Optical Coupling Arrangement Using Adiabatic Tapering
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Solution Overview
Problem
The high cost of photonic chip packaging, particularly due to inefficient fiber coupling, which involves complex alignment procedures with tight mechanical tolerances, making silicon photonics devices expensive for short-distance applications like data communication and interconnects.
Innovation Solution
An optical coupling arrangement using adiabatic tapering of silicon waveguides for vertical coupling, compatible with chip-on-board packaging, which reduces scattering losses and allows for high package density, employing a glass block as a mode converter written with femto-second lasers for efficient coupling between silicon photonic chips and single-mode fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If standard horizontal fiber coupling is used, then coupling efficiency can be achieved, but alignment complexity and mechanical tolerance requirements increase significantly
Solution Approach 1:
The patent inverts the conventional coupling approach by using vertical coupling instead of horizontal coupling. The optical waveguide element is coupled vertically to the lightwave circuit, reversing the traditional horizontal alignment approach. This inversion simplifies the coupling geometry and reduces alignment complexity while maintaining coupling efficiency.
Solution Approach 2:
The patent introduces a coupling element as an intermediary component between the optical waveguide element and the lightwave circuit. This coupling element facilitates efficient optical coupling while relaxing the mechanical tolerance requirements, acting as a mediator that bridges the gap between the two components with less stringent alignment needs.
2Loss of energy
If tight mechanical tolerances are imposed for fiber coupling, then coupling efficiency improves, but manufacturing cost increases
Solution Approach 1:
The patent changes the coupling parameters by transitioning from horizontal to vertical coupling geometry. This parameter change in the coupling configuration allows for relaxed mechanical tolerances while maintaining efficient optical coupling, thereby reducing manufacturing costs associated with tight tolerance requirements.
Solution Approach 2:
The coupling element serves as an intermediary that decouples the strict tolerance requirements from the final assembly. By introducing this intermediate component, the system achieves efficient coupling without requiring tight mechanical tolerances in the final assembly, thus reducing manufacturing costs.
3Measurement precision
If complex alignment procedures are used, then coupling precision improves, but packaging time and complexity increase
Solution Approach 1:
By inverting the coupling geometry from horizontal to vertical, the patent simplifies the alignment procedure. The vertical configuration naturally guides the alignment process, reducing the complexity of alignment procedures while maintaining coupling precision, thereby decreasing packaging time.
Solution Approach 2:
The coupling element acts as an intermediary that simplifies the alignment process. It provides a straightforward coupling interface that reduces the complexity of alignment procedures while achieving the required coupling precision, thus reducing packaging time and complexity.
4Reliability
If conventional coupling methods are used, then optical signal transmission is achieved, but package density decreases
Solution Approach 1:
The patent transitions from horizontal coupling to vertical coupling, utilizing the vertical dimension for optical signal transmission. This dimensional change allows for more compact packaging arrangements, increasing package density while maintaining reliable optical signal transmission through the vertical coupling path.
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 solution provides a cost-effective, wideband, and efficient coupling method that reduces packaging costs, enabling the production of low-cost silicon photonics devices suitable for high-volume applications like fiber-to-the-home and datacenter components, with minimal alignment tolerance and increased package density.
Implementation Method 1
D. W. Vernooy et al., Alignment-Insensitive Coupling for PLC-Based Surface Mount Photonics, IEEE PTL, 2004 describes a way of using adiabatic coupling between III-V chips and silica planar lightwave circuit, PLC.
Implementation Method 2
To reduce the scattering losses coming from a change in the waveguide dimension the transition needs to happen over a certain minimum distance
Implementation Method 3
T. Meany, et al., Appl. Phys. A 114 (1), 113-118 (2013) describes using femto-second lasers to write waveguides in glass. This technique is called femto-second laser direct-write (FLDW) and is based on the non-linear absorption of high intensities pulses in a transparent material.
Implementation Method 4
As a result, when a laser is focused below the surface of a transparent material, due to a nonlinear effect, the absorption is highly localized at the laser focus point
Implementation Method 5
Along the first surface area of the lightwave circuit, an optical waveguide is provided
Data Source
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Figure 7A~8
AI summary
An optical coupling arrangement (10) is provided, comprising a lightwave circuit, LC, (100), a coupling element (200) and an optical waveguide element (300), wherein the LC (100) has a first surface area (110) and wherein the coupling element (200) is attached to the first surface area (110) such that an optical signal can be transmitted from the LC (100) to the coupling element (200). The optical waveguide element (300) is attached to the coupling element (300) at a first junction zone (202) such that the optical signal can be transmitted from the coupling element (200) to the optical waveguide element (300). The coupling element (200) is configured to perform mode transformation to the optical signal transmitted from the LC (100) to the optical waveguide element (300) and such that adiabatic coupling of the optical signal to the optical waveguide element (300) is enabled. Thus, a better coupling efficiency can be achieved.