Mode Converter Using Evanescent Wave Coupling for Optical Switching
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Solution Overview
Problem
Existing optical switching systems face high insertion loss and large size due to the need for two conversion devices (multimode demultiplexer and multiplexer) for mode conversion between multimode and single-mode waveguides, and they convert all modes uniformly, making it difficult to implement efficient switching between different modes.
Innovation Solution
A mode converter with an input multimode waveguide, an output multimode waveguide, and a first conversion waveguide that performs evanescent wave coupling using input and output coupling waveguides with different effective refractive indices, allowing for selective mode conversion between different modes using a single device, reducing insertion loss and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two conversion devices (multimode demultiplexer and multiplexer) are used for mode conversion, then mode conversion between multimode and single-mode waveguides can be achieved, but insertion loss increases and device size increases
Solution Approach 1:
The patent combines the functions of multimode demultiplexer and multiplexer into a single mode converter device. The converter uses evanescent wave coupling between a multimode waveguide and a single-mode waveguide to achieve mode conversion in one integrated structure, eliminating the need for separate demultiplexer and multiplexer components, thereby reducing insertion loss and device size.
Solution Approach 2:
The patent introduces an evanescent wave coupling region as an intermediary mechanism between the multimode and single-mode waveguides. This coupling region enables efficient energy transfer and mode conversion without requiring complete mode decomposition and recombination, thus reducing energy loss while maintaining conversion capability.
2Reliability
If two conversion devices (multimode demultiplexer and multiplexer) are used for mode conversion, then mode conversion between multimode and single-mode waveguides can be achieved, but device size increases
Solution Approach 1:
The patent combines the functions of multimode demultiplexer and multiplexer into a single mode converter device. The converter uses evanescent wave coupling between a multimode waveguide and a single-mode waveguide to achieve mode conversion in one integrated structure, eliminating the need for separate demultiplexer and multiplexer components, thereby reducing insertion loss and device size.
3Reliability
If all modes are converted in a unified manner, then mode conversion can be achieved, but device size increases and switching between specific modes becomes difficult
Solution Approach 1:
The patent segments the mode conversion process into selective mode coupling channels. Each channel is designed to convert specific modes between multimode and single-mode waveguides independently. This segmentation enables selective mode conversion without requiring complete conversion of all modes, thereby reducing device size and improving switching flexibility.
Solution Approach 2:
The patent applies different coupling characteristics to different mode conversion channels. By designing waveguides with specific geometric parameters and coupling regions, the converter achieves different conversion efficiencies for different modes. This local optimization allows selective mode conversion while maintaining a compact device structure.
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 mode converter achieves efficient mode conversion with reduced insertion loss and size, enabling convenient switching between multiple modes in optical switching systems by using a single conversion device, thereby improving the efficiency and compactness of the system.
Implementation Method 1
perform, by using the input coupling waveguide, evanescent wave coupling on the first signal that is in the first mode and that is transmitted in the input multimode waveguide
Data Source
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AI summary
A mode converter provided in embodiments of the present invention includes an input multimode waveguide, an output multimode waveguide, and a first conversion waveguide, where the input multimode waveguide is configured to receive a first signal, and a mode of the first signal is a first mode; the first conversion waveguide has an input coupling waveguide with a first effective refractive index, and has an output coupling waveguide with a second effective refractive index; the first conversion waveguide is configured to: perform, by using the input coupling waveguide, evanescent wave coupling on the first signal that is in the first mode and that is transmitted in the input multimode waveguide, and couple the first signal to the second mode of the output multimode waveguide by using the output coupling waveguide, so as to obtain the first signal in the second mode; and the output multimode waveguide is configured to output the first signal in the second mode.