waveguides each having a lower ridge and an upper ridge, two mode transformers respectively connecting the coupling waveguides with an optical modulator waveguide. The optical modulator waveguide has a silicon fin waveguide structure with a narrower fin structure on top of a wider lower ridge structure. Each coupling waveguide and the corresponding mode transformer form a two-stage horizontal taper structure, namely a taper in the lower ridge of the coupling waveguide and a taper of the mode transformer. The light travelling in the coupling waveguide with majority of light in the upper ridge can gradually shift to the lower ridge of the optical modulator where an electro-optic region is positioned. The electro-optic region changes its optical property in response to an applied electric field.

主权项

1. An optical device, comprising:
a silicon on insulator substrate; a silicon optical coupling waveguide on the substrate for coupling light in or out of the optical device, the optical coupling waveguide being configured to guide a light in a form of optical mode, the optical coupling waveguide having a double-ridge structure including a lower ridge with a first width and an upper ridge on top of the lower ridge with a second width which is narrower than the first width; a silicon fin optical modulator on the substrate, having a double-ridge structure including a lower ridge and a tall and narrow fin structure on top of the lower ridge, the optical modulator including an electro-optic modulation region inside the lower ridge, the optical modulator being configured to guide a light with a majority portion of the light confined inside the lower ridge, at least a portion of the light overlapping with the electro-optic modulation region, the optical modulator including field source regions configured to sandwich the electro-optic region to apply an electric field across the electro-optic region, wherein at least one optical property of the electro-optic region changes in response to the electric field applied to the electro-optic region; and a silicon mode transformer on the substrate for optically and physically connecting the optical coupling waveguide and the optical modulator.