Curved Grating Coupler for InP-Silicon Photonics Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The precise alignment required for optically connecting active and passive optical chips with sub-micron accuracy is challenging due to narrow waveguides and fast diverging beams, necessitating a solution for higher tolerance and coupling efficiency in hybrid integration of InP and silicon photonics.
Innovation Solution
A novel grating coupler system featuring a substrate with a grating structure and cladding layer, where the grating curves are arranged to diffract light into a focused beam, utilizing a refractive index difference to enhance coupling efficiency and tolerate misalignment, with the grating structure comprising arcs that form a narrowing beam on a silicon substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If narrow waveguides are used to achieve high density and complexity in PICs, then the beam diverges fast requiring sub-micron alignment accuracy, but this makes precise alignment challenging and reduces tolerance to misalignment
Solution Approach 1:
The patent introduces a grating coupler as an intermediary component between the active InP waveguide and passive silicon waveguide. The grating coupler transforms the fast-diverging beam from the narrow InP waveguide into a slower-diverging or focused beam that can be efficiently coupled into the silicon waveguide, thereby reducing the alignment tolerance requirement while maintaining high density
Solution Approach 2:
The grating coupler changes the propagation parameters of the optical beam by diffracting it at a controlled angle. This parameter change transforms the beam characteristics from fast-diverging to a more controllable trajectory, enabling relaxed alignment tolerances while preserving the benefits of narrow waveguides for high-density integration
2Adaptability or versatility
If hybrid integration of active InP PICs with passive silicon photonics PICs is implemented to achieve low cost and full functionality, then coupling efficiency between different material platforms is improved, but precise alignment is still required due to narrow waveguides
Solution Approach 1:
The grating coupler serves as a mediator that bridges the coupling between InP and silicon photonics platforms. It transforms the optical beam from the InP waveguide in a manner that facilitates efficient coupling into the silicon waveguide, achieving high coupling efficiency across different material platforms while reducing the stringent alignment requirements
Solution Approach 2:
The grating coupler introduces a spatial transformation by diffracting the beam at an angle, effectively changing the propagation dimension. This angular deviation allows the beam to be redirected and focused onto the silicon waveguide, improving cross-platform coupling efficiency while providing tolerance to lateral misalignment
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 solution achieves higher coupling efficiency and tolerance to misalignment, enabling cost-effective, high-density photonic integrated circuits by shaping the diffracted beam to match the passive optical chip's waveguide, thereby improving the hybrid integration of active and passive optical chips.
Implementation Method 1
a grating structure having grating curves (lines) arranged on the substrate, the grating structure having a second refractive index n2, wherein the grating curves (lines) have line width w and height d and are arranged by a pitch Λ
Implementation Method 2
a cladding layer configured to cover the grating structure, wherein the cladding layer has a third refractive index n3, wherein the third refractive index n3 is different from the second refractive index n2, wherein the cladding layer is arranged so as to reflect the light beam diffracted from the grating structure
Implementation Method 3
the substrate having a first refractive index n1; a grating structure having grating curves (lines) arranged on the substrate, the grating structure having a second refractive index n2, wherein the second refractive index n2 is greater than first refractive index n1
Data Source
AI summary
A grating coupler having first and second ends for coupling a light beam to a waveguide of a chip includes a substrate configured to receive the light beam from the first end and transmit the light beam through the second end, the substrate having a first refractive index n1, a grating structure having curved grating lines arranged on the substrate, the grating structure having a second refractive index n1, wherein the curved grating lines have line width w and height d and are arranged by a pitch Λ, wherein the second refractive index n2 is less than first refractive index n1, and a cladding layer configured to cover the grating structure, wherein the cladding layer has a third refractive index n3. The curves of the grating lines are constructed such that the emitting beam is shaped for efficient coupling to another optical component. The curves can also be tilted to reduce coupling back into the waveguide.