Tapered Optical Coupler for Heterogeneous Waveguide Integration
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Solution Overview
Problem
Efficiently coupling light between different optical components or materials, such as diamond-based qubits and photonic integrated circuits, is challenging due to differences in refractive indices, mode profiles, and geometric constraints, which complicates scaling for large-scale quantum processors.
Innovation Solution
An optical coupler design featuring tapered ridges of different dielectric materials, such as silicon nitride and diamond, with controlled alignment and adiabatic mode conversion to facilitate efficient light transfer between dissimilar materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If heterogeneous integration techniques are used to interface different optical components, then coupling between different materials (e.g., diamond qubits and PIC waveguides) is achieved, but maintaining high coupling efficiency across fabrication tolerances and operating conditions becomes challenging
Solution Approach 1:
The patent introduces a mode converter as an intermediary component between the diamond waveguide and silicon nitride waveguide. This mode converter acts as a mediator that transforms the optical mode from one waveguide type to another, enabling efficient coupling despite material differences and fabrication variations. The mode converter's tapered structure gradually transforms the optical field distribution, making the coupling process robust against alignment tolerances.
Solution Approach 2:
The patent employs parameter changes by designing a tapered mode converter where the width varies continuously from the diamond waveguide width to the silicon nitride waveguide width. This gradual parameter change enables adiabatic mode conversion, where the optical mode evolves smoothly without abrupt transitions, maintaining high coupling efficiency across fabrication tolerances and operating conditions.
2Adaptability or versatility
If precise alignment and bonding of separate components is performed, then heterogeneous integration is achieved, but scaling for large-scale quantum processors becomes challenging
Solution Approach 1:
The patent merges the diamond waveguide and silicon nitride waveguide through a continuous tapered structure rather than maintaining them as separate bonded components. This merging approach eliminates the need for precise alignment and bonding of separate components, significantly improving scalability for large-scale quantum processors while maintaining integration capability.
3Adaptability or versatility
If different dielectric materials with different refractive indices are used, then material compatibility for specific applications is achieved, but efficient light coupling between materials becomes complex
Solution Approach 1:
The patent applies local quality by creating a tapered region with gradually changing material composition and geometric dimensions. This localized tapered structure is positioned specifically at the interface between different dielectric materials, where it provides the necessary mode transformation. The rest of the waveguides maintain their original simple structures, thus achieving efficient coupling without overall device complexity.
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
The design achieves improved coupling efficiency, relaxed alignment tolerances, and compatibility with existing fabrication processes, enabling scalable integration of quantum components with photonic circuits.
Implementation Method 1
the guided optical wave is adiabatically coupled between the first and second ridges
Data Source
AI summary
Systems and methods for optical coupling are disclosed. An optical coupler for operation at a target wavelength includes a layer of a first dielectric material having a first refractive index at the target wavelength; a first ridge including the first dielectric material, disposed on the layer along a first axis, configured to guide an optical wave at the target wavelength and terminating at a first termination point; and a second ridge including a second dielectric material having a second refractive index greater than the first refractive index at the target wavelength, disposed along a second axis, parallel to the first axis, and terminating in a taper, disposed on the layer, having a varying width that decreases in a direction, along the second axis to a second termination point in proximity to the first termination point, whereby the guided optical wave is adiabatically coupled between the first and second ridges.