Multi-Mode Waveguide Couplers for Low-Loss Vertical Coupling
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Solution Overview
Problem
Conventional optical waveguides experience significant loss, particularly in applications like single-photon optics, due to interactions with irregular side walls, and couplers have lower efficiency when waveguides are placed side-by-side, increasing size and attenuation.
Innovation Solution
The optical coupler design includes multi-mode waveguides positioned adjacent to each other, either above or below, with specific dimensions and configurations to maintain fundamental mode coupling and reduce interaction with side walls, using adiabatic coupling and evanescent coupling mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional optical waveguides are used for light transmission, then light can be transmitted through the waveguide, but significant loss occurs due to interactions with irregular side walls
Solution Approach 1:
The patent transitions from conventional side-by-side waveguide coupling to vertical stacking configuration, where waveguides are positioned above each other in the vertical dimension rather than adjacent in the lateral dimension. This dimensional change allows the waveguides to avoid interaction with irregular side walls while maintaining coupling efficiency through evanescent field overlap in the vertical direction.
Solution Approach 2:
The patent inverts the traditional horizontal coupling approach by implementing vertical coupling between waveguides. Instead of placing waveguides side-by-side and coupling laterally, the waveguides are stacked vertically and couple through their evanescent fields in the vertical direction, thereby avoiding the harmful interaction with irregular side walls.
2Reliability
If waveguides are placed side-by-side for coupling, then coupling can be achieved, but the coupler size increases and attenuation increases
Solution Approach 1:
The patent employs vertical stacking of waveguides in the vertical dimension, allowing coupling to occur over a shorter interaction length compared to lateral coupling. This reduces the overall coupler footprint while maintaining effective coupling through optimized vertical separation distance between the waveguide cores.
Solution Approach 2:
The patent optimizes the vertical separation distance between stacked waveguides to achieve desired coupling efficiency. By adjusting this critical parameter, the coupler achieves high reliability coupling performance while minimizing the interaction length and overall device size.
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 reduces loss and increases coupling efficiency while minimizing the size of the coupler, maintaining low attenuation and high coupling performance.
Implementation Method 1
using adiabatic coupling and evanescent coupling mechanisms
Implementation Method 2
using adiabatic coupling and evanescent coupling mechanisms
Data Source
AI summary
An optical coupler includes a first waveguide including a first multi-mode waveguide section having a cross-section characterized by a first height and a first width that is greater than the first height and a second waveguide including a second multi-mode waveguide section having a cross-section characterized by a second height and a second width that is greater than the second height. The first multi-mode waveguide section is positioned adjacent to the second multi-mode waveguide section at least partially above or below the second multi-mode waveguide so that light entering the first multi-mode waveguide section is coupled from the first multi-mode waveguide section to the second multi-mode waveguide section. Methods for coupling light between waveguides with the optical coupler and optical devices that include the optical coupler are also described.