Reflective Grating Couplers for Si-PIC Optical Alignment
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Solution Overview
Problem
The existing optical coupling methods between silicon photonic integrated circuit (Si-PIC) chips and optical fibers are inefficient due to misalignment between the Si-PIC chip and the XYZ stage, requiring significant time and effort for alignment.
Innovation Solution
The method involves using pairs of reflective grating couplers (RGCs) on the Si-PIC chip to identify optimal coordinate pairs for maximum optical coupling, determining angles between the stages and the chip, and generating lookup tables to correct alignment, allowing for faster and more precise optical fiber positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional XYZ stage alignment is used, then optical coupling can be achieved, but alignment time and effort increase significantly due to misalignment between chip and stage
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing lookup tables (LUTs) that map between chip coordinate systems and stage coordinate systems. These LUTs are generated in advance based on the known geometric relationship between the chip and stage, allowing for rapid alignment without time-consuming real-time calculations during the actual coupling process.
Solution Approach 2:
The patent uses coordinate transformation matrices to create a virtual copy or representation of the chip's coordinate system in the stage's coordinate system. By maintaining this transformed coordinate mapping through lookup tables, the system can quickly determine positions without physically re-aligning the stage for each measurement, thus reducing alignment time while preserving precision.
2Productivity
If manual alignment procedures are used, then coupling can be performed, but the process requires significant effort and is inefficient
Solution Approach 1:
The patent implements self-service by enabling the system to automatically determine and correct alignment parameters using pre-stored lookup tables. The coordinate transformation is performed automatically based on the relationship between chip and stage coordinate systems, eliminating the need for manual adjustment and significantly reducing operator effort while improving productivity.
Solution Approach 2:
The patent replaces manual mechanical alignment adjustments with an automated computational approach using lookup tables and coordinate transformations. Instead of physically adjusting the stage position for each alignment, the system uses pre-calculated coordinate mappings to automatically determine correct positions, substituting mechanical operations with computational processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves the speed and accuracy of optical alignment, reducing the time and effort required for alignment and enhancing the efficiency of optical coupling between the Si-PIC chip and optical fibers.
Implementation Method 1
identifying, by using a pair of first reflective grating couplers (RGCs) disposed on a silicon photonics chip
Data Source
AI summary
An optical coupling method and apparatus are disclosed. The optical coupling method improve the speed of optical alignment between an optical fiber and a grating coupler (GC) of an optical coupling apparatus for a characteristic test of a silicon photonic integrated circuit (Si-PIC) chip by using a reflective grating couplers disposed on the Si-PIC chip.