Integrated Optical Waveguide Extensions for Dense WDM
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Solution Overview
Problem
Conventional angled multimode interferometers (MMIs) are limited by geometric constraints, allowing only coarse wavelength-division multiplexing due to fabrication and device size limitations, which restricts channel spacing and efficiency in optical signal processing.
Innovation Solution
An integrated optical structure with waveguide extension structures adjacent to the main waveguide, allowing control and reduction of channel spacing without altering the length or pitch of the main waveguide, by employing asymmetric extensions and reflective features to manipulate light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the geometrical spacing of output channels is reduced to achieve smaller channel spacing, then channel spacing is improved, but fabrication limitations are exceeded
Solution Approach 1:
The patent introduces waveguide extension structures that protrude from the side surfaces of the main waveguide into the cladding layer, adding a lateral dimension to the waveguide configuration. This dimensional extension allows control of channel spacing without reducing the geometrical spacing between output waveguides, thereby avoiding fabrication limitations while achieving dense WDM.
2Manufacturing precision
If the length of the main waveguide is increased to reduce channel spacing, then channel spacing is improved, but device size increases
Solution Approach 1:
Instead of extending the main waveguide length in the propagation direction, the patent extends waveguides laterally from the side surfaces into the cladding layer. This lateral extension provides an additional degree of freedom to control channel spacing without increasing the device length, thereby maintaining compact form factor while achieving dense WDM.
3Manufacturing precision
If the pitch of second waveguides is reduced to achieve smaller channel spacing, then channel spacing is improved, but output coupling efficiency deteriorates
Solution Approach 1:
The patent segments the waveguide system by adding separate extension structures to different side surfaces of the main waveguide. These extensions are positioned at specific locations along the propagation direction and can have different configurations, allowing independent optimization of channel spacing control and output coupling efficiency for different wavelength channels.
Solution Approach 2:
The waveguide extension structures are positioned locally at specific regions of the main waveguide side surfaces, creating localized modifications to the optical field distribution. This local quality change allows control of channel spacing without globally reducing the pitch of output waveguides, thereby maintaining output coupling efficiency while achieving dense WDM.
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
Enables dense wavelength-division multiplexing by reducing channel spacing to sub-micron levels, enhancing optical signal processing capabilities without increasing the main waveguide length or reducing waveguide pitch, thus overcoming fabrication limitations.
Implementation Method 1
employing asymmetric extensions and reflective features to manipulate light propagation
Implementation Method 2
angled multimode interferometer (MMI) based multiplexers on silicon-on-insulator (SOI) have been developed that use dispersive self-imaging in a multimode waveguide
Data Source
AI summary
An integrated optical structure for multiplexing and/or demultiplexing an optical signal comprises a main waveguide having two parallel side surfaces, a first waveguide which meets the main waveguide at a first region on one of the two side surfaces, and a plurality of second waveguides which meet the main waveguide at a second region on one of the two side surfaces. The second region is spaced at a determined distance from the first region. The two side surfaces are arranged at a first angle relative to an extension direction of the first waveguide and a second angle relative to extension directions of the plurality of second waveguides. The optical structure further comprises one or more waveguide extension structures. Each waveguide extension structure is arranged adjacent to one of the two side surfaces of the main waveguide at a region that is different to the first and the second region.