S-Shaped Optical Waveguide Core for Low-Loss Broadband Coupling
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Solution Overview
Problem
Conventional optical waveguide coupling techniques, such as grating and edge coupling, face challenges in broadband applications due to high loss and sensitivity to process variations and temperature, particularly in Coarse Wavelength Division Multiplexing (CWDM4) systems, and adiabatic coupling methods suffer from additional propagation losses and complex tooling requirements.
Innovation Solution
The implementation of an optical waveguide with a S-shaped core fabricated using ion exchange technology, where the core extends centrally within the waveguide body and transitions to a surface portion with a curved intermediate section, allowing for adiabatic coupling without abrupt refractive index changes, thereby reducing losses and simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If grating coupling is used to facilitate wafer level testing and top surface coupling, then ease of operation is improved, but loss over a large wavelength range increases
Solution Approach 1:
The waveguide core employs a curved or S-shaped intermediate portion that gradually transitions the optical mode from a central position to a surface position. This curvature enables adiabatic coupling that maintains low propagation loss across broadband wavelengths while achieving surface coupling for wafer level testing.
Solution Approach 2:
The waveguide structure changes the position parameter of the optical mode continuously along the propagation direction. The core transitions from a centrally positioned first portion to a surface-proximate second portion through a curved intermediate section, enabling broadband low-loss coupling.
2Loss of energy
If edge coupling is used to reduce propagation loss, then loss of energy is reduced, but wafer level testing capability is lost
Solution Approach 1:
The curved or S-shaped intermediate portion of the waveguide core enables the optical mode to follow a gradual path from the center to the surface, achieving surface coupling that facilitates wafer level testing while maintaining low propagation loss comparable to edge coupling methods.
3Loss of energy
If adiabatic coupling with S-shaped core is used to achieve broadband coupling, then loss of energy is reduced, but device complexity increases
Solution Approach 1:
The S-shaped or curved intermediate portion is integrated directly into the waveguide core geometry, creating a monolithic structure that achieves adiabatic coupling without requiring separate components or complex assembly processes.
Solution Approach 2:
The coupling function is merged into the waveguide core itself through the curved intermediate section, eliminating the need for separate coupling components and simplifying the overall device structure while maintaining broadband low-loss performance.
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 minimizes propagation losses and simplifies the fabrication process, enabling efficient broadband coupling with reduced system loss and eliminating the need for complex tooling, while maintaining low bend loss and precise control over the waveguide dimensions.
Implementation Method 1
an optical waveguide with a S-shaped core fabricated using ion exchange technology
Implementation Method 2
allowing for adiabatic coupling without abrupt refractive index changes
Data Source
AI summary
An optical waveguide includes a glass waveguide body and a waveguide core through which optical radiation propagates. The waveguide core includes: a body portion extending within the waveguide body, a coupling portion extending at the surface of the waveguide body, and an S-bent intermediate portion coupling the body portion and the coupling portion. An optical coupling arrangement (e.g., for coupling one or more optical fibers to a silicon photonics device) includes one such optical waveguide and a second optical waveguide including a respective waveguide body and one or more waveguide members. The second optical waveguide is coupled with the first optical waveguide with the waveguide member(s) facing the coupling portion of the first optical waveguide.