Femtosecond Laser Interface Pattern for Photonic Integrated Circuit Coupling
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Solution Overview
Problem
The high cost and complexity of packaging photonic integrated circuits (PICs) arise from the need for precise alignment of compact integrated optical waveguides with larger external optical fibers, leading to bandwidth limitations and increased costs in existing coupling methods.
Innovation Solution
A method for forming an optical interface between integrated waveguides on a photonic integrated circuit and external optical components using a femtosecond laser to write an interface pattern in a cover layer, allowing for passive alignment and efficient coupling without active monitoring, thereby reducing alignment errors and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active alignment procedure is used to couple light between integrated waveguides and optical fibers, then coupling efficiency is optimized, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies preliminary action by pre-defining the positions of integrated waveguides and optical fibers during the fabrication process, and pre-forming the cover layer with appropriate thickness and material properties. This preliminary positioning and preparation eliminates the need for active alignment procedures during packaging, as components are already optimally positioned before final assembly.
Solution Approach 2:
The patent implements self-service through self-aligning structures where the cover layer and embedded waveguides automatically position themselves relative to external optical fibers during packaging. The system uses its own structural features (cover layer thickness, waveguide positioning) to achieve alignment without external intervention or active monitoring, making the alignment process self-performing.
2Reliability
If precise alignment is employed to couple light from compact waveguides to larger optical fibers, then coupling efficiency improves, but packaging cost increases
Solution Approach 1:
The patent reduces packaging cost by performing alignment-critical actions during low-cost fabrication processes rather than during expensive packaging operations. Waveguide positions are predetermined in the fabrication stage, and the cover layer is pre-formed with optimal properties, transferring the alignment function to the manufacturing stage where it is more economical.
Solution Approach 2:
The self-aligning structure eliminates the need for expensive active alignment equipment and procedures during packaging. The system uses its own structural design (cover layer with specific thickness, embedded waveguide positioning) to achieve precise coupling automatically, replacing costly external alignment processes with inherent structural alignment.
3Adaptability or versatility
If out-of-plane coupling using diffraction gratings is used, then optical access is enabled anywhere on chip surface, but bandwidth is limited
Solution Approach 1:
The patent introduces a cover layer as an intermediary element between the integrated waveguides and external optical fibers. This cover layer with optimized thickness and material properties acts as a mediator that enables efficient light coupling while maintaining broadband performance, resolving the bandwidth limitation of direct grating coupling approaches.
4Reliability
If inverse tapers are used in combination with polymer or SiO2 waveguides, then coupling losses are reduced over wide wavelength ranges, but highly precise positioning of external fibers is still required
Solution Approach 1:
The patent extends the self-aligning principle to work with inverse taper waveguides made of polymer or SiO2. The cover layer structure provides automatic positioning that works in conjunction with inverse taper geometry, eliminating the need for highly precise manual fiber positioning while maintaining the broadband low-loss coupling characteristics of inverse taper designs.
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 enables optical coupling with losses less than 1 dB over a wide wavelength range, reduces packaging costs, and allows for independent formation of each optical connection, avoiding bulkiness and fragility associated with vertical coupling methods.
Implementation Method 1
writing the interface pattern in the cover layer of the photonic integrated circuit by means of a femtosecond laser
Implementation Method 2
designing an optical interface pattern for optically connecting the optical coupling facet with the integrated optical waveguide
Data Source
AI summary
The present disclosure generally relates to a method of optically coupling a photonic integrated circuit and an external optical component. In one aspect, a method comprises: providing a photonic integrated circuit comprising at least one integrated optical waveguide, the photonic integrated circuit having a cover layer; providing at least one optical component external to the photonic integrated circuit, the at least one optical component having an optical coupling facet and configured to be optically coupled to the at least one integrated optical waveguide, thereby forming an assembly; determining a position of the optical coupling facet of the at least one optical component in the assembly; determining a position of the at least one integrated optical waveguide; designing an optical interface pattern between the optical coupling facet of the at least one optical component in the assembly and the at least one integrated optical waveguide; and writing the interface pattern in the cover layer of the photonic integrated circuit by means of a femtosecond laser, thereby forming an optical interface for optically coupling the optical coupling facet and the at least one integrated optical waveguide.