Shared MMI Waveguide for Optical (De)multiplexers
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Solution Overview
Problem
Existing optical (de)multiplexers, particularly those on silicon-on-insulator platforms, are sensitive to dimensional variations in fabrication, leading to alignment issues and requiring individual tuning mechanisms for multiplexer and demultiplexer structures, which increases complexity and power consumption.
Innovation Solution
A multimode interference waveguide configuration with access regions or windows at the sidewalls allows for shared use of a single MMI waveguide to implement multiple angled multimode interferometers, ensuring identical spectral responses and reducing the need for multiple tuning elements and control circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple separate MMI waveguides are used to implement multiple (de)multiplexers, then each (de)multiplexer can be independently tuned, but the device complexity and power consumption increase due to multiple tuning elements and control circuits
Solution Approach 1:
The patent merges multiple (de)multiplexer functions into a single shared MMI waveguide structure. By positioning multiple input and output waveguides at specific locations along the shared MMI waveguide, multiple (de)multiplexers are implemented within one common optical path, eliminating the need for separate tuning elements and control circuits for each (de)multiplexer.
Solution Approach 2:
The shared MMI waveguide serves multiple functions simultaneously, acting as the optical core for multiple (de)multiplexers. This universal structure allows different wavelength channels to be routed through the same MMI waveguide with different input-output waveguide combinations, providing multi-functionality without requiring separate dedicated waveguides for each (de)multiplexer.
2Ease of operation
If traditional separate MMI waveguide configurations are used for each (de)multiplexer, then individual tuning is possible, but insertion loss increases and cross-talk remains high
Solution Approach 1:
The patent merges multiple (de)multiplexer functions into a single shared MMI waveguide structure. By positioning multiple input and output waveguides at specific locations along the shared MMI waveguide, multiple (de)multiplexers are implemented within one common optical path, eliminating the need for separate tuning elements and control circuits for each (de)multiplexer.
Solution Approach 2:
The patent applies local quality by positioning input and output waveguides at specific locations along the shared MMI waveguide where the optical field distribution provides optimal coupling. This spatial arrangement ensures that each (de)multiplexer operates with minimal insertion loss and cross-talk by exploiting the local optical field characteristics at different positions within the MMI waveguide.
3Manufacturing precision
If dimensional variations occur in fabrication, then alignment between multiplexer and demultiplexer structures deteriorates, but using a shared MMI waveguide ensures identical spectral responses
Solution Approach 1:
The patent merges multiple (de)multiplexer functions into a single shared MMI waveguide structure. By positioning multiple input and output waveguides at specific locations along the shared MMI waveguide, multiple (de)multiplexers are implemented within one common optical path, eliminating the need for separate tuning elements and control circuits for each (de)multiplexer.
Solution Approach 2:
The patent exploits the fact that the shared MMI waveguide has identical physical parameters (dimensions, material properties, thermal behavior) for all (de)multiplexers implemented within it. This ensures that all (de)multiplexers exhibit identical spectral responses and wavelength characteristics, automatically maintaining alignment between multiplexer and demultiplexer structures without requiring additional tuning mechanisms to compensate for fabrication variations.
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 achieves reduced insertion loss, low cross-talk, and simplified fabrication, with identical spectral responses for all (de)multiplexers, requiring only a single tuning element and control circuit, thus minimizing power consumption and device complexity.
Implementation Method 1
a multimode interference waveguide; at least one first coupling waveguide which meets the multimode interference waveguide at at least one first location and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations
Data Source
AI summary
An optical demultiplexer/multiplexer, comprising: a multimode interference waveguide; at least one first coupling waveguide which meets the multimode interference waveguide at least one first location and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations which are spaced in a direction of transmission in relation to the at least one first location, with the at least one first coupling waveguide and the second coupling waveguides together with the multimode interference waveguide providing a first angled multimode interferometer which operates to demultiplex a first optical signal having optical channels of a plurality of wavelengths or multiplex optical signals of a plurality of wavelengths into a first optical signal having optical channels of the plurality of wavelengths; at least one third coupling waveguide which meets the multimode interference waveguide at least one third location and a plurality of fourth coupling waveguides which meet the multimode interference waveguide at a plurality of fourth locations which are spaced in a direction of transmission in relation to the at least one third location, with the at least one third coupling waveguide and the plurality of fourth coupling waveguides together with the multimode interference waveguide providing a second angled multimode interferometer which operates to demultiplex a second optical signal having optical channels of a plurality of wavelengths or multiplex optical signals of a plurality of wavelengths into a second optical signal having optical channels of the plurality of wavelengths; whereby the demultiplexer/multiplexer provides for the demultiplexing/multiplexing of first and second optical signals having optical channels of a plurality of wavelengths. In a further embodiment the first coupling waveguide of an optical demultiplexer/multiplexer comprising a first angled multimode interferometer is stepped or tapered in order to couple a signal having a broadened spatial, or spectral, profile. In another embodiment of an optical demultiplexer/multiplexer comprising a first angled multimode interferometer a plurality of first coupling waveguides are coupled to a photonic structure which provides a plurality of output signals having substantially equal intensity and a phase difference, also in order to couple a signal or signals having a broadened spatial, or spectral, profile. In yet another embodiment of an optical demultiplexer/multiplexer comprising a first angled multimode interferometer the multimode interference waveguide includes a reflector at one end.