Spiral Waveguide Absorber Reduces Optical Return Loss
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Solution Overview
Problem
Semiconductor optical waveguide structures face issues with optical return loss and crosstalk due to backscattering from unconnected ports, which can lead to instability in lasers and increased bit-error-rate in communication links, particularly with Ge-based absorbers that have high optical return loss.
Innovation Solution
A spirally configured waveguide absorber made of Si, SiN, or polysilicon is integrated into semiconductor waveguide components, providing bending and propagation losses to reduce optical return loss without the need for additional fabrication steps or Ge material, and is coupled using a tapered coupler to enhance absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Ge-based absorbers are used to prevent optical signal leakage and backscatter, then absorption capability is improved, but optical return loss increases significantly
Solution Approach 1:
The patent changes the material parameter from Ge to Si-based materials (single-crystal silicon, polysilicon, or amorphous silicon), fundamentally altering the optical properties to reduce optical return loss while maintaining absorption capability through the spiral waveguide structure
Solution Approach 2:
The patent introduces a spiral configuration to the waveguide absorber, using curved geometry to provide bending losses that enhance absorption while reducing back-reflection and optical return loss compared to straight waveguide structures
2Ease of manufacture
If Ge material is used for absorbers, then ease of integration into fabrication processes is improved, but optical return loss and back-reflection increase
Solution Approach 1:
The patent changes the material parameter from Ge to Si-based materials that are compatible with standard CMOS fabrication processes, eliminating the need for additional fabrication steps while reducing back-reflection through the combination of Si material properties and spiral geometry
Solution Approach 2:
The Si-based spiral waveguide absorber uses the inherent optical properties of silicon and the geometric configuration to achieve absorption and reduce optical return loss without requiring additional materials or fabrication steps beyond standard CMOS processes
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 spirally configured waveguide absorber significantly reduces back reflection and improves signal integrity by offering higher attenuation compared to conventional Ge-based absorbers, with modeling results showing improved performance in reducing optical return loss and footprint.
Implementation Method 1
the spiral waveguide absorbers described herein provide bending loss and propagation loss of the optical signal to reduce optical return loss
Implementation Method 2
the spiral waveguide absorbers described herein provide bending loss and propagation loss of the optical signal to reduce optical return loss
Implementation Method 3
As to the propagation loss, the spiral waveguide absorbers described herein provide a scattering loss induced by sidewall roughness
Implementation Method 4
a tapered coupler coupling the rectangular or circular concentrically spiraled waveguide absorber to the semiconductor waveguide component
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to Waveguide absorbers and methods of manufacture are provided. The waveguide structure includes a photonics component and a spirally configured waveguide absorber coupled to a node of the photonics component which reduces optical return loss.