Optical Multiplexing Element MMI Waveguide Coupler
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Solution Overview
Problem
Existing arrayed waveguide grating (AWG) optical multiplexing and de-multiplexing elements face significant radiation loss at the connection parts between slab waveguides and channel waveguides, which is not adequately addressed by previous solutions, and require complex manufacturing processes.
Innovation Solution
The implementation of a multi-mode interference (MMI) waveguide coupler connected with a narrow-width waveguide, featuring step portions and tapered sections, reduces radiation loss by optimizing the connection area between slab and channel waveguides, employing a silicon-on-insulator substrate and silicon oxide clad for efficient light confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a silicon fine wire waveguide is used to reduce the curvature radius and make the AWG small, then the device size is reduced, but radiation loss increases at the connection part between slab waveguide and channel waveguide
Solution Approach 1:
An MMI (multi-mode interference) waveguide coupler is introduced as an intermediary component between the slab waveguide and the channel waveguide. This MMI coupler serves as a transition zone that matches the mode profiles and reduces radiation loss at the connection interface, allowing the use of tight-bending silicon waveguides without excessive loss.
Solution Approach 2:
The waveguide width is varied along the propagation direction, creating a tapered transition from the wider slab waveguide to the narrower channel waveguide. This gradual parameter change reduces abrupt mode mismatch and minimizes radiation loss while enabling small curvature radii.
2Loss of energy
If a rib waveguide structure is used to reduce radiation loss, then radiation loss is reduced, but manufacturing complexity increases
Solution Approach 1:
The invention uses a simple planar waveguide structure without complex rib formations, sacrificing some confinement strength but gaining significant manufacturing simplicity. The shallow etching process is more tolerant and easier to implement than precise rib waveguide fabrication.
Solution Approach 2:
The waveguide dimensions and refractive index profile are optimized through parameter adjustments in the planar structure, achieving adequate light confinement without requiring complex rib geometries. This maintains manufacturing simplicity while controlling radiation loss.
3Loss of energy
If the curvature radius of curved waveguide is increased to reduce radiation loss in rib waveguide, then radiation loss is reduced, but device size increases
Solution Approach 1:
The waveguide width is gradually increased along the curved path, creating a tapered effect that allows tighter curvature radii. This parameter variation along the waveguide enables small device size while maintaining low radiation loss through improved mode confinement in the bending section.
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 configuration effectively minimizes radiation loss at the connection points, enabling smaller AWG designs with reduced excess loss and improved manufacturing simplicity, while maintaining high optical performance.
Implementation Method 1
an optical multiplexing and de-multiplexing element (100, 200) comprising a slab waveguide (11, 11b) and a waveguide structure (4, 4a, 4b), wherein the waveguide structure (4, 4a, 4b) comprises a multi-mode interference (MMI) waveguide coupler (14, 114) and a narrow-width waveguide (19, 119)
Implementation Method 2
employing a silicon-on-insulator substrate and silicon oxide clad for efficient light confinement
Data Source
AI summary
There is provided an optical multiplexing and de-multiplexing element which is provided with a slab waveguide and a waveguide structure and can reduce radiation loss caused in a connection part between the slab waveguide and the waveguide structure. The waveguide structure includes a multimode interference (MMI) waveguide coupler and a narrow-width waveguide, the MMI waveguide coupler and the narrow-width waveguide are connected to each other in this order from a connection position with the slab waveguide along the waveguide direction, step portions are formed on both sides of the MMI waveguide coupler along the waveguide direction, and the thickness of the step portion is smaller than the thickness of the MMI waveguide coupler.