Interposer Circuit with Angled Waveguides for Crosstalk Reduction
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Solution Overview
Problem
The use of an interposer circuit to connect optical fibers and silicon optical circuits increases the number of connection points, leading to crosstalk issues due to leaking light being unintentionally coupled between connection points, and existing solutions to reduce crosstalk, such as using S-shaped waveguides, result in a larger module size.
Innovation Solution
An interposer circuit with straight or angled connection waveguides is used to connect the optical circuit and fiber block, where the angle between the connection waveguides and the surfaces is consistent, reducing crosstalk while maintaining a compact size by optimizing the length and shape of the interposer circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an interposer circuit is used to connect optical fibers and silicon optical circuits, then connection flexibility and MFD matching are improved, but the number of connection points increases leading to crosstalk
Solution Approach 1:
The interposer circuit serves as an intermediary component between the silicon optical circuit and fiber block, providing MFD matching and connection flexibility. The patent applies this principle by introducing the interposer with specific waveguide structures that bridge the two different optical systems, accepting the trade-off of increased connection points while managing crosstalk through geometric design.
Solution Approach 2:
The patent uses curved or bent waveguide paths within the interposer circuit to redirect light signals. This curvature allows light to travel from one connection point to another without directly coupling to adjacent ports, thereby reducing crosstalk while maintaining the necessary connection flexibility provided by the interposer.
2Object-generated harmful factors
If S-shaped waveguides are used to reduce crosstalk, then crosstalk is improved, but the module size increases
Solution Approach 1:
The patent employs curved waveguide paths within the interposer circuit to achieve crosstalk reduction. The curvature of the waveguides allows light to be redirected away from adjacent ports, reducing crosstalk while containing the size increase within the interposer component rather than the entire module.
Solution Approach 2:
The patent utilizes the third dimension (vertical height) by tilting the connection surfaces of the interposer circuit relative to the silicon optical circuit and fiber block. This angular arrangement allows light to couple between ports while physically separating the propagation paths, reducing crosstalk without requiring excessive lateral space.
3Ease of manufacture
If optical fibers are arranged along V-shaped grooves in fiber block, then manufacturing is simplified, but precise positioning of all fibers with respect to input/output waveguides cannot be achieved
Solution Approach 1:
The interposer circuit acts as a mediator that compensates for positioning inaccuracies. The V-shaped groove structure in the fiber block remains simple for manufacturing, but the interposer's waveguides are designed with tolerance compensation features that accommodate variations in fiber positions while maintaining low-loss connections to the silicon optical circuit.
Solution Approach 2:
The patent employs adjustable or optimized waveguide parameters in the interposer circuit, such as mode field diameters and coupling angles, to compensate for positioning variations. By tuning these parameters, the system achieves low-loss connections despite the simplified V-shaped groove manufacturing process that inherently produces dimensional variations.
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 effectively improves crosstalk between ports while keeping the interposer circuit small, achieving crosstalk values of −45 dB or less, and allows for a more compact optical module design.
Implementation Method 1
An Si waveguide has a large specific refractive index difference between the core and the clad material, and accordingly, the cross-sectional area and the minimum bend radius of the waveguide are significantly smaller than those in optical circuits constituted by other materials
Implementation Method 2
In order to reduce the connection loss by increasing the MFD of the Si waveguide side, a spot size converter (SSC) 105 is provided in the vicinity of an input/output end surface of each input/output waveguide 103
Data Source
AI summary
An object is to improve crosstalk between ports while keeping an interposer circuit small. In an interposer circuit that includes a first surface connected to an optical circuit, a second surface that is connected to a fiber block and is located opposite to the first surface in parallel with the first surface, and a plurality of connection waveguides connected to a plurality of input/output waveguides included in the optical circuit and a plurality of input/output fibers included in the fiber block, the connection waveguides each have a straight shape, and an angle (θ) formed between the first surface and each of the connection waveguides is the same as an angle (φ) formed between the second surface and each of the connection waveguides.