Fiber-Waveguide Coupler Alignment with Crystallographic Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in manufacturing photonic integrated circuits (PICs) lies in achieving precise alignment between V-Grooves and optical waveguides due to misalignment between the crystalline plane and the processing direction, which affects the orientation of optical fibers.
Innovation Solution
A fiber-waveguide coupler is designed with a crystalline substrate where the V-groove and optical waveguide are aligned by determining and compensating for misalignment angles using anisotropic etching, ensuring the fiber core is within a predetermined displacement from the waveguide core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If anisotropic etching is used to create V-Grooves, then the V-Grooves serve as entry points for optical fibers, but misalignment between the crystalline plane and processing direction causes orientation uncertainties
Solution Approach 1:
The patent applies preliminary action by fabricating reference structures (reference V-Groove and primary marker) before the final V-Groove and optical waveguide. These reference structures enable measurement of misalignment angles, which are then used to compensate for crystallographic misalignment in subsequent processing steps, ensuring precise orientation of the final structures.
Solution Approach 2:
The patent implements feedback by measuring the actual misalignment angles between the crystalline plane and processing direction using the reference structures, then using these measured values to adjust and compensate for the misalignment in the final V-Groove and waveguide fabrication, closing the loop between measurement and correction.
2Ease of operation
If the wafer surface is tilted with respect to the (100) Si crystalline plane, then processing can be performed, but misalignment between the fiber core and waveguide core occurs
Solution Approach 1:
The patent replaces mechanical alignment methods with a measurement and compensation approach. Instead of relying on physical alignment tools or fixtures, the system uses optical or metrological methods to measure misalignment angles and compensates for them through adjusted processing parameters, achieving sub-micrometer alignment precision.
Solution Approach 2:
The patent changes processing parameters based on measured misalignment angles. The etching depth, lithography alignment, and other fabrication parameters are adjusted according to the measured angular deviations, transforming a fixed mechanical alignment problem into a controllable parameter adjustment problem.
3Device complexity
If conventional alignment methods are used, then manufacturing is simpler, but displacement between fiber core and waveguide core exceeds predetermined limits
Solution Approach 1:
The patent segments the alignment process into distinct measurement and compensation phases. First, reference structures are fabricated and measured to determine misalignment angles. Then, these measured values are used to guide the fabrication of final structures with corrected orientations, breaking down the complex alignment problem into manageable sequential steps.
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 alignment method ensures reliable coupling of light between optical fibers and waveguides, independent of crystallographic plane orientations, enhancing light coupling efficiency and reducing misalignment-induced losses.
Implementation Method 1
The manufacturing process of photonic integrated circuits (PIC) recently relies on the strategic use of anisotropic etching using wet etching with e.g. TMAH to create V-Grooves
Data Source
AI summary
A fiber-waveguide coupler includes, comprising a crystalline substrate of a type having a top surface and a crystallographic plane, the substrate including: a V-groove extending in a Z-direction in a projection towards the top surface, the Z-direction is within a crystallographic plane of the substrate, the top surface and a crystallographic plane of the substrate open a first angle in a X/Y-plane normal to the Z-direction, and an optical waveguide disposed on the top surface of the substrate, extending along the Z-direction in a projection towards the top surface, the V-groove and the waveguide are such that when an optical fiber and having a fiber core tip, set into the V-groove, the fiber core is aligned with a waveguide core such that displacement of the cores is less than a predetermined displacement. A method is also provided.