Angled-Facet Edge Couplers for Low Optical Return Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional edge couplers in photonics chips experience significant back reflection and optical return loss due to mode mismatch, which has proven difficult to correct effectively.
Innovation Solution
The edge coupler is designed with a waveguide core that includes an inverse taper with a multi-directionally angled end surface and dielectric layers, strategically angled to direct reflected light outside the numerical aperture of the light source, reducing optical return.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional edge coupler with a flat end surface is used, then the structure is simple and easy to manufacture, but significant back reflection and optical return loss occur due to mode mismatch
Solution Approach 1:
The patent applies asymmetry by tilting the end surface of the waveguide core at a specific angle (e.g., 10 degrees) relative to the longitudinal axis. This asymmetric orientation prevents reflected light from returning along the original path, thereby reducing optical return loss and back reflection while maintaining manufacturing feasibility through standard lithography and etching processes.
Solution Approach 2:
The patent introduces a new dimensional parameter by tilting the end surface in the longitudinal direction, transforming the conventional flat (2D) end surface into an angled (3D) surface. This dimensional change redirects reflected light outside the numerical aperture of the light source, effectively reducing optical return loss without significantly complicating the manufacturing process.
2Reliability
If the end surface is tilted at an angle, then back reflection is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a particular tilt angle parameter (e.g., 10 degrees) that optimizes the balance between back reflection reduction and manufacturing feasibility. This parameter change transforms the conventional flat end surface into an angled surface that effectively redirects reflected light while remaining compatible with standard semiconductor fabrication processes and acceptable manufacturing tolerances.
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 design significantly reduces or eliminates optical return loss by effectively managing reflections at multiple material interfaces, enhancing light transfer efficiency.
Implementation Method 1
significantly reduces optical return to the light source by directing reflected light beyond the acceptable range
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Structures including an edge coupler, and methods of fabricating a structure that includes an edge coupler. The structure (10) includes an edge coupler having a waveguide core (12) with an end surface (14) and a longitudinal axis (18). The end surface (14) defines a plane tilted in a first direction at a first acute angle relative to the longitudinal axis (18) and tilted in a second direction at a second acute angle relative to the longitudinal axis (18). The second direction differs from the first direction.