Optical Chip Edge Coupler Alignment Tolerance
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Solution Overview
Problem
Current optical chip designs face challenges in achieving high alignment tolerance for coupling with active devices, leading to increased insertion loss due to misalignment, and existing solutions either complicate fabrication or result in separate output channels that cannot be easily recombined into a single channel.
Innovation Solution
An optical chip with an edge coupler capable of receiving light on two orthogonal modes of the same polarization, featuring a demultiplexer to separate these modes into independent intermediate waveguides and a polarization multiplexer to recombine them into a single output waveguide, utilizing polarization diversity to avoid power loss and maintain alignment tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional butt-coupling approach is used with accurate alignment, then insertion loss is minimized, but alignment tolerance is poor and fabrication becomes complex
Solution Approach 1:
The input waveguide is segmented into two separate output waveguides that carry orthogonal polarization modes independently. This segmentation allows each waveguide to be optimized for its specific mode, improving coupling efficiency and alignment tolerance while maintaining low insertion loss through independent mode propagation
Solution Approach 2:
The invention introduces polarization diversity as an additional dimension for signal separation. By utilizing orthogonal polarization states (TE and TM modes) of light, the system can distinguish and separate signals without requiring precise spatial alignment, thereby improving alignment tolerance while maintaining low insertion loss
2Manufacturing precision
If waveguide engineering is used to enlarge optical mode for alignment tolerance, then alignment tolerance improves, but fabrication complexity and chip cost increase significantly
Solution Approach 1:
The invention changes the polarization state parameter of the optical signal to achieve mode separation. By utilizing the polarization diversity inherent in optical waves (TE and TM modes), the system achieves alignment tolerance without modifying the physical dimensions or geometry of the waveguides, thereby avoiding increased fabrication complexity
3Manufacturing precision
If trident coupler is used to increase horizontal alignment tolerance, then alignment tolerance improves, but the two output waveguides cannot be easily recombined into a single channel
Solution Approach 1:
The invention implements a feedback mechanism where the polarization state information is preserved and utilized in the recombination process. The orthogonal polarization modes that are separated for alignment tolerance can be recombined by reversing the polarization-dependent routing, maintaining both alignment tolerance and recombination capability through polarization state feedback
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 allows for low-loss recombination of light into a single channel, significantly improving alignment tolerance and enabling cost-effective assembly suitable for various applications by maintaining power conservation through orthogonal polarization recombination.
Implementation Method 1
an input edge coupler (101) having at least one input waveguide (102) configured to receive light on two orthogonal modes of same polarization from an active device butt-coupled to the optical chip (100)
Implementation Method 2
a demultiplexer (103) configured to demultiplex and divide the two orthogonal modes of the light received by the input edge coupler (101) into a mode carried on a first intermediate waveguide (104) and the mode carried on a second intermediate waveguide (105)
Implementation Method 3
a polarization multiplexer (106) configured to recombine the modes carried on the intermediate waveguides (104, 105) into two polarization-orthogonal modes carried on one output waveguide (107)
Data Source
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AI summary
The present invention provides an optical chip 100 and a method 600 for coupling light. The optical chip 100 comprises an input edge coupler 101 having at least one input waveguide 102, and configured to receive light on two orthogonal modes of same polarization. It further comprises a demultiplexer 103 configured to divide the two orthogonal modes into a mode carried on a first intermediate waveguide 104 and a mode carried on a second intermediate waveguide 105 independent from the first intermediate waveguide 104. The optical chip 100 also comprises a polarization multiplexer 103 configured to recombine the modes carried on the intermediate waveguides 104, 105 into two polarization-orthogonal modes carried on one output waveguide 107.