Integrated Edge-Oriented Couplers for Photonic Integrated Circuit Optical Alignment
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Solution Overview
Problem
Current photonic integrated circuit (PIC) chip technologies face challenges in efficiently and accurately optically coupling with optical fibers, particularly in achieving high-speed and low-power communication due to limitations in coupling techniques and waveguide structures.
Innovation Solution
The implementation of a substrate-based assembly that includes a PIC chip with integrated edge-oriented couplers (IECs) and a planar optical waveguide structure, where the IECs form divergent lens surfaces for edge-wise optical coupling with optical fibers, facilitating efficient beam expansion and mode conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional grating structures are used for optical coupling between silicon waveguides and optical fibers, then optical coupling is achieved, but coupling efficiency and alignment accuracy are limited
Solution Approach 1:
The patent employs spherical lens structures formed at the output end of the optical waveguide to replace traditional planar grating couplers. These spherical lenses focus and expand the optical beam, improving coupling efficiency to optical fibers by transforming the divergent wavefront into a more collimated beam that better matches the fiber acceptance cone, thereby resolving the contradiction between coupling efficiency and alignment complexity
Solution Approach 2:
The invention changes the geometric parameters of the waveguide output by forming spherical lenses with specific radii of curvature (e.g., 5-50 micrometers) and controlled depths. This parameter modification transforms the optical field distribution, enabling more efficient coupling to optical fibers while maintaining manufacturability through standard semiconductor processing techniques combined with focused ion beam or laser processing
2Area of moving object
If submicron cross-section silicon waveguides are used for dense integration, then device integration density increases, but optical coupling difficulty increases
Solution Approach 1:
The patent addresses the coupling challenge of submicron waveguides by adding a vertical dimension to the optical field transformation. Spherical lenses are formed extending from the waveguide output into the upper cladding layer, creating a three-dimensional optical structure that expands the beam in multiple directions. This dimensional transformation allows efficient coupling from tightly confined submicron waveguides to larger-mode-area optical fibers without compromising integration density
Solution Approach 2:
The spherical lens structure acts as an optical intermediary between the submicron silicon waveguide and the optical fiber. It serves as a mode converter that bridges the modal mismatch between the small core waveguide and the larger fiber mode field, enabling efficient power transfer while maintaining the benefits of dense waveguide integration
3Volume of moving object
If edge-wise optical coupling is implemented for compact device profile, then device size is reduced, but coupling alignment precision becomes more challenging
Solution Approach 1:
The patent implements preliminary optical field shaping by forming spherical lenses directly at the waveguide output before coupling to the fiber. This pre-conditioning of the optical beam creates a more robust coupling interface that is less sensitive to alignment errors, thereby enabling compact edge-wise coupling while maintaining acceptable alignment precision through the lens's beam-transforming capability
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 enhances the ease, efficiency, and accuracy of optical signal communication between PIC chips and optical fibers, enabling high-speed and low-power optical signal transmission while maintaining a compact device profile.
Implementation Method 1
integrated edge-oriented couplers (IECs) which are configured to be optically coupled for horizontal signal communication with the optical waveguide structure
Implementation Method 2
facilitating efficient beam expansion and mode conversion
Data Source
AI summary
Techniques and mechanisms for optically coupling a photonic integrated circuit (PIC) chip to an optical fiber via a planar optical waveguide structure. In an embodiment, a PIC chip comprises integrated circuitry, photonic waveguides, and integrated edge-oriented couplers (IECs) which are coupled to the integrated circuitry via the photonic waveguides. The PIC chip forms respective divergent lens surfaces of the IECs, which are each at a respective terminus of a corresponding one of the photonic waveguides. A planar optical waveguide structure, which is adjacent to the IECs, comprises a core which is optically coupled between the PIC chip and an array of optical fibers. In another embodiment, an edge of the PIC forms a stepped structure, wherein an upper portion of the stepped structure comprises the plurality of coplanar IECs, and a lower portion of the stepped structure extends past the plurality of coplanar IECs.