Staggered Optical I/O Arrays for High Density Photonic Integration
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Solution Overview
Problem
Existing photonic integrated circuit (PIC) technologies face limitations in scalability and cost due to fixed optical input/output (I/O) density and inflexible optical interconnects, which restrict chip density and increase costs, especially when a large number of optical I/Os are required, and hinder wafer-scale automated testing.
Innovation Solution
The solution involves staggering two arrays of surface grating coupler optical I/O elements on a PIC chip, reducing the distance between neighboring elements to 68.5 μm while maintaining the standard 127 μm pitch, allowing for higher density and flexibility in optical interconnects by enabling connectivity from both sides without additional waveguide crossings, and incorporating an optical feedback alignment loop for efficient fiber array alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fibers and optical I/Os are arranged in an array configuration with standard pitch of 127 microns, then optical alignment efficiency is improved, but PIC chip density is limited and cost increases
Solution Approach 1:
The patent introduces a third dimension by implementing two-layer optical I/O arrays stacked vertically with alternating first and second optical I/O elements. This vertical stacking approach allows the system to maintain the standard 127 micron pitch for alignment compatibility while dramatically increasing the number of optical I/Os per chip by utilizing the z-dimension, thereby resolving the contradiction between alignment efficiency and chip density
Solution Approach 2:
The patent embeds two complete optical I/O arrays within the vertical space of what would traditionally be a single array plane. By nesting the first and second optical I/O elements in alternating positions across two layers, the system effectively doubles the I/O capacity within a compact footprint while maintaining compatibility with standard fiber array pitch requirements
2Adaptability or versatility
If the number of optical I/Os per chip is increased, then interconnect capability is improved, but optical I/O footprint becomes prohibitively expensive
Solution Approach 1:
By transitioning from a two-dimensional array expansion to a three-dimensional stacked architecture, the patent enables significant increases in interconnect capability without proportional increases in lateral footprint. The vertical stacking of alternating optical I/O elements allows hundreds of interconnects to be packed into a compact area, making high-capacity optical I/O arrays cost-effective
3Adaptability or versatility
If standard pitch of 127 microns is maintained for fiber array and GC optical I/Os, then compatibility is improved, but PIC chip density is limited
Solution Approach 1:
The patent resolves the compatibility-density contradiction by maintaining the standard 127 micron pitch within each layer while utilizing vertical stacking to achieve higher overall density. The alternating first and second optical I/O elements are positioned in the third dimension, allowing the system to preserve interface compatibility with standard fiber arrays while dramatically increasing the number of I/Os per chip through the vertical dimension
Data Source
AI summary
System and method embodiments are provided for high density on-chip optical input/output (I/O) arrays with partition waveguide routing topology. System and apparatus embodiments for on-chip optical I/O arrays provide for doubling the density of optical I/O arrays in a given footprint on a photonic integrated circuit (PIC) chip. System and apparatus embodiments for on-chip optical I/O arrays also provide waveguide routing topology to provide signal feedback to facility automated active alignment and coupling of optical fiber arrays in to surface grating coupler elements without use of waveguide crossings and without intersecting with waveguides connecting devices to I/O ports. In an embodiment, a PIC chip includes a plurality of first optical I/O elements and a plurality of second optical I/O elements, wherein a row of I/O elements comprises alternating ones of the first optical I/O elements and the second optical I/O elements.