Passively-aligned fiber array to waveguide configuration
Passive alignment and connection between a fiber array and a plurality of optical waveguides terminating along an edge of a photonic IC (PIC) is provided by a controlled mating between alignment V-grooves formed in a fiber array support substrate and extra-array alignment ridges formed beyond the extent of a waveguide array integrated within the PIC. The height and width of the alignment ridges are formed to engage with the alignment V-grooves upon mating of the fiber array substrate with the PIC, providing passive alignment while maintaining a physical gap spacing g between the components (ensuring the integrity of the passive alignment).
1. An interconnection arrangement providing passive alignment between an array of N optical fibers and an array of N optical waveguides, the interconnection arrangement comprising:
a photonic integrated circuit (PIC) including
an optical substrate having a top planar major surface and adjoining planar side edge surfaces;
the array of N optical waveguides formed as an integrated element and disposed on the top planar major surface of the optical substrate, terminating at a selected adjoining planar side edge surface thereof, and
a plurality of M extra-array alignment ridges disposed on the top planar major surface of the optical substrate and terminating at the selected adjoining planar side edge surface thereof, the plurality of M extra-array alignment ridges positioned beyond the extent of the array of N optical waveguides, where each extra-array alignment ridge exhibits a defined height h; and
a fiber array substrate including
an array of N fiber-supporting V-grooves formed in a top surface thereof, and
a plurality of M extra-array alignment V-grooves disposed to engage with the plurality of M extra-array alignment ridges in a one-to-one relationship and provide passive alignment between the array of N optical waveguides and the array of N optical fibers, the fiber array substrate positioned over the top planar major surface of the PIC to overlap the plurality of M extra-array alignment ridges such that each extra-array alignment V-groove engages with its associated extra-array alignment ridge, with a pair of upper corners of each extra-array alignment ridge contacting inner sidewalls of the associated extra-array alignment V-groove at a location that creates alignment between a core region of an optical fiber supported within the associated V-groove and the optical waveguide integrated within the PIC so as to provide passive alignment between the array of N optical fibers and the array of N optical waveguides, with the alignment ridge height h selected to ensure that a gap spacing g remains between the top surface of the fiber array substrate and the top planar major surface of the PIC upon engagement of the plurality of M alignment V-grooves with the plurality of M extra-array alignment ridges.
2. The interconnection arrangement as defined in claim 1 wherein the plurality of N fiber-supporting V-grooves and the plurality of M extra-array alignment V-grooves terminate at a same depth D below the top surface of the fiber array substrate.
3. The interconnection arrangement as defined in claim 2 wherein the plurality of N fiber-supporting V-grooves and the plurality of M extra-array alignment V-grooves comprise etched V-grooves positioned to exhibit a defined pitch for the plurality of N fiber-supporting V-grooves and a defined position of each extra-array alignment V-groove of the plurality of M extra-array alignment V-grooves.
4. The interconnection arrangement as defined in claim 3 wherein the fiber array substrate comprises a silicon material.
5. The interconnection arrangement as defined in claim 1 wherein the plurality of M extra-array alignment ridges comprises a first alignment ridge disposed beyond a first waveguide of the plurality of N optical waveguides and a second alignment ridge disposed beyond a last waveguide of the plurality of N optical waveguides.
6. The interconnection arrangement as defined in claim 1 wherein the plurality of N optical waveguides are formed as a monolithic, integrated optical component across the top planar major surface of the PIC, the monolithic, integrated optical component defined as having opposing first and second side edges beyond the extent of the array of N optical waveguides as formed therein.
7. The interconnection arrangement as defined in claim 6 wherein the monolithic, integrated optical component exhibits a width w such that an interior edge of a first fiber supporting V-groove of the plurality of N fiber-supporting V-grooves is positioned in physical contact with the first side edge of the monolithic, integrated optical component.
8. The interconnection arrangement as defined in claim 7 wherein an interior edge of a final, N th supporting V-groove of the plurality of N fiber-supporting V-grooves is positioned in physical contact with the second side edge of the monolithic, integrated optical component.
9. The interconnection arrangement as defined in claim 1 wherein M≥2.
10. The interconnection arrangement as defined in claim 1 wherein the plurality of N fiber-supporting V-grooves terminate at a first depth below a top surface of the fiber array substrate and the plurality of M extra-array alignment V-grooves terminate at a second depth below a top surface of the fiber array substrate.
11. The interconnection arrangement as defined in claim 1 wherein
the array of N fiber-supporting V-grooves extends across a portion of the fiber array substrate, terminating before a proximal end portion of the fiber array substrate; and
the plurality of M extra-array alignment V-grooves extend fully across the fiber array substrate including the proximal end portion thereof.