Tilted Si Photonic Waveguide for High-Density Optical Module Packaging
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Solution Overview
Problem
Conventional Si photonic lightwave circuits face challenges in high-density packaging due to large optical coupling loss and space constraints when connecting fine optical waveguides to standard optical fibers, requiring significant spacing between modules to accommodate the curvature of optical fibers.
Innovation Solution
The optical waveguides in the Si photonic lightwave circuit are tilted at an oblique angle with respect to the output end surface, and the optical fiber array is fixed at the same angle, allowing for a shift in the position of the waveguides and fibers to reduce the inter-package gap, along with the use of spot size increasing portions to enhance coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the optical waveguide is tilted at an oblique angle and the optical fiber array is fixed at the same angle, then the inter-package gap is reduced enabling high-density packaging, but the alignment precision between waveguide and fiber becomes more difficult to maintain
Solution Approach 1:
The patent applies asymmetry by tilting the optical waveguide at an oblique angle (5-45 degrees) relative to the normal of the end surface, and correspondingly tilting the optical fiber array at the same angle. This asymmetric configuration allows the optical fibers to route around package modules more efficiently, reducing the inter-package gap from conventional values to enable high-density packaging while maintaining optical coupling efficiency through matched tilt angles.
Solution Approach 2:
The patent introduces a dimensional change by shifting the center of the optical waveguide on the end surface from the center of the package module side surface in the direction of the tilt. This positional shift in the lateral dimension, combined with the angular tilt, creates an optimized spatial arrangement that reduces the required inter-package spacing while maintaining proper optical alignment.
2Volume of moving object
If the Si core optical waveguide is made finer to reduce device size, then the miniaturization is achieved, but the optical coupling loss increases significantly
Solution Approach 1:
The patent addresses the coupling loss issue by changing the mode field diameter parameter of the optical waveguide. A spot size increasing portion is introduced to enlarge the mode field diameter at the output end of the fine Si core waveguide, making it more compatible with standard optical fibers. This parameter change allows the waveguide to maintain its small size while improving optical coupling efficiency to acceptable levels.
3Ease of manufacture
If the optical waveguide output end surface is made perpendicular to the side surface for simple connection, then the manufacturing is simplified, but the optical fiber routing space is insufficient due to heat dissipation constraints
Solution Approach 1:
The patent transitions from a static perpendicular connection to a dynamic oblique angle configuration. By tilting the optical waveguide and matching it with a correspondingly tilted optical fiber array, the system adapts the connection geometry to accommodate thermal management requirements. This dynamic geometric adjustment allows optical fibers to route around package modules while maintaining proper alignment, solving the space constraint issue.
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 configuration enables high-density packaging by reducing the inter-package gap between modules, minimizing optical coupling loss, and preventing reflection, thus facilitating more compact and efficient optical module arrangements.
Implementation Method 1
the mode field diameter of light emitted from an end of each optical waveguide needs to be increased
Implementation Method 2
the optical coupling loss is large. Accordingly, the mode field diameter of light emitted from an end of each optical waveguide needs to be increased
Data Source
AI summary
An optical module that is connectable to an optical fiber array and that can be packaged in a high density. Two package modules are mounted on a board, and optical waveguides in a Si photonic lightwave circuit mounted on the package module are connected to an optical fiber array fixed to an optical fiber block. Moreover, output end surfaces of the optical waveguides in the Si photonic lightwave circuit are perpendicular to a mount surface of the package module. The optical waveguides in the Si photonic lightwave circuit may be tilted at an appropriate angle with respect to a direction perpendicular to a right end surface. Moreover, the optical fiber block fixes optical fibers with the optical fibers tilted with respect to a direction perpendicular to an end surface connected to the Si photonic lightwave circuit.