Fiber Optic Coupling to Planar Grating via Folding Optic
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Solution Overview
Problem
Current methods for coupling light between optical fibers and planar grating waveguide couplers on photonic integrated circuits face challenges in achieving efficient coupling while maintaining a low packaging height and proper optical parameters.
Innovation Solution
The use of single-mode optical fibers with integrated lenses and a folding optic, along with chirped gratings and a transponder module with multiple surface grating couplers, allows for efficient light coupling and reduced packaging height by redirecting light with a turning mirror and focusing it onto the bottom of the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional coupling methods are used, then coupling efficiency is achieved, but packaging height increases
Solution Approach 1:
The patent redirects light propagation from a vertical path to a horizontal path using a folding optic and turning mirror. This dimensional change allows the light to travel along the bottom of the assembly rather than vertically through the packaging, significantly reducing packaging height while maintaining coupling efficiency through the grating couplers.
Solution Approach 2:
The patent introduces a folding optic and turning mirror as intermediary elements between the optical fiber and the grating coupler. These intermediaries redirect and focus the light path, enabling efficient coupling while accommodating the low-profile packaging requirement by bending the light path horizontally at the bottom of the assembly.
2Adaptability or versatility
If standard grating couplers are used, then device simplicity is maintained, but optical bandwidth is limited
Solution Approach 1:
The patent employs chirped gratings where the grating period varies locally across the structure. This local variation in grating period allows different wavelengths of light to be coupled at different positions, thereby expanding the optical bandwidth. The chirped characteristic creates a wavelength-dependent coupling profile that accommodates broader spectral ranges.
Solution Approach 2:
The patent changes the physical parameter of the grating period across the grating structure to create a chirped profile. By systematically varying the grating period parameter, the device achieves enhanced optical bandwidth while maintaining a relatively simple overall grating coupler architecture without requiring complex additional components.
3Productivity
If multiple fibers are coupled without integration, then individual coupling is achieved, but assembly complexity increases
Solution Approach 1:
The patent merges multiple single-mode fibers with integrated lenses into a single optical mechanical assembly. The folding optic and turning mirror are shared resources that serve all fibers in the assembly, redirecting light from multiple fibers to multiple grating couplers on the photonic integrated circuit. This consolidation reduces overall complexity compared to individual coupling mechanisms for each fiber.
Solution Approach 2:
The turning mirror and folding optic serve universal functions for all fibers in the assembly simultaneously. A single turning mirror redirects light from multiple fibers toward the bottom of the assembly, and a single set of grating couplers handles multiple wavelength channels. This multi-functionality reduces the number of discrete components needed compared to individual fiber coupling solutions.
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 enhances the efficiency of light coupling, reduces packaging height, and allows for a wider optical bandwidth, addressing the limitations of prior techniques by integrating lenses and chirped gratings with a compact and mechanically stable design.
Implementation Method 1
A single-mode optical fiber having an integrated lens
Implementation Method 2
A single turning mirror is employed to redirect the light toward a bottom of the assembly
Implementation Method 3
a grating exhibiting a chirped characteristic such that light is more efficiently coupled from an optical fiber in a diverging optical field
Data Source
AI summary
Techniques, methods, structures and apparatus that provide the efficient coupling of light to/from one or more optical fibers to/from planar grating waveguide couplers positioned on photonic integrated circuits.